Engineering

Abstract: This study examined the mechanical and hygrothermal response of cement mortars in-corporating recycled low-density polyethylene (LDPE) as a partial replacement of fine ag-gregate at levels of 2.5%, 5.0%, and 7.5% by weight of sand. A reference mixture without polymer was also prepared. The experimental program included determining density, workability, and compressive strength at 7 and 28 days. Based on the mechanical results, the formulation containing 2.5% LDPE was selected for further hygrothermal assessment in 1:5 scale chambers coated with conventional and modified mortars. The incorporation of LDPE progressively decreased both density and compressive strength. At 28 days, the reference mortar reached 5.243 MPa, whereas the mixture with 2.5% LDPE attained 1.461 MPa. Hygrothermal monitoring showed no substantial improvement in indoor tempera-ture regulation; however, the LDPE-modified coating maintained higher indoor relative humidity than the conventional system during the test period. These results indicate that recycled LDPE can be incorporated into cement-based mortars at low replacement levels for exploratory non-structural applications. However, the resulting decrease in mechani-cal strength restricts its wider applicability and highlights the necessity for further verifi-cation to satisfy performance standards tailored to specific applications.

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Trenchless technologies are critical for global urban sewerage construction; however, existing Life Cycle Assessments (LCA) predominantly focus on horizontal segments under standard soft soil conditions, neglecting the massive embodied carbon of "vertical nodes" in extreme geology. Based on EN 15804, this study conducts an upfront carbon (A1–A5) inventory and scenario analysis of microtunneling shafts in Hualien, Taiwan, characterized by deep excavations (10–12 m) and hard gravel formations (SPT N > 50). The research reveals a dual climate challenge induced by extreme geology: the "Geological Premium" resulting from increased machinery energy consumption, and the "Forced Carbon Lock-in Effect" triggered by the necessity of high-strength permanent structures. Empirical results demonstrate that the product stage (A1–A3) of vertical nodes accounts for 51.1% of total emissions, while the construction stage (A5) contributes 42.5%. Consequently, a material-based compensation mechanism is proposed. Scenario simulations verify that introducing geopolymer precast manholes (50% cement replacement) generates a "Green Premium" that effectively neutralizes the construction's geological premium. This study fills the LCA gap for underground infrastructure, providing scientific support for integrating geological variables and low-carbon materials into Green Public Procurement (GPP) policies.

Abstract: Urban flooding in rapidly urbanizing coastal megacities is increasingly intensified by climate variability, declining permeability, ecological degradation, and infrastructure pressures. In Mumbai, India, flood management continues to rely predominantly on conventional grey stormwater infrastructure despite growing international advocacy for Blue-Green Infrastructure (BGI). However, limited research has examined institutional readiness and governance conditions shaping BGI design, planning and implementation within Indian municipal systems. This study investigates institutional knowledge, perception, and implementation readiness regarding BGI within the Municipal Corporation of Greater Mumbai (MCGM) through a mixed-methods approach combining informal interviews with senior municipal officials and a structured survey administered across the Storm Water Drains (SWD), Planning, and Gardens departments. The findings indicate that Mumbai’s stormwater governance framework remains largely engineering and drainage-capacity oriented, with flooding increasingly recognized as a multi-causal challenge associated with high-intensity rainfall, reduced permeability, drainage limitations, tidal interactions, and rapid urbanization. While institutional responses continue to prioritize grey infrastructure interventions, the interviews and survey findings reveal growing openness toward ecological and hybrid grey–green approaches within future flood-management planning. The survey findings demonstrate widespread institutional awareness regarding flooding occurrence and strong willingness toward BGI implementation across departments. However, technical understanding related to BGI multifunctionality, hydrological performance, implementation mechanisms, and limitations under extreme rainfall conditions remained comparatively uneven across institutional groups. The Planning Department demonstrated comparatively stronger conceptual understanding of BGI and ecological planning approaches, while the SWD and Gardens departments demonstrated comparatively stronger implementation willingness despite lower technical familiarity. The study identifies an important institutional gap between conceptual understanding and implementation readiness within the MCGM and highlights the need for integrated governance, technically grounded hydrological capacity building, and context-specific ecological planning approaches. The findings contribute empirical insights into governance transitions shaping hybrid grey–green stormwater management within dense tropical coastal megacities and support the development of integrated ecological and climate-resilient urban flood-management frameworks.

