International Journal of Steel Structures最新文献

In this study, a novel composite slab integrating truss girders was introduced. Flexural tests were conducted on a total of eight composite slab specimens to evaluate their negative flexural capacities. Based on the test results, the negative flexural behavior of the composite slabs was analyzed, including the development of catenary action, and the effects of truss girders and diagonally bent integrity reinforcements. All specimens showed satisfactory performance in terms of their flexural strength and stiffness and exhibited high ductility capacities. The test specimens did not show any noticeable degradation in flexural strength, and the tests were terminated due to the displacement stroke limitation of the actuator. Strain measurements clearly indicated an effective transition of the negative moment-resisting mechanism from flexural to catenary action at large deformations, causing the entire section to be subjected to tensile forces. The development of catenary action was the main reason for the high ductility observed in the specimens. The truss girders, although not spanning the entire width of the supporting beams, effectively enhanced the negative flexural strength of the composite slabs as their ends partially extended through the critical failure section. The effects of the truss girder were particularly notable in specimens supported by H-section beams, where the negative flexural strengths increased by about 10 –20%. Furthermore, diagonally bent integrity reinforcements, primarily introduced for ease of construction, were also found to effectively increase the negative flexural strength of the composite slabs by developing tensile forces when diagonal cracks developed in concrete sections.

The research aims to investigate the impact resistance of steel-aluminum laminated target plates, which is crucial for the design of high-performance anti-invasion structures. Previous studies have presented conflicting views on the protective performance of steel-aluminum laminated target plates, highlighting the need to clarify the influence of structural parameters on their protection capabilities. To address this, two groups of steel and aluminum plates with similar strengths and large differences in strengths were selected and tested. The ballistic limits characteristics of these double-layered plates were analyzed under different projectile nose shapes. Additionally, a 3D finite element model was established using ABAQUS/Explicit software, after the validity of the model was verified, the influence of the arrangement order of the steel and aluminum on the impact resistance was numerically simulated. The results show that the strength of the steel and aluminum plate materials is the key factor influencing the order of the best impact resistance of the target plate, and the shape of the projectile's nose and the thickness of the target plate don't have much influence on the order of the best impact resistance, which is also proved by the simulation results of the isoplanar density (same surface density). This study is instructive for the design and application of steel-aluminum laminated target plate structures with protective ends.

HSB690 steel is high-performance steel for bridges manufactured by POSCO of Korea through a thermo-mechanical controlled process (TMCP). However, the application of these high-performance steels to the entire structure is challenging in terms of cost. The combination of dissimilar steels can be a good alternative. Welding of HSB690 steel is mainly used for joining dissimilar steel materials. Residual stresses and deformations caused by welding affect the fatigue performance of the structure. In particular, tensile residual stress around welds significantly affects the fatigue and fracture behavior of dissimilar materials by increasing the mean stress. Bridge structures using HSB690 are gradually increasing, but the features of residual stress at the similar or dissimilar welded joint using HSB690 have not been reported. The physical and mechanical properties at each temperature are essential for residual stress analysis. However, the mechanical properties of HSB690 with temperature are not clear yet. Thus, before the residual stress analysis, the mechanical properties of HSB690 were determined by high-temperature tensile tests. Then, the three-dimensional (3D) thermal elastic–plastic finite element (FE) analysis was conducted to assess the residual stresses in the butt-welded member composed of SM355 and HSB690 steel. The residual stresses measured by the strain release method were compared for the precision of the analysis results. Moreover, residual stress analysis in welds composed of the same kind of steel materials was also performed for comparison. As a result of simulations and experimental measurements, in the member welded with dissimilar steels, the SM355 side showed almost similar residual stress distribution compared to corresponding similar steel welds, but the residual stress distribution in the HSB690 side was higher than that of the similar steel welds.

