REVIEW | doi:10.20944/preprints202309.1590.v1
Subject: Engineering, Civil Engineering Keywords: Keywords: Digital Image Correlation; Surface displacements; Structural monitoring; Full-scale test design
Online: 25 September 2023 (12:37:28 CEST)
Digital Image Correlation (DIC) is an optical technique used to measure surface displacements and strains in materials and structures. This technique has demonstrated significant utility in structural examination and monitoring. This manuscript offers a comprehensive review of contemporary research and applications that have leveraged the DIC technique in laboratory-based structural tests. The reviewed works encompass a broad spectrum of structural components, such as concrete beams, columns, pillars, masonry walls, infills, composite materials, structural joints, steel beams, slabs, and other structural elements. These investigations have underscored the efficacy of DIC as a metrological instrument for precise quantification of surface deformation and strain in these structural components. Moreover, the constraints of the DIC technique have been highlighted, especially in scenarios involving extensive or complex test configurations. Notwithstanding these constraints, the DIC methodology has validated its effectiveness as a strain measurement instrument, offering numerous benefits such as non-invasive operation, full-field measurement capability, high precision, real-time surveillance, and compatibility with integration into other measurement instruments and methodologies.
ARTICLE | doi:10.20944/preprints202309.1674.v1
Subject: Engineering, Civil Engineering Keywords: Soil Stabilization; Precipitated Calcium Carbonate (PCC); Energy Dispersive X-ray Spectrometer (EDX); Collapsible Soil
Online: 25 September 2023 (10:27:21 CEST)
This study aims to investigate utilizing Precipitated Calcium Carbonate (PCC), a by-product of sugar beet, as a soil stabilizer for addressing settlement issues beneath pavements. Various tests were conducted to assess the engineering properties of PCC-stabilized subgrades using PCC obtained from Amalgamated Sugar Cooperation in Twin Falls, Idaho. Local loess samples, like those found beneath pavements, were collected for testing purposes. Initial tests involved evaluating the unconfined compressive strength of compacted loess samples, followed by tests on samples mixed with different weight percentages of PCC. The results revealed a significant average increase of 10% to 28% in the strength of loess samples stabilized with 5% PCC compared to the strength of the native soil. The chemical composition and microstructure of PCC were further analyzed through X-ray Diffraction (XRD), Energy Dispersive X-ray Spectrometer (EDX), and Scanning Electron Microscopy (SEM) Tests conducted at the Idaho National Laboratory (INL). XRD analysis indicates the presence of calcium carbonate and silica. EDX analysis unveiled a carbon content of 9% by weight in PCC, which could contribute to the carbon footprint when it breaks down. Additionally, SEM images displayed an irregular microstructure and particle shape of PCC. Furthermore, the inclusion of PCC improved the resistance of loess to saturation collapse.
ARTICLE | doi:10.20944/preprints202309.1650.v1
Subject: Engineering, Civil Engineering Keywords: Tension cable-supported power transmission structure; Wind-induced vibration; Nonlinear finite element; Wind-induced fatigue damage
Online: 25 September 2023 (09:32:35 CEST)
The tension cable-supported power transmission structure (TC-PTS) is a new type of power transmission structure suitable for mountainous terrain, which is sensitive to wind load. In this regard, a nonlinear finite element analysis model of wind-induced vibration is proposed for the TC-PTS, and the wind-induced vibration response of the structure is analyzed. Firstly, the tangent stiffness matrix of the three-dimensional truss element for the supporting suspension cable and transmission line, considering the geometric nonlinearity of structures, is derived through the relationship between the element elastic energy and its displacement. Subsequently, the element mass matrix and damping matrix of the supporting suspension cable and transmission line, as well as the element nodal load vector obtained from wind load equivalence are given. Then, based on the nonlinear finite element theory, the nonlinear dynamic equation of wind-induced vibration is established for the TC-PTS and solved by Newmark-β method combined with Newton-Raphson iterative method. Furthermore, the rain-flow counting method and Miner's linear fatigue cumulative damage theory were used for wind induced fatigue damage assessment. Finally, a two-span TC-PTS is selected as an example, and the wind-induced nonlinear vibration and fatigue damage assessment are analyzed through the proposed model. The results show that the proposed model has high computational accuracy and efficiency. With the increase of wind speed and wind direction angle, the maximum lateral displacement and tension of the supporting suspension cable and transmission line increase, and their degree of increase shows a nonlinear trend. In terms of the wind-induced fatigue analysis results of TC-PTS, the fatigue damage at the end of the supporting-conductor suspension cable is greater than the fatigue damage at its midpoint. Compared to the fatigue damage at the midpoint of the conductor, the fatigue damage at the end of the conductor is less affected by wind direction angle, and both are more significantly affected by the wind speed.
ARTICLE | doi:10.20944/preprints202309.1622.v1
Subject: Engineering, Civil Engineering Keywords: collaborative philosophy; contractual management; NEC4 ECC; public infrastructure procurement
Online: 25 September 2023 (05:21:03 CEST)
The modern civil engineering and construction sector requires collaborative work environments, learning and trust among all parties involved, qualities that are absent in the Peruvian reality. This research, which is based on an extensive literature review, investigates this challenge. The study reflects upon (i) the current situation of public works procurement in Peru and (ii) the New Engineering Contract (NEC). Comparisons are presented between the characteristics, documentation and roles of these two systems, with the purpose of understanding and representing the advantages, disadvantages and possibilities of integrating tools of NEC4 Engineering and Construction Contract to the Peruvian State Contracting Law (Ley de Contrataciones del Estado: LCE). The research is validated through the case study of a high impact road infrastructure project in the city of Arequipa, Peru; which revealed five main negative impacts on good contractual management and, also, facilitated an initial assessment of challenges and improvement opportunities in public infrastructure procurement. Thus, contribution is made to closing the knowledge gap regarding the implementation of NEC4 ECC in public sector works.
ARTICLE | doi:10.20944/preprints202309.1480.v1
Subject: Engineering, Civil Engineering Keywords: Lean Construction; Last Planner system; Information flow; Project management; priority index
Online: 25 September 2023 (03:57:16 CEST)
This research describes a detailed analysis in the enactment of a Lean Tool, the Last Planner System during pandemic period which helps in optimizing the resources for better coordination among all stakeholders in pandemic period. LPS as it is known, focusses on minimizing the factors such as uncertainties, barriers and variability to make construction projects more flexible for better project management. These include variations and deviations, supervision, delays in approvals, change resistance, subcontractor dedication which are all related to various stakeholders in the project. Following that, a Design Science Research technique is used to evaluate the effect of applying LPS in buildings. An action strategy is being used to attain this goal, and four case studies were being documented which were concerned in the implementation of LPS in the building of the Boy's Hostel, Research Scholar Quarters, Faculty Housing, and Girls' Hostel at Chennai, Tamilnadu, India. Data was gathered by observation of site activities, interviews, documentation analysis, and a questionnaire survey and grouped into various factors. While adopting the LPS tool in the research the factors affecting the implementation were found in the covid-19 pandemic period. Further these factors were anlayzed, measured, ranked and validated for adopting in projects.
ARTICLE | doi:10.20944/preprints202309.1495.v1
Subject: Engineering, Civil Engineering Keywords: order statistics; residual Tsallis entropy; Shannon entropy; residual lifetime; (n-i+1)-out-of-n system
Online: 22 September 2023 (11:09:46 CEST)
In this paper, we concentrate on the study of the properties of residual Tsallis entropy for order statistics. Order statistics have an important role in reliability structural engineering for example for modelling lifetimes of series and parallel systems. The residual Tsallis entropy of ith order statistic from a continuous distribution function and its deviation from the residual Tsallis entropy of ith order statistics from a uniform distribution is investigated. In a mathematical framework, a method to express the residual Tsallis entropy of the ith order statistic from a continuous distribution in terms of the residual Tsallis entropy of the ith order statistic from a uniform distribution is provided. This approach may provide insight into the behavior and properties of the residual Tsallis entropy for order statistics. Further, we study the monotonicity properties of the residual Tsallis entropy of order statistics under dierent conditions. By studying these properties, deeper understanding of the relationship between the position of order statistics and the resulting residual Tsallis entropy is gained.
ARTICLE | doi:10.20944/preprints202309.1523.v1
Subject: Engineering, Civil Engineering Keywords: mountain orchard transporter; vibration test; trailer; transmission box; modal
Online: 22 September 2023 (09:09:00 CEST)
In order to reduce the vibration of the transporter and improve the stability of the transporter, the vibration characteristics and key structure optimization research of the mountain orchard transporter are carried out. In this paper, the vibration of electric monorail transporters under different working conditions is tested, and the causes of vibration generated by monorail transporter during operation are explored. The three-dimensional model of the trailer and transmission box is established using Solidworks, and the modal vibration modes of the structure are analyzed theoretically. The modal test system is used for modal test analysis of trailers and transmission boxes. By comparing the results of finite element and experimental modal analysis, the second-order frequency of the trailer is close to the motor's rotating excitation frequency of 50 Hz at rated speed, which is easy to generate resonance. By optimizing the structure of the trailer, the second and third natural frequencies are increased to 54.79 Hz and 58.35 Hz respectively, which avoid the resonance of the trailer during operation and effectively reduce the vibration generated during the transportation of the trailer. Through vibration testing of the optimized electric monorail transporter, the results of vibration testing before and after structural optimization are compared and analyzed, and it is found that the vibration amplitudes of the transporter in X, Y and Z directions are reduced by 0.308m/s², 0.351m/s² and 0.334m/s² respectively, the running stability of the conveyer is improved.
ARTICLE | doi:10.20944/preprints202309.1447.v1
Subject: Engineering, Civil Engineering Keywords: fly ash; precast concrete; compressive strength; steam curing; high alite cement; 3D FEM analysis; drying shrinkage; cracking resistance
Online: 21 September 2023 (08:47:55 CEST)
Fly ash cement has rarely been used in Japan, mainly because its strength development is slower than ordinary Portland cement. In this research, the effect of the new fly ash cement with both high alite (C3S) cement and fly ash modified by electrostatic belt separation method on cracking resistance of precast concrete prepared by steam curing was studied. The mechanical and shrinkage properties of the proposed fly ash concrete were compared with those of concrete made using OPC cement without fly ash. In order to study the cracking tendency of precast concrete with the proposed fly ash cement, thermal stress analysis was conducted taking into consideration of the experimental data of concrete properties with the different concrete mix proportions. A standard precast concrete box culvert model was used in this 3D FEM analysis and the distribution of temperature and relative humidity in cross section and induced restraint stress during and after steam curing were discussed. Steam-cured concrete with fly ash and high alite cement developed higher compressive strength on the first day of age than concrete with OPC. The proposed fly ash concrete developed high cracking resistance in the early days. On the other hand, the results showed that the drying shrinkage at later ages was the main cause of cracking.
ARTICLE | doi:10.20944/preprints202309.1439.v1
Subject: Engineering, Civil Engineering Keywords: continuous assessment; protocol; sewer; structural defecets
Online: 21 September 2023 (08:28:09 CEST)
In order to better plan new or update sewer pipe condition assessment protocols, this paper presents systematic comparisons of four most widely-used sewer condition assessment protocols, including the fourth edition of Sewer Rehabilitation Manual (SRM-4) in UK, Pipeline Assessment and Certification Program (PACP) in America, Sewer Physical Condition Grading Protocols (SPCCM) in Canada, and Technical Specification for Inspection and Evaluation of Urban Sewer (TSIEUR) in China. In qualitative comparison, the defects, deduct values and assessment methods of the four protocols were analyzed; in quantitative comparison, protocols were used to evaluate the same 182 sewer pipe segments based on field data and the assessment results were compared. It was found that SRM-4 are the most optimistic with 59% pipes being Grade 1 and Grade 2, while SPCCM gives the most pessimistic results with 62% pipes being Grade 3 and Grade 4. Assessment results by PACP and TSIEUR are in the middle. The main reasons for the different evaluation results were due to the different weight of defect and evaluation methods used.
ARTICLE | doi:10.20944/preprints202309.1367.v1
Subject: Engineering, Civil Engineering Keywords: steel members; crack stop hole (CSH); CHS/CFRP hybrid composite; low cycle fatigue; average tensile strength
Online: 20 September 2023 (10:49:33 CEST)
The stress concentrations have become common phenomenon of steel elements when arresting a fracture by implementing the crack stop hole (CSH) technique. Embedding the CSH with Carbon Fibre Reinforced Polymer (CFRP) enhance the fatigue life by delaying the fractures while achieving a stiffness recovery due to superior mechanical characteristics of CFRP material. Hence, low cyclic fatigue (LCF) behaviour of 162 strengthened and non-strengthened CSH specimens were examined in this context. These specimens were subjected to a range of 0 to10,000 fatigue load cycles with the frequency of 5 Hz. At the end of fatigue exposure, the average tensile strength was measured in each case. The average strength reductions in the range between 13% to 25% was noted in steel elements with CSH subjected to fatigue exposure. The application of a CFRP patch on CSH had effectively recovered the strength losses while enhancing the strength in the range between 32% to 45% with respect to the non-strengthened non specimens. The developed numerical model based on cyclic J-integral technique agrees with test results and is capable of predicting characteristics for this novel hybrid technique.
ARTICLE | doi:10.20944/preprints202309.1310.v1
Subject: Engineering, Civil Engineering Keywords: cold-formed steel; blast load; stud wall; strain energy; artificial neural network (ANN); energy absorption
Online: 20 September 2023 (04:44:01 CEST)
This paper focused on the finite element analysis of structural system in extreme loading condition. Two different stud shape and thicknesses were analyzed under blast. The stud thickness such as 1.19 mm and 1.5 mm were modelled and analyzed using ABAQUS 6.14. FEM is a tool which predicts the engineering physics of the real structure. To validate the finite element modelling performed by authors, a reference work published by earlier researchers on cold-formed steel stud wall is considered and examined in the present study. The novelty of this study was web corrugation and influence of flange width on stud. The models mimic like an air bag in a car to delay the pressure timing inside the stud wall. The mass of explosive used as 1.56 kg at a standard scaled distance. Time versus displacement was captured out at four locations in the stud wall. One of the objectives is to develop mathematical model to validate the deformation of stud under blast loading. Two mathematical models were validated using Artificial Neural Network (ANN). The results captured in ANN model was error histogram, regression plot, best performance fit and training data. The models were capable of resisting the moderate blast load. The response surface methodology (RSM) was employed to evaluate model performance Regression equations are useful for predicting future trends and outcomes, which is crucial for planning and decision-making. The primary goal of this work is to evaluate cold-formed steel stud walls with varying stud sizes under blast loading using finite element analysis and validated by ANN and RSM.
ARTICLE | doi:10.20944/preprints202309.1306.v1
Subject: Engineering, Civil Engineering Keywords: maximum index void ratio; minimum index void ratio; sand-silt mixtures; void ratio predictive models; filling coefficient; embedment coefficient
Online: 20 September 2023 (04:36:06 CEST)
In estimating the maximum and minimum index void ratios for mixtures of sand and silt, the values of several empirical constants must be determined based on the type of sand and silt involved. These empirical constants are the filling coefficient, a, and embedment coefficient, b, both of which can be determined either through lab testing or correlations. These constants are then used in equations to predict the maximum and minimum index void ratios of the sand-silt mixtures. The study reported here developed simple correlations for estimating the filling and embedment coefficients using readily obtained laboratory data. These models were found to be excellent in developing filling and embedment coefficients that accurately (R2 values typically of 0.94 or greater.) predicted values of the index void ratios for sand and silt mixtures.
ARTICLE | doi:10.20944/preprints202309.1218.v1
Subject: Engineering, Civil Engineering Keywords: quay wall; piles; port; finite element analysis; case study
Online: 19 September 2023 (15:33:05 CEST)
In recent years, with the increase in maritime trade, the necessity of increasing the capacities of the ports has emerged. However, while it is planned to increase the capacities of the ports, it is important that the port continues to operate at the same time. In this respect, the old port structures should not be damaged during the capacity increase. In this study, the strengthening of a port in Guinea is discussed as a case study. In the study, the existing quay wall was evaluated, and geotechnical and structural alternatives of the new structure to be built for capacity increase were evaluated. A combined system was designed as a pile foundation and a reinforced foundation with plastic piles so as not to damage the existing quay wall. The pile capacities obtained as a result of the analyses were verified by loading tests.
