Search Results (308)

Lightweight steel-framing (LSF) systems have become increasingly prominent in modern construction due to their structural efficiency, design flexibility, and sustainability. However, traditional facade materials such as stone are often cost-prohibitive, and brick veneers—despite their popularity—pose seismic performance concerns. This study introduces an innovative porcelain sheathing system for cold-formed steel (CFS) shear walls. Porcelain has no veins thus it offers integrated and reliable strength unlike granite. Four full-scale CFS shear walls incorporating screwed porcelain sheathing (SPS) were tested under combined cyclic lateral and constant gravity loading. The experimental program investigated key seismic characteristics, including lateral stiffness and strength, deformation capacity, failure modes, and energy dissipation, to calculate the system response modification factor (R). The test results showed that configurations with horizontal sheathing, double mid-studs, and three blocking rows improved performance, achieving up to 21.1 kN lateral resistance and 2.5% drift capacity. The average R-factor was 4.2, which exceeds the current design code values (AISI S213: R = 3; AS/NZS 4600: R = 2), suggesting the enhanced seismic resilience of the SPS-CFS system. This study also proposes design improvements to reduce the risk of brittle failure and enhance inelastic behavior. In addition, the results inform discussions on permissible building heights and contribute to the advancement of CFS design codes for seismic regions. Full article

The operation of heavy-haul railway trains with large loads results in significant cracking issues in reinforced concrete beams. Atmospheric carbon dioxide, oxygen, and moisture from the atmosphere penetrate into the beam interior through these cracks, accelerating the carbonation of the concrete and the corrosion of the steel bars. The rust-induced expansion of steel bars further exacerbates the cracking of the beam. The interaction between environmental factors and beam cracks leads to a rapid decline in the durability of the beam. To address this issue, a multi-physics field coupling durability assessment method was proposed, considering concrete beam cracking, concrete carbonation, and steel bar corrosion. The interaction among these three factors is achieved through sequential coupling, using crack width, carbonation passivation time, and steel bar corrosion rate as interaction parameters. Using this method, the deterioration morphology and stiffness degradation laws of 8 m reinforced concrete beams under different load conditions, including those of heavy and light trains in heavy-haul railways, are compared and assessed. The analysis reveals that within a 100-year service cycle, the maximum relative stiffness reduction for beams on the heavy train line is 20.0%, whereas for the light train line, it is only 7.4%. The degree of structural stiffness degradation is closely related to operational load levels, and beam cracking plays a critical role in this difference. Full article

Light-gauge steel frame (LGSF) materials are inherently susceptible to stochastic imperfections arising from their design, manufacturing, and erection. These defects can compromise operational integrity and adversely impact structural stability, especially during the construction period. Consequently, a thorough investigation into the buckling characteristics of LGSF materials with such imperfections is imperative. Conventional stochastic probabilistic methods, such as Monte Carlo simulations, often fail to fully capture intrinsic material and complex structural properties, leading to discrepancies between computational predictions and actual behavior. To address these limitations, this study introduces an innovative model using the Criteria Importance Through Intercriteria Correlation (CRITIC) method to assess LGSF materials under combined defects scenarios. The CRITIC method systematically evaluates various buckling modes in LGSFs under combined defects to identify the most detrimental modal combination, representing the most unfavorable scenario. Rigorous finite element analysis is then performed on the LGSF model based on this critical scenario. Compared to conventional approaches, the proposed CRITIC-based combined defects analysis model predicts a 0%~5% reduction in the critical load factor and a 1%~3% increase in ultimate displacement at control nodes. These findings indicate that the CRITIC-based method yields a more critical combination of buckling modes, thereby enhancing the reliability and safety of the simulation results. Furthermore, this research demonstrates that, for LGSF materials, the common assumption that the first-order buckling mode is inherently the most deleterious failure pattern is inaccurate. Full article