Abstract: This study evaluates the feasibility of using asphalt concrete as an impermeable core material for rockfill dams under tropical conditions. Laboratory testing and numerical modeling were conducted to assess the hydraulic and mechanical performance of asphalt concrete mixtures produced with locally available aggregates in Thailand. Asphalt mixtures were designed using the Marshall method with asphalt binder contents of 6% and 7% and target air void contents between 1-4%. Laboratory testing included permeability testing, Marshall stability testing, and triaxial compression tests to determine hydraulic conductivity, shear strength parameters, and deformation characteristics. Results show that asphalt concrete mixtures with air void contents below 1% exhibit extremely low permeability, with hydraulic conductivity on the order of 10⁻¹¹–10⁻¹² m/s, satisfying requirements for impervious dam cores. Triaxial compression tests yielded cohesion values between 97-572 kPa and friction angles ranging from 31° to 52°, indicating adequate shear resistance. Numerical simulations performed using GeoStudio compared rockfill dams with asphalt concrete cores and conventional clay cores. The results demonstrate that a 0.5‑m‑thick asphalt concrete core provides comparable seepage control and slope stability while requiring significantly smaller material volume. The findings suggest that asphalt concrete cores represent a technically feasible and economically advantageous alternative to clay cores, particularly in regions where suitable clay materials are limited.

Abstract: The social dimension of sustainability in building construction has long occupied an uncomfortable position in the research literature; acknowledged in theory, yet sidelined in practice. Environmental performance dominates assessment frameworks globally, while economic viability commands institutional attention. What is left, all too often, is a thin layer of social indicators that lack contextual grounding, statistical validation, or practical operationalizability, particularly in rapidly urbanizing settings across the developing world. This study confronts that gap directly. Drawing on an original mixed-methods investigation conducted across the twin cities of Rawalpindi and Islamabad, Pakistan, we develop and validate a comprehensive social sustainability assessment framework specifically tailored to building construction projects in South Asian urban environments. Employing a three-round Delphi technique with industry experts, a structured Likert-scale survey administered to 50 experienced construction professionals, and confirmatory factor analysis (CFA) using AMOS, the study identifies and statistically validates eighteen social sustainability indicators organized under five latent constructs: (i) Social Responsibility and Human Well-being, (ii) Institutional Governance and Knowledge, (iii) Stakeholder Engagement and Community Trust, (iv) Workforce Development and Labor Equity, and (v) Inclusive Design and Service Accessibility. Reliability analysis returned a Cronbach's alpha of 0.984, while the Relative Importance Index (RII) ranked project experience (SCL8, RII = 0.856), health, safety and environment at the site (SCL7, RII = 0.848), and project manager awareness (SCL12, RII = 0.828) as the most influential indicators. Kruskal-Wallis tests confirmed cross-group consensus. Crucially, the study finds that social sustainability is not merely a welfare afterthought, it is deeply interwoven with economic performance and environmental stewardship through measurable cross-pillar correlations. The resulting framework, the first of its kind validated through expert consensus and inferential statistics within the Pakistan context, offers a practical decision-support tool for project managers, urban planners, and regulatory bodies including the Pakistan Engineering Council (PEC) and the Capital Development Authority (CDA). Broader implications for South Asian and developing-country construction governance are discussed.

Abstract: We present a 3D laser-scanning method for fast, accurate dimensional inspection of large high-speed-rail precast box girders. The pipeline uses low-pass filtering plus sequential registration to suppress noise, and voxel filtering with curvature-aware enhancement to reduce point-cloud size by 3–5× while preserving key geometry. Reconstruction employs K-nearest-neighbors and PCA to detect boundaries and curvature jumps, B-spline fitting with moving least squares for surface completion, and CSS corner detection to extract key dimensions at millimeter precision. Field tests report absolute errors ≤2.0 mm versus manual measurement, validating the method for automated, digital acceptance.