ARTICLE | doi:10.20944/preprints202309.1244.v1
Subject: Engineering, Civil Engineering Keywords: frequency spectrum; theoretical analysis; moving vehicle; vehicle velocity; turbulent crosswinds
Online: 19 September 2023 (08:17:19 CEST)
Wind loads have become one of the key influence factors for the running safety of vehicles and comfort of passengers. Investigation on the wind speed spectrum characteristics of a moving vehicle under turbulent crosswinds is of great influence. Expressions of the wind speed spectrum of a moving vehicle was obtained from the von Kármán spectrum based on Taylor’s frozen flow hypothesis. The influence factors, including the ratio of the vehicle speed to the wind speed and the wind yaw angle from 15° to 175°, were analyzed. The maximum value of the wind speed spectrum and the corresponding frequency were studied as well. The results show that the maximum values of the wind speed spectrum of the moving vehicle were larger than those of the static vehicle. The maximum value of the wind speed spectrum corresponding to the moving vehicle first increased and then decreased as the wind yaw angle increased. Some of the frequencies corresponding to the longitudinal wind speed spectrum values of the moving vehicles were smaller than those of the static vehicle. For moving vehicles, the frequency values corresponding to the maximum values of the longitudinal wind speed spectrum first increased and then decreased as the ratio of the vehicle speed to the wind speed and the wind yaw angle increased.
ARTICLE | doi:10.20944/preprints202309.1189.v1
Subject: Engineering, Civil Engineering Keywords: Art collections; displayer’s frequency; seismic vulnerability; seismic safety assessment; Museums content’s conservation; experimental dynamic monitoring
Online: 19 September 2023 (08:14:18 CEST)
Artworks play a fundamental role in the cultural and economic asset of communities, enforcing their identity and helping the social integration. Despite their importance, they are not always adequately protected against degradation, which can be induced by the aging, atmospheric and human-induced occurrence, and catastrophic events. Earthquakes certainly represent one of the main risks for art goods; however, traffic, construction works, and shipment can also represent a threat for art goods. Therefore, the assessment of the vulnerability of art collection to dynamic excitations plays a crucial role in their conservation, and it has been collecting an increasing attention by researchers, academics, and Museums’ managers. This work focuses on the vulnerability of the art collections exhibited at the Museum “Gaio Cilnio Mecenate” in Arezzo. Namely, it aims at assessing the effective dynamic loading experienced by the artworks, which is a function of the dynamic propagation plaid by the foundation soil, by the building and by the displayers used for exhibition. In this study the dynamic properties of some of the displayers used for exhibiting the art collections are investigated by performing an experimental survey. The analysis of the experimental data lead to assess the proper frequencies of the displayers, which have been compared to the ones of the building and the foundation soil of the Museum.
ARTICLE | doi:10.20944/preprints202309.1266.v1
Subject: Engineering, Civil Engineering Keywords: shield tunneling; kirchhoff plate; space effect; ground heave; diaphragm wall deformation; field monitoring
Online: 19 September 2023 (07:36:11 CEST)
The ground surface deformation induced by shield tunnels passing through enclosure structure of existing tunnels is a particular underground construction scenario, which is encountered in Wuhan metro line 12 engineering cases in China. The classic ground deformation theory is difficult to accurately predict this ground deformation. This paper develops a semi-analytical method to predict ground heave considering space effect in this engineering condition. Based on improved ground deformation theory, a novel deformation prediction method of ground and enclosure structure is derived combined with Kirchhoff plate theory. Comparing with field deformation measurements, the maximum difference between measured and calculated deformation is 14.6%, which demonstrating that the proposed method can be used to predict the ground heave induced by shield tunnels passing through the enclosure structure of existing tunnels. The parameters of underground diaphragm wall used in Wuhan metro line 12 are further studied in detail. The results show that the ground heaves have positive correlation with embedded ratio of diaphragm wall, but negative correlation with its elastic modulus and thickness. But the thickness and embedded ratio has a limited effect on ground heaves. This study provides a technical reference for optimization setting of enclosure structure in protecting existing building.
ARTICLE | doi:10.20944/preprints202309.1178.v1
Subject: Engineering, Civil Engineering Keywords: demountable RCS joints; seismic performance; numerical simulation; parameter analysis; shear bearing capacity
Online: 19 September 2023 (03:55:30 CEST)
In this study, three new demountable joints consisting of reinforced concrete columns and steel beams were proposed and their seismic performance was investigated using cyclic loading tests. The test results demonstrated that the three demountable RCS joints had good seismic performance. Using the finite element software ABAQUS, the influence of parameters such as beam flange thickness, bolt strength, and connector steel strength on the seismic performance of each joint was analyzed, and the influence of different parameters on the seismic behavior of the joint was determined. The results also showed that the three demountable RCS joints were sensitive to changes in the thickness of the steel beam flange, while the connector steel strength and bolt type had little impact on the joint's capacity. Additionally, shear capacity calculation formulas for the joint core area provided by different codes and researchers were compared with test and finite element results. The results showed that the calculation results of the ASCE guidance method, the Nishiyama method, and the CECS 347-2013 method were higher than the test values, while the calculation results of the Para method were lower because it did not consider the contribution of the cylindrical steel plate to the shear capacity of the joint core area.
ARTICLE | doi:10.20944/preprints202309.1170.v1
Subject: Engineering, Civil Engineering Keywords: Wastewater; Circular Economy; Life Cycle Sustainability Assessment; Decision Making
Online: 18 September 2023 (10:25:55 CEST)
The wastewater circular economy (WW-CE) promises a solution to improve water and sanitation management worldwide. However, the transition from conventional to circular wastewater treatment plants (WWTPs) requires facilitation to aid in decision makers understanding of integral sustainability impacts of alternative WW-CE configurations. This research implemented Life Cycle Sustainability Assessment (LCSA), combining Life Cycle Assessment, Social Life Cycle Assessment and Life Cycle Costing with a Multi-criteria Decision Making (MCDM) model to quantify environmental, socio-cultural, and economic impacts of conventional WWTPs with the WW-CE. Two real WWTPs in Chile have embraced the WW-CEs and adopting the title of Biofactories. These were considered as case studies, compared under three scenarios to demonstrate the sustainability trade-offs of the transition from no sanitation to conventional WWTPs and Biofactory WW-CE configurations. Results demonstrated that the transition to WW-CEs improved integral sustainability according to the LCSA model implemented in both WWPTs. This study highlights the urgent need to adopt sustainable decision-making models to not only improve sanitation coverage, but also improve sustainability performance of the sanitation industry across the globe.
ARTICLE | doi:10.20944/preprints202309.1122.v1
Subject: Engineering, Civil Engineering Keywords: Dynamic response characteristics; Damage evolution; Tunnel portal slope; Shaking table tests; Numerical simulations
Online: 18 September 2023 (05:23:18 CEST)
With more and more transportation tunnels have been and will be constructed in loess areas in Northwest China with high earthquake potential, the overall stability of portal section under earthquakes actions and the related aseismic countermeasures attracted the attentions from both the scholars and engineers, especially the tunnels in the upper slope connecting the high bridges crossing rivers or valleys. In order to study the dynamic response characteristics and damage evolution of steep loess slope with a tunnel under the earthquake actions, a large-scale shaking table tests were performed on steep loess slope with a tunnel. Wenchuan-tangyu (WT) wave and El Centro (El) wave records were applied on the model to investigate the displacement response and acceleration response of loess slope with a tunnel under the horizontal (X) and the combined action of horizontal and vertical (X-Z) seismic loads, respectively. In particular, three-dimensional non-contact optical measurement techniques were used to obtain the slope surface displacements. The results showed that the main deformation pattern of the slope was horizontal movement and settlement when the seismic wave input was in the X and X-Z directions, respectively. However, the X direction seismic wave had a greater impact on the deformation of the slope, and the tunnel portal slope was destroyed under the action of a large horizontal seismic acceleration finally. Slope failure ahead of a tunnel could be divided into four stages, i.e. elastic deformation stage, plastic deformation accumulation stage, local failure stage, and overall failure stage. The peak ground displacement of X direction (PGDX) and peak ground displacement of Z direction (PGDZ) of the slope surface increased with the increasing of the input peak ground acceleration (PGA) when the input wave was same waveform and same direction. The existence of the tunnel had a great influence on the PGA and the PGA amplification factor (PGAAF) of the soil mass surrounding it. This was because the seismic waves encounter a tunnel surface with clear differences in the physical properties of the medium during their propagation in the slope, thereby forming a strong reflection and refraction effect, and the amplitude changed significantly. Numerical simulation results were basically consistent with the experimental results.
ARTICLE | doi:10.20944/preprints202309.0981.v1
Subject: Engineering, Civil Engineering Keywords: hydrophobic coating; nanoparticles; ice adhesion force; contact angle; asphalt concrete
Online: 15 September 2023 (04:50:00 CEST)
Despite their anti-icing ability, hydrophobic coatings have the disadvantages of easy falling off and poor wear resistance, resulting in insufficient durability of ice/snow melting. To improve the surface stability and durability of superhydrophobic coatings, nanoparticle/epoxy coatings were prepared with three types of nanoparticles, two types of dispersion methods, three types of application methods and two types of introduction methods of epoxy resin. Water contact angles, ice adhesion force and icing rate of asphalt concrete coated with hydrophobic coatings were tested. The molecular structures of coatings were analyzed by Fourier transform infrared spectroscopy. The surface morphology of hydrophobic coatings was observed using Scanning electron microscopy. Results indicated that nano-ZnO, TiO2 and SiO2 particles can be modified into hydrophobicity by stearic acid. The hydrophobic coating could improve the hydrophobicity of concrete, reduce the adhesion strength of ice and asphalt concrete and delay the beginning icing time. Moreover, The dosages of stearic acid, nanoparticle and epoxy resin need to be in a certain range to ensure the best hydrophobicity and durability of coatings.
ARTICLE | doi:10.20944/preprints202309.0935.v1
Online: 14 September 2023 (09:35:31 CEST)
The purpose of the investigation was to determine the relationship between rotary kiln liner loss and steel structure ovality. As measurement apparatus, a terrestrial laser scanner was used. The interior and exterior of the rotary kiln were measured. The primary focus object was inner-lining loss and the geometric characteristics of cylindrical shells. The research uncovered significant disparities in inner lining loss between sections. A correlation was found between ovality and elimination of inner lining. Due to the hypothesis of constant inner linig loss from the middle of the rotary kiln, the investigation found that the loss of brick lining was less than the value reported from the boreholes. The study offers significant information on maintenance and repair strategies for rotary kilns, which have the potential to increase their efficiency and useful life.
ARTICLE | doi:10.20944/preprints202309.0955.v1
Subject: Engineering, Civil Engineering Keywords: construction industry; construction companies; investment and construction projects; sustainable activity; destabilizing factors; SEM-PLS; Smart PLS.
Online: 14 September 2023 (07:23:20 CEST)
Failure to meet the deadlines for the implementation of investment and construction projects is a problem in all countries of the world, and leads to unstable activity of construction companies. The article studies the most important destabilizing factors affecting the main indicator of sustainable activity of construction companies-the duration of the implementation of an investment and construction projects. To determine and assess the impact of destabilizing factors on the duration of implementation of selected investment and construction projects, a survey was conducted, in which a number of customers, consultants and contractors involved in construction projects took part. Questionnaires developed on the basis of a cluster sample were sent to respondents, 48 responses were received in response to the assessment of destabilizing factors. To analyze the received and grouped information, structural equation modeling using the Smart-PLS program was used. As a result of modeling, a number of results were obtained, the most important of which are the identification of the main reasons that lead to an average (20% - 50%) increase in the duration of projects in the construction sector. The most significant were: the lack of an appropriate procurement program for materials; inefficient scheduling by contractors and instability of construction production; poor-quality processing of incoming information and untimely deci-sion-making due to changes in projects during their implementation. Destabilizing factors con-tribute to an increase in the duration of construction sector projects, which leads to time overruns, cost overruns, and an increase in the negative impact on the overall use of resources. As a result of the study, a set of recommendations was formed, the most important of which is the use of possible compensatory measures that can allow construction companies to eliminate the risks of disrupting construction deadlines for sustainable activities. These compensatory measures include: - recommendations to customers of the construction project; - recommendations to contractors; - recommendations to the consultant. Moreover, the control of destabilizing factors that can cause delays, the improvement of contracts and the precise and clearer definition of all elements of the project can help to reduce the duration of construction, and will allow companies to maintain sustainable activities in the construction industry.
ARTICLE | doi:10.20944/preprints202309.0900.v1
Subject: Engineering, Civil Engineering Keywords: Pile foundation replacement beam construction; Polymer reinforced planting bar adhesive; interface between new and old concrete; experiment; finite element simulation analysis
Online: 14 September 2023 (04:59:22 CEST)
In view of the complexity of the pile foundation underpinning structure system and the stringent requirements of the construction process, this paper briefly describes the necessity of introducing epoxy resin reinforcing adhesive of planting rebar in the design of pile foundation underpinning beam structure to im-prove the mechanical properties of the underpinning beam new and old concrete joint surfaces and proposes a new type of pile foundation underpinning beam system construction method by “chiseling + prestressed reinforcement + epoxy resin reinforcing adhesive”. This paper uses an actual pile foundation underpinning project of an urban overpass as a prototype, designs and creates a model structure with a similarity ratio of 1/6, and performs repeated pro-gressive static loading tests to study the load carrying capacity, displacement change, and other properties of the underpinning structure, as well as analyses and distorts the overall working performance and failure mode of them. On this basis, the prototype structure's finite element analysis model was built, and the finite element analysis results were compared with the test results to get the mechanical properties and deformation characters of the actual pile foundation under-pinning structure system corresponding to the actual underpinning beam load. This paper's study can lay the theoretical and experimental foundation for the smooth development of similar projects.
ARTICLE | doi:10.20944/preprints202309.0872.v1
Subject: Engineering, Civil Engineering Keywords: concrete; simulation computing; GPU; parallel computing; CUDA FORTRAN; shared memory; asynchronous parallel
Online: 14 September 2023 (03:36:36 CEST)
With the development of engineering technology, engineering has higher requirements for the accuracy and the scale of simulation calculation. The computational efficiency of traditional se-rial program can not meet the requirements of engineering。Therefore, reducing the calcula-tion time of temperature control simulation program has important engineering significance for real-time simulation of temperature field and stress field, and then adopting more reasona-ble temperature control and crack prevention measures. GPU parallel computing is introduced into the temperature control simulation program of massive concrete to solve this problem and the optimization is carried out. Considering factors such as GPU clock rate, number of cores, parallel overhead and Parallel Region, The improved GPU parallel algorithm analysis indicator formula is proposed. It makes up for the shortcomings of traditional formula that focus only on time. According to this formula, when there are enough threads, the parallel effect is limited by the size of the parallel domain, and when the parallel domain is large enough, the efficiency is limited by the parallel overhead and the clock rate. This paper studies the optimal Kernel execu-tion configuration. Shared Memory is utilized to improve memory access efficiency by 155%. After solving the problem of bank conflicts, an accelerate rate of 437.5x was realized in the sub-routine of the matrix transpose of the solver. The asynchronous parallel of data access and logi-cal operation is realized on GPU by using CUDA Stream , which can overlap part of the data access time. On the basis of GPU parallelism, asynchronous parallelism can double the compu-ting efficiency. Compared with the serial program, the accelerate rate of inner product matrix multiplication of the GPU asynchronous parallel program is 61.42x. This study further proposed a theoretical formula of data access overlap rate to guide the selection of the number of CUDA streams to achieve the optimal computing conditions. The GPU parallel program compiled and optimized by CUDA Fortran platform can effectively improve the computational efficiency of the simulation program for concrete temperature control, and better serve for engineering computing.
ARTICLE | doi:10.20944/preprints202309.0896.v1
Online: 14 September 2023 (02:49:00 CEST)
Accurate fuel mapping plays a crucial role in fire detection and management strategies. This paper presents a method for discriminating between wildfire fuel types by exploiting together remote sensing data and Convolutional Neural Networks (CNN). Specially, a CNN-based classification approach that leverages Sentinel-2 imagery is exploited to accurately classify fuel types into seven preliminary main classes (conifers, broadleaf, shrubs, grass, bare soil, urban areas, and water bodies) with an high accuracy of 0.99$\%$. To further refine the fuel mapping results, subclasses were generated from the seven principals by using biomass and bioclimatic maps. These additional maps provide complementary information about vegetation density and climatic conditions, respectively. By incorporating this information, we align our fuel type classification with the widely used Scott/Burgan fuel classification system. This refinement step allows for a more detailed and comprehensive assessment of fuel types, enhancing the accuracy and effectiveness of fire management efforts, which can be utilized by fire management agencies, policymakers, and researchers for improved fire behavior prediction and mitigation practices. The proposed approach presents a valuable tool for enhancing fire management, contributing to more effective wildfire prevention and mitigation efforts.
