Abstract: Lamb waves offer a series of desirable features for SHM-applications, such as the ability to detect small defects, allowing to detect damage at early stages of its evolution. On the downside, their propagation through media with multiple geometrical features results in complicated patterns, which complicate the task of damage detection, thus hindering the realization of their full potential. This is exacerbated by the fact that numerical models for Lamb waves, which could aid in both the prediction and interpretation of such patterns, are computationally expensive. The present paper provides a flexible surrogate to rapidly evaluate the sensor response in scenarios where Lamb waves propagate in plates that include multiple features or defects. To this end, an offline-online ray tracing approach is combined with FRF and transmissibility functions. Each ray is thereby represented either by a parametrized FRF, if the origin of the ray lies in the actuator, or by a parametrized transmissibility function, if the origin of the ray lies in a feature. By exploiting the mechanical properties of propagating waves, it is possible to minimize the number of training simulations needed for the surrogate, thus avoiding the repeated evaluation of large models. The efficiency of the surrogate is demonstrated numerically, through an example, including different types of features, in particular through holes and notches, which result in both reflection and conversion of incident waves.

Abstract: Including ultra-high performance fiber reinforced concrete (UHPFRC) layer in tension with normal strength concrete (NSC) significantly enhances the structural properties of concrete infrastructures. However, the durability of the interfacial bond between the two materials under aggressive chemical exposure remains uncertain. This study investigates the impact of severe magnesium sulfate exposure in conjunction with drying-wetting cycles, a common environmental challenge for infrastructures, on the mechanical properties of composite concrete systems (CCS) consisting of a UHPFRC tension layer and an NSC compression layer. In addition, the effect of varying steel fiber concentrations (0%, 1%, 1.5%, and 2%) in the UHPFRC layer was examined. The results show that the reduction in compressive strength was approximately 40% regardless of the fiber content. However, the use of fibers highly enhanced the mechanical interaction between the NSC and UHPFRC layers, resulting in superior mechanical resistance against the effect of the magnesium sulfate exposure. Adding 1% steel fibers slightly increased toughness, further increasing the fiber content to 2% resulted in a negligible effect on the energy absorption capacity under the severe magnesium sulfate environment.

Abstract: Transition zones are in the places on the track with a change in the main composition of the railway infrastructure. There are many sections with a sudden change in the stiffness of the structures built. When the trains are running, a longitudinal shock wave is created from the wheels, which hits these building objects with a higher stiffness and deforms the surroundings of these zones. The most outstanding attention should be paid mainly to the transition points from the fixed track to the classic track with a track bed, including objects of the railway substructure such as bridges, portals of tunnels, etc. As part of the research sections on the main corridor lines, a long-term inspection and monitoring were carried out using the KRAB trolley with a continuous measurement system. Height changes in the deflections of rails are evidence of their behaviour. The measurements took place on a fixed track and a track with a ballast. Changes in the height jumps between the fixed railway track and the track with a gravel bed are significant and have been recorded since the tracks were put into operation. These certain height deflections allow designers to develop new, more durable construction designs.

Abstract: The establishment of a linear seismic response analysis model that considers ground rotation effects and eccentric torsion informed the investigation of the linear response characteristics of coupled lateral-torsional vibration, considering eccentricity and ground rotation, after which the lateral–torsional coupling linear response pattern of special-shaped column structures is examined. The results show that: The floor torsion angle is the same as both the inter-story and pure torsion angles caused by eccentric torsion and ground rotation, respectively. The natural vibration frequency of the structure considering ground rotation effects is a function of relative eccentricity; the period ratio of translation to torsion caused by ground rotation; and the period ratio of translation to torsion when considering only eccentric torsion. When the translation to torsion period ratio, considering eccentric torsion, is greater than 1.0, the torsional amplitude increases remarkably, but the first order participation mode is considerably higher under the same conditions. The natural vibration characteristics, translational response, torsional response, and seismic force distribution are obtained for special-shaped columns by conducting the shaking table test on a Steel Reinforced Concrete (SRC) frame structures. After comparative analysis, the lateral–torsional natural frequency ratio considering ground rotation, torsional effect, torsional stiffness, and seismic force of the special-shaped columns are similar to the test results.