Abstract: Fenestration systems play a critical role in building thermal performance, particularly in cooling-dominated climates where envelope inefficiencies directly amplify electricity demand. In Saudi Arabia and other Gulf Cooperation Council (GCC) countries, cooling accounts for the majority of building energy consumption. Nevertheless, the façade and insulated glass industries are experiencing rapid market expansion. Despite this technological evolution, prevailing regulatory frameworks, including the Saudi Building Code (SBC), ASHRAE 90.1, and the International Energy Conservation Code (IECC), primarily rely on area-weighted U-values and solar heat gain coefficients (SHGC), without explicitly integrating multidimensional thermal bridge effects such as linear thermal transmittance (ψ). This paper investigates the structural omission of ψ within current energy compliance systems, evaluates its implications in cooling-dominated climates, and proposes a phased regulatory integration pathway aligned with sustainability objectives under Vision 2030. Literature synthesis indicates that thermal bridges may increase cooling loads by up to 25% and total building energy use by 5–30%, while remaining structurally omitted from compliance metrics. The findings highlight the need to transition from simplified prescriptive compliance toward physics-informed governance capable of addressing evolving façade complexity in hot-arid environments. The proposed framework offers a systematic pathway for integrating linear thermal transmittance requirements while supporting regional sustainability goals and the advancement of high-performance building technologies.

Abstract: This paper presents a laboratory-validated integrated assessment framework combining Ground Penetrating Radar (GPR) and Electrical Resistivity Tomography (ERT) for the non-destructive evaluation of reinforced concrete (RC) structures. A single RC beam specimen (3000 × 300 × 200 mm; C30/37, w/c = 0.50, CEM I 42.5N; 3 × T12 at 35 mm soffit cover) was subjected to four precisely controlled deterioration states: intact dry (Model A), water-filled crack (Model B), fully saturated (Model C), and chloride-induced active corrosion (Model D). Seven ERT datasets were acquired using a Wenner-Schlumberger array at electrode spacings of a = 7, 15, and 30 mm, and three 800 MHz GPR profiles were recorded for Models A, B, and C/D respectively. The ERT results demonstrate a systematic three-orders-of-magnitude decrease in median resistivity from the intact state (ρ₀ = 558 Ω·m) to the corroded condition (ρ = 10.6 Ω·m), with a depth-preferential low-resistivity distribution at rebar depth (z ≈ 24–48 mm; ρ < 10 Ω·m) providing partial discrimination between active corrosion and bulk moisture saturation. GPR analysis at 800 MHz confirms a reference wave velocity of v = 0.096 ± 0.008 m/ns by hyperbola fitting, localised 25–35% amplitude attenuation at the water-filled crack position, and pervasive 50–65% attenuation under saturated and corroded conditions. A four-stage integrated interpretation framework is validated against known ground-truth conditions: Stage 1 establishes local reference baselines (ρ₀, A₀); Stage 2 identifies anomalies against threshold criteria; Stage 3 cross-validates co-located GPR and ERT signatures; Stage 4 assigns risk categories 1–4. Explicit failure mode analysis identifies six conditions under which the framework is unreliable, most critically the moisture–corrosion ambiguity and the invisibility of dry cracks. The framework correctly classifies all four beam conditions and provides higher diagnostic confidence than either method applied independently.