ARTICLE | doi:10.20944/preprints202309.0750.v1
Subject: Engineering, Civil Engineering Keywords: integral transforms; contour integration; ballasted railway track; critical velocity; instability of moving inertial objects
Online: 13 September 2023 (02:25:59 CEST)
Ballasted railway tracks can be modelled using reduced/simplified models composed of several layers of discrete components. This paper deals with the two-layer model, which is very popular due to its computational efficiency. In order to provide some recommendations for track design, it is necessary to identify which set of parameters leads to some irregular/unexpected behavior. Such irregularity is investigated at three levels, such as: (i) critical velocity of moving constant force; (ii) instability of a single moving mass; (iii) instability of two moving masses. All results are presented in dimensionless form to cover a wide range of real parameters. Irregular cases are identified by sets of parameters leading to them and then general conclusions are drawn. Regarding the method, all results are obtained analytically or semianalytically, where “semi” refers to solving the roots of a given polynomial by predefined numerical procedures in symbolic software. No numerical integration is involved in all results presented. This means that the results are highly accurate and refer to exact values, so any kind of parametric or sensitivity analyses is readily possible.
ARTICLE | doi:10.20944/preprints202309.0724.v1
Subject: Engineering, Civil Engineering Keywords: long short-term memory network; ambient vibration measurements; earthquake response; multi-degree-of-freedom models; structural response phase and magnitude images.
Online: 12 September 2023 (17:00:19 CEST)
Deep neural networks (DNNs) have gained prominence in addressing regression problems, offering versatile architectural designs that cater to various applications. In the field of earthquake engineering, seismic response prediction is a critical area of study. Simplified models such as single-degree-of-freedom (SDOF) and multi-degree-of-freedom (MDOF) systems have traditionally provided valuable insights into structural behavior, known for their computational efficiency facilitating faster simulations. However, these models have notable limitations in capturing the nuanced nonlinear behavior of structures and the spatial variability of ground motions. This study focuses on leveraging ambient vibration (AV) measurements of buildings, combined with earthquake (EQ) time-history data, to create a predictive model using a neural network (NN) in image format. The primary objective is to predict a specific building's earthquake response accurately. The training dataset consists of 1,197 MDOF 2D shear models, generating a total of 32,319 training samples. To evaluate the performance of the proposed model, termed MLPER (Machine Learning based Prediction of building structures' Earthquake Response), several metrics are employed. These include mean absolute percentage error (MAPE) and mean deviation angle (MDA) for comparisons in the time domain. Additionally, we assess magnitude-squared coherence values and phase differences (Δφ) for comparisons in the frequency domain. This study underscores the potential of MLPER as a reliable tool for predicting building earthquake response, addressing the limitations of simplified models. By integrating AV measurements and EQ time-history data into a neural network framework, MLPER offers a promising avenue for enhancing our understanding of structural behavior during seismic events, ultimately contributing to improved earthquake resilience in building design and engineering.
ARTICLE | doi:10.20944/preprints202309.0737.v1
Subject: Engineering, Civil Engineering Keywords: construction enterprise; digital transformation maturity; AHP-Decision Testing and Evaluation Laboratory (AHP-DEMATEL)
Online: 12 September 2023 (07:21:55 CEST)
With the continuous development of digital transformation and upgrading of Chinese construction enterprises, it is becoming increasingly important to measure their digital level, find the problems in the enterprise transformation process, and identify the key factors of enterprise digital capacity enhancement. This paper constructs a construction enterprise digital transformation maturity evaluation model from six first-level indicators and 20 second-level indicators, including digital strategy, digital business application, digital technology capability, data capability, digital organization capability, and change management. Digital maturity is divided into five levels: business management, process operation, intelligent construction, intelligent scene application, and industrial ecological collaboration. A detailed process of digital maturity evaluation based on the method of Analytic Hierarchy Process (AHP)-Decision Testing and Evaluation Laboratory (DEMATEL) is then developed. A questionnaire survey of 25 experts is used to weight the various parameters in the model, which is then demonstrated with an example construction enterprise. The model comprehensively reflects digital levels under the background of the digital economy. Its application will help understand the advantages and disadvantages enterprises face in their digital transformation to enable targeted measures to improve their digital transformation capabilities and efficiency, enhance their core competitiveness of enterprises, and promote the development of digital transformation in the construction industry.
REVIEW | doi:10.20944/preprints202309.0627.v1
Subject: Engineering, Civil Engineering Keywords: Bio-cementation; Sustainable Construction Materials; Building Construction; Soil Stabilization; Sporosarcina Pasteurii
Online: 11 September 2023 (09:54:56 CEST)
With the development of bioinspired green solutions for sustainable construction over the past two decades, bio-cementation, which exploits the naturally occurring phenomenon of calcium carbonate precipitation in different environments, has drawn a lot of attention in both building construction and soil stabilization. Various types of microorganisms, along with specific enzymes derived from these microorganisms, have been utilized to harness the benefits of bio-cementation. Different application methods for incorporating this mechanism into the production process of the construction material, as well as a variety of experimental techniques for characterizing the outcomes of bio-cementation, have been developed and tested. Despite the success of bio-cementation as a sustainable method to construction has been demonstrated in a significant body of literature at the laboratory scale, the expansion of this strategy to construction sites and field application remains a pending subject. The issue may be attributed to two primary challenges. Firstly, the complexity of the bio-cementation phenomenon is influenced by a variety of factors. Secondly, the extensive body of literature examines various types of microorganisms under different conditions, leading to a wide range of outcomes. Hence, this study aims to examine the recent advancements in utilizing the most commonly employed microorganism, Sporosarcina Pasteurii, to emphasize the significance of influential factors identified in the literature, discuss the findings that have been brought to light, and outline future research directions toward scaling up the process.
ARTICLE | doi:10.20944/preprints202309.0600.v1
Subject: Engineering, Civil Engineering Keywords: Symmetrical cable-stayed bridge structure; Wind resistance time-varying performance; Reliability index; Safety factor; Symmetrical reliability theory
Online: 11 September 2023 (07:12:48 CEST)
Long span cable-stayed bridge is the main bridge type with a span of more than 400 meters. It is generally designed as a double tower long-span structure with good spanning capacity and economic performance. Wind resistance safety performance is the main index to control the long-span cable-stayed bridge structure. During the operation of long-span cable-stayed bridge structure, because the service life of the cable is far less than the design life of the structure, the wind resistance performance of the structure will inevitably deteriorate significantly, which will seriously affect the structural service performance of symmetric cable-stayed bridge. Based on symmetric reliability theory, this paper takes flutter and static wind stability of long-span cable-stayed bridge structure as the main design control index, uses positive reliability theory to calculate the reliability index of symmetric cable-stayed bridge structure, uses inverse reliability theory to calculate the safety factor of symmetric cable-stayed bridge structure, and evaluates the wind resistant time-varying performance of long-span cable-stayed bridge structure by comprehensively considering the reliability index and safety factor. Taking a practical project of a long-span cable-stayed bridge as a specific case, the wind resistant time-varying reliability of the bridge during its operation for more than 30 years is analyzed, and the parameter sensitivity is analyzed. The results show that the wind resistance performance of the cable-stayed bridge structure is obviously affected by the cable, and the degradation of the cable performance will have an important impact on the wind resistance time-varying performance of the structure, especially the critical wind speed of the structure has obvious time-varying characteristics. The safety factor and reliability index can objectively evaluate the wind resistance time-varying performance of the long-span cable-stayed bridge structure.
ARTICLE | doi:10.20944/preprints202309.0568.v1
Subject: Engineering, Civil Engineering Keywords: hydraulic conductivity; well logging; formation factor; fluid conductivity; resistivity
Online: 8 September 2023 (04:10:08 CEST)
The development of cost-effective methods for estimating hydraulic conductivity profiles has been an ongoing effort in the field of engineering practice, which can be used to increase availability to clarify the hydrogeological complexity of fractured rock aquifers for the aid of solving groundwater-related problems. A methodology is presented, which combines electrical well logs, fluid conductivity logs, double packer hydraulic tests, Archie’s law, and the Kozeny-Carman-Bear equation to investigate relations between formation factor and hydraulic conductivity. This method was applied to develop hydraulic conductivity profiles based on the data collected from 88 boreholes in Taiwan's mountainous areas. The investigation results include: (1) Well logging signals were suggested to be categorized by rock types to establish effective relationships with hydraulic conductivity. (2) Removing the mud-bearing section data with two proposed data clustering techniques could effectively enhance the correlation between the formation factor and hydraulic conductivity. (3) The predictive models for estimating hydraulic conductivity have been developed for sandstone, schist, and slate. (4) The prevalence of clay content in most of Taiwan's mountainous rock formations has been found, which implies that careful consideration of clay-related issues in complex geologic formations is essential while applying Archie's law theory.
ARTICLE | doi:10.20944/preprints202309.0477.v1
Subject: Engineering, Civil Engineering Keywords: subgrade engineering; risk assessment; game theory; approximate comprehensive evaluation method
Online: 7 September 2023 (07:03:11 CEST)
The construction safety risks (such as landslides or slumps) of the high-fill subgrade are characterized by uncertainty and variability. In order to ensure the construction safety of the high-fill subgrade of the expressway, a comprehensive risk assessment model of high-fill subgrade construction according to the combination weighting method based on game theory was established. Firstly, settlement rate, lateral differential settlement, horizontal displacement at the foot of the slope, deep horizontal displacement, and excess pore pressure were selected as evaluation indicators, and an evaluation index system of high-fill subgrade was constructed. Secondly, the subjective and objective weights were obtained via the analytic hierarchy process and entropy method. Furthermore, the optimized weights were obtained by introducing game theory, and the construction risk of the high-fill subgrade was evaluated and analyzed using the fuzzy comprehensive evaluation method. Finally, based on the high-fill section of the Zhijiang-Tongren Expressway in Hunan Province (China), the evaluation model was validated through field measurement data. The results show that the safety scores obtained using the three methods of analytic hierarchy process, entropy method, and combination weighting method based on game theory are similar. The combination weighting evaluation model can correct the evaluation result error caused by a single weight and avoid information delay caused by the manual processing and analysis of monitoring data. The high-fill subgrade safety evaluation grade based on the combination weighting method and game theory is consistent with the engineering situation, and its fault tolerance range is within 20%. The evaluation model proposed in this study can scientifically and effectively evaluate the safety risks of high-fill subgrade construction, significantly improving the safety and reliability during the construction process.
ARTICLE | doi:10.20944/preprints202309.0446.v1
Subject: Engineering, Civil Engineering Keywords: flood; sediment deposition; bridge deck; impact pressure; fluctuation; model experiment
Online: 7 September 2023 (04:54:34 CEST)
This paper investigates the impact of sediment deposition and inflow conditions on horizontal impact pressure and frequency analysis of bridge deck vibrations during flooding. Flooding-induced pressure and vibrations contribute to bridge collapse, and sediment deposition influences water flow and impact pressure. The study explores the relationship between sediment deposition height and impact pressure, revealing a significant increase as sediment approaches 50% of bridge deck clearance. Sediment amplifies impact pressure response to flow velocity changes. The dimensionless sediment deposition height has a greater influence on impact pressure compared to the inflow Froude number. Two distinct frequencies, dominant and secondary, are identified for impact pressure and water level fluctuations. Dominant frequencies positively correlate with sediment deposition height and Froude number, indicating an increasing trend. Secondary frequencies remain stable (0.31-0.58 Hz). These findings enhance understanding of flow dynamics and bridge-flow interaction in sediment-deposited channels, providing theoretical support for evaluating and managing disasters related to bridges in such environments. Overall, this research contributes to the field of bridge engineering and supports improved design and maintenance practices for bridges exposed to sediment-deposited channels.
ARTICLE | doi:10.20944/preprints202309.0435.v1
Subject: Engineering, Civil Engineering Keywords: RC beam specimen; local rebar corrosion; degree of corrosion; corrosion rate; corrosion area; monotonic loading; cyclic loading; structural performance
Online: 7 September 2023 (04:49:08 CEST)
This paper aims to determine the effect of local corrosion at three different corrosion areas, the 1. entire area, 2. constant moment area, and 3. constant shear area, on the flexural performance of RC beams. To analyze this, an experimental study was carried out to prepare two series of RC beams (200×300×2800mm) created with three different degree of corrosion inducing local rebar corrosion. Furthermore, two-series of experimental tests were conducted under different loading types by monotonic and cyclic loading. It was observed that strength capacity reduction grows in the order of the corroded RC specimens induced: the 1. entire area > 2. constant moment area > 3. constant shear area, as the average corrosion rate increases. Our test results further show that the yield and ultimate strength was kept nearly equivalent to the uncorroded RC specimen by the average corrosion rate of 10% and 15%, respectively. Over these corrosion rates, the yield strength and ultimate strength dropped significantly. Compared to test results under a monotonic loading condition, the structural capacity under a cyclic loading condition decreased with a more pronounced tendency for each corrosion case as the corrosion rate increased. A longitudinal crack was developed throughout and adjacent to the corrosion areas, as the corrosion rate increased. Thus, we can infer that strength reduction may be strongly influenced by this longitudinal crack.
ARTICLE | doi:10.20944/preprints202309.0410.v1
Subject: Engineering, Civil Engineering Keywords: Earthquake-resistant structures; Capacity design; Ductile truss beam-to-column joint; Experimental tests; Nonlinear modelling.
Online: 7 September 2023 (03:31:01 CEST)
This paper presents the experimental and numerical study on a ductile beam-column connection between a composite reinforced concrete truss (CRCT) beam and Concrete Filled Tube (CFT) column subjected to bending and shear loads. Two experimental models with different beam-column joint testing schemes, extracted from the same prototype three-dimensional structure designed according to the rules of the capacity design provided by seismic code, were subjected to quasi-static cyclic tests by applying gravitational loads and the horizontal seismic force. The main objective of this paper is to verify the experimental ductile behavior of both specimens and to simulate the experimental global and local response by nonlinear static analysis considering different modelling approaches. The comparison between the experimental and numerical results highlights, for both models considered, the ductile and dissipative capacity of the connection system, designed following the criterion of the hierarchy of resistances proposed by the current Italian code. Different experimental setup showed similar results demonstrating the repeatability of the test and its reproducibility through the nonlinear numerical analysis.
ARTICLE | doi:10.20944/preprints202309.0448.v1
Subject: Engineering, Civil Engineering Keywords: 2D Netzgitterträger; NetzGT reinforcement; Non-metallic reinforcement; Carbon textile reinforcement
Online: 7 September 2023 (02:52:26 CEST)
The increasing popularity of carbon-reinforced concrete (CRC) is attributed to its exceptional tensile properties, low density, no corrosion phenomenon, and remarkable flexibility, allowing it to be easily shaped into various forms. This research investigates the feasibility of using a special 2D Netzgitterträger (NetzGT) reinforcement system, featuring a net-shaped fabricated textile made of multiple diagonally offset rovings with overlapping edge strands, as a viable alternative to traditional steel reinforcement in concrete beams. This reinforcement is manufactured from carbon rovings with three different diagonal angles of 50⁰, 60⁰, and 70⁰ respectively. Laboratory experiments were conducted to assess the mechanical behavior of beams reinforced with the 2D NetzGT reinforcement. Bending and shear tests were performed on beams with varying numbers of overlapped edge roving and roving angles to evaluate the tensile capacity and failure characteristics of beams. The increase in the number of overlapped edge rovings led to a noticeable increase in the maximum tensile force. Tensile tests on strands were also performed with the increasing number of overlapped rovings to analyze their tensile strength. Additionally, single yarn pull-out tests were also conducted to examine the influence of the roving angle on the bond strength between the carbon textile roving and the concrete matrix
ARTICLE | doi:10.20944/preprints202309.0359.v1
Subject: Engineering, Civil Engineering Keywords: deeply buried tunnels; deep soft rocks; elasto-visco-plastic creep constitutive model; closed-form solutions; long-term stability; structural integrity; long-term monitoring
Online: 6 September 2023 (03:40:19 CEST)
The time-dependent behavior and long-term stability of deep-buried tunnels in soft rocks have received lots of considerations in tunnel engineering and allied sciences. To better explore and deepen the engineering application of rock creep, extensive research studies are still needed, although fruitful outcomes have already obtained in many related investigations. In this article, the Weilai Tunnel in China’s Guangxi province is studied taking its host rocks as the main research object. In fact, aiming at forecasting the time-varying deformation of this tunnel, a novel elasto-visco-plastic creep constitutive model with two variants is proposed, by exploiting the typical complex load-unload process of rock excavation. The model is well validated and good agreements are found with the relevant experimental data. Moreover, the time-dependent de-formation rules are properly established for the surrounding rocks, by designing two new closed-form solutions based on the proposed creep model and the Hoek-Brown criterion. The convergence deformations calculated from the closed-form solutions conform well to the on-site monitoring data. In only 27 days after excavation, the creep deformation of the Weilai tunnel overtakes 400 mm, which is enormous. To guarantee the long-term stability of this tunnel, a ro-bust support scheme and its long-term monitoring with appropriate remote sensors are strongly suggested.
