High-strength built-up columns in modern structures offer efficiency and load capacity, but axial impact behaviour remains poorly understood currently. A comprehensive numerical investigation was performed using 88 finite element models developed in ABAQUS/Explicit. This study analysed twenty unique cross-sectional designs, two column lengths (420 mm and 800 mm), three hammer velocities (3000, 7000, and 10,000 mm/s), and three hammer weights (224, 424, and 824 kg). The finite element models were tested against previously published experimental results to ensure accuracy in simulating dynamic impact behaviour. Cross-sectional geometry was identified as the principal factor influencing axial impact resistance, with double-web and wide-flange sections demonstrating the greatest capabilities and energy absorption levels. Dimensional scaling markedly improved resistance; however, the column length affected the failure modes, ranging from localised crushing in shorter specimens to a combination of local and global buckling in longer components. The correlation between hammer velocity and mass exhibited nonlinear traits, with peak performance achieved at intermediate velocities and modest masses due to a balance between strain-rate hardening and stability. The recognised failure mechanisms included local buckling, tearing at connection sites, corner cracking, and flexural deformation. The findings provide critical insights into the relationships between geometry, loading circumstances, and failure mechanisms in high-strength built-up columns.
Cable force estimation is critical for ensuring the structural health of cable-stayed bridges. This study assesses the accuracy of three vibration-based models - classical string theory, a least-squares beam formulation, and a two-mode beam combination - using lift-off test results as ground-truth validation. Field measurements were analysed to extract natural frequencies, which served as inputs to predict axial forces. The correlation between estimated forces and lift-off measurements was evaluated using the Pearson coefficient and mean absolute error (MAE). Results show strong agreement between vibration-based estimates and lift-off forces, with correlation coefficients ranging from 0.8610 to 0.8619. Beam-theory approaches outperformed the string model, achieving 7-8% lower MAE confirming that incorporating bending stiffness and multi-mode effects improves accuracy. However, small numerical differences suggest axial tension remains the dominant factor, with flexural rigidity having minor influence on long and slender cables. The near-perfect correlation between the beam-based models (r > 0.9996) highlights their internal consistency. Overall, these findings demonstrate that vibration-based models are reliable tools providing essential insights for structural health monitoring and maintenance strategies.
Design methods for extra-large-diameter welded hollow spherical joints (WHSJs; diameter > 900 mm) are essential for engineering applications. This study presents a parametric analysis of the ultimate axial compressive capacity of such joints, utilising finite element models calibrated against experimental data. The investigation focuses on the effect of sphere diameter, tube diameter, wall thickness, stiffener height, and stiffener thickness, on failure modes and ultimate capacity. The results reveal that the failure mode of extra-large-diameter WHSJs under axial compression is characterised by a circumferential plastic hinge at the tube-sphere junction following substantial plastic deformation. For unstiffened joints, the ultimate capacity is positively correlated with the tube-to-sphere diameter ratio. Increasing the height and thickness of stiffeners significantly enhances the load-bearing capacity of the hollow-sphere wall. To facilitate design optimisation, the joint capacity is decomposed into two components: (1) the enhanced capacity of the stiffeners, and (2) the bearing capacity of the stiffener. Building on this decomposition model, an analytical formula is proposed to evaluate the ultimate compressive capacity of extra-large-diameter WHSJs. The accuracy of this formula is subsequently validated against parametric analysis results.
This study investigates the critical buckling load of cold-formed thin-walled complex rolled-edge channel steel (CF-TWCRC) columns under eccentric axial compression. An energy-based theoretical model incorporating torsion and warping effects was developed and validated experimentally using columns of varying heights (21-72 mm) and lengths (330-530 mm). Failure modes transitioned from flexural-torsional buckling (small sections) to local-global interaction (large sections) with increasing slenderness. Nonlinear finite element models (ABAQUS/S4R shells) accurately simulated complex buckling behaviours. Results show: (1) Theoretical predictions align with experiments (errors <10%) and simulations (errors <6.3%), confirming model reliability; (2) Load eccentricity significantly reduces buckling capacity by inducing compression-bending coupling; (3) Section height and member length critically govern failure modes and strength. The proposed model provides essential tools for safe CF-TWCRC column design under realistic eccentric loading.