Abstract: Intense rainfall, and the resulting increase in ground saturation can significantly modify the mechanical performance of rock masses in natural slopes. This is particularly important if material fractured is present. Extended infiltration accelerates material degradation, reduces shear strength along discontinuities, and increases pore-water pressures, reducing effective stresses, and in turn, raises the probability of large-scale landslides. Evaluating these processes requires a thorough understanding of the geotechnical and hydrogeological properties controlling slope response, as well as reliable stability assessments under varying saturation conditions, including factor of safety and deformation estimates. However, in engineering practice most of the time ground exploration is limited, and laboratory testing in rocks only provides an estimation of the rock performance expected in the slope within a reduced zone. This study examines a landslide triggered in a shale–limestone slope after heavy rainfall. A back-analysis was performed within a performance-based design (PBD) framework to reproduce the observed failure and, thus, characterize representative geomechanically parameters for design validation, using three-dimensional finite difference modeling. The performance under monotonic and seismic loading of a tunnel built adjacent to the slope was analyzed as a mitigation measure, thus establishing its technical soundness, from both state limit of failure and service, of the tunnel-slope system.

Abstract: In Jordan, the construction industry and businesses are burdened by the high prices of materials in terms of extraction, production, transportation, and purchasing, as well as the volatility of their market value. The environment is primarily affected by construction and demolition activity since the construction sector in Jordan is based on a linear economy model and does not rely on the circular economy (CE) by reusing or recycling building materials rather than discarding them. Therefore, this study aims to develop a CE framework for managing construction waste in residential buildings during the construction phase and facilitating the adoption of the proposed model within the construction sector in Jordan. Therefore, a questionnaire was distributed to 31 experts, the results were analyzed, and the Delphi technique was then applied to validate the proposed framework and study findings. The findings indicate that the CE contributes to minimizing construction waste. The researcher sought to identify the most significant challenges hindering the implementation of the CE. The most influential challenges were low demand for reused or recycled materials, limited stakeholder awareness, and difficulties in disassembly. Furthermore, the results indicated use of visual management and 5S techniques, the use of BIM to map materials and components for circular lifecycle planning, and offering tax incentives and grants for using recycled materials are the most important strategies for minimizing construction waste. This study contributes to minimizing construction waste and advancing sustainable development, while also supporting Jordan’s Vision 2025 as outlined by the Jordanian government and the Ministry of Environment.

Abstract: Limited access to clean water and reliable electricity infrastructure remains a major challenge in many remote regions of Indonesia, particularly for building‑scale domestic use. Conventional water treatment systems are often constrained by high operational costs and dependence on grid power, highlighting the need for sustainable and autonomous infrastructure solutions. This study presents the design, development, and performance evaluation of an integrated solar‑powered clean water treatment system for smart building applications in remote areas using a Research and Development (R&amp;D) approach. The proposed system combines off‑grid polycrystalline photovoltaic panels with a multi‑stage water treatment process consisting of a floss (mud) filter, activated carbon filter, water hyacinth cellulose bio‑filter, ultraviolet (UV) sterilization unit, storage tank, and an IoT‑based real‑time water quality monitoring system. System performance was evaluated through microbiological, physical, and chemical water quality testing, with monitoring conducted via Wi‑Fi‑enabled sensors connected to the Blynk platform. The results demonstrate substantial improvements in treated water quality. Escherichia coli and total coliform bacteria were eliminated (100% reduction). Total dissolved solids (TDS) decreased from 450 mg/L to 218 mg/L (51.6%), and dissolved manganese was reduced from 30 mg/L to 0.01 mg/L (99.97%), while nitrate levels decreased by 50%. Water pH and temperature remained stable and within regulatory limits. All treated water parameters complied with national clean water standards for hygiene and sanitation. The system operated independently using solar energy and achieved a clean water production capacity of 1,000–1,500 L/day. These findings indicate that the proposed system is a feasible, cost‑effective, and sustainable civil engineering solution for clean water infrastructure in remote building environments.