ARTICLE | doi:10.20944/preprints202309.0338.v1
Subject: Engineering, Civil Engineering Keywords: climate change; land use change; QSWAT; runoff components; Upper Chi Basin
Online: 5 September 2023 (14:50:23 CEST)
Climate and land use changes are major factors affecting runoff in regional basins. Understanding variation by considering interactions among hydrological components is an important process for water resource management. This study aimed to assess the variation of future runoff in the Upper Chi Basin, Northeastern Thailand. QSWAT hydrological model was integrated to 3 CMIP6 GCMs including ACCESS-CM2, MIROC6, and MPI-ESM1-2-LR under SSP245 and SSP585 scenarios during 2023 – 2100. Land Change Modeler (LCM) was also used for future land use simulation. The results revealed that future average of long-term precipitation and temperature tended to increase while forest land tended to decrease and be replaced by sugarcane plantations. The accuracy assessment of baseline year runoff calculation by QSWAT during 1997 – 2022 showed acceptable result as can be seen from R2, NSE, RSR, and PBIAS indices. This result could lead to temporal and spatial simulation of future runoff. Likewise, runoff of 2 SSPs scenarios tended to increase consecutively, especially in SSP585 scenario. In addition, in case of long-term spatial changes in the subbasins scale, over 90% of the area, from upstream to outlet point, tended to get higher due to 2 major factors including future increased precipitation and changes in cultivation, which would be influential to groundwater and interflow components respectively. Methodology and result of this study can be useful to stakeholders in understanding changes in hydrological system so that they can apply it to develop a strategy for water resource management and handling factors affecting different dimensions properly and sustainably.
ARTICLE | doi:10.20944/preprints202309.0106.v1
Subject: Engineering, Civil Engineering Keywords: Cold Formed Steel; Residential construction; material characteristics; durability; design philos-ophy.
Online: 5 September 2023 (10:23:55 CEST)
According to a recent estimate by UN Habitat, approximately 3 billion individuals will require suitable housing by the year 2030. This staggering demand translates to the need for around 96,000 affordable housing units to be constructed each day. However, the conventional construction methods that rely on cement-based concrete and masonry are outdated, lacking innovation, efficiency, and sustainability. In light of these challenges, cold-formed steel emerges as an appealing alternative to traditional construction materials like masonry and concrete. It offers numerous advantages, including easy fabrication, lightweight properties, energy efficiency, the ability to reuse the material at the end of its service life, and a higher level of recyclability. Cold-formed steel buildings are also recognized for their superior insulation and lower energy consumption during operation. Cold-formed steel (CFS) members are created by rolling structurally sound steel sheets into the required shapes using a forming machine, without the need for heat as in the case of hot-rolled steel. While the thickness of these members can range from 0.01 mm to 7 mm, commercial construction of load-bearing walls, roof trusses, and floor joists typically utilizes steel thicknesses of 0.7 mm to 1.2 mm. This paper tries to illustrate the materials and methods employed in the construction of cold-formed steel modular buildings in Sri Lanka. It delves into the material and durability characteristics of cold-formed steel, the design philosophy behind these structures, the development of the building envelope, and the energy efficiency features of the building elements. The findings of this study demonstrate that cold-formed steel buildings can be a highly sought-after alternative for residential construction, offering faster construction timelines, cost-effectiveness, and energy-efficient practices.
ARTICLE | doi:10.20944/preprints202309.0250.v1
Subject: Engineering, Civil Engineering Keywords: soil stabilization; durability; expansive soils; compressibility; shrinkage
Online: 5 September 2023 (08:07:51 CEST)
This paper assesses the performance of an embankment constructed in 2010 with a stabilised expansive soil. Two types of treatment were employed at construction time: 4% lime and a mix of 2% lime and 3% cement. A sampling campaign was carried out in 2021 to evaluate the long-term performance of the stabilised soil properties. To assess the compressibility of the soil, oedometer tests were carried out on samples from different parts of the embankment. The results were compared to the compression curve of the untreated soil, also sampled in the same embankment. Complementary shrinkage tests were performed to investigate the effect of the treatment on swelling and shrinkage. The obtained results showed that the behaviour of the material from the outer part was similar to the mechanical performance of the untreated soil, demonstrating strong alteration in the effect of both treatments over time. This alteration was noticeable to a distance of approximately two metres from the external surface. Beyond this distance, the performance of the soil was comparable to the behaviour of recently treated soil. These observations, similar for each treatment dosage, raise questions as to the durability of the treatment on the outer part of the backfill.
ARTICLE | doi:10.20944/preprints202309.0067.v1
Subject: Engineering, Civil Engineering Keywords: lightweight aggregate concrete; durability; prestress loss; prestressed box girder; creep; shrinkage; chloride ion
Online: 4 September 2023 (03:59:13 CEST)
This study aimed to compare the differences in durability and prestress loss between normal-weight concrete (NC) and lightweight aggregate concrete (LWC) prestressed box girders, which were constructed at the same time in the same area, so as to verify the superiority of using synthetic lightweight aggregate (LWA) made from reservoir sediments in prestressed bridges. For the NCs and LWCs used in prestressed box girders, the basic mechanical properties were tested on the one hand, and the durability properties were tested on the other hand. Then, through the prestress monitoring system, the prestress loss of the two groups of the prestressed box girders was tracked. The results of the durability test confirmed that LWC can inhibit the penetration of air, water, and chloride ions by strengthening the interfacial transition zone between the aggregate and the cement paste, thereby improving its durability. Moreover, the magnetic flux prestress loss of the NC prestressed box girder reached 8.1%. In contrast, the magnetic flux prestress losses on both sides of the LWC prestressed box girder were 4.6% and 4.9%, respectively. This verified that, under the same environmental conditions, the use of LWC produced less of a prestress loss than the use of NC.
ARTICLE | doi:10.20944/preprints202309.0046.v1
Subject: Engineering, Civil Engineering Keywords: grouped stud connectors; finite element analysis; grouped stud effect; calculation of shear capacity
Online: 1 September 2023 (10:32:52 CEST)
In order to further investigate the study of the effect of grouped stud effect on the force properties of stud connector, based on the premise that the correctness of the finite element simulation method in this paper, finite element modeling of grouped stud connectors was developed, the grouped stud effect and its sensitivity factors were analyzed, to validate the recommended formula for calculating the shear capacity of grouped stud connectors. Results show that the number of grouped stud rows and row spacing have a significant effect on the grouped stud effect, and the unevenness coefficient of grouped stud force Ⅰ is negatively correlated with the number of grouped stud rows as well as the grouped stud row spacing. For grouped stud connectors with commonly used concrete grades greater than C50 and height-to-diameter ratios greater than 4 in steel-concrete composite structural bridges, which is insensitive to changes in the concrete strength grades and the length of the studs. The direction of force transmission for the grouped stud changes with the change of loading angle, and the unevenness coefficient of force for the grouped stud will therefore be reduced. By comparing the results of the 62 existing groups of grouped stud connectors push-out tests, the mean value of the ratio of tested to calculated values is found to be 1.12, the variance is 0.023, the dispersion is small, it is shown that the recommended formula has a high degree of accuracy. The results of this paper can be used as a theoretical basis for the study of the shear stress performance of grouped stud connectors.
ARTICLE | doi:10.20944/preprints202309.0021.v1
Subject: Engineering, Civil Engineering Keywords: Permanent deformation; High-cycle accumulation model; Pavements; Engineer-oriented model; Rutting
Online: 1 September 2023 (10:24:58 CEST)
The paper presents a simplified laminar model with which the deformation of soil layers (base, subbase and subgrade courses) under flexible pavements due to repeated traffic load can be determined. In the first step, the cyclic strain amplitude is calculated using a nonlinear material model that is based on particle size distribution parameters (d50 and CU) and dependent on the mean normal stress, relative density and actual strain level. In the second step, the HCA (High Cycle Accumulation) model is used to calculate the residual settlement of each sublayer as a function of the number of cycles. It is shown that the developed model is suitable for describing different types of subgrades and pavement cross-sections. It is also demonstrated with finite element calculations that the developed model describes both the elastic and plastic strains sufficiently accurately. The developed model can predict the settlement and rutting of pavement structures with sufficient accuracy based on easily available particle size distribution parameters without the need of complex laboratory and finite element tests.
ARTICLE | doi:10.20944/preprints202308.2197.v1
Subject: Engineering, Civil Engineering Keywords: damage identification; modal curvature; beamforming algorithms; MVDR
Online: 1 September 2023 (03:34:57 CEST)
This paper presents an approach to damage identification in beams by modal curvatures based on the use of beamforming algorithms. These processors have been successfully used in acoustics for the last thirty years to solve the inverse problems encountered in source recognition and image reconstruction, based on ultrasonic waves. In addition, beamformers apply to a broader range of problems in which the forward solutions are computable and measurable, especially regarding the field of structural vibrations, where the use of such estimators has not received attention to date. In this paper, modal curvatures will play the role of the replica vectors of the imaging field. By means of numerical studies and experimental tests on a steel beam, we motivate the choice of modal curvatures as observed quantities. Furthermore, we compare the performance of the Bartlett and minimum variance distortionless beamformers (MVDR) with an estimator based on the simple minimization of the difference between model and measured data. The results suggest that the application of the MVDR beamformer is highly effective, especially in cases of slight damage between two sensors. MVDR enabled both damage localization, and quantification.
ARTICLE | doi:10.20944/preprints202308.2160.v1
Subject: Engineering, Civil Engineering Keywords: debris flow; hazard zoning; mathematical modeling; intensity of debris flow; debris size
Online: 31 August 2023 (08:41:10 CEST)
Debris flows have generated major disasters worldwide due to their great destructive capacity, which is associated with their high energy levels and short response times. To achieve an adequate risk management of these events, it is necessary to define as accurately as possible the different hazard levels to which the territory is exposed. This article develops a new methodology to estimate this hazard based on the hydrodynamic characteristics of the flow and the granulometry of the sediments that can be mobilized by the flow. The hydrodynamic characteristics of the flow are determined through a mathematical modeling that considers the rheology of non-Newtonian flows and the different volumes of sediments that could be transported during events corresponding to different return periods. The proposed methodology was implemented in the Jamundí River basin (Colombia). The results obtained indicate that in the upper part of this basin there is a low hazard level, while in the lower part of the basin approximately 15% of the affected territory has a medium hazard level and the remaining 85% has a low hazard level. The methodology developed is simple to implement but technically rigorous since it considers all relevant aspects in the generation of debris flows.
ARTICLE | doi:10.20944/preprints202308.2075.v1
Subject: Engineering, Civil Engineering Keywords: dry density; moisture content; Kaolin; brass; Interface; shear adhesion
Online: 31 August 2023 (02:56:24 CEST)
This study aims to assess the interface shear adhesion behaviour between compacted clay and a metallic surface. A new testing approach was developed in this study for this purpose. The proposed method is simple and requires neither advanced equipment nor special test procedures, and thus represents an improvement on existing practice in this field. The experimental program involves determining the interface shear adhesion strength of reconstituted Kaolin clay/metallic surface where the Kaolin clay testing specimens were compacted dynamically at different energy levels and moisture contents. In general, the results show that the interface shear adhesion strength increases as the dry density of the clay increases, whereas it decreases as the moisture content increases. Furthermore, the results in this study reveal a unique multistage interfacial shear adhesion strength behaviour as the moisture content changes that could be related to the compaction curve of the clay. The observed behaviour, in this study, could be interpreted in terms of the effect of clay dry density and moisture content on the contact area and moisture-induced capillary adhesion at clay particles-continuum interface surface.
ARTICLE | doi:10.20944/preprints202308.2021.v1
Subject: Engineering, Civil Engineering Keywords: Groundwater Modeling; MODFLOW; West Africa; GRACE; Sustainability
Online: 30 August 2023 (14:05:34 CEST)
Groundwater modeling is a useful tool for assessing sustainability in water resources planning. However, groundwater models are difficult to construct in regions with limited data availability. We illustrated how remote sensing data can be used leverage limited in situ data to build and calibrate a regional groundwater model in the Goulbi Maradi alluvial aquifer in Southern Niger in Western Africa. We used data from the NASA Gravity Recovery and Climate Experiment (GRACE) satellite mission to estimate recharge rates, the primary source of water to the aquifer. Additionally, we incorporated groundwater storage changes obtained from GRACE data from 2009 to 2021 to establish an overall water budget from which we could back-calculate groundwater withdrawals from pumping in the region. This approach allowed us to calibrate the model and then convert it to a predictive tool to analyze the impact of various assumptions about future recharge and groundwater extraction patterns associated with the development of groundwater infrastruction in the region. The results indicate that the Goulbi Maradi alluvial aquifer is sustainable, even an increase of groundwater extraction up to 28%.
ARTICLE | doi:10.20944/preprints202308.2013.v1
Subject: Engineering, Civil Engineering Keywords: chip seal; quality control; quality acceptance; macro-texture; mean segment depth; mean profile depth; machine learning; DBSCAN-Isolation Forest; proportion control chart; anomaly detection
Online: 30 August 2023 (10:15:21 CEST)
Efforts to enhance quality control (QC) practices in chip seal construction have predominantly relied on single surface frictional metrics such as mean profile depth (MPD) or friction number. These metrics assess chip seal quality by targeting issues such as aggregate loss or excessive bleeding, which may yield low friction numbers or texture depths. However, aggregate loss particularly due to snowplow operations doesn't always result in slippery conditions and may lead to uneven surfaces. The correlation between higher MPD or friction number and superior chip seal quality isn't straightforward. This research introduces an innovative machine learning-based approach to enhance chip seal QC. Using a hybrid DBSCAN-Isolation Forest model, anomaly detection is conducted on a dataset comprising 183,794 20-meter MPD measurements from actual chip seal projects across six districts in Indiana. This results in typical 20 m-segment MPD ranges of [0.9, 1.9], [0.6, 2.1], [0.3, 1.3], [1.0, 1.7], [0.6, 1.9], and [1.0, 2.3] for the respective six districts in Indiana. A two-step QC procedure tailored for chip seal evaluation is proposed. The first step calculates outlier percentages across 1-mile segments, with an established limit of 25% outlier segments per wheel track. The second step assesses unqualified rates across projects, setting a threshold of 50% for 1-mile unqualified wheel track segments. While the results are data-specific, this framework offers pavement construction practitioners a foundational QC standard for chip seal projects.
ARTICLE | doi:10.20944/preprints202308.2000.v1
Subject: Engineering, Civil Engineering Keywords: spatial pattern; land use/land cover dynamic change; transition; remote sensing; driving factors
Online: 30 August 2023 (03:33:59 CEST)
Land use and land cover (LULC) datasets for Jinan in 1992, 1998, 2002, 2006, 2011, 2017, and 2022 were developed from Landsat images using the Random Forest (RF) classification approach. The relationships between social-economic, political factors and time-series LULC data were exam-ined for the periods between 1992 and 2022. The results showed the effectiveness of using the RF classification method for LULC classification with time series of Landsat images. Combined with driving forces analysis, our research can effectively explain the detailed LULC change tra-jectories corresponding to different stages and give new insights into Jinan LULC change pat-terns. The results show a significant increase in impervious surface which opposite change to bare land which experienced a huge decline declined by 95%, due to urbanization and rapid in-crease of population. The driving forces behind these changes are related to population growth, economic development, and climate change. Moreover, the present research employed Principal Components Analysis (PCA) methodology in order to understand the relative significance of disparate driving factors. The analysis results prove that the economy (population, GDP) and climate change were the primary factors that have an obvious impact on land use/land cover changes and that the driving factors for impervious surface, bare land, woodland, farmland, and water were distinct. Government policies also have a substantial impact on LULC change as well, such as the Construction of Harmonious Jinan (COHJ). The results were helpful for better understanding the mechanisms of LULC change and can provide useful knowledge for effective land resource management and planning.