Abstract: Dam and Reservoir (D&R) systems during their long history suffered from hundreds of failures, whose mechanisms are accelerated by climate change. To assess the vulnerability of D&R systems to climate change a methodology is presented based on literature that is consistent with the EC technical guidelines. This methodology includes (i) the typologization of the groups of the potential climate hazards, the components of the D&R systems, and the impacts of the groups of hazards on D&R systems, and (ii) the presentation of climate indicators that are usually employed in D&R systems. The typologization of the methodology facilitates its fast application and its comparison with other methodologies. The methodology is applied to the Almopeos D&R system in Greece. Three General Circulation Model and Regional Climate Model combinations from the EURO-CORDEX ensemble are selected, bias-corrected against ERA5Land and used to estimate the values of the selected indicators and thus to quantify the potential climate impacts. The vulnerability analysis identified three groups of climate hazards that are (i) temperature increase and extreme heat, (ii) precipitation decrease, aridity and droughts and (iii) extreme precipitation and flooding, as potential significant hazards, for which a detailed risk assessment is required to propose the required adaptation strategies.

Abstract: The increasing frequency and magnitude of flood-related disasters has led to adopting advanced flood models to provide a better understanding of flood vulnerability, particularly for human lives. Human flood vulnerability assessment is a primary objective when planning and designing in urban areas. Results of a numerical model in the coastal hamlet of Solanas (Sardinia, IT) in terms of water velocity and depth, have been processed using the empirical method of the regional legislation (RAS) as suggested by the National Network for the Environmental Protection. Vulnerability maps and statistical parameters were compared and benchmarked with the DEFRA method largely used in UK regarded as a state-of-the-art empirical approach. The main findings from the benchmark results between the DEFRA and RAS methods suggest that the applicability threshold of RAS method can significantly underestimate the pedestrian vulnerability to urban flood in Solanas and this paper suggests a preliminary step in improving that method could consider a tentative threshold value of 0.10 m depth to assure a more realistic evaluation of human vulnerability in Solanas.

Abstract: This study presents a structural analysis of a 15-storey RCC framed building with different plan configurations, including Rectangular, L-shape, I-shape, C-shape, and an additional hexagonal plan. Using ETABS, the study evaluates key structural parameters such as storey shear, bending moments, lateral displacement, and overturning moments under different loading conditions. The analysis follows IS-875 and IS-1893 (2002) standards to ensure accurate assessment of seismic and gravity loads. The results indicate that the rectangular configuration provides the best structural stability, while irregular shapes such as L and C configurations exhibit higher lateral displacements and reduced shear resistance. The Hexagonal plan, introduced as a new alternative, demonstrates balanced performance with improved load distribution and moderate seismic resistance. The findings suggest that symmetrical designs like the rectangular and hexagonal configurations offer better structural efficiency, making them suitable choices for earthquake-prone regions. Further research can refine the hexagonal plan to optimize its load-bearing capacity and material efficiency.

Abstract: This study evaluates low-strength concrete with rubber and polymer fiber for "forgiving" safety barriers. These barriers should absorb collision energy, reduce vehicle deceleration, and minimize accident severity. Key requirements for such concrete are: low strength, low elastic modulus, high ductility, high toughness, and minimal dispersion of large fragments upon failure. The study examined various concrete mixes with varying percentages of recycled rubber (0-20% by volume) and polymer fibers (0-1.2% by volume). Compression, flexural, and dynamic impact tests were performed to assess the additions' effect on the concrete properties. Key findings include: Recycled rubber reduces concrete strength with a low contribution to energy absorption. Polymer fibers improve concrete's elongation and toughness, increasing overall energy absorption. The number of fibers in the fracture area is crucial to energy absorption. Energy absorption under dynamic load is higher than under quasi-static load. However, as the percentage of fibers increases, the results become more similar. Quasi-static tests of fiber-reinforced concrete can be used to assess its behavior under impact loads. In conclusion, combining recycled rubber and polymer fibers in low-strength concrete can be used to produce "forgiving" safety barriers. Attention should be paid to the distribution of fibers in the concrete, as it significantly impacts energy absorption.