This study investigates the thermal performance of 23 different mortar types, each containing different mixes, properties, and additives. A comprehensive literature review was conducted to collect experimental data on the thermal properties of these mortars, which were then used in a numerical analysis through thermal finite element modeling. The results showed that all mortar types contributed to reducing the internal temperature of structural steel and reinforced concrete elements, with performance primarily influenced by key factors such as the mortar’s thermal conductivity, specific heat capacity, thermal diffusivity, and coating thickness. In particular, the mortar with glass fiber reinforced polymer (GFRP) as a slag substitute and the mortar with expanded perlite replacing sand showed the highest thermal protection and achieved a temperature reduction on the order of 100%. In contrast, mortars containing 30% vermiculite or 15% light expanded polyvinyl chloride (PVC) as a sand substitute showed the lowest thermal performance. Full article

Vehicle collisions with street lighting poles generate extremely high impact forces, often resulting in serious injuries or fatalities. Therefore, enhancing the structural resilience of pole bases is a critical engineering objective. This study investigates a comprehensive dynamic analysis conducted with respect to base material behavior and energy absorption of GFRP lighting pole structures under impact loads. A finite element (FE) model of a 5 m-tall tapered GFRP pole with a steel base sleeve, base plate, and anchor bolts was developed. A 500 kg drop-weight impact at 400 mm above the base simulated vehicle collision conditions. The model was validated against experimental data, accurately reproducing the observed failure mode and peak force within 6%. Parametric analyses explored variations in pole diameter, wall thickness, base plate size and thickness, sleeve height, and anchor configuration. Results revealed that geometric parameters—particularly wall thickness and base plate dimensions—had the most significant influence on energy absorption. Doubling the wall thickness reduced normalized energy absorption by approximately 76%, while increases in base plate size and thickness reduced it by 35% and 26%, respectively. Material strength and anchor bolt configuration showed minimal impact. These findings underscore the importance of optimizing pole geometry to enhance crashworthiness. Controlled structural deformation improves energy dissipation, making geometry-focused design strategies more effective than simply increasing material strength. This work provides a foundation for designing safer roadside poles and highlights areas for further exploration in base configurations and connection systems. Full article

To address the challenges of slow construction and high self-weight in steel–concrete composite floors for rural light steel frame structures in China, a new prefabricated floor system was developed. This system features prefabricated slabs made from recycled concrete, connected via reinforced shear pocket joints. In seismic environments, assembly floor joints often become vulnerable points, making their shear resistance particularly crucial. This study investigated the shear performance of this new type of floor joint, examining the effects of various parameters such as joint configuration, stud diameter, recycled concrete strength, and grout strength. A refined finite element model was established for an in-depth parameter analysis. The research revealed stud–shear failure as the mode of floor joint failure under different design parameters. The detailed design of the new joint structure ensures safety in the floor joint area. Increasing stud diameter, recycled concrete strength, and grout strength all contributed to enhancing the joint’s shear capacity and stiffness, with stud diameter having the most significant impact. Higher recycled concrete strength improved shear capacity, although its influence decreased beyond a certain threshold. Optimal reserved hole diameter proved beneficial for enhancing joint shear performance, with a diameter of 40 mm showing superior performance. Full article