ARTICLE | doi:10.20944/preprints202308.1939.v1
Subject: Engineering, Civil Engineering Keywords: autonomous vehicles; last-mile transport; preference heterogeneity; theory of planned behavior; latent class logit model
Online: 29 August 2023 (13:39:19 CEST)
The accessibility of public transportation is also known as the last mile problem, and it is one of the main obstacles that affect travelers to choose public transport. Although autonomous vehicles (AVs) have made much progress, they have not been officially put into commercial use. This paper adopts stated preference experiments to explore the impact of shared AVs on train trips’ last-mile travel behavior and takes Wuhan as an example for case analysis. First of all, this paper establishes a structural equation model (SEM) based on the theory of planned behavior to explore the latent psychological variables, including travelers’ attitudes (ATTs), subjective norms (SNs), perceived behavior control (PBC), and behavioral intention to use (BIU) toward AVs. These latent psychological variables are incorporated into the latent class (LC) logit model to establish a hybrid model to study the factors and degree of influence on the travel mode choice for the last mile of train trips. The results show that travelers have preference heterogeneity for the travel mode choice of the last mile of train trips. Through the analysis of LCs, education, career, and income significantly impact the classification of LCs. The latent psychological variables towards AVs have a significant impact on the travel behavior of respondents, but the impacts vary among different segments. Elastic analysis results illustrate that a 1% increase in the travel cost for shared AV in segment 1 leads to a 7.598% decrease in the choice probability of shared AV. Respondents from different segments vary significantly in their willingness to pay, and the value of travel time for high-income groups is relatively higher.
REVIEW | doi:10.20944/preprints202308.1967.v1
Subject: Engineering, Civil Engineering Keywords: Network Arch Bridge; arch bridge; hanger arrangement; arch curvature; curvature variation; tied arch bridge
Online: 29 August 2023 (09:39:13 CEST)
The first Network Arch Bridge (NAB) was opened to traffic 60 years ago and since then the idea spread around the world. It is a type of a tied arch bridge that combines the benefits of tied arch bridges and trusses in a single system, thus it has a very good stiffness even in the case of extremely slender structures. In a Network Arch the hangers are inclined and some of them intersect each other at least twice. The core of a NAB is the hanger arrangement that minimizes the bending moment in the arch to very small values, leading thus to compression in the arch. This paper reviews the Network Arch idea devised by prof. Tveit and extended by researchers and engineers worldwide. A comprehensive review of the literature about the Network Arch is provided and the situation of NABs around the world from the standpoint of location, span, structural system used for the cross-section, bridge type (road, railway, combined or pedestrian) and opening year is discussed.
ARTICLE | doi:10.20944/preprints202308.1957.v1
Subject: Engineering, Civil Engineering Keywords: Combined Sewer Overflow (CSO); Long-Term Control Plan; Wireless Sensor Technology; Stormwater Management; Storm Water Management Modeling (SWMM)
Online: 29 August 2023 (08:47:26 CEST)
Combined sewer overflow (CSO) is a significant environmental concern and public health (e.g., water contamination, eutrophication, and beach closure). The Environmental Protection Agency (EPA) has introduced the National Pollutant Discharge Elimination System (NPDES) permitting program to regulate and address this matter. This program mandates the control of CSOs for more than 700 municipalities obligated to devise Long-term Control Plans (LTCPs) to curb combined sewer overflows and bring them down to safe levels. LTCP involves diverse strategies, including sewer separation, green infrastructure improvements, and conventional gray infrastructure upgrades. This study investigates several municipalities’ solutions for CSO problems in conventional methods and wireless sensor technology as real-time control. The investigation mainly focuses on a comparative analysis of two cities, Richmond, Virginia, and South Bend, Indiana, such as average rainfall, the frequency of overflows, and the capacity of treatment plants. The findings indicate that integrating sensor technology could significantly enhance modeling endeavors, bolster the capacity of existing structures, and substantially enhance preparedness for storm events. The EPA’s Storm Water Management Modeling (SWMM) software is utilized. Through an analysis of SWMM data, the study suggests the potential for leveraging wireless sensor technology to achieve more robust control over CSOs as a part of LTCPs.
ARTICLE | doi:10.20944/preprints202308.1921.v1
Subject: Engineering, Civil Engineering Keywords: Hydrology analysis; Riverine Bridges; Infrastructure Intervention; Bridges Prioritization
Online: 29 August 2023 (08:44:55 CEST)
Globally, bridges fail mostly due to hydrological causes such as scour or flooding. Therefore, under a hydrological approach, this study proposes a methodology that contributes to prioritize the intervention of bridges to prevent their collapse. Through an exhaustive literature review, an evaluation matrix subdivided into 4 dimensions was developed and a total of 18 evaluation parameters were considered, distributed as follows: 4 environmental, 6 technical, 4 social and 4 economic. This matrix was applied to eight bridges with a history of hydrological problems in the same river and validated through semi-structured interviews with specialists. Data were collected through field visits, journalistic information, review of the gauged basin historical hydrological flow rates and consultations with the population. Then, the modeling, which considered the influence of gullies that discharge additional flow, was carried out using HEC-HMS and HEC-RAS and subsequently calibrated. The application of the matrix revealed that five bridges have a high vulnerability, and three bridges have a medium vulnerability. The multidimensional approach can be adapted for studies of other riverine bridges.
ARTICLE | doi:10.20944/preprints202308.1839.v1
Subject: Engineering, Civil Engineering Keywords: reclaimed asphalt mixture; roundness; road performance
Online: 29 August 2023 (04:22:29 CEST)
Recycled asphalt mixture is a material remixed with old asphalt recycled material (RAP) and new aggregate, and its application is of great significance in environmental protection.Due to the wear and tear of the old asphalt mixture, the road performance of the recycled asphalt mixture will decrease. This paper uses IPP software to obtain the shape characteristics of the old and new aggregates, and found that the roundness of the old aggregate of 9.5mm-16mm is the most serious wear. Therefore, the 30% RAP, and the influence of the roundness of the recycled asphalt mixture on the road performance is studied.
ARTICLE | doi:10.20944/preprints202308.1860.v1
Subject: Engineering, Civil Engineering Keywords: Monopile; offshore wind turbines (OWT); lateral ultimate capacity; green energy
Online: 29 August 2023 (02:59:04 CEST)
Offshore Wind Turbines (OWT) with increasingly higher energy output are being developed to meet energy demand, posing challenges for their foundation design. Several foundation types are used to support these turbines with monopiles (MP) accounting for 80% of the installed capacity. In this study, three-dimensional (3D) nonlinear finite element models (FEM) were employed to investigate the behaviour of monopile foundation supporting a 5MW wind turbine when subjected to lateral loading. Results indicate that the MP behavior depending on the pile length to diameter (L/D) ratio and the soil shear strength. Inspection of bending moment profiles at the lateral ultimate capacity indicated the monopiles can behave in flexible manner even with low L/D ratio. The L/D ratio affected the MP normalized lateral ultimate capacity at varying degrees and the biggest effect was for soft clays, amounting to around 5 folds increase for L/D values of 3.33 to 13.33. Lesser effects were found for stiff clays.
ARTICLE | doi:10.20944/preprints202308.1807.v1
Subject: Engineering, Civil Engineering Keywords: Steel octagon-web beam(SOWB); Pure shear buckling; Buckling capacity; The strut model
Online: 25 August 2023 (13:35:12 CEST)
Based on the principle of lightweight and easy construction of prefabricated structures, steel octagon-web beam (SOWB) was proposed. SOWB with opening web combines the advantages of both honeycomb beam and steel structure bridge. In order to calculate the pure shear buckling capacity of the web, the finite element (FE) method was used to verify the pure shear buckling coefficients under three boundary conditions, so as to obtain reasonable boundary conditions of the FE model. Based on the data fitting method, the pure shear buckling coefficients of octagonal thin plate with rounding opening under three boundary conditions were obtained. In order to evaluate the buckling capacity of SOWB, a calculation method was proposed through the strut model. In order to verify the reliability of the proposed method, a buckling analysis model of SOWB was established by using the FE software ABAQUS. The influence of two parameters, such as expansion ratio and the ratio of flange plate thickness to web thickness, on the buckling capacity of the web was analyzed. Furthermore, the proposed method which can be used to calculate the buckling capacity of the web was improved by introducing the constraint effect coefficient of the flange.
ARTICLE | doi:10.20944/preprints202308.1765.v1
Subject: Engineering, Civil Engineering Keywords: minimum cost design; minimum area; moments; bending shear; punching shear
Online: 25 August 2023 (07:08:18 CEST)
This work presents a new model to obtain the minimum cost design for a rectangular isolated footing, taking into account that the column is located in any part of the footing. The methodology is developed by integration to obtain the moments, bending shear and punching shear according to the American Concrete Institute ACI 318-14. This document presents the simplified and precise equations of the four moments, four bending shears and one punching shear acting on the footing. Some designs have been developed by the trial and error method to determine the footing dimensions, and later the thickness and steel area of the footing are obtained. Some authors present the minimum cost design for a rectangular isolated footing taking into account that the column is located in the center of gravity of the footing, and other authors present very complex algorithm. Numerical examples are presented to obtain the minimum cost design of rectangular isolated footings under biaxial bending, and some results are compared with those of other authors considering the same conditions. The new model presents a smaller contact area with the soil and a lower design cost than those presented by other authors.
ARTICLE | doi:10.20944/preprints202308.1743.v1
Subject: Engineering, Civil Engineering Keywords: distributed fiber optic strain monitoring; structural health monitoring; cementitious matrix; concrete beams
Online: 25 August 2023 (04:52:58 CEST)
Distributed fiber optic strain measurement techniques have become increasingly important in recent years, especially in the field of structural health monitoring of reinforced concrete structures. Numerous publications show the various monitoring possibilities from bridges to special heavy structures. The present study is intended to demonstrate the possibilities, but also the challenges, of distributed fiber optic strain measurement in reinforced concrete structures. For this purpose, concrete beams for 3-point bending tests were equipped with optical fibers on the reinforcement and concrete surface as well as in the concrete matrix in order to record the strains in the compression and tension zone. In parallel, an analytical approach based on the maximum strains in the uncracked and cracked states was performed using the Eurocode~2 interpolation coefficient. In principle, the structural design correlates with the measured values, but the strains are underestimated, especially in the cracked zone. During load increase, structural distortions in the compression zone affected the strain signal, making reliable evaluation in this zone difficult. The information content of distributed fiber optic strain measurement in reinforced concrete structures can offer tremendous opportunities. Future research should consider all aspects of the bond, sensor selection and positioning. In addition, there is a lack of information on the long-term stability of the joint and the fiber coating, as well as the effects of dynamic loading.
ARTICLE | doi:10.20944/preprints202308.1617.v1
Subject: Engineering, Civil Engineering Keywords: concrete waste; alternative aggregate; supplementary cementitious material; SEM; PXRD
Online: 25 August 2023 (03:01:47 CEST)
Concrete is a heterogeneous material, one of the most widely used materials on the Planet and a major consumer of natural resources. Carbon emissions are largely due to the extensive use of cement in its composition, which contributes to 7% of global CO2 emissions. Extraction and processing of aggregates is another sources of CO2 emissions. Many countries have succeeded in moving from a linear economy to a circular economy by partially or fully replacing non-renewable natural materials with alternatives from waste recycling. One such alternative consists in partially replacing cement by supplementary cementitious materials (SCMs) in concrete mixes. Thus, the work is based on the experimental investigation of the fresh and hardened properties of civil engineering concrete, hereafter referred to as road concrete, in which, crushed river aggregate have been replaced with recycled waste aggregates of uncemented concrete and partial replacement of cement with a SCM material in the form of glass powder that improves the durability characteristics of this sustainable concrete. The microstructure and compositional features of the selected optimum composite has been also investigated by polarized light optical microscopy (OM) Scanning electron microscope (SEM) and X-ray diffraction by the Powder method (PXRD) for the qualitative analysis of crystalline constitutive materials.
ARTICLE | doi:10.20944/preprints202308.1636.v1
Subject: Engineering, Civil Engineering Keywords: machine learning; supervised classification; drinking water quality; data-driven; artificial intelligence
Online: 24 August 2023 (03:20:26 CEST)
Water quality assessments are crucial for human health and environmental safeguards. The utilization of a subset of artificial intelligence such as Machine Learning (ML) presents significant impacts to enhance the prediction and classification of water quality. In this research, a set of diverse ML algorithms was evaluated to handle a comprehensive dataset of water quality measurements over an extended period. The aim was to develop a robust approach for accurately forecasting water quality. This approach employed machine learning classifiers such as Logistic Regression (LR), Support Vector Machine (SVM), Stochastic Gradient Descent (SGD), K-Nearest Neighbors (KNN), Gaussian Process Classification (GPC), Gaussian Naive Bayes (GNB), Random Forest (RF), Decision Tree (DT), XGBoost, and Multilayer Perceptron (MLP). The water quality parameters assessed for pH, hardness, solids, chloramines, sulfate, conductivity, organic carbon, trihalomethanes and turbidity. The XGBoost model exhibited the highest accuracy of 89.47% among the classifiers and Stacked Ensemble Classifiers (SEC) improved the prediction further to 92.98%. The findings suggest that XGBoost and the SEC hold promise as reliable approaches for water quality assessments in contrast of artificial intelligence.
ARTICLE | doi:10.20944/preprints202308.1612.v1
Subject: Engineering, Civil Engineering Keywords: repair of bridges; hot cracking; structural health monitoring; test setup; welding; cyclic loads; fatigue
Online: 23 August 2023 (09:18:25 CEST)
Steel structures, such as bridges, must be continuously maintained. Due to increasing trac loads, design and execution shortcomings, many steel bridges are subject to various types of damage, such as cracks. The bridges must be maintained by crack removal and re-welding the cracks. During this work, the bridge is closed for trac in order to suppress the crack ank movement during welding. As a result, trac loads on other routes are higher, which increases further damage on detour routes and subsequently additional welding work and costs on theses structures. Therefore, the aim is to provide a method that allows welding work on steel structures under running trac, respectively under cyclic loads. First, measurements at a representative steel bridge were conducted to derive gap opening parameters of amplitude and frequency for welding tests under cyclic loads. In a test setup for reproducible and comparable welding tests, specimen were welded under cyclic loads. Deep grinding of the root layer allowed defect-free welding within the range of 0.1 mm amplitude at a frequency of 2 Hz loadings. For such welds, the weld quality and the fatigue strength was comparable to the standard requirements.
ARTICLE | doi:10.20944/preprints202308.1609.v1
Subject: Engineering, Civil Engineering Keywords: truncated Timoshenko nanotubes; vibration; analytical modelling; surface effect
Online: 23 August 2023 (09:17:02 CEST)
Carbon nanotubes have sparked a substantial amount of scientific and technological research due to their exceptional mechanical, physical and electrical characteristics compared to conventional materials. As a result, detailed studies on their mechanical properties have been conducted, and static and dynamic behavior of single-walled and multi-walled carbon nanotubes have been proposed using Euler-Bernoulli and Timoshenko beam models. The main objective of this paper is to study the free vibration of a Timoshenko-Ehrenfest single-walled carbon nanotube based on the nonlocal theory and taking surface effects into account. To model these effects on frequency response of nanotubes, we use Eringen’s nonlocal elastic theory and surface elastic theory proposed by Gurtin and Murdoch to modify the governing equation. A modified version of Timoshenko nonlocal elasticity theory - known as the nonlocal truncated Timoshenko beam theory - is put forth to investigate the free vibration behavior of single-walled carbon nanotubes (SWCNT). Using the Hamilton’s principle, the governing equations and the corresponding boundary conditions are derived. Finally, to check the accuracy and validity of the proposed method, some numerical examples are carried out. The impacts of the nonlocal coefficient, surface effects and nanotube length on the free vibration of single-walled carbon nanotube (SWCNT) are evaluated and the results are compared with those found in the literature. The findings indicate that the length of the nanotube, the nonlocal parameter and the surface effect all play important roles and should not be disregarded in the vibrational analysis of nanotubes. Finally, the results show how effective and successful the current formulation is at explaining the behavior of nanobeams.
ARTICLE | doi:10.20944/preprints202308.1584.v1
Subject: Engineering, Civil Engineering Keywords: Ground temperature distribution; Geothermal energy; Renewable sources; In-depth temperature acquisition; Mediterranean climate
Online: 23 August 2023 (07:49:20 CEST)
Shallow Geothermal Energy (SGE) exchanges heat with the ground. In continuous long-term operation, the initial temperature field can be disturbed, and subsurface thermal plumes can be developed. In this paper, the thermal impact of a SGE system under Mediterranean climate is handled. Temperature recordings from 104 thermal probes placed in depth along 15 monitoring boreholes are analysed. Those boreholes were drilled 1-2m from thermos-active boreholes of the case study system installed in a university building. The analysis handles one year of SGE system operation. Temperature depth profiles, reaching up to 140 m depth, were registered with a 10-minute time-step resulting in a large amount of data. Ground thermal conductivity was estimated experimentally and semi-empirically allowing to compute the initial undisturbed ground temperature profiles and compare it with the monitored values. Climate data was recorded by the university meteorological station. Globally, the measured and computed data were coherent and a non-negligible impact of the SGE system operation in the first year was observed. The building orientation as well as the nearby departments had significant impacts on shallow ground temperature. Maximum ground temperature changes, ranging from 2 to 3º C as observed in different boreholes indicating that the system is operating efficiently.