Abstract: Digital models of water distribution networks are essential for the optimal design and management of infrastructure systems. By utilizing Building Information Modeling (BIM) technology, it is possible to develop new flow charts for the efficient design of hydraulic infrastructures. The interoperability offered by these technologies allows for the integration of various workflows, enabling tailored solutions for specific case studies. Among these tools, AutoCAD Civil 3D (C3D) is one of the most versatile BIM platforms, providing robust solutions for better integration and management of infrastructure projects. This paper introduces DyEHS, a powerful new tool that integrates seamlessly within the C3D environment. DyEHS combines the capabilities of Dynamo, EPANET 2.2, and the Harmony Search algorithm to optimize the design of water distribution networks. The tool generates a comprehensive 3D BIM model, automatically recognizing fittings and appurtenances (in C3D environment). Additionally, DyEHS simplifies the management of both the horizontal layout and vertical profiles of the network, making it an efficient and adaptable solution for water distribution projects.

Abstract: Buildings constantly consume energy to maintain internal temperature, and the thermal difference between the interior and exterior of a wall panel provides an opportunity for energy generation through the Seebeck effect. Due to their strength and durability, cement-based thermoelectric materials are gaining interest among materials scientists for their potential applications in thermal energy harvesting in buildings. Though thermoelectric cementitious materials have been developed, there has been little research into the mechanical properties of these materials with the addition of conductive fillers. This study investigates the incorporation of the carbon-based additive, reduced graphene oxide (rGO) and the transition metal oxide, manganese dioxide (MnO2) to improve the thermoelectric properties of cement composites while maintaining adequate compressive strength. In order to test both thermoelectric and mechanical properties with the same sample, cube samples measuring 50x50x50 mm were prepared instead of the typical cuboid shape samples. The Seebeck effect was assessed by heating one side of each sample to 65°C using a hotplate and recording the temperature and generated voltage. The same samples were then used for compressive strength testing, and the samples with the best properties were then subjected to microstructural analysis. The findings indicate that while both rGO and MnO2 enhance the thermoelectric properties of cement, their reactions with the cement phases produce distinct relationships with compressive strength specially when rGO and MnO2 added together. It was found that increasing rGO from 0.025 to 0.075 wt.% decreased compressive strength as workability was reduced, whereas increasing MnO2 from 2.5% to 7.5% wt.% increased compressive strength by more than 60% as workability improved. Thermoelectric properties were best in the composite sample with 0.075 wt.% rGO + 7.5% wt.% MnO2. To evaluate the integrative properties a new index called “Thermoelectric Strength Index (TSI)” is developed, which showed MnO2 is better in the integrative development of mechanical strength and thermoelectric properties in cement composites with 7.5 wt.% giving the best results.

Abstract: After developing the experimental database of RC column specimens retrofitted with stiff type polyurea (STPU), this study implemented STPU in finite element (FE) modeling. The numerical analysis aimed to evaluate seismic performance factors by establishing a structural analysis model based on the experimental data. The model was calibrated and validated against experimental results, showing consistency in maximum displacement and strain within acceptable deviations. Key findings indicate that the dissipation energy and crack propagation were significantly reduced in reinforced specimens compared to unreinforced ones, demonstrating the effectiveness of STPU and glass fiber-reinforced polyurea (GFPU). The FE model further confirmed that circular specimens exhibited superior reinforcement effects compared to rectangular specimens due to their continuous surface geometry. These results enhance the understanding of STPU's seismic reinforcement capabilities and provide a foundation for its practical application. The study results are discussed in detail in the paper.

Abstract: In this paper, we analyze the displacements of a geodetic reference pillar due to thermal loading, which typically occurs when the sunlit side of the pillar heats up more than the shaded side. This temperature differential induces bending of the pillar, resulting in the horizontal displacement of the screw used for forced centering of the instrument. Measuring displacement in the field is challenging, as it is difficult to thermally isolate the displacement sensor mount from the environment, whereas measuring rotations is much easier. Under controlled laboratory conditions, we measured the inclination of the plate with the forced-centering screw and simultaneously recorded the displacements near the top of a test pillar. We found excellent agreement between the displacements calculated from the inclination and the directly measured displacements. Our results demonstrate that using an isolated inclinometer and converting the measured inclination values into displacements provides a representative characterization of the behavior of a pillar for precise geodetic measurements.

