ABSTRACT 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.

ABSTRACT 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°C hot water followed by 250°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.

ABSTRACT Managing bridges with substandard structural capacity presents an ongoing challenge for asset owners as infrastructure ages and vehicle loads increase. Many legacy structures do not conform to current design standards or adequately accommodate contemporary freight demands. Conventional strengthening techniques include externally bonded steel plates, concrete or steel jackets, and external post-tensioning. Since the early 2000s, fibre-reinforced polymer (FRP) systems, particularly carbon fibre-reinforced polymer (CFRP), have been adopted in Australia as an alternative strengthening method due to their high strength-to-weight ratio, corrosion resistance, and ease of installation. Recent advancements in research and material technology have led to increased industry recognition of CFRP systems. The Queensland Department of Transport and Main Roads (TMR) identified a portfolio of bridges requiring strengthening to accommodate current freight loads and selected CFRP as a potential solution. Given its limited prior application within TMR projects, a research-based pilot was initiated to evaluate feasibility, define performance criteria, and establish quality assurance protocols. This paper presents the pilot project’s implementation. The Routh Creek pilot project demonstrated the effectiveness of the CFRP strengthening in accordance with relevant standards. The field implementation demonstrated that vacuum-assisted installation and rigorous surface preparation procedures supported by robust quality assurance and environmental controls can ensure adequate bond performance despite environmental challenges. It also highlighted the significance of climate-adapted material handling, skilled workforce mobilisation and contingency planning. The technical challenges, mitigation strategies, and recommendations for future applications of CFRP in bridge strengthening are discussed.

ABSTRACT 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.

ABSTRACT 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.

ABSTRACT 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.

ABSTRACT 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.

ABSTRACT 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.

ABSTRACT This study presents a BIM-centred framework that integrates FEMA P-58 seismic performance assessment with component-level repair cost estimation for existing buildings. The main contribution is a unified, data-driven workflow in which a BIM model is used to extract component geometry and attributes, to map FEMA P-58 performance groups, and to export model data to Robot Structural Analysis for linear time-history analysis. Engineering demand parameters (interstory drift ratios and peak floor accelerations) obtained from the structural analyses are associated back to BIM components and evaluated with FEMA P-58 fragility/consequence functions to predict damage states and estimate repair costs. The methodology is demonstrated on a four-story reinforced concrete moment-resisting frame building located in İstanbul. Results highlight the feasibility of a BIM-integrated approach for accelerating component-level seismic loss estimation and indicate that the implementation can support decision makers in pre- and post-earthquake assessments.

ABSTRACT This paper presents an advanced computational method for analysing structural members exposed to fire, using a novel second-order flexibility-based fibre beam-column element. Built on the complementary strain energy approach and the Engesser-Crotti theorem, the formulation captures both geometric and material nonlinearities, including biaxial bending-axial force interaction, thermal elongation and slenderness effects. Tailored for reinforced concrete and composite steel-concrete members, the model reflects their specific material behaviour and interaction mechanisms at elevated temperatures. The second-order flexibility-based framework, combined with the Finite Analytic Method (FAM) for numerical integration, integrates distributed plasticity and geometric nonlinearities with only one element per member. The method supports isothermal analysis for strength interaction diagrams and non-isothermal analysis for predicting fire resistance under progressive heating. By enabling interaction diagrams for slender columns subjected to combined axial load and biaxial bending in fire conditions, the approach addresses a notable gap in current research. Validation through benchmark examples and preliminary comparative studies confirms both the accuracy and computational efficiency of the method. The results provide a robust foundation for performance-based fire design and a benchmark for future parametric and sensitivity studies on coupled thermal, material and geometric nonlinear behaviour.