ARTICLE | doi:10.20944/preprints202308.1618.v1
Subject: Engineering, Civil Engineering Keywords: n/a; double-beam system, static analysis, crack, closed-form solution, CDM, FEM.
Online: 23 August 2023 (07:36:23 CEST)
Based on the elasticity theory, this paper deals with the static analysis of a cracked double beam system in presence of a Winkler medium. The double-beam system is also supposed to be constrained at both ends by elastically flexible springs, with transverse and rotational stiffness. Using a variational formulation, the static governing equations are derived and solved by using analytical and numerical approaches. In the first approach, the closed-form solutions for the displacements functions are obtained based on the Euler-Bernoulli beam theory. In the second approach, the Cell-Discretization Method (CDM) is performed, according to which the two beams are reduced to a set of rigid bars linked together by means of elastic constraints, where the bending stiffness of the bars is concentrated. The resulting stiffness matrix is easily deduced, and the governing equations of the static problem can be immediately solved. A comparative analysis is performed in order to verify the accuracy and validity of the proposed method. This study focuses on the effect of various parameters including the crack depth and position, boundary conditions, elastic medium and slenderness. The validity of the proposed analysis is confirmed by comparing the present results with those obtained from the other approach. In particular, the results obtained by closed-form solution and Cell-discretization method (CDM) are compared by Finite element method (FEM). Accuracy of the results has been evaluated by making comparisons with the results in literature and reported in bibliography. It is demonstrated that the proposed algorithm provides a simple and powerful tool in dealing with the static analysis of a double-beam system. Finally, some concluding remarks are made.
ARTICLE | doi:10.20944/preprints202308.1624.v1
Subject: Engineering, Civil Engineering Keywords: mathematical model; crack repair; MICP; CACO3; biofilm growth; suspended biomass
Online: 23 August 2023 (07:13:56 CEST)
Concrete cracks have a detrimental effect on the strength properties and durability of the structures. So, repairing of concrete cracks to recover their strength parameters is more important task in civil engineering. To repair concrete cracks, MICP has been widely analysed in recent times; but, zero research is conducted to deeply investigate the repair effects of MICP on concrete cracks with rough surface by using the theoretic model. In current research, MICP with a novel mathematical model was attained by taking the precipitation of calcium carbonate (CaCO3), ureolysis, suspended biomass, geochemistry, transport of solute and biofilm growth. Furthermore, crack repair experiments were performed to check the workability of the new mathematical method. The outcomes revealed that the designed suspended biomass concentrations in cracks diminished step by step. The comparison in between the experimental results and calculated results verified the precision of migration behaviour of the suspended biomass. At the inlet, the solute concentrations and biofilm volume fractions was higher, causing in rise of yield amounts for calcium carbonate. The consumed solutes concentrations were higher for cracks of less rough surface, ultimately causing in smaller sonic time; and the values of sonic time for upper portions of cracks was smaller, showing good repair impacts. The recommended mathematical model provides a better tool that controls repair time and microbial metabolism process to report a new adjustive, bioremediation and biomineralization to concrete, which could provide a firm base for remediation of material in civil engineering field.
ARTICLE | doi:10.20944/preprints202308.1588.v1
Subject: Engineering, Civil Engineering Keywords: vacuum preloading; sand-drained foundations; large strain; nonlinear consolidation; non-darcy flow; radical permeability coefficient variation
Online: 23 August 2023 (04:50:38 CEST)
The vacuum preloading method effectively strengthens the soft soil foundations with vertical drainage, which will produce a smear effect when laying sand drains. Meanwhile, the seepage of pore water and soil deformation during consolidation exhibits nonlinear characteristics. Therefore, based on Gibson's 1D large strain consolidation theory, this paper developed a more generalized large strain radical consolidation model of sand-drained soft foundations under free strain assumption. In this system, the double logarithmic compression permeability relationships for soft soils with large strain properties, the variation of the radical permeability coefficient in the smear zone, and the effect of the non-Darcy flow were all included. Then, the partial differential control equations were numerically solved by the finite difference method and validated with existing radical consolidation test results and derived analytical solutions. Finally, the influences of relevant model parameters on consolidation are discussed. The analysis shows that the greater the maximum dimensionless vacuum negative pressure P0, the faster the consolidation rate of sand-drained foundations. Meanwhile, the decrease in the negative pressure transfer coefficient k1 will result in a decreasing final settlement amount. Moreover, the consolidation rate of sand-drained foundations is slower considering the non-Darcy flow, but the final settlement is unaffected.
ARTICLE | doi:10.20944/preprints202308.1501.v1
Subject: Engineering, Civil Engineering Keywords: strengthening; micro-reinforced concrete; ferrocement; RC beams; flexure; numerical simulation
Online: 22 August 2023 (07:27:06 CEST)
The practical necessity of strengthening of reinforced concrete structure elements requires a choice of a method which would provide cost-effectiveness, simplicity of construction and durability of the chosen solution. One of the ways is strengthening using the material belonging to the group of micro-reinforced concretes called ferrocement. The paper presents the comparative analysis of some of the results of RC beams exposed mainly to flexure, strengthened with ferrocement elements (strips) applied by gluing on the on the tensed side of RC beams. The results are obtained using the experimental, analytical and numerical research on the adequate models. Strengthening of the beams was performed in the form of four types of ferrocement strips (four different strip widths and four different numbers of wire mesh layers). The numerical non-linear analysis using finite elements method (FEM) was employed, with the introduction of the corresponding characteristics of constitutive material obtained by the experiments on the test specimens. The analytical researches were performed using known analytical calculation methods in order to formulate the model for the calculation of the ultimate and serviceability limit states of the strengthened cross-section. The results presented in the paper, through their comparative compatibility, confirmed the applicability of this strengthening method.
ARTICLE | doi:10.20944/preprints202308.1341.v1
Subject: Engineering, Civil Engineering Keywords: Uncertainty; Flood Frequency; Rainfall Disaggregation; Peak Flow Continuous Simulation
Online: 18 August 2023 (10:23:06 CEST)
Estimating peak flow for a catchment is commonly undertaken using the design event method, however this method does not allow for the understanding of uncertainty in the result. This research first presents a simplified method of fragments approach to rainfall disaggregation that ignores the need to consider seasonality, offering a greater diversity in storm patterns within the resulting sub-daily rainfall. By simulating 20 iterations of the disaggregated sub-daily rainfall within a calibrated continuous simulation hydrologic model, we were able to produce multiple long series of stream flow at the outlet of the catchment. With this data, we investigated the use of both the annual maximum and peaks over threshold approaches to flood frequency analysis and found that for a one in 100 year annual exceedance probability peak flow, the peaks over threshold method (333m3/s ±50m3/s) was significantly less uncertain than the annual maximum method (427m3/s ±100m3/s). For the one in 100 year annual exceedance probability, the median peak flow from the peaks over threshold method (333m3/s) produced an outcome comparable to the design event method peak flow (328m3/s), indicating that this research offers an alternative approach to estimating peak flow, with the additional benefit of understanding the uncertainty in the estimation. Finally, the paper highlighted the impact that length and period of streamflow has on peak flow estimation and noted that previous assumptions around the minimum length of gauged streamflow required for flood frequency analysis may not be appropriate in particular catchments.
ARTICLE | doi:10.20944/preprints202308.1300.v1
Subject: Engineering, Civil Engineering Keywords: heavy metal; chromium ions; contaminated sludge; electro kinetic remediation; fixed anode; membrane.
Online: 18 August 2023 (07:52:57 CEST)
Abstract Aims: In recent years, electro kinetic (EK) remediation has become more popular as a novel method for removing chromium contamination from soil. This approach, however, is ineffective since it uses both cationic and anionic forms of chromium. In this work, a membrane –based technique was employed to increase the efficiency of the electro kinetic removal of chromium. Methods: Chromium removal from polluted sludge was studied in four bench-scale experiments, two of which used distilled water (EK-1, EK2 & Membrane) and two of which used acetic acid as a catholyte (EK-3, EK4 &Membrane). Results: The pH, total chromium, and fractionation of chromium in the sludge were measured after remediation. In the EK-1, EK-2 & Membrane and EK-3, EK-4 & Membrane trials, the average removal efficiency of total chromium was 47.6%, 58.6%, and 74.4%, 79.6%, respectively. Conclusion: In contrast to the electro kinetic remediation strategy, which left approximately 80% of the sludge neutral or alkaline after treatment, the use of the membrane created acidic soil conditions throughout the sludge. For example, the high field intensity used in the membrane tests may have helped to facilitate chromium desorption, dissolution and separation from the sludge, as well as enhance chromium mobility. The findings show that the membrane can improve the effectiveness of chromium removal from sludge when utilized in the EK remediation process.
ARTICLE | doi:10.20944/preprints202308.1246.v1
Subject: Engineering, Civil Engineering Keywords: Damage identification; instantaneous eigen-frequencies diagram; pushover capacity curve; nonlinear analysis of reinforced concrete structures; seismic target-displacement; beam-sway plastic mechanism
Online: 17 August 2023 (05:25:48 CEST)
The effectiveness of a recently proposed methodology in the identification of damage in planar, multi-storey, Reinforced Concrete (RC) moment-frames, which develop a plastic-yield mechanism on their beams, is showcased here via the examining of a group of such existing multi-storey frames with three or more unequal spans. According to the methodology, the diagram of the instantaneous Eigen-Frequencies of the frame in the nonlinear regime is drawn as a function of the inelastic seismic roof displacement by performing a sequence of pushover and instantaneous modal analyses with gradually increasing target displacement. Using this key-diagram, the locations of severe seismic damage in an existing moment-frame can be evaluated if the instantaneous fundamental eigen-frequency of the damaged frame, at an analysis step within the nonlinear area, is known in advance by “the monitoring and the identification of frequencies” using a local network of uniaxial accelerometers. This is a hybrid technique because both procedures, the instrumental Monitoring of the structure and the Pushover analysis on the frame (M and P technique), are combined. Moreover, the damage image of the planar multi-storey moment-frame is illustrated, and the lateral stiffness matrix of the damaged frame is calculated with high accuracy.
ARTICLE | doi:10.20944/preprints202308.1198.v1
Subject: Engineering, Civil Engineering Keywords: seismic behavior; mid-rise framed buildings; composite building columns; concrete-filled steel tubes; confinement effect; active hoop prestress
Online: 16 August 2023 (11:08:09 CEST)
This paper presents a numerical study on the vertical (axial) and lateral (flexure) behavior of CFST (Concrete-Filled Steel Tube) columns with active hoop prestress; this transverse prestressing effect is achieved by bolting together two steel half-tubes. This study refers to new construction only (i.e., no retrofit). 12 prototype CFST column specimens (segments) are analyzed. These specimens differ in the prestressing force (3 levels) and in the gravity loading ratio (4 levels); they are selected to represent typical ground columns of mid-rise buildings. The structural behavior of these column specimens is simulated with a nonlinear model implemented in Abaqus; the concrete and steel behavior are described with a damage-plasticity and a plasticity model, respectively. Finally, the interface concrete-steel interaction is represented by a hard (compression-only) surface-to-surface contact model. The calculations involve three consecutive loading steps: (i) transverse prestress, (ii) axial force, and (iii) lateral loading (shear force and bending moment). The structural behavior of the CFST columns is deeply examined and discussed; the results show that their axial-flexural capacity is adequate. Noticeably, it is concluded that the overall benefits of prestressing the columns are only modest. Preliminary studies on the aforementioned mid-rise buildings equipped with the CFST columns show that their gravity and wind capacities are largely enough; conversely, their seismic capacity is sufficient for moderate seismic ground motions only.
ARTICLE | doi:10.20944/preprints202308.1084.v1
Subject: Engineering, Civil Engineering Keywords: composite structures; observability method; shear rotation; stiffness matrix method; structural system identification
Online: 16 August 2023 (03:20:07 CEST)
Shear deflection effects are traditionally neglected in most structural system identification methods. Unfortunately, this assumption might lead to significant errors in some structures, like deep beams. Although some inverse analysis methods based on the stiffness matrix method including shear deformation effects have been presented in the literature, none of these methods is able to deal with actual rotations in their formulations. Recently, the observability techniques, one of the first methods for the inverse analysis of structures included the shear effects into the system of equations. In this approach, the effects of shear rotation are neglected. When actual rotations on site are used to estimate the mechanical properties in the inverse analysis, it can result in serious errors in the observed properties. This characteristic might be especially problematic in structures such as deep beams where only rotations can be measured. To solve this problem and increase the observability techniques' applicability, this paper proposes a new approach to include shear rotations into the inverse analysis by observability techniques. This modification is based on the introduction of a new iterative process. To illustrate the applicability and potential of the proposed method, the inverse analysis of several examples of growing complexity is presented.
ARTICLE | doi:10.20944/preprints202308.1131.v1
Subject: Engineering, Civil Engineering Keywords: Moroccan gypsum; natural additives; synthetic and mineral additives; bio-based gypsum plasters; thermal conductivity; acoustic performance.
Online: 15 August 2023 (12:43:37 CEST)
Due to the high impact of the building sector on the environment, a growing interest focuses on insulating materials able to ensure good thermo-acoustic performance for the building envelope, in a sustainable and circular economy perspective. In this context, Moroccan natural gypsum was mixed with natural waste local materials. Thermal and acoustic properties of the samples were measured; they were compared to those of synthetic- and mineral-based gypsum plasters, manufactured with the same technique. A Small Hot Box apparatus was used for thermal characterization, whereas acoustic performance was investigated by means of a Kundt’s Tube. Natural and synthetic additives involved a reduction in density and an improvement in thermal performance. Conductivity values in the 0.181 – 0.238 W/mK range were obtained, depending on the type of natural additive, with respect to 0.275 – 0.323 W/mK of mineral-based gypsum plasters. The acoustic measurements showed that all the composites have similar performance in terms of acoustic absorption, whereas high Transmission Loss values were obtained for the natural additives (TL = 35 – 59 dB). Petiol of Palm and Stipa Tenacissima were found as the materials able to improve both thermal and acoustic properties.
ARTICLE | doi:10.20944/preprints202308.1091.v1
Subject: Engineering, Civil Engineering Keywords: Free-form Space Structure; Parametric Modelling; Artificial Neural Network; Aesthetics
Online: 15 August 2023 (11:51:10 CEST)
Parametric form findings of free-form space structures and qualitative assessment of their aesthetics are among the concerns of architects. This study aims to evaluate the aesthetic aspect of these structures using ML algorithms based on the expert's experiences. First, various datasets of forms were produced using a parametric algorithm of free-form space structures written in Grasshopper. Then, three multilayer perceptron ANN models were adjusted in their most optimal modes using the results of the preference test based on the aesthetic criteria including simplicity, complexity, and practicality. The results indicate that the ANN models can quantitatively evaluate the aesthetic value of free-form space structures.
ARTICLE | doi:10.20944/preprints202308.1103.v1
Subject: Engineering, Civil Engineering Keywords: Bridge testing; DSSI; FEM; large-amplitude shaking
Online: 15 August 2023 (09:00:16 CEST)
This paper presents results from numerical simulations validated by experimental results related to the effects of DSSI on the dynamic response of bridges. An in-service overpass was shaken using the T-Rex, a large-amplitude mobile shaker from the National Hazards Engineering Research Infrastructure (NHERI) facilities. Studies implementing Finite Element Modeling to develop time histories, response spectra, and eigenmodes were conducted in a forward-modeling problem setup. Two models were created to assess the DSSI effects on the dynamic response of the bridge. One model included elements that incorporate DSSI effects, while the other had fixed-base boundary conditions. The response from the DSSI FEM model matched the field results better than the fixed-base model, in terms of the peak response amplitudes and identified natural frequencies and modes. The influence of a series of factors, such as the soil shear wave velocity, bridge height, bridge foundation embedment depth and the corresponding rigidity, slenderness, and embedment ratios, on the bridge response is presented.