This article proposes a novel approach for constructing ground-supported structural slabs. It applies machine learning (ML) to predict the residual flexural strength of fibre-reinforced concrete under bending. Adaptive Boosting (AdaB) estimates post-peak flexural strength of steel-fibre-reinforced concrete at two crack-width levels. A few of these crack widths are 0.5 mm (fR,1) as well as 2.5 mm (fR,3). Two advanced optimisation methods, Catch Fish Optimization (CF) and Coati Optimization (Co), are assessed for this reason. The AdaB models' performance is significantly influenced by their hyperparameters, which can be changed through optimisation methods. In order to obtain data, 216 test samples were collected. The dataset was split into 20% (44) for evaluation, and the rest 80% (172) was used in learning and model construction. Various pre-processing steps are carried out to introduce the dataset to the models. Tenfold cross-validation, the normalisation and randomisation process and feature importance are some of these steps. The results indicated that AdaB-CF has the smallest U95% values of 1.82496 and 1.4848 (fR,1) and 2.1401 and 1.709 (fR,3), but AdaB-Co displays higher U95% values during both the training and assessment stages, recording 1.9244 and 1.7138 (fR,1) and 2.3463 and 1.7951 (fR,3). All models are reliable, but AdaB-CF shows superior performance.
A comprehensive study was conducted to evaluate seismic-induced stresses, structural response, and differential settlement between consecutive bridge foundations considering soil-pile interaction. The bridge analysed has mixed foundation types: a mat foundation on hard rock at the end support and a pile foundation in soft soil at the mid support. A three-dimensional finite element model with nonlinear spring elements was developed to simulate pile-soil interaction. Twelve spectrum- matched seismic records to the target maximum-level ground motion were selected, consistent with NBC 105:2020 and normalized to the bridge's natural period and resulting accelerograms were scaled in 0.025g increments upto 1.5g for incremental dynamic analysis. Key responses, including stresses in piers and piles, vertical and lateral displacements, and curvature, were recorded and compared between two models: rigid pile base (Model A) and flexible base (Model B). Results indicate that flexible foundations reduce stress demand but significantly increase displacement-related vulnerabilities, highlighting a critical design trade-off. The performance of the Tuninara Bridge underscores the importance of detailed geotechnical investigation, accurate soil-structure interaction modelling and foundation solutions. The findings provide practical insights for the design, assessment, and retrofitting of bridges in Nepal's seismically active and geotechnically complex regions.
Earthquake damage assessment is essential for effective disaster response and resilience plan-ning. Many existing machine learning models lack the engineering interpretability necessary for practical decision-making. This research presents an interpretable framework applied to the 2015 Gorkha earthquake in Nepal, employing XGBoost and SHAP (Shapley Additive exPlanations) to analyse data from over 760,000 buildings across 11 districts. The model predicts multi-class damage states based on structural and geometric attributes, including age, height, plinth area, and types of roofs, foundations, floors, and superstructures. The results indicate that XGBoost achieves high sensitivity in identifying severe damage, which supports prioritisation of collapse risks. SHAP analysis highlights key factors such as mud-mortar stone superstructures, age, height, and plan irregularity as primary drivers of damage. Additionally, district-level SHAP aggregation combined with K-means clustering uncovers distinct vulnerability signatures across regions, influenced by local construction practices, topography, and materials. These findings confirm that seismic vulnerability varies regionally rather than being uniform. By integrating predictive modelling with structural engineering principles, the proposed framework offers a transparent, data-driven foundation for targeted retrofitting, policy development, and disaster risk reduction.
Orthotropic Steel Decks (OSDs) are widely used in modern bridge construction for their lightweight and high-strength properties, yet they face significant fatigue challenges under dynamic loading. This paper presents an experimental investigation into OSD fatigue performance using a sequential, multi-position loading protocol. Focusing on strain and deflection measured through strain gauges and linear potentiometers, a scaled-down specimen was developed to analyse stress distributions and identify fatigue-prone areas. The findings revealed significant strain concentrations at rib-to-deck connections, identifying them as key locations for early plastic deformation and fatigue damage initiation. Additionally, rib-to-diaphragm (RTD) connections exhibited elevated fatigue sensitivity, indicating complex load transfer mechanisms and non-uniform stress distribution across the deck. The main highlight of this paper lies in its sequential loading protocol and detailed monitoring strategy, which accurately approximate the spatial variability of in-service traffic compared to conventional single-point static approaches. By comparing these findings with existing research, the paper highlights the specific fatigue challenges associated with dynamic traffic loading and contributes to a deeper understanding of fatigue-resistant mechanisms in long-span steel bridges. These insights provide a useful basis for informing the development of monitoring and fatigue-assessment strategies for long-span OSD structures.