Mass optimization of crane box girder considering both ribs and diaphragms is a crucial aspect of crane structural design in mechanical engineering. However, two common challenges often obscure this process: the sizing of stiffeners such as diaphragms and ribs, and the selection of constraints on state variables related to stresses and deformations for various load cases. In response, this paper focuses on optimizing the dimensions, number, and placement of stiffeners, including ribs and diaphragms, in a two-girder overhead crane structure. The paper begins by establishing criteria for the initial height of the box girder through a comparative analysis of structural strength and stiffness. Subsequently, dimensional relationships between stiffeners and the girder section are built in accordance with the principles of local plate stability. Following this, the ANSYS Parametric Design Language (APDL) program is coded and executed to optimize the crane mass using three methods: sub-problem approximation, sweep, and first-order methods via Module Design OPT for four chosen sets of state variables. A comparative analysis of the optimum crane mass, based on the rounded-up design variables, reveals that constraints on stresses and deformations from both vertical and transversal impact cases, as well as the vertical frequency from dynamic vibration cases, yield the best results. Furthermore, the proposed APDL method is compared and validated against Grey Wolf Optimizer, Whale Optimization Algorithm, Particle Swarm Optimization, and Genetic Algorithm. Finally, a parametric study is conducted using curves and tables to explore the influence of structural stiffness and material property on the optimized dimensions of the girder and stiffeners, as well as the overall mass and mechanical performance.

In this study, a total of 70 experiment specimens, 56 of circular cross-section concrete filled steel tube (CFST) columns and 14 hollow steel tubes with various geometric and material properties, were tested under axial loading. Composite columns with four different concrete compressive strength (f_c), three different diameter/thickness (D/t) ratio and seven different length/diameter (L/D) ratio used in the experiment samples were designed. The ultimate axial force, axial deformation, and failure modes of the CFST columns obtained from the experiment results were determined. Concrete contribution Ratio index, and strength index were determined from the test results obtained. The ultimate axial force of CFST columns were compared with standards such as AISC360-16 and Eurocode 4. Finally, the finite element (FE) model is proposed to predict the ultimate axial force and behaviour of CFST columns. According to the results obtained, the ultimate axial force of the CFST columns increased as the fc and D/t ratio increased, while the ultimate axial force decreased as the L/D ratio increased. According to the experiment results, it has been seen that the ultimate axial force of the CFST columns is closer to the Eurocode 4 standard. The results obtained from the FE models were calculated on mean 5% more than the experimental results.

To address the difficulty in forming ultra-thin stainless steel strips, this study focuses on 304 stainless steel ultra-thin strips. By conducting tension and forming limit experiments, the basic mechanical properties and FLC (Forming Limit Curve) of the material are determined, and its formability is systematically investigated. Additionally, to improve testing efficiency and reduce resource consumption, this paper predicts the FLC forming curve of the ultra-thin strip based on the M–K ductile damage model, which is then validated against experimental results, establishing a reliable FLC prediction model. Moreover, to relate it to practical industrial production applications, this study simulates the stamping process of box-shaped components made from the ultra-thin strip based on the theoretical model, exploring the influencing factors of stamping processes on the formability of the ultra-thin strip. The research findings indicate that among the hard, semi-hard, and soft stainless steel ultra-thin strips, the soft one exhibits the best formability, and the 0.05 mm thickness is less formable compared to the 0.1 mm strip. The simulation results demonstrate that the M–K ductile damage theory can reasonably predict the formability of the ultra-thin strip. Furthermore, optimizing the chamfer size in the stamping process, reducing the friction coefficient between the die and the ultra-thin strip, and lowering the stamping speed effectively improve the formability of the ultra-thin strip.

Web-crippling was a usual failure in cold-formed steel due to the thin gauge steel. The high rate of web-crippling is the result of this beam failure. Past studies have discussed the web crippling range based on different beam thicknesses. However, the optimization of web crippling is not studied. Considering this, the reduction of web crippling rate is studied in this research work with the use of vulture optimal features. Henceforth, the current study proposed a novel intelligent vulture decision model (IVDM) to determine the proper Z-section beam thickness, which has reduced the web-crippling rate. The Strength of the cold-formed steel Z-section beam was ascertained by examining the beam’s Strength under three distinct loading scenarios: point load, uniformly distributed load, and eccentric load. Additionally, the Z-section beam is designed on the ABAQUS platform, while the designed model is run in the MATLAB environment. Performing the various execution trails allowed for predicting the appropriate beam thickness range. As a result, the optimal beam thickness value for the Z-section beam is designed using the ABAQUS software. Ultimately, all other