Abstract:

Structure design in Europe should strongly follow EN 1998-1 or, so called Eurocode 8 (EC8), for a seismic resistance assessment of structures. Eurocode 8 recommends two linear methods and two nonlinear. The nonlinear methods require some knowledge about the nonlinear behavior of beams and joints in the structure, which makes the linear methods preferable. An alternative method of the seismic loading representation is to use artificial accelerograms with the same or similar spectra as the response spectrum used for modal spectrum analysis. Using an artificial diagram, three approaches in finite element methods exist: explicit time integration, implicit time integration, and modal dynamics. Typical 6-storey steel structure is modeled in finite element method and all linear methods are examined in both horizontal directions. The structure is examined by the modal response spectrum method using sufficient modes as well as with and without the residual mode. The results are compared and conclusions concerning the efficiency and precision of methods are deduced. Time-history loading by accelerograms reveals higher dynamics and stress in the structure response than modal response spectrum and lateral forces methods. The time-history analysis methods have almost no difference in accuracy and the modal dynamics method is the cheapest one.

Abstract: This paper presents an analytical solution to the Levinson beam theory (LBT) for the first-order analysis of uniform beams with simple symmetrical cross-sections, contrarily to most papers on LBT that analyzed beams with rectangular or double symmetrical cross-sections. LBT is a higher-order shear deformation theory characterized by a displacement field which includes warping of the cross-section and satisfies the shear free conditions on the lower and upper surfaces of the beam. In this study, the shear stresses were assumed to have their maximal values at the centroidal axis. This led to a displacement field that was fourth-order for beams with simple symmetrical cross-sections and third-order for beams with double symmetrical cross-sections. The equilibrium equations set on a vectorial basis were composed of two coupled differential equations combining the transverse deflection and the rotation of the cross-section at the centroidal axis: after some manipulations the governing equation (a fourth-order differential equation), the efforts and deformations were expressed in terms of the transverse deflection. Finally, closed-form solutions for efforts and deformations were presented for various loading and support conditions, as well as element stiffness matrices. The results were in agreement with those in the literature for beams with rectangular cross-sections.

Abstract:

The combination of reclaimed asphalt pavement (RAP) and foamed bitumen content (FBC) in bitumen mixtures presents a viable and economically advantageous approach to asphalt pavement construction. This investigation delves into the optimal combinations of RAP and FBC to attain a perfect performance, particularly concerning rutting resistance and tensile strength, as assessed through the Hamburg Wheel Tracking Test (HWTT) and the Indirect Tensile Strength (ITS) test. Advanced artificial intelligence (AI) methodologies, such as Random Forest, Support Vector Regression (SVR), and Linear Regression, were utilized to check performance data and attain optimal mix designs. The findings indicate that RAP content ranging from 60% to 80%, in conjunction with FBC levels between 1.5% and 1.8%, yields the most adequate performance under both wet and dry conditions, conforming enhanced rutting resistance and tensile strength.

Abstract:

The study of vibration isolation devices has become an emerging area of research in view of the extensive damage to buildings caused by earthquakes. The ability to effectively isolate seismic vibrations and maintain the stability of a building is thus addressed in this paper, which evaluates the effect of horizontal ground excitation on the response of a structure isolated by a coupled isolation system consisting of a non-linear damper (QZS) and a friction pendulum system (FPS). A single-degree-of-freedom system was used to model structures whose bases are subjected to seismic excitation in order to assess the effectiveness of the QZS-FPS coupling in reducing the structural response. The results obtained revealed significant improvements in structural performance when the QZS-FPS uses a damper of optimum stiffness. A 30% reduction in displacement was recorded compared with the QZS for two signals, one harmonic and the other stochastic. In addition, the study demonstrated that the QZS-FPS combination can offer better control of building vibration in terms of horizontal displacements.

