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.

ABSTRACT 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 C shp,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.

ABSTRACT Maintaining the integrity of bolted joints is vital across engineering domains. Bolt loosening under dynamic loads can compromise structural safety. We present a robust neural approach using YOLOv11 for detecting loosening through pose-based estimation of nutbolt relative rotation. A dataset of 419 bolt images and 385 nut images supports training and evaluation. The method achieves an average relative angular error of 0.94 with prediction confidence up to 98%, and remains reliable under challenging illumination, with a maximum error of 3. This innovative approach offers a highly reliable and accurate tool for monitoring bolt loosening, even detecting minute rotational movements, thereby enhancing the safety and reliability of bolted connections in diverse engineering structures.

ABSTRACT Wall ties are a metal fitment used in masonry walls that provide an important connection between the external leaf of masonry and the internal wall or frame. In a cavity brick wall, the internal wall is masonry, mirroring the external wall, with an air cavity in between. The wall tie is embedded in both leaves of masonry and, in the event of strong winds or an earthquake, transfers lateral loads between them. Inevitably, the wall ties experience losses due to corrosion mechanisms occurring within the microenvironments of the cavity wall. The impact corrosion losses have on the behaviour of the wall ties in tension and compression are useful for understanding when a cavity brick wall might be vulnerable to collapse. The present study reports on the axial tension and compression testing results of cavity brick wall subassemblies, comparing the findings of non-corroded and artificially corroded wall ties. Subassembly specimens represent a single connection, and hence numerical models were also completed to show the behaviour of the cavity wall when corrosion losses are induced to the wall ties within a full-scale wall.

ABSTRACT The integrity of concrete structures is paramount for the safety and longevity of civil infrastructure. Traditional methods for detecting cracks in these structures are often time-consuming, subjective and prone to human error. This study introduces an automated, high-performance crack detection system based on the YOLOv8 deep learning architecture, designed for real-time and accurate identification of cracks in concrete images. YOLOv8, renowned for its superior speed and accuracy, integrates a powerful convolutional backbone with decoupled head structures for detection and localisation, enabling the detection of fine and irregular crack patterns under varied lighting and background conditions. The system trained and tested on a comprehensive dataset of 4000 concrete images, achieved a precision of 91.80%, recall of 92.50% and overall accuracy of 93% in detecting cracked regions. For non-cracked images, the system demonstrated an accuracy of approximately 90%. These results underscore the model’s robustness in accurately identifying crack damages with minimal false positives and negatives, highlighting YOLOv8 as a reliable solution for automated structural health assessment.

ABSTRACT This study presents a comprehensive investigation into the flexural-torsional buckling behaviour of perforated cold-formed steel lipped channels (CSLC). A theoretical model based on the principle of stationary potential energy is developed, incorporating a finite element formulation to predict critical buckling loads under various conditions. Experimental tests on nine practical CSLC specimens with three cross-section heights (21, 42 and 72 mm) and lengths (350 mm, 450 mm and 550 mm) validate the model, demonstrating good agreement with relative errors ranging from 4.74% to 15.92%. The results reveal that perforations reduce the buckling capacity by 10–20%, with smaller sections showing greater sensitivity due to their lower torsional rigidity. Parametric studies further examine the effects of beam-column length and boundary conditions, indicating that shorter CSLCs exhibit localised buckling near perforations, while longer CSLCs are governed by global buckling modes. Both hinged and fixed boundary conditions exhibit consistent perforation-induced load reductions of 9.37–12.66%. This research establishes a reliable analytical framework for predicting the complex buckling behaviour of perforated thin-walled CSLC, with potential applications in lightweight structural design.

ABSTRACT Assessing the condition of wall ties in masonry cavity wall systems using a non-destructive approach is challenging due to the hidden nature of installation and subtle wall tie deterioration mechanisms. This study presents a vibration-based damage identification approach to address this issue using the impact hammer test. The test measured the natural frequencies and the corresponding mode shapes of a one-story masonry cavity wall with six different test cases of wall tie deterioration. A significant reduction in natural frequencies of up to 64% was observed when all wall ties were fully cut, indicating the suitability of using natural frequency as a damage detection indicator. In terms of damage localisation, four mode shape-based analyses were compared and discussed, including the coordinate modal assurance criterion (COMAC), parameter-based method, curvature damage factor (CDF) and mode shape derivative-based damage identification method (MSDBDI). Among the four mode shape-based methods, parameter-based and CDF methods demonstrated a higher accuracy in locating damage locations by identifying high damage indices near the affected regions. The findings highlight the potential of vibration-based damage identification methods for the detection of wall tie deterioration and contribute to a more robust structural risk assessment for masonry structures.

ABSTRACT Several characteristics of concrete, such as its tensile, flexural and shear capacity, are enhanced by incorporating steel fibres. In beams, steel fibre-reinforced concrete (SFRC) has a well-established use where it may be utilised to replace transverse reinforcement and boost shear capacity. A lot of studies on the shear response and capacity have been carried out by utilising various fibre densities, lengths, and volumes. However, little work is available on evaluating the yield strength of straight steel fibre and its effect on the shear behaviour of RC beams. As a result, this research investigates the impact of steel fibre yield strength on the performance of SFRC beams under a four-point load. Six beams having identical geometrical and material properties, but variable strength steel fibres, are evaluated as part of the current experimental program. The findings demonstrate that the use of high-strength steel fibres in beams enhances the shear capacity, enhances displacement control, and produces higher damage tolerance. Furthermore, the high-strength steel fibres may reduce the quantity of transverse reinforcement in beams subjected to normal load.