This study investigates the combined effects of metakaolin (MK) and steel fibres (SF) on the mechanical and durability properties of M30-grade concrete. An experimental programme was designed comprising six concrete mixes with varying MK replacement levels (5%, 10%, 15%, 20%, and 25%) and a constant 1% SF dosage. The experimental results showed that the mix containing 15% MK and 1% SF produced the highest compressive strength at both 7 days (37.06 MPa) and 28 days (58.13 MPa), with increases of 59.7% and 69.9% compared to the conventional M30 mix. Significant improvements were also observed in split tensile and flexural strengths, with increases of 106.1% and 129% at 7 days, and 98.2% and 129% at 28 days, respectively. Durability tests showed a 29.9% reduction in water absorption, a 28.7% decrease in chloride permeability, and a 156.1% increase in electrical resistivity for the optimal mix compared to the control. The UPV results rated the 15% MK + 1% SF mix as 'Excellent', with a pulse velocity of 4.781 km/sec. This research highlights that a 15% MK replacement level, combined with 1% SF, offers the best balance of strength and durability, making it a promising approach for enhancing the performance of concrete in construction applications.
Bolted joints are critical to engineering structures and their integrity is essential for safety and functionality. Traditional monitoring methods are often expensive and intrusive, necessitating the development of more efficient approaches. Preload loss in pretensioned bolts is inevitable in practice, making the reliable detection of loosening vital for structural reliability. This study presents a novel structural health monitoring (SHM) method based on vibration and percussive audio-emission signals generated during controlled percussion. A single bolted lap joint was subjected to percussion, and the resulting audio and vibration signals were recorded and analyzed in both the time and frequency domains to assess bolt tightness. As the bolt torque increased from 0 Nm to 25 Nm, significant variations were observed in signal characteristics. For the vibration signals, the Signal Energy, Peak-to-RMS ratio, and kurtosis changed by 48.84%, 61.02%, and 90.15%, respectively. For audio signals, the corresponding variations were 39.53%, 44.77% and 80.79%. Fast Fourier Transform (FFT) analysis showed a correlation between bolt tightening levels and frequency amplitudes, with slight frequency increases in both signal types with an increase in bolt torque. The results demonstrate that percussion-induced signals effectively reflect bolt tightness. Comparative analysis of vibration and audio responses highlights the potential of this multi-modal approach to enhance the reliability of bolted joint SHM applications.
Permeability is a fundamental parameter governing the long-term durability of concrete structures, as it controls the ingress of water and aggressive ions, such as chlorides and sulphates, which initiate deterioration mechanisms including microcracking, expansive reactions, and reinforcement corrosion. This review synthesises the primary mechanisms influencing concrete permeability, with emphasis on pore structure evolution, microcrack formation, and mix design parameters. Strategies for permeability mitigation, including optimised aggregate grading and incorporation of supplementary cementitious materials, are critically examined in relation to durability enhancement. A comprehensive evaluation of Non-destructive Testing (NDT) techniques, Acoustic Emission (AE), Electrical Resistivity (ER), Resonance Frequency Testing (RFT), and Ultrasonic Pulse Velocity (UPV), is presented, highlighting their underlying principles, sensitivity to permeability-related parameters, and applicability under laboratory and field conditions. A comparative case study analysis demonstrates how environmental exposure, moisture conditions, and specimen characteristics influence the interpretation of NDT results. The findings underscore that no single technique is sufficient for reliable permeability assessment; instead, integrated multi-method approaches, supported by appropriate calibration, provide improved diagnostic confidence. This review offers a structured framework to support informed selection and implementation of permeability evaluation strategies in both new construction and existing infrastructure.