Abstract:

The construction industry is experiencing a sweeping transformation as innovative technologies revolutionize project management, enhancing efficiency, sustainability, and safety. This study examines the integration and impact of these technologies in Chad’s construction sector, leveraging data from 79 industry participants. The research demonstrated strong reliability and validity using exploratory factor analysis, with a KMO value exceeding 0.75, statistical significance below 0.001, and a Cronbach’s Alpha above 0.8. The analysis, supported by Promax rotation, identified 15 significant factors, providing a deeper understanding of how tools like Building Information Modeling (BIM), Artificial Intelligence (AI), Internet of Things (IoT), and Digital Twin technology are reshaping construction processes. These advancements facilitate improved design accuracy, real-time decision-making, and reduced material waste while aligning with global sustainability goals such as the United Nations' SDGs. Adopting these technologies presents a crucial opportunity for Chad to modernize its construction industry and address challenges like resource inefficiency and environmental sustainability. However, significant barriers, including high implementation costs, restricted access to advanced tools, and a shortage of skilled professionals, hinder broader adoption. Overcoming these obstacles will require strategic investments in education, infrastructure, and supportive policies. By fully embracing innovation, Chad can develop a more resilient and sustainable construction sector, contributing to national growth and aligning with international sustainability efforts.

Abstract: This study examines factors affecting the thermal expansion behavior of continuous welded rails (CWRs) in urban rail systems and investigates conditions that lead to rail weld fractures. Parameters affecting CWR fractures near ventilation shafts in urban rail systems are identified through field investigations and machine learning analysis. Further, a computational fluid dynamics analysis is employed to evaluate the range of temperature variation around tunnel ventilation shafts that affects the CWR fractures. Load conditions that incorporate temperature variations are applied using a validated numerical model to analyze changes in the axial force on the CWRs. The results confirm that increased localized temperature fluctuations around tunnel ventilation shafts lead to a higher frequency of CWR fractures.

Abstract: In the context of global carbon peak and carbon neutrality, this work proposes a carbon accounting method for construction engineering based on life-cycle assessment (LCA) and construction cost quota. By incorporating China’s national standards, relevant databases and publications, three major global carbon accounting databases—ICE, EU-EFDB, and IPCC-EFDB—were expanded to enable each database to independently perform full life-cycle carbon accounting for specific construction projects in China. The method is capable of flexibly selecting different databases and quantifying the carbon emissions of construction projects, by directly importing bill of quantities. Finally, a web-based carbon accounting tool was developed, and three databases were used to conduct full life-cycle carbon accounting on three real-world construction projects, to verify the feasibility of the proposed method and compare the carbon accounting results across different databases. Our study showed that, although there were discrepancies in carbon emission results across different stages and processes for the construction projects, the proportions of carbon emissions at each stage and process were relatively consistent.

Abstract: Historic infrastructure preservation demands innovative and sustainable methodologies that safeguard structural integrity while minimizing environmental impact. This study explores the application of Remotely Piloted Aircraft Systems (RPAS) for the non-invasive inspection of the Requejo Bridge, a centennial metallic arch bridge that spans the Duero River within a protected natural environment in Spain. Through high-resolution aerial surveys, RPAS technology enabled the exhaustive assessment of areas traditionally difficult to access, identifying localized corrosion and material degradation critical for preventive conservation planning. By eliminating the need for scaffolding and heavy machinery—elements that pose significant ecological risks to sensitive landscapes—the drone-based inspections substantially reduced carbon emissions and resource consumption, while optimizing operational costs and minimizing workplace hazards. The findings confirm that RPAS not only enhance the accuracy and efficiency of structural diagnostics but also embody a sustainable maintenance strategy aligned with multiple Sustainable Development Goals (SDGs), including climate action, responsible resource use, and occupational safety. This research advocates for the widespread adoption of drone-assisted methodologies in heritage infrastructure management, offering an environmentally responsible, economically viable, and safer alternative that extends the service life of historic structures through proactive and minimally invasive interventions.