ARTICLE | doi:10.20944/preprints202308.1074.v1
Subject: Engineering, Civil Engineering Keywords: biomineralization; microbial‑induced calcium carbonate precipitation; reducing slag; stabilization; free calcium oxide; calcium carbonate
Online: 15 August 2023 (08:44:51 CEST)
Most of the current methods for stabilizing electric arc furnace (EAF) slag are time-consuming and cannot be completely stabilized. In view of this, this study aimed to apply microbial‑induced calcium carbonate precipitation (MICP) technology in the stabilization of EAF reducing slag, and this was to be achieved by using the reaction between carbonate ions and free calcium oxide (f-CaO) in reducing slag to form a more stable calcium carbonate to achieve the purpose of stabilization. The test results showed that, when the EAF reducing slag aggregates (ERSAs) were immersed in Bacillus pasteurii bacteria solution or water, the f-CaO contained in it would react such that stabilization was achieved. The titration test results showed that the f-CaO content of the ERSAs immersed in the bacterial solution and water decreased. The expansion test results of the ERSAs that were subjected to hydration showed that the seven-day expansion of ERSAs after biomineralization could meet the Taiwan regulation requirement of a less than 0.5% expansion rate. The thermogravimetric analysis showed that both the experimental group and the control group might contain calcium carbonate compounds. The results of the X-ray diffraction analysis showed that the CaCO3 content in the ERSAs that were immersed in the bacterial solution was significantly higher than those that were immersed in water. Moreover, the compressive strength test results of concrete prepared with ERSAs showed that the compressive strength of the control group concrete began to decline after 28 days. In contrast, the experimental group concrete had a good stabilization effect, and there was no decline in compressive strength until the age of 180 days. At the age of 240 days, the surface cracks of the experimental group were particularly small, while the surface of the control group showed obvious cracks. These results confirmed that a mineralization reaction with B. pasteurii bacteria could be used as a stabilization technology for ERSAs.
ARTICLE | doi:10.20944/preprints202308.1040.v1
Subject: Engineering, Civil Engineering Keywords: Beams with openings; Basalt fiber-reinforced polymer (BFRP); Stiffness, Ductility; Energy; Hybrid Reinforcement; Strengthening
Online: 15 August 2023 (02:44:01 CEST)
The opened beams always confused the designers due to the guidelines missing. In this research, six hybrid reinforced beams reinforced with mixed steel and basalt fiber reinforced polymer (BFRP) bars had constant cross-sections of 150mm x 300mm and a clear span of 1800mm. Generally, five beams have symmetrical rectangular openings with dimensions of 150mm x 250mm located at a distance of 250mm (equivalent to the beam effective depth) from the beam support in addition to a solid beam that is served as a control reference. The studied parameters included the effect of using internal reinforcement (steel or BFRP bars) provided along the opening or by incorporating an external BFRP sheet around the opening corners. Also, the conduction of double enhancement with internal steel reinforcement bars further external strengthening BFRP sheet was investigated. The relevant results showed that the opened beam without enhancement lost almost 74.66% of the maximum load compared with the solid beam. Placing internal steel or BFRP bars around the openings increased the maximum load by 62.07% and 59.68%, respectively in comparison to the non-enhanced opened beams. Using an external BFRP sheet to strengthen the opening corners of the beam enhanced the maximum load by 76.39% compared with the non-enhanced opened beam. Therefore, if the beam double enhancement with an external BFRP sheet and internal steel reinforcement around the openings, the maximum load increased by 137.40% compared with the non-enhanced opened beam. Ultimately to further analyze the experimental results and confirm their findings, the study was extended to include the numerical analysis using three dimensional finite element modeling and the results correlated very well with the experimental ones.
ARTICLE | doi:10.20944/preprints202308.0986.v1
Subject: Engineering, Civil Engineering Keywords: water distribution network (WDN); leak detection; GIS; remote sensing; infrared (IR)
Online: 14 August 2023 (10:15:32 CEST)
Leakages in the water distribution networks (WDNs) are real problems for utilities and other governmental agencies. Timely leak detection and location identification has been a challenge. In this paper, an integrated approach to geospatial and infrared image processing method was used for robust leak detection. The method combines drops in flow, pressure, and chlorine residuals to determine potential water leakage locations in the WDN using Geographic Information System (GIS) techniques. GIS layers were created from the hourly values of these three parameters for the city of Sharjah provided by Sharjah Electricity, Water and Gas Authority (SEWA). These layers are then analyzed for locations with dropped values of each of the parameters and are overlaid with each other. In the case where there were no overlaying locations between flow and pressure, further water quality analysis was avoided, assuming no potential leak. In the case where there are locations with drops in flow and pressure layers, these overlaying locations are then examined for drops in chlorine values. If overlaying locations are found, then these regions are considered potential leak locations. Once potential leak locations are identified, a specialized remote sensing technique can be used for precise leak location. This study also demonstrated the suitability of using an infrared camera for leak detection in a laboratory-based setup. This paper concludes that the following methodology can help water utility companies in the timely detection of leaks, saving money, time, and effort.
ARTICLE | doi:10.20944/preprints202308.0994.v1
Subject: Engineering, Civil Engineering Keywords: BIM methodology; BIM manager; coordination; integration; interoperability
Online: 14 August 2023 (07:11:18 CEST)
Abstract: Building Information Modelling (BIM) methodology has been empowering the quality of the construction activity in all sectors: multidisciplinary designs development; construction planning and monitoring; building management and maintenance. A BIM environment aggre-gates several disciplines and different professional skillsets and in order to control and improve the quality of a BIM project, a BIM manager is required. The BIM manager has the responsibility to coordinate all tasks involved in a building design and associated activities usually workout over the project documents. This professional can access to the distinct discipline models, located in a shared platform, and request for amendments if inconsistencies are detected. The topic of the present study is illustrated with three building cases were distinct specific projects, disciplines and tasks were elaborated: collaboration between disciplines (architecture, structures and con-struction); structural analyses and reinforcement details; quantity take-off of materials and cost estimation; construction scheduling and simulation. Although there are still limitations in the implementation of BIM methodology in all sectors and stages, within the construction industry, BIM has been bringing an important improvement in the quality of a building design, reflected in the quality of the final product. The present study put in evidence the BIM manager role in pro-jects that aggregates several disciplines and experts, bringing an important contribution in the quality of a building design. BIM methodology is a current demand in the construction industry supported on advanced technology and in an adequate management of projects.
ARTICLE | doi:10.20944/preprints202308.0961.v1
Subject: Engineering, Civil Engineering Keywords: Bitumen; Synthetic Bitumen; Adhesion; Waste Engine Oil; Crumb Rubber; PPA; High-Temperature Performance
Online: 11 August 2023 (19:07:54 CEST)
Bitumen is produced from non-renewable natural resources, continuously deplete and intrigues researchers to look for alternative binders. Annually, tons of waste engine oil (WEO) and crumb rubber (CR) are discarded unsustainably and pose a significant environmental threat. Adding these industrial waste products to asphalt provides a safe and cost-effective way for their disposal and improves the bitumen's performance in parallel. This study uses various combinations of waste engine oil and crumb rubber with 60/70 penetration grade bitumen to produce a partially synthetic bitumen. Adhesion being one of the critical characteristics of the bituminous binder has been assessed using the bitumen bond strength test along with physical and rheological properties. Results showed that waste engine oil with crumb rubber inclusion increases penetration and decreases the softening point, viscosity, complex modulus, and bonding strength. Additionally, polyphosphoric acid (PPA) in smaller dosages was also incorporated into the optimum percentage of CR + WEO to improve the properties of the binder. The results confirm that binder modification with waste engine oil and crumb rubber can be more effective with PPA. It is concluded that 35% of waste can replace the virgin binder giving a cost-effective and environmentally friendly solution.
ARTICLE | doi:10.20944/preprints202308.0862.v1
Subject: Engineering, Civil Engineering Keywords: localized corrosion; corrosion pit radius; steel section loss; crack extension; maximum corrosion level
Online: 10 August 2023 (12:40:47 CEST)
A novel prediction model for crack development of reinforced concrete (RC) piles with localized chloride corrosion in marine environment is proposed. A discrete method is used to solve the corrosion pit radius model and a crack extension model is developed to investigate the initiation and extension of cracks. The maximum corrosion degree of reinforced concrete pile is predicted according to the limit crack criterion, and finally a sensitivity analysis is carried out on the important parameters of crack extension. The results show that the radius of corrosion pit, the depth corrosion pit and cross-sectional area loss of reinforcement gradually increase as the corrosion level increases. The loss of local reinforcement section at crack initiation decreases with the increase of the ratio of concrete cover to initial diameter, and increases with the increase of pitting factor. The required pit depth for reinforcement cracking increases with the increase of the ratio of concrete cover thickness to diameter. The loss of cross-sectional area of reinforcement and the radius of corrosion pit increase with the increase of initial diameter of reinforcement. Increasing the pitting factor will reduce the pit depth and make the crack width develop faster before reaching the limit crack width. Increasing the concrete cover thickness can provide an improvement in the propagation of cracks. A comparative analysis shows that the localized corrosion pattern is more in conformity with marine engineering practice.
ARTICLE | doi:10.20944/preprints202308.0718.v1
Subject: Engineering, Civil Engineering Keywords: Binder modification; Organophilic nano clay; Rutting; Viscosity, and Wheel tracker test.
Online: 9 August 2023 (07:56:32 CEST)
Organophilic nano clay is the composition of mostly clay and organic molecules designed to improve various materials' physical and chemical properties. Permanent deformation in asphalt pavements is primarily the result of inadequate compaction, excessive loading, and high temperatures. Rutting can result in aquaplaning, leading to accidents and costly maintenance and rehabilitation works that drain the economy. Such behavior of asphalt pavements may be attributable to poor selection of aggregate, asphalt binder, or substandard asphalt binders. This study used different percentages of organophilic nano clay ranging from 3.0% - 5.0% with two penetration grade bitumen, i.e., N.R.L 60-70 & N.R.L 80-100. Adding organophilic nano clay to asphalt binder significantly reduced the rutting potential under cyclic loading at high temperatures (55 °C). Ten modified formulations and two virgin bitumen specimens were prepared. The modified binders' viscosity and rutting were tested using the Rotational Viscometer and Wheel Tracker Test (W.T.T.), respectively. The results were analyzed using software for Statistical Analysis. It was recorded that organophilic nano clay-modified bitumen significantly affected rutting to interpret the results. The results indicated that rutting decreased and viscosity increased in all nano clay-modified bitumen samples, with a 4.5% O.N.C modified binder showing the most significant improvement.
ARTICLE | doi:10.20944/preprints202308.0564.v1
Subject: Engineering, Civil Engineering Keywords: ВIM-technologies; AIoT; information modeling; retrofitting; historical buildings; sustainability
Online: 8 August 2023 (03:52:54 CEST)
The construction industry of Ukraine shall not only recover but also to upgrade, enhance and reevaluate projects of existing buildings. Further research raises simultaneously two pertinent issues for Ukraine - retrofitting as well as reconstruction of destroyed infrastructure. The priority objective of the research is to restore damaged and ruined buildings rapidly. It may be achieved by means of a creation of recovery methods in Ukraine and countries in the post-conflict stage of development. The approach implies using Building Information Modeling (BIM) and Artificial Intelligence of things (AIoT) to make reconstruction faster, better and less costly. In addition, we acquire a reduction of energy consumption and increase in the lifespan of the building by choosing retrofitting methods. The effectiveness of BIM and AIoT technologies allows imple-menting modern requirements to reduce the time and cost of design, optimize design solutions based on experience in designing new buildings and structures, providing the necessary infor-mation support of the investment project throughout its life cycle.
ARTICLE | doi:10.20944/preprints202308.0532.v1
Subject: Engineering, Civil Engineering Keywords: Concrete-filled steel tubular; Travel time tomography; Piezoelectric lead zirconate titanate; Defect imaging; Parameter analysis
Online: 8 August 2023 (03:31:38 CEST)
Concrete-filled steel tube (CFST) members have been widely used in the field of civil engineering due to their advanced superior mechanical properties. However, internal defects such as concrete core voids and interface debonding are likely to weaken the load-carrying capacity and stiffness of these members, which affects safety and serviceability of CFST structures. Visualizing the inner defects of concrete core in CFST members have been a critical need in civil engineering construction, a travel time tomography (TTT) is introduced to quantitatively identify and visualize the sizes and positions of CFST members in this paper. Moreover, a parameter analysis is performed to investigate the relationship between TTT imaging qualities and influence factors, e.g. inversion parameters, defect sizes and positions. The effectiveness and accuracy of the TTT algorithm are verified by several numerical examples and the results demonstrate that TTT can identify the sizes and positions of concrete core void defects in CFST members efficiently and several inversion parameters including model weighting matrix and inversion grid size really pose a significant impact on the imaging results of CFST members. In addition, several optimum parameters are recommended to benefit the future study of the promising TTT approach for CFST members.
ARTICLE | doi:10.20944/preprints202308.0358.v1
Subject: Engineering, Civil Engineering Keywords: microplastics; activated sludge; nutrient removal; microbial activity; microbial community
Online: 4 August 2023 (14:43:30 CEST)
A large number of microplastics (MPs) have been found in various stages of wastewater treatment plants, which may affect the functional microbial activity in activated sludge and lead to unstable pollutant removal performance. In this study, the effects of different concentrations of polylactic acid microplastics (PLA MPs) on system performance, nitrification and phosphorus (P) removal activities, and extracellular polymeric substances (EPS) were evaluated. The results showed that under the same influent conditions, low concentrations (50 particles/(g TS)) of PLA MPs had no significant effect on effluent quality. The average removal efficiencies of chemical oxygen demand, phosphate and ammonia were all above 80%, and the average removal efficiencies of total nitrogen remained above 70%. High concentrations (200 particles/(g TS)) of PLA MPs inhibited the activities of polyphosphate accumulating organisms (PAOs) and nitrifying bacteria. The specific anaerobic P release rate decreased from 37.7 to 23.1 mg P/(g VSS·h), and the specific aerobic P uptake rate also decreased significantly. The specific ammonia oxidation rate decreased from 0.67 to 0.34 mg N/(g VSS·h), while the change in specific nitrite oxidation rate was not significant. The dosing of PLA MPs decreased the total EPS and humic acid content. As the concentration of PLA MPs increased, microbial community diversity increased. The relative abundance of potential PAOs (i.e., Acinetobacter) increased from 0.08% to 12.57%, while the relative abundance of glycogen accumulating organisms (i.e., Competibacter and Defluviicoccus) showed no significant changes, which would lead to improved P removal performance. The relative abundance of denitrifying bacteria (i.e., Pseudomonas) decreased from 95.43% to 58.98%, potentially contributing to the decline in denitrification performance.
ARTICLE | doi:10.20944/preprints202308.0300.v1
Subject: Engineering, Civil Engineering Keywords: hydropower; energy storage; pumped storage hydropower (PSH); batteries; net present cost (NPC); levelized cost of energy (LCOE); microgrids
Online: 3 August 2023 (11:27:08 CEST)
: There has been an ever-increasing demand for energy from the past decades. Renewable energy technologies play a major role in satisfying the energy demand as well as in a decreased CO2 emissions. Solar and Wind energies are the major upcoming technologies in renewable energies. Decentralized power production is a system where the energy production and consumption are very close to each other. Microgrids can be decentralized or grid connected and they, with renewable energy sources, encounter a problem of storage as the power production from solar and wind is intermittent. This paper discusses the comparison between using batteries and pumped storage hydropower (PSH) as an energy storage system and the integration of wind and solar PV energy sources. HOMER software simulations are used to obtain optimized renewable energy integration in microgrid and to understand its economic analysis. Two scenarios are run with the model where one considers battery and the other considers PSH to obtain the economic and technical best results of these microgrids. The economic analysis showed a lower net present cost (NPC) and levelized cost of energy (LCOE) for the microgrid with PSH. The results show that microgrid with storage of PSH is economical with an NPC of 45.8 M€ and an LCOE of 0.379 €/kWh in comparison with batteries solution which has an NPC of 95.2M€ and an LCOE of 0.786 €/kWh. The role of storage is understood by differentiating the data into different seasons using Python for data analysis. Furthermore, sensitivity analysis is made by varying the capital cost multiplier of Solar PV and Wind Turbine to obtain optimal solutions.
ARTICLE | doi:10.20944/preprints202306.0541.v2
Subject: Engineering, Civil Engineering Keywords: Artificial neural network; Procurement management; Construction budgeting; Machine learning
Online: 3 August 2023 (10:55:35 CEST)
Big data technologies are disruptive technologies that affect every business, including those in the construction industry. The Thai government has also been affected, and attempted to use machine learning techniques with the analytics of big data technologies to predict which construction projects have a winning price over the project budget. However, this technology was never developed, and the government did not implement it because they had data obtained via a traditional data collection process. In this study, traditional data were processed to predict behavior in Thai government construction projects using a machine learning model. The data were collected from the government procurement system in 2019. There were seven input data, including project owner department, type of construction project, bidding method, project duration, project level, winning price over estimated price, and winning price over budget. A range of classification techniques, including an artificial neural network (ANN), a decision tree (DC), and K-nearest neighbor (KNN), were used in this study (ANN). According to the results, after hyperparameter tuning, ANN had the greatest prediction accuracy with 78.9 percent. This study confirms that data from the Thai government procurement system can be investigated using machine learning techniques from big data technologies.