Utilisation of high-strength concrete in modern infrastructure requires materials that combine high load-carrying capacity with improved ductility and serviceability. This study provides an extensive experimental programme carried out to evaluate the influence of SF on the mechanical properties of flexural beam testing supported by a numerical simulation and microstructural characteristics of high-strength M60 grade concrete. SFs were added at volume fractions of 0.75%, 1.0% and 1.25% to identify optimal dosage. Standard tests were conducted to evaluate compressive strength, split tensile strength and flexural strength at a curing age of 7, 28 and 56 days, while full-scale reinforced concrete beams are tested under monotonic loading to investigate load vs deflection behaviour, stiffness degradation, crack development and ductility. In addition, microstructural analysis was performed using scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction to investigate fibre-matrix bonding and hydration processes. The results indicated that addition of SFs significantly improved tensile and flexural performance at an optimal dosage of 1.0% fibre content. SFRC beams showed delayed crack initiation, reduced crack width and improved ductility compared to conventional high-strength concrete beams. The numerical simulation showed closed agreement with the experimental results, confirming the validity of the developed finite element model.
Concrete structures are prone to degradation due to various internal flaws and external stresses, with crack formation being one of the most critical challenges affecting their strength and durability. Traditional methods of condition assessment are often limited by their inability to systematically detect and differentiate between crack types. In this study, a hybrid methodology is proposed in which manual crack assessment is complemented by classical image processing techniques, specifically, Otsu-Thresholding and Canny Edge Detection. Through this integration, the process of crack evaluation is automated and enhanced, allowing for more consistent identification and classification of cracks. The methodology is applied to real-world examples, where its effectiveness is demonstrated in detecting crack patterns at multiple scales and associating them with their underlying structural causes. It is shown that the proposed approach may provide a practical and resource-efficient tool for improving the consistency and reliability of structural assessments.
This study aims to critically investigate the development of self-compacting ultra-high-performance geopolymer concrete (SCUHPGC), with a particular focus on the influence of the type of alkaline activator and curing regime on mechanical performance, embodied CO2 emissions, and cost efficiency. A detailed comparative analysis was conducted between ambient-cured mixtures activated by a sodium hydroxide (SH)-sodium silicate (SS) mixture versus combined-cured mixtures (a 90 degrees C hot water followed by 250 degrees C dry-air curing) activated by calcium carbide residue (CCR). The ambient-cured SH-SS-activated mixtures were designed using a ternary binder, achieving a slump flow diameter of 740 mm and a compressive strength of 132.7 MPa. The CCR-activated mixtures reported in the literature consisted of a binary binder. It was reported that under combined curing conditions, the plain CCR-activated mixture achieved a slump flow diameter of 700 mm and a compressive strength of 130.4 MPa. The total carbon dioxide equivalent (CO2-e) emissions and production cost of the ambient-cured SH-SS-activated SCUHPGC were lower than the corresponding total CO2-e emissions and production cost of the combined-cured CCR-activated SCUHPGC by approximately 15.9% and 13.5%, respectively. The ambient-cured SH - SS-activated SCUHPGC demonstrates superior efficiency, combining ultra-high mechanical performance with a lower environmental impact.
This study proposes a comprehensive methodology for the structural health assessment of ageing infrastructure with limited available documentation. The case study involves a reinforced concrete structure constructed in 1971, for which only architectural drawings with a limited technical document are available. An initial finite element model (FEM) is developed based on geometric information inferred from the available drawings and standard material assumptions. To overcome uncertainties arising from the absence of structural and reinforcement details, a suite of non-destructive tests, Schmidt hammer rebound tests and Profometer are employed. The experimental results are used to update and calibrate the FEM, enabling a more accurate representation of the in-situ condition. The refined model is then used to evaluate structural performance and compare results against current design codes. This integrated approach highlights the value of combining limited documents with in-situ testing to support informed decision-making in the assessment and management of ageing concrete. When reassessed against AS 1170 and AS 3600 provisions, the structure failed to meet key performance requirements, particularly in lateral resistance and reinforcement capacity, highlighting the need for retrofit.