Abstract: Ground failure during major seismic events associated with soil liquefaction can lead to major structural damage in both the columns and the bridge upper deck, due to large seismic-induced displacements in the support foundation. Liquefaction-driven ground motion incoherence during the dynamic event, and permanent soil deformations are key variables in the observed damage. This paper summarizes a numerical study of an alternative bridge foundation design proposed to reduce support displacements and bearing capacity failure during and after an earthquake, as well as relative settlement associated with partial loss of bearing capacity when the bridge column is founded on a potential liquefiable layer. Three-dimensional numerical models were developed using FLAC3D. The seismic environment was characterized by a uniform hazard spectrum, UHS, for intraplate and interplate earthquakes, as presented in the current construction Mexico City regulations. Initially, a one-dimensional analysis was performed using SHAKE to evaluate liquefaction susceptibility. Results show that the structured cell foundation reduces excess pore pressure generation by up to 42% compared to shallow foundations and 25% compared to pile systems. This improvement is associated with (i) restriction of cyclic shear strain, (ii) modification of deformation patterns, (iii) partial hydraulic isolation of the confined soil, and (iv) preservation of effective stresses during shaking. Additionally, the system reduces shear strain localization and decreases acceleration transmitted to the superstructure by up to 25%. The findings demonstrate that structured confinement systems can significantly alter the mechanisms governing liquefaction, offering a promising alternative for bridge foundations in seismic regions.

Abstract: Determining the compatible prestress and geometry under self-weight constitutes a key challenge in the form-finding of cable-truss structures. To overcome the limitations of experience-dependent trial methods and enhance computational efficiency, this paper proposes an automated and integrated methodology by synergistically combining a simplified mechanical model with an improved Particle Swarm Optimization (PSO) algorithm. The core of the method lies in formulating the form-finding process as an optimization problem, where the horizontal inclination angles of the lower chord cables serve as the design variables for all radial cable-truss frames. To efficiently solve this high-dimensional optimization problem, an improved PSO algorithm, which introduces logistic chaotic mapping for particle initialization and a mutation operator within the iterative loop. Ablation studies confirm the individual contribution of each algorithmic enhancement. The algorithm intelligently searches for the optimal angle set, thereby simultaneously resolving the prestress and geometry. The proposed approach is rigorously validated through two representative numerical examples: a circular Type I and an elliptical Type II cable-truss, considering both cases with and without self-weight. The results demonstrate that the improved PSO-based solution achieves prestress distributions and nodal coordinates in excellent agreement with established benchmark data. More importantly, it attains this high precision with significantly reduced computational cost in terms of particle swarm size and iteration number. In conclusion, this improved PSO‑based approach provides an efficient, accurate, and automated tool for the integrated prestress‑geometry design of cable‑truss structures, demonstrating strong potential for practical engineering application.

Abstract: The growing demand for sustainable and economically efficient road maintenance solutions has driven the development of materials that reduce the use of natural aggregates and promote waste valorization. In this context, this study evaluates the use of reclaimed asphalt pavement (RAP) and Panasqueira mine waste, in the form of greywacke aggregates, as partial or total substitutes for granite aggregates in cold asphalt mixtures intended for rapid pothole repair. Reference mixtures and recycled mixtures were produced with controlled proportions of RAP and greywacke, using cationic bituminous emulsion and hydrated lime, as well as an additional mixture composed only of RAP with a fluxing cold binder. Three commercial mixtures, identified as CCM1, CCM2, and CCM3, were also evaluated. Performance was analyzed through Cantabro particle loss, Marshall stability and flow, indirect tensile stiffness modulus, and water sensitivity (ITSR). The results show that greywacke provides a robust granular skeleton, while RAP content and binder type influence stiffness, cohesion, and moisture resistance. Overall, the combination of RAP and greywacke proved to be technically viable and, in several cases, superior to the commercial mixtures studied.

Abstract: Piles with continuous helix (referred to herein as "screw pile") is a new configuration of helical piles. It features a continuous helix spiraling several pitches around a smooth shaft forming a "threaded shaft". This study investigates the compressive capacity and behavior of helical and screw piles using 3D numerical models calibrated and validated against full-scale field testing. The bearing capacity factor, Nc, for helical piles is back-calculated from the numerical results and compared against standard theoretical assumptions to evaluate their accuracy in predicting ultimate capacity. Parametric studies are conducted considering screw piles configuration, including shaft diameter, pitch size, helix diameter, as well as soil strength. The results reveal that shaft resistance accounts for up to 89% of the total capacity. Analysis of load distribution, shear contours, and displacement contours at failure allowed for the identification of different failure modes of soil adjacent to the pile’s threaded shaft: Individual Bearing Mode (IBM), Cylindrical Shear Mode (CSM), and a combined mode. The study identifies specific parametric thresholds for these modes in both sand and clay layers. Furthermore, varying clay strength is found to alter the development of the shear surface, transitioning from localized bearing to continuous shearing along the threaded shaft. Finally, apparent shaft resistance factors, α and β, are back-calculated to provide ractical parameters for evaluating the resistance of threaded shafts in layered soil.