ARTICLE | doi:10.20944/preprints202308.0303.v1
Subject: Engineering, Civil Engineering Keywords: depopulation; inland areas; rural areas; seismic risk; hydraulic risk; hydrogeological risk; risk mitigation; risk measures; RI.P.R.O.VA.RE. project
Online: 3 August 2023 (10:50:47 CEST)
The abandonment of inland areas has become a major demographical challenge, establishing a condition of local fragility in terms of spatial marginalization. To deal with this issue, a number of policy actions have been released over the time, namely the National Strategy for Inland Areas, established in Italy a decade ago, and more recently the Next Generation EU (NGEU) to foster local economic recovery and employment. In this context, RI.P.R.O.VA.RE., a project funded by the former Italian Ministry of the Environment and Protection of Land and Sea (MATTM), aimed at strengthening the resilience characteristics of communities and territories, focusing on areas falling in the Matese and Ufita in Campania Region and the Medio Agri in Basilicata Region (Southern Italy). Besides the ability to respond to different pressure factors (demographics, economic, geophysical, etc.), the project dealt with seismic, hydraulic and landslide risk conditions in the Matese area, proposing mitigation measures. After presenting the developed methodology, the results obtained for the study area are presented and discussed. The procedure can be applied as supporting tool to enhance the regeneration of inland areas.
ARTICLE | doi:10.20944/preprints202308.0331.v1
Subject: Engineering, Civil Engineering Keywords: anchorage performance; UHPC grouted bellow connection; aperture ratio; anchorage length; bond-slip
Online: 3 August 2023 (10:20:44 CEST)
The UHPC grouted bellow is an innovative technology for connecting assembled buildings, where the anchorage performance of the rebar and UHPC filled in bellows plays a critical role in determining the overall connection effectiveness. To ascertain a dependable anchorage length and establish a bond-slip relationship between the rebar and UHPC within the bellow, we conducted tests on 8 groups of 16 specimens of metal corrugated pipes filled with UHPC and rebar under tension. The tests considered varying parameters such as the aperture ratio D/d and anchorage length L. By analyzing the failure modes, load versus deflection curves, and steel strain data, we gained valuable insights into the influence of the aperture ratio and anchorage length on the anchorage performance. Furthermore, we calculated the experimental curve of the bond-slip relationship between the rebar and the UHPC interface grouted in the bellows and derived a bond-slip model through fitting. These findings serve as a crucial foundation for the force analysis of assembled structures connected using UHPC grouted bellows.
ARTICLE | doi:10.20944/preprints202308.0253.v1
Subject: Engineering, Civil Engineering Keywords: Seepage erosion; Model test; DEM-CFD coupling model; Cohesionless soil; Skeleton structure
Online: 3 August 2023 (10:07:01 CEST)
Seepage erosion is one of the main reasons for the local collapse or instability of embankments. To investigate the characteristics and mechanism of seepage erosion for cohesionless soils, the model tests by using an independently developed seepage erosion device and the numerical simulations based on the Discrete Element Method-Computational Fluid Dynamics (DEM-CFD) coupling model were carried out. The results show that the seepage erosion process of the cohesionless soil can be characterized by four stages: stable seepage stage, fine particles upward migration stage, sand samples boiling stage, and erosion damage stage. The skeleton structure of soil sample under seepage flow is continually changed due to the loss of fine soil particles, which results in a significant decrease in the sample strength and may ultimately lead to the failure of the sample. The results of this study can provide references and bases for the design, construction, and long-term service of embankments or earth dams under the complex seepage condition, reducing the risk of seepage erosion.
ARTICLE | doi:10.20944/preprints202308.0251.v1
Subject: Engineering, Civil Engineering Keywords: Green pavement; Polyethylene Terephthalate; Limestone and Basalt Aggregates; Modified Asphalt mixtures; Mixture properties
Online: 3 August 2023 (05:24:28 CEST)
The global environmental impact of plastic waste is significant, with only 9% being recycled, causing pollution and harming the environment and humans. Due to increased traffic, limited funding, and dwindling natural resources, Jordan's road network is deteriorating rapidly. Pavement performance can be improved through high-quality materials and sustainable construction practices. The research investigates using Polyethylene Terephthalate as a polymer additive in asphalt mixtures to enhance their properties. Basalt and limestone mixtures were applied to asphalt mixtures. The optimal binder content for the control mixture was 4.8% for basalt and 4.93% for limestone. When modified with 10% PET, the basalt mixture showed slightly better stability than the control mix, while higher PET proportions led to reduced strength. PET-modified mixtures consistently displayed higher flows and bulk densities, with a more pronounced impact on the basalt mixture. PET increased the air-void ratio in basalt but had minimal effect on VMA. PET offers economic and environmental advantages, saving 8.4% of the original bitumen cost. As a result, limestone mixture properties, which are inferior to basalt mixture properties, improved significantly compared to basalt mixture properties. PET has the potential to create sustainable and high-performing asphalt mixtures, providing valuable insights for road construction and environmental management.
ARTICLE | doi:10.20944/preprints202308.0211.v1
Subject: Engineering, Civil Engineering Keywords: Landsat; random forest classification; performance assessment; irrigation; cropland map; remote sensing; satellite image
Online: 3 August 2023 (02:50:08 CEST)
With growing global concern of food and water insecurity, an efficient method to monitor irrigation projects is essential, especially in the developing world, where irrigation performance is often suboptimal. In Nepal, the irrigated area has not been objectively recorded, although their assessment has substantial implications on national policy, project’s annual budgets, and donor fund-ing. Here we present the application of Landsat images to measure irrigated areas in Nepal for the past 17 years to contribute to the assessment of the irrigation performance. Landsat 5 TM (2006-2011) and Landsat 8 OLI (2013-2022) images were used to develop a machine-learning model which classifies irrigated and non-irrigated areas in study areas. The random forest classification achieved overall accuracy of 82.2% and kappa statistics of 0.72. For the class of irrigation areas, the producer’s accuracy and the consumer’s accuracy were 79% and 96%, respectively. Our regionally trained machine-learning model outperforms the existing global cropland map, highlighting the need of such models for local irrigation project evaluations. We assess irrigation project performance and its drivers by combining long-term changes in satellite-derived irrigated area with local data related to irrigation performance, such as annual budget, irrigation service fee, crop yield, precipitation, and main canal discharge.
REVIEW | doi:10.20944/preprints202308.0167.v1
Subject: Engineering, Civil Engineering Keywords: bamboo culms; building Materials; Construction; codes and standards; MATLAB
Online: 2 August 2023 (07:48:01 CEST)
Bamboo is the building material of the past and future. It offers numerous properties that make it versatile for various applications, including construction. Its impressive strength-to-weight ratio enables it to bear substantial loads and stresses, while its good elasticity allows efficient energy absorption. However, its mechanical properties can vary based on factors such as species, age, locations, methods, and treatment. Treating bamboo is essential to enhance its properties and durability. The literature provides various natural and chemical treatments which enhanced some of the properties but also reported a drawbacks on higher temperature, content and duration. This paper reviewed 57 articles from Scopus database, specifically focusing on article-document type publications from the years 2003 to 2023. Additional references were also incorporated to address concerns in properties, treatment and standards to provide systematic understanding. MATLAB was utilized for data text analytics. With extensive assessment on the articles, the following gaps and concerns were observed and recommends for further study and assessment such as for bamboo properties, the development of centralized guidelines and procedures for the preparation and processing; exploration of alternative materials to reinforce bamboo without compromising its ductility; development of joint connections, and testing of mechanical properties considering seismic, wind and vibration. For treatment methods, the standardization of procedures using natural, chemical or combination. Lastly, for bamboo codes and standards, assessment of existing codes and standards for testing the mechanical properties of bamboo highlighting the potential limitations and areas, uniformity, differences with all existing similar standards. By filling these gaps, it can support the reliability and robustness of bamboo as a sustainable material, fostering its promotion and adoption in construction industry.
ARTICLE | doi:10.20944/preprints202308.0038.v1
Subject: Engineering, Civil Engineering Keywords: brick concrete aggregate; brick content; random aggregate; interface transition zone; microscopic damage
Online: 1 August 2023 (10:00:18 CEST)
To achieve sustainable development during urbanization, construction waste is recycled for use as an aggregate in recycled concrete (RC). To determine the influence of the brick content in coarse recycled aggregates on the damage sustained by the resultant RC, the RC was first divided into seven phases: natural crushed stone, old gravel inside waste concrete, bricks, new mortar, old mortar on waste concrete surfaces, and new and old interface transition zones. The Monte Carlo method was then applied to establish a two-dimensional random aggregate model of the RC made with coarse brick aggregates. The ABAQUS software package was used to simulate a uniaxial compression test, the results of which were combined with those of a macro-test to determine the internal damage change rule of brick-containing RC. The stress–strain curves obtained from the simulation coincided well with that of the macroscopic tests. As the brick content increased, the damage zone inside the specimen and the number of microcracks increased. The stress concentration area decreased, as indicated by a lower compressive strength in the macro-test. The results indicate that higher brick contents in RC yield more initial damage inside the concrete and a lower compressive strength.
ARTICLE | doi:10.20944/preprints202307.2155.v1
Subject: Engineering, Civil Engineering Keywords: Carpool; Traffic sustainability; Traffic perception; Mode Choice; Mediated Regression Analysis; CO2 Emissions
Online: 1 August 2023 (08:28:39 CEST)
As urban populations and transport demand expand, Pakistani metropolitan centers face traffic congestion and environmental challenges. This research aims to assess carpooling (CP) to alleviate traffic congestion, fuel demand, and pollution. This study was conducted in Islamabad, a fast-growing city with a high percentage of personal cars in Pakistan, to assess the travelers’ perceptions, and public acceptance of CP and determine the effects on traffic congestion, fuel consumption, and CO2 emissions. The investigation of travelers' perceptions towards CP was conducted through a stated preference questionnaire survey. A total of 700 responses from one million population of Islamabad were collected as per Sloven's Formula. SPSS and Smart PLS software were used for data analysis. Various factors influencing peoples’ travel perceptions, mode choice, and tendency to carpool, were categorized to evaluate the relationship between travelers’ perception and the tendency to carpool in the presence of mode choice as a mediating variable. Confirmatory factor analysis was conducted in SMART PLS to refine the number of scale items for each variable. One-way ANOVA, step-wise and mediated multiple regression analysis was conducted in SPSS to check the direct and mediating relationship between different variables. Moreover, the probability of reducing traffic congestion and assessing fuel reduction resulting from CP was also analyzed. The findings imply that travelers’ mode choice acts as a mediator between the relationship between travelers’ perception and tendency to carpool. Furthermore, results predicted that CP might reduce 0.25 million cars on the road, about 33.6% of the total private vehicles. Thereby, saving up to 546,810 barrels per year, about 3.42% of Pakistan's total petrol consumption. The findings of this study could be helpful for transport planners, environmentalists, and policymakers to implement carpool systems. Thus, reducing traffic congestion and harmful CO2 emissions and maintaining a sustainable environment.
ARTICLE | doi:10.20944/preprints202307.2114.v1
Subject: Engineering, Civil Engineering Keywords: Graphene oxide; Cement; Mechanical properties; Durability.
Online: 31 July 2023 (11:51:14 CEST)
The effect of graphene oxide (GO) on mechanical strengths and durability of cement composites has been studied by preparing GO-modified cement mortars. Thermogravimetric analysis (TGA) and nuclear magnetic resonance (29Si MAS-NMR) were performed on the cement paste to research the influence of GO on the hydration process and chain structure of calcium-silicate-hydrate (C-S-H) gels. In addition, mechanical strength test, such as compressive and flexural, were performed on cement mortars. The addition of GO at 0.05 wt.% (by weight of cement) increased the compressive strength by 9.02% after 28 days. Furthermore, the flexural strength of cement mortars with 0.05 wt.% GO and superplasticizer (SP) after 7 and 28 days increased by 12.26% and 21.86%, respectively, compared with reference mortar. At the same time, the effect of GO proved to be more significant and effective in the durability tests, suggesting that GO can enhance the microstructure through hydration products to create a highly cross-linked micro structure.
ARTICLE | doi:10.20944/preprints202307.2051.v1
Subject: Engineering, Civil Engineering Keywords: urban runoff; irrigation; stormwater; urban hydrology
Online: 31 July 2023 (11:50:27 CEST)
One of the main problems is handling rainwater management in urban areas is water quality from urban run-off. Currently, the emphasis is on using rainwater in cities as much as possible. The concentration of pollutants is the most problematic in rainwater. After precipitation falls on surfaces, surface water is immediately contaminated. This pollution must be cleaned or contained and transported to a wastewater treatment plant through the sewer network. Among the primary pollutants that we can identify in surface water are, for example, heavy metals. In our research, we focus on the analysis of real surface waters taken from 13 lo-cations on the territory of the Slovak Republic. The result of the research is an analysis of the suitability of reusing these waters. From the results of the analyses, it is clear that not a single sample is suitable for irrigation, as the limits of at least one monitored parameter were exceeded in all samples. The monitored lead concentration parameter was exceeded in all monitored samples.
ARTICLE | doi:10.20944/preprints202307.2107.v1
Subject: Engineering, Civil Engineering Keywords: roof; insulation; granary; carbon emission; economic analysis model
Online: 31 July 2023 (10:53:15 CEST)
The optimization design of buildings is very important the energy consumption, carbon emissions ,and sustainable development of buildings. The low-temperature granary has low grain storage temperature and high energy consumption indexes. The design scheme of roof insulation for low-temperature granary should be determined in actual building design processes by considering economy, carbon emissions, and outdoor climate, comprehensively. In this paper, the low-temperature granary roof insulation for different ecological grain storage zones in China are optimized by using a new low-carbon optimization design method. The low-carbon optimization design method can response to the economical issue, emission reduction issue, and outdoor climate issue, simultaneously. The application results of the optimization design method in ecological grain storage zones in China indicate that outdoor climate has significant impacts on the economic performance and carbon reduction effect of roof insulation. The considering of carbon emission cost can apparently increase economic efficiency of roof insulation. The optimal economic thickness of expanded polystyrene (EPS) in Urumqi, Harbin, Zhengzhou, Changsha, Guiyang and Haikou cities is 0.025 m, 0.037 m, 0.085 m, 0.097 m, 0.072 m and 0.148 m, respectively. The different outdoor climates of seven ecological grain storage areas in China have important influences on the comprehensive economic performances of low-temperature granary roof insulation. The design of low-temperature granary roof insulation in Haikou city has the best economic performances among the seven ecological grain storage zones in China.
TECHNICAL NOTE | doi:10.20944/preprints202307.2101.v1
Subject: Engineering, Civil Engineering Keywords: virtual stiffness method; Material Inelasticity and Prestress Loss Coupling Effect; excessive deflection; Palau bridge; stress redistribution; moment redistribution; boundary condition; cantilever beam; segmental concrete beam
Online: 31 July 2023 (10:40:07 CEST)
The reason for excessive multidecade deflections is still unclear after 70 years of the cantilever method that has been applied in building large-span segmental concrete bridges. The failure of the Koror-Babeldaob bridge gives the author a clue that the reason might be the boundary condition. The asymmetric properties of the bearing and prestress tendon draw the author’s attention. To understand the process of stress redistribution, the virtual stiffness method which is derived from the principle of minimum potential energy was created, and the phenomenon the author suggested named Material Inelasticity and Prestress Loss Coupling Effect is discovered. The unexplainable excessive deflection and prestress loss are found in the new load model. The calculation of excessive deflection is discussed. The new model fits the experience well. The optimization design methods and construction key points are proposed.
ARTICLE | doi:10.20944/preprints202307.1742.v2
Subject: Engineering, Civil Engineering Keywords: Slope reliability; Entry and exit method; Monte Carlo simulation; Failure probability; Critical slip surface
Online: 31 July 2023 (03:08:38 CEST)
The entry and exit method is a simple and practical method to determine the critical slip surface of slope. However, it has the drawback of sacrificing computational efficiency to improve search accuracy. To solve this problem, this paper proposes an improved entry and exit method to search for the critical slip surface. Based on the random fields generated by using Karhunen–Loève expansion method, the simplified Bishop’s method combined with the improved entry and exit method is used to determine the critical slip surface and its corresponding minimum factor of safety. Then, the failure probability is calculated by conducting Monte Carlo simulation. Two examples are reanalyzed to verify the accuracy and efficiency of the proposed method. Meaningful comparisons are made to demonstrate the calculating accuracy and calculating efficiency of the improved entry and exit method in searching for the minimum safety factor of slope, based on which the effect of the reduced searching range on slope reliability was explored. The results indicate that the proposed method provides a practical tool for evaluating the reliability of slopes in spatially variable soils. It can greatly improve the computational efficiency in relatively high-computational accuracy of slope reliability analysis.