This study focused on the advanced analysis of the crack resistance of reinforced concrete structures and provides proposals for improvement of the theory of calculation of reinforced concrete structures for serviceability and ultimate limit state. Despite the fact that the crack opening is a key parameter of reinforced concrete structures that frequently determines the reinforcement area, the design models and theory of calculation of this parameter are still not sufficiently perfect. The recent studies performed worldwide with the use of more advanced instrumentation have shown that the accuracy of theoretical prediction of crack opening in structures experiencing a complex stress–strain state, and especially structures made of high-strength concrete, fiber-reinforced concrete, lightweight concrete, and etc., remains unsatisfactory. This study analyzed and summarizes experimental studies of crack resistance of reinforced concrete structures and reveals new physical regularities in the deformation of concrete and steel reinforcement in zones adjacent to the crack. It introduces hypotheses that account for these regularities and proposes a general block model for calculating the width of irregular and single cracks in reinforced concrete structures under different stress states. In this model, crack opening is modeled by the double-cantilever element (DCE), which allows incorporation of the corresponding experimentally revealed effects and at the same time combines deformation parameters of both the theory of reinforced concrete and fracture mechanics. The DCE is two conventionally separated rigid cantilevers that include the crack surfaces, and are embedded on one side in the concrete at the neutral axis. On the other side, they are connected with reinforced steel bars crossing the crack. Using this model, a method for calculating the crack opening width in reinforced concrete structures with different types of cracks is proposed. The paper demonstrates the results of experimental investigations of crack resistance of simply supported and cantilever beams made of ordinary, light, and high-strength concrete. These results confirm the effects considered in the calculation model and the hypotheses accepted in the theory. The study also provides a physical explanation of the phenomena under consideration and shows acceptable agreement between theoretical and experimental values of crack opening calculated according to the proposed theory. Full article

In recent years, protecting stainless steel from corrosion has become crucial, particularly in harsh environments. The present study focuses on improving the photocathodic corrosion resistance of 304 stainless steel (304SS) by fabricating TiO₂/CuO composite coatings using the spin coating technique with varying CuO weight percentages. Structural characterization through X-ray diffraction (XRD) confirmed the presence of the anatase phase of TiO₂ and the successful integration of CuO. Raman spectroscopy demonstrated redshifts in the TiO₂ characteristic peaks, suggesting changes in bond lengths attributed to CuO incorporation. These findings were further corroborated by Fourier-transform infrared (FTIR) spectroscopy. Surface characterization showed uniform, porous coatings with pore sizes ranging from 75 to 200 nm, which contributed to improved barrier properties. UV–visible diffuse reflectance spectroscopy (UV-DRS) demonstrated enhanced visible light absorption in the heterostructures. Mott–Schottky analysis confirmed improved charge carrier density and favorable band alignment, facilitating efficient charge separation. The electrochemical performance was evaluated in 3.5% NaCl solution under dark and light environments. The results demonstrated that the TiO₂/CuO heterostructure significantly enhanced electron transfer and suppressed electron-hole recombination, providing adequate photocathodic protection. Notably, under illumination, the TiO₂/CuO (0.005 g) coating achieved a corrosion potential of −255 mV vs SCE and reduced the corrosion current density to 0.460 × 10⁻⁶ mA cm⁻². These findings suggest that TiO₂/CuO coatings offer a promising, durable, and cost-effective solution for corrosion protection in industries such as oil, shipbuilding, and pipelines. Full article

Thin steel plates with stiffeners are widely used in shipbuilding, aeronautics, and civil construction due to their lightness and structural strength. This study presents a numerical model developed using ANSYS Mechanical APDL with SHELL281 finite elements to evaluate the deflection of thin steel plates with trapezoidal-shaped box-beam stiffeners, known as hat-stiffened plates. The structure is analyzed under a uniformly distributed load perpendicular to the plate, with simply supported boundary conditions. The constructal design method combined with the exhaustive search technique is employed to optimize the geometry. A volume fraction of 30% is used, transferring material from the reference plate (without stiffeners) to the stiffeners, defining parameters such as number, height, and thickness—considered degrees of freedom. The stiffener angle is fixed at 120°. The results show that increasing stiffener height and reducing thickness generally improve structural performance by reducing deflections. The best configuration with transverse stiffeners reduced deflection by 97.15% compared to the reference plate, and by 79.27% compared to the best longitudinal configuration from previous studies. Therefore, transverse stiffeners were more effective than longitudinal ones. This study highlights the importance of stiffener orientation and geometry in the structural optimization of thin steel plates. Full article

Mass timber construction is gaining popularity in mid-rise and tall buildings due to its sustainability, aesthetics, versatile prefabrication, light weight, and faster construction time compared to conventional building materials such as concrete and steel. One of the challenges with timber construction is a potential fire hazard, and the risk is even aggravated in taller buildings due to the increased evacuation period. Several researchers have identified and reported important parameters that will have direct influence over mass timber fire performance behaviour. However, the current findings from the literature do not provide a correlation between the key parameters and the fire performance behaviour. This paper presents a review of experimental fire testing of mass timber structures and analyses the fire performance results output obtained from the experimental testing. This paper attempts to identify several key parameters that influence the fire performance behaviour of mass timber structures, such as peak temperature, charring rate and decay behaviour. The correlation between the key parameters and the fire performance behaviour of mass timber structures will enhance in developing a rational model to determine the time to reach the fire growth, peak temperature, charring behaviour, structural integrity (strength and stiffness reduction) and decay behaviour of the exposed timber. Full article

This study elucidates the dynamic tribo-mechanical response of laser-cladded FeNiCr-B₄C metal matrix composite (MMC) coatings on AISI 1040 steel substrate, unraveling the intricate interplay between microstructural features and phase transformations. A multi-faceted approach, employing high-resolution scanning electron microscopy (SEM) and advanced X-ray diffraction/Raman spectroscopy techniques, provided a comprehensive characterization of the coatings’ behavior under mechanical and scratch testing, shedding light on the mechanisms governing their wear resistance. Specifically, microstructural analysis revealed uniform coatings with a columnar structure and controlled defect density, showcasing an average thickness of 250 ± 20 μm and a transition zone of 80 ± 10 μm. X-ray diffraction and Raman spectroscopy confirmed the presence of α-Fe (Im-3m), γ-FeNiCr (Fm-3m), Fe₂B (I-42m), and B₄C (R-3m) phases, highlighting the successful incorporation of B₄C reinforcement. The addition of 5 and 7 wt.% B₄C significantly increased microhardness, showing enhancements up to 201% compared to the B₄C-free FeNiCr coating and up to 351% relative to the AISI 1040 steel substrate, respectively. Boron carbide addition promoted a synergistic strengthening effect between the in situ formed Fe₂B and the retained B₄C phases. Furthermore, scratch test analysis clarified improved wear resistance, excellent adhesion, and a tailored hardness gradient. These findings demonstrated that optimized short-pulsed laser cladding, combined with moderate B₄C reinforcement, is a promising route for creating robust, high-strength FeNiCr-B₄C MMC coatings suitable for demanding engineering applications. Full article

Adhesively bonded fibre-reinforced polymer (FRP) anchors have emerged as a progressive alternative to traditional steel anchors in concrete structures, owing to their superior corrosion resistance, high tensile strength, and light weight. Despite their increasing use, a robust mechanics-based bond model capable of accurately predicting the load transfer behaviour has not yet been developed. This study presents a fracture mechanics-based analytical bond model for post-installed adhesive FRP anchors embedded in concrete. The model formulation is derived from fundamental equilibrium and compatibility principles, incorporating a bilinear bond–slip law that captures both elastic and softening behaviours. A new expression for the effective bond length is also proposed. Validation of the model against a comprehensive database of direct pull-out tests reported in the literature shows excellent agreement between predicted and experimental pull-out forces (R² = 0.980; CoV = 0.058). Future research should aim to extend the proposed model to account for confinement effects, long-term durability, the impact of adhesive type, and cyclic loading conditions. Full article

Shaping or splitting of a Gaussian beam is often desired to optimise laser–material interactions, improving throughput and quality. This can be achieved holographically using liquid crystal-on-silicon spatial light modulators (LC-SLMs). Until recently, maximum exposure has been limited to circa 120 W average power with a Gaussian profile, restricting potential applications due to the non-linear (NL) phase response of the liquid crystal above this threshold. In this study, we present experimental tests of a new SLM device, demonstrating high first-order diffraction efficiency of η = 0.98 ± 0.01 at 300 W average power and a phase range Δφ > 2π at P = 383 W, an exceptional performance. The numerically calculated device temperature response with power closely matches that measured, supporting the higher power-handling capability. Surface modification of mild steel and molybdenum up to P = 350 W exposure is demonstrated when employing a single-mode (SM) fibre laser source. Exposure on mild steel with a vortex beam (m = +6) displays numerous ringed regions with varying micro-structures and clear elemental separation created by the radial heat flow. On molybdenum, with multi-spot Gaussian exposure, both MoO₃ films and recrystallisation rings were observed, exposure-dependent. The step change in device capability will accelerate new applications for this LC-SLM in both subtractive and additive manufacturing. Full article