Abstract: Infrastructure expansion in Indonesia has increased the demand for paving blocks, raising concerns regarding cement production costs and environmental impact. This study investigates the comparative effectiveness of pineapple leaf fibre (PALF) and sisal fibre as natural reinforcements to enhance paving block performance. An experimental design was employed with fibre contents varying from 0% to 7% by cement volume. Specimens were cured for 28 days and tested for water absorption and compressive strength; analysis was performed using descriptive statistics and two-way ANOVA. Results indicated that fibre content significantly influenced both response variables (p < 0.001). Water absorption increased monotonically with fibre content, while compressive strength exhibited an inverted-U relationship with a distinct optimum at 3% fibre addition. Sisal fibre exhibited greater mechanical enhancement than PALF, achieving a maximum strength of 15.2 MPa at 3% (R² = 0.973), meeting Indonesian National Standard SNI 03-0691-1996 Class B requirements (minimum 12.5 MPa). A significant interaction between fibre type and fibre content was identified for compressive strength (F = 3.697, p = 0.012), confirming that the response to dosage differs between the two species. These findings demonstrate the potential of agricultural waste fibres for producing sustainable, eco-friendly paving blocks, supporting circular economy principles in the construction industry.

Abstract: Previous studies by the authors and others have shown that ultra-high performance concrete (UHPC) is an ideal printing material for 3D concrete printing (3DCP). However, its high carbon emissions may limit its application in 3DCP. As a solution, this study reports the development of a 3D-printed low-carbon UHPC using limestone calcined clay cement (LC3), denoted as 3DP-LC3-UHPC. The fresh and hardened properties of 3DP-LC3-UHPC were evaluated and compared with those of conventional 3D-printed UHPC using Portland cement (3DP-PC-UHPC). Conventionally mold-cast mixtures were also prepared for comparison. Fresh properties included flowability, setting time, rheological properties, extrudability, and buildability. Hardened properties included compressive strength and flexural performance in different directions. The effect of two curing regimes (heat- and ambient temperature-curing) on hardened properties was also investigated. The results showed that 3DP-LC3-UHPC possessed higher dynamic yield stress, plastic viscosity, and thixotropy recovery, and exhibited satisfactory extrudability and buildability. The 3DP-LC3-UHPC achieved compressive strengths of 130.4-169.4 MPa and flexural strengths of 26.9-30.6 MPa, depending on the testing direction. Environmental and cost assessments confirmed that 3DP-LC3-UHPC reduces carbon dioxide emissions, embodied energy, and cost by about 25%, 10%, and 9%, respectively, compared to 3DP-PC-UHPC. Overall, the findings demonstrate that 3DP-LC3-UHPC is a sustainable and cost-effective alternative to conventional 3DP-PC-UHPC.

