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.

ABSTRACT Aluminum plates, owing to their performance advantages such as high strength and excellent durability, are extensively employed in various engineering structures. Nevertheless, crack damages are inevitable during their service. In response to this problem, this article presents an imaging and localization method based on Lamb waves. This method, through analyzing the propagation characteristics of Lamb waves before and after the damage of the aluminum plate, proposes a novel damage index – the Crack Damage Factor (CDF). The study initially collected the Lamb wave signals in the undamaged and cracked damage states, respectively, through simulation and experiments and subsequently calculated the CDF. Then, in combination with the Reconstruction Algorithm for Probabilistic Inspection of Damage (RAPID), the initial imaging of the damaged area was accomplished. On this basis, the grouping refinement method for obtaining the parallel path of the crack was proposed. Finally, by rectifying the CDF value of the parallel path and re-combining it with the RAPID algorithm, the imaging and localization of the crack damage were accomplished. The experimental results indicate that this method can effectively and accurately conduct visual location and imaging of the crack in the aluminum plate, verifying its feasibility and effectiveness in practical applications.

ABSTRACT Steel wall ties are essential structural components of brick buildings. In brick veneer and cavity brick walls, the wall ties connect the external leaf of masonry to the internal load-bearing frame or internal masonry leaf, transferring lateral forces from wind and earthquakes. Corrosion of steel wall ties diminishes their effectiveness by reducing their cross-sectional area, compromising their strength when subject to lateral forces. The experimental work conducted for this study involved the compression testing of brick couplet, wall tie and timber subassembly systems replicating those used in a masonry veneer wall system with a timber backup frame. Each subassembly specimen included an artificially corroded wall tie with known section loss. Our findings reveal a decline in strength and a change in the failure mechanism of the wall tie as corrosion-induced section loss increases. This highlights the clear impact that the corrosion of steel wall ties has on the performance of brick veneer wall systems.

ABSTRACT l Open framed buildings are a feature of mining and mineral processing facilities. While often unclad, they can vary significantly in the density of structural elements and equipment within, creating wind flow blockages that strongly influence wind loads. Estimating these loads presents challenges for structural engineers in developing a conservative yet practical wind force-resisting system. A limited number of publications provide guidance, generally based on low-blockage lattice structures, and their application to higher-blockage frames may not be appropriate. A review of the historical basis of several guidelines highlights the need for further work examining higher blockages. To address this, a conceptual model of flow through an idealized open framed building was developed as the basis for reviewing published guidance. This was undertaken using calculations from Australian Standard AS/NZS 1170.2 “Structural design actions, Part 2: Wind actions,” ASCE “Wind Loads for Petrochemical and Other Industrial Facilities,” and CFD simulations, with results compared across the three methods. While the study cannot fully determine applicability, it shows that predicted force coefficient trends from AS/NZS 1170.2 and CFD are generally aligned, whereas ASCE predictions are consistently higher.

ABSTRACT A stress relaxation phenomenon is one of the key influencing factors that govern long term mechanical behaviour of basalt fibre reinforced polymer (BFRP) in structural applications. This paper proposes a prediction model for the flexural stress relaxation behaviour of BFRP plates through applying a time series parameter method (TSPM) in experimental data processing. To improve the accuracy of the model, sub-data-groups are selected from the experimental data base. Individual prediction formulas are simulated by direct extrapolation functions based on each sub-data-group, respectively. It should be noted that the coefficients in the individual prediction formulas from different sub-data-groups are different. To develop a general prediction formula, coefficients in the formula are replaced through undetermined time-related coefficient functions, which can be fitted through all the individual coefficient values from sub-data-groups. Thus, a general prediction equation that considers the characteristics of all sub-data-groups is constructed. Finally, an experimental study on two BFRP specimens is conducted through three-point bending tests. Two sub-data-groups are used to predict the experimental results through the TSPM method. Comparison between prediction results and experimental data verifies that the proposed TSPM method is with high precision and is more accurate than the traditional extrapolation function fitting method as time grows.

ABSTRACT An innovative built-up beam section has recently been developed, comprising multiple 150 × 75 lipped channels mounted vertically and connected with screws through their lips and webs. These built-up sections offer a high section modulus, making them an economical option for use as rafters in portal and wide-span frames. However, current design codes do not provide specific guidance or rules for these sections. Predicting their flexural capacity and performance requires complex analyses, such as Finite Element Analysis, as well as experimental testing, both of which are costly and time intensive. To address this gap, a simplified design method is proposed based on the Direct Strength Method (DSM) from AISI and AS/NZS standards, which assumes a linear stress distribution across the cross-section. This approach enables straightforward prediction of the flexural capacity of such built-up sections. The accuracy of this design procedure has been validated by comparing predictions with experimental results.

ABSTRACT The incorporation of recycled aggregate (RA) in concrete production has garnered significant attention due to environmental sustainability concerns and the need for resource conservation in construction materials. This study investigates the strength development of Recycled Plastic Aggregate and Recycled Brick Aggregate over time, focusing on the compressive, tensile, and flexural strengths of SCC with varying recycled aggregate (RA) contents at different curing ages. The primary objective is to evaluate the long-term performance of RA-SCC, which is crucial for sustainable construction practices. Concrete mixes (cylinder blocks) with different RA replacement levels (25%, 50%, 75%, and 100%) were prepared and subjected to standard curing conditions. The mechanical properties of the concrete, including compressive strength, tensile strength, and flexural strength, were measured at 7, 28, 56, and 90 days. The compressive strength was determined using a uniaxial compression test, tensile strength through a split-cylinder test, and flexural strength using a four-point bending test. Statistical analysis was performed to compare the results and identify trends in strength development. The result shows that the reduction in flexural strength is more pronounced, with a steady decline from 4.50 MPa at lower replacement levels to 3.60 MPa at full replacement, implemented using Python software. Future research should explore optimising RA-SCC formulations to mitigate strength reductions and address durability concerns. This study underscores the potential of RA to foster sustainable concrete practices while highlighting avenues for further enhancing the mechanical properties of recycled aggregate-based concretes. The effects of partial cement replacement with pozzolanic materials, such as fly ash and volcanic ash, on the mechanical properties of SCC were investigated to further enhance sustainability and long-term strength development.

ABSTRACT This study investigates the influence of geometric parameters on the flexural stiffness of corrugated sheets using a two-dimensional symmetric trapezoidal corrugation pattern. Three key parameters were varied: the number of corrugation cells (N), height (H), and slope angle (θ). Finite element simulations were conducted in ABAQUS (v6.14), based on 3D models created in SOLIDWORKS. Each configuration was analysed for vertical deflection under self-weight using a thin steel plate (260 × 260 mm), and a flexural stiffness index was defined as the ratio of sheet weight to maximum deflection. The results showed that stiffness improved with increasing N, reaching an optimum at N = 9, beyond which structural efficiency declined due to geometric softening. To validate the simulations, experimental tests were performed using 3D-printed PLA models. Despite material differences, the experimental results followed similardeflection trends, confirming the geometric influence. PLA was chosen for its cost-effectiveness and accessibility compared to custom-fabricated steel sheets. Von Mises stress analysis was also conducted to evaluate internal stress distribution. While fewer cells yielded higher stiffness, they also led to greater stress concentrations. The N = 9 configuration offered the best balance between stiffness and stress, supporting the hypothesis that optimising corrugation geometry enhances structural performance. This work contributes a validated parametric framework for improving the mechanical behaviour of corrugated sheets and offers valuable guidance for the geometric design of lightweight structural panels.