Currently, there are many infrastructures for which these design service lives are expired. These lifespans have been extended through retrofitting and strengthening. Usually, the existing reinforced concrete (RC) structures are strengthened by applying steel plate bonding and concrete enlargement methods. However, since fiber-reinforced polymer (FRP) composite materials have properties that are better than those of steel and concrete materials, i.e., being light weight, with anticorrosive material, a high ratio of strength to weight, and better workability, FRP sheet bonding methods for RC members have been developed, and practical applications have been gradually increased worldwide, statically. The methods may also have some potential to strengthen the members under impact and blast loading. In this paper, to rationally improve the impact resistance of RC beams under flexure, beams were strengthened by bonding an FRP sheet to the bottom tension side. Then, low-velocity impact loading tests (hereafter referred to as impact loading tests) using a 300 kg steel weight were carried out on the beams strengthened with carbon FRP (CFRP) sheets of different areal masses to investigate the failure mode at the ultimate state of the beams, in which the areal mass is physically similar to the amount of the sheet reinforcing RC beams and hereafter referred to as the sheet volume. Two sheet volumes (one is an areal mass of 300 g/m² having a 0.17 mm thickness and the other is of 600 g/m² having a 0.33 mm thickness) were compared, and two static failure modes, concrete crushing-intermediate crack (IC) debonding and premature IC debonding, were observed. The following results were obtained from this study: taking a static calculated moment ratio M_y/M_u of the rebar yield-moment M_y to the ultimate moment M_u for each beam, in the case of the beams having an M_y/M_u (=0.67) larger than 0.65 that went through static failure in the concrete crushing-IC debonding mode, the beams failed in sheet rupturing mode subjected to an impact load. When the sheet volume was comparatively large and a static calculated moment ratio M_y/M_u (=0.6) was less than 0.65, the beams collapsed in the premature IC debonding mode under not only static but also impact loading, and the impact resistance of the beams was enhanced with an increasing sheet volume; this increase was greater in the impact loading case than in the static loading case. Full article

Proper surface lubrication with optimal grease thickness is essential for extending steel wire rope service life. To achieve automated lubrication quality control and address challenges like variable lighting and motion blur that degrade recognition accuracy in practical settings, this paper proposes an improved lightweight GEMR-MobileViT. The model is designed to identify the grease thickness on steel wire rope surfaces while mitigating the high parameters and computational complexity of existing models. In this model, part of the standard convolution is replaced by GhostConv, a novel efficient multi-scale attention (EMA) module is introduced into the local expression part of the MobileViT block, and the structure of residual connections within the MobileViT block is designed. A transfer learning method is then employed. A custom dataset of steel wire rope lubrication images was constructed for model training. The experimental results demonstrated that GEMR-MobileViT achieved a recognition accuracy of 96.63% across five grease thickness categories, with 4.19 M params and 1.31 GFLOPs computational complexity. Compared to the pre-improvement version, recognition accuracy improved by 4.4%, while its parameters and computational complexity were reduced by 15.2% and 10.3%, respectively. When compared with current mainstream classification models such as ConvNeXtV2, EfficientNetV2, EdgeNeXt, NextViT, and MobileNetV4, our GEMR-MobileViT achieved superior recognition accuracy and demonstrated significant advantages in its model parameters, striking a good balance between recognition precision and model size. The proposed model facilitates deployment in steel wire rope lubrication working sites, enabling the real-time monitoring of surface grease thickness, thereby offering a novel approach for automating steel wire rope maintenance. Full article