Abstract: Since tires from end-of-life vehicles are not entirely biodegradable and pose a serious environmental problem, their disposal has grown to be a significant global environmental concern. One technique to decrease these environmental issues is incorporating waste rubber to make sustainable green concrete. This study examined the usage of waste supplementary cementitious materials (SCMs) such as fly ash (FA), metakaolin (MK), marble powder (MP), slag (SL), and silica fume (SF) for surface precoating of crumb rubber (CR) to improve the mechanical properties of the produced crumb rubber concrete (CRC) by strengthening the bond between CR and cement paste in the Interfacial Transition Zone (ITZ). The CR replaced (0, 15%, and 25%) of sand by weight in the preparation of CRC mixtures. A total of eleven CRC mixes were cast to investigate the fresh properties, compressive strength, and splitting tensile strength. In addition, the compressive stress-strain curve was investigated, and peak stress, peak strain, energy absorption, toughness, and modulus of elasticity have been evaluated. The outcomes showed that pre-coating CR using FA, followed by MK, has the maximum effect in increasing the CRC compressive performance. The 25% substitution of sand with FA-treated CR increased compressive strength after 28 days, splitting tensile strength, peak stress, toughness, and modulus of elasticity by 34.7%, 23.7%, 34.8%, 26.1%, and 25.2%, respectively, in comparison to the same percentage of untreated CR. The proposed approach demonstrates a viable pathway for integrating waste materials and SCM-based technologies to develop high-performance, sustainable cementitious composites.

Abstract: Sensors are a fundamental component of Structural Health Monitoring (SHM) systems. Among the different types of sensors, piezoelectric (PZT) sensors are widely used due to their desirable properties, such as dual actuation–sensing capability, high sensitivity, low cost, and suitability for real-time monitoring. In addition to proper sensors, SHM also requires effective signal processing techniques for interpreting the data acquired by the sensors. Recently, the rapid advancement of Artificial Intelligence (AI) has significantly improved the automated SHM of structures and demonstrated how effective SHM can become when combined with artificial intelligence. Thus, the use of appropriate sensors, effective signal processing techniques, and AI can significantly enhance SHM performance. Guided by these developments, this paper presents a critical review of signal processing and machine learning approaches in PZT-based SHM systems, with emphasis on engineering structures. The fundamental principles of PZT sensing and wave propagation are first outlined. Next, signal processing techniques and their importance in SHM are discussed with a focus on recent advancements in the use of AI in PZT-based SHM. This work also discusses the Hybrid frameworks that integrate signal processing with data-driven AI models which are promising directions for improving robustness and accuracy of SHM. Finally, existing key challenges such as environmental variability, sensor degradation, data scarcity, and model generalization are discussed, along with future directions including physics-informed learning, transfer learning, explainable AI, and baseline-free SHM systems.

Abstract: The proliferation of high-speed railway (HSR) networks necessitates frequent construction activities adjacent to operational lines, posing significant risks to the structural integrity and safety of existing infrastructure. This study addresses the critical need for a comprehensive framework to assess and monitor the deformation of HSR piers throughout the entire construction process of a new, nearby bridge, which includes the cumulative effects of both substructure and superstructure construction. A hybrid methodology integrating quantitative risk assessment and real-time, non-contact monitoring was developed and implemented. A risk evaluation model was established using the Analytic Hierarchy Process (AHP) to structure the problem, combined with Triangular Fuzzy Numbers to handle the inherent uncertainties in expert judgments. The Fuzzy Comprehensive Evaluation method was then employed to quantify the risk levels of various construction stages. Concurrently, a vision-based monitoring system utilizing Digital Image Correlation (DIC) technology was deployed to capture the three-dimensional deformation of adjacent HSR piers with high precision and frequency. The case study, focusing on the construction of a new bridge crossing the operational Beijing-Shanghai HSR, demonstrated the application of this framework. The risk assessment model identified the pile cap and pier construction phase as the highest-risk stage, with a risk weight of 0.311. The DIC monitoring system, validated against total station measurements with a relative error of less than 5%, recorded the cumulative pier deformations throughout 31 distinct construction stages. The maximum recorded deformations in the transverse, longitudinal, and vertical directions were all maintained within the early warning threshold of ±1.2 mm stipulated by railway regulations. The study confirms that the integrated AHP-Fuzzy and DIC framework provides a robust paradigm for proactive risk management in adjacent-line construction projects. The risk model accurately predicted the most critical construction phase, and the DIC system offered a reliable and efficient solution for real-time safety assurance. The findings validate that with appropriate risk-informed monitoring, the impact of new bridge construction on existing HSR infrastructure can be effectively controlled within safe limits, offering a valuable reference for similar engineering projects globally.