Beyond ensuring the structural integrity of the foundation system, its sustainability is equally important, as enhancing the environmental performance of foundations plays a key role in advancing sustainable construction. There are different types of foundation systems, and their applicability varies on the type of the building and the soil conditions. The main objective of this research is to evaluate the sustainability of screw piles (SP) and bored piers (BP) through a life cycle analysis (LCA) from the perspectives of carbon emission and energy consumption. A cradle-to-grave LCA is performed for the pile systems, starting from the manufacturing to the end-of-life, to quantify the associated global warming potential (GWP) and energy consumption (EC) of both BP and SP. This study follows a process-based approach, where individual processes associated with each life cycle stage are considered separately in the analysis. For an average job with 50, 3-m piles under normal circumstances (i.e. standard material and machinery use, normal weather), screw piles showed a 56% reduction in GWP and a 34% reduction in EC compared to an equivalent bored pier system. However, based on the pile length and the diameter impacts can vary and at higher length, SP have significant low environmental impacts compared to BP.
Eccentrically Braced Frames (EBFs) are widely used to resist lateral forces, leveraging ductile design principles to reduce seismic demands. However, the current New Zealand Steel Structures Standard (NZS 3404) provides limited guidance for computing deformation demands, overlooking variability of inelastic behaviour along the frame height and potentially leading to inaccurate seismic performance assessments. The provisions also disregard the contribution of post-yield stiffness by adopting an elastic-perfectly plastic link response, which can underestimate the load-carrying capacity of EBF systems. This study evaluates the seismic performance of multi-storey EBFs through nonlinear pushover analyses of an eight-storey case study, developed using an experimentally validated finite element model. Predictions from design provisions and an alternative analytical method are benchmarked against the nonlinear results, focusing on displacement profiles, storey drift demands, link rotations, and the influence of base rotational stiffness, post-yield stiffness, and shear link length. The findings show that while standard methods provide acceptable accuracy in the elastic range, they fail to capture redistribution of plastic demands in the nonlinear regime. The results also demonstrate that parameters such as base rotational restraint and strain-hardening can significantly influence the seismic response of EBF systems, highlighting the need for advanced design methodologies to provide more accurate seismic design.
A model was developed to predict construction risks for bridges by coupling the analytic hierarchy process (AHP) with an optimised Extreme Learning Machine (ELM) neural network. Firstly, by using the AHP method, 22 factors were identified to comprehensively represent risks during bridge construction. These factors were formulated in a two-level hierarchical structure. Secondly, a risk assessment system was formulated. Thirdly, an ELM neural network model was built to automate the risk prediction process and minimise the subjectivity associated with the traditional expert assessment system. The ELM model was optimised by the Sparrow Search Algorithm (SSA). Finally, the AHP-SSA-ELM model was tested on 50 bridge construction cases, and showed a 96% agreement with the expert assessment. This means that the proposed model can be used confidently to assess risks during bridge construction in complex environments. The model is accurate, practical, and efficient. It will inform risk management to avoid social and economic losses during bridge construction.
This paper investigates the effect of recycled coarse aggregates as partial replacement of natural stone and recycled rubber particles as partial replacement of natural sand in concrete mix on the structural behaviour of concrete-filled steel tubular (CFST) members. Both experimental study and numerical simulations were conducted. Two types of concrete were employed: RA concrete with recycled coarse aggregates and RRA concrete with recycled rubber particles and recycled coarse aggregates. In total, eight CFST specimens made from square steel tubes and RA concrete or RRA concrete were tested under axial, eccentric and pure bending loading conditions. The material experimental results showed that the inclusion of 20% crumb rubber in concrete mix reduced the compressive strength of RA concrete by approximately 27%, while the steel composite effect effectively compensated this reduction, leading to only 9-19% lower ultimate loads in RRA-CFST components compared with RA-CFST specimens. Finite element (FE) models in ABAQUS accurately reproduced the observed load-displacement responses, with less than 10% deviation in ultimate load. Finally, prediction formulas for section compressive capacity and moment capacity were developed for RRA-CFST and RA CFST members. Good agreements were achieved among the results from experimental study, numerical simulation and prediction formulas.
This paper provides the net wind pressures on a series of curved open canopy (i.e. free) roofs. Net wind pressures acting across the roof were obtained by testing two 1/50 scale model configurations in a boundary layer wind tunnel. Design data for such structures are not readily available in codes and standards. The paper determines net pressure coefficients across taps on the top and bottom surfaces of the roofs. Large net negative (outward) and positive (inward) pressures were measured at the leading edges. Net aerodynamic shape factors Cshp,n are given in a form appropriate for the Australian/New Zealand wind loading standard, AS/NZS 1170.2:2021 to obtain loads for the design of cladding and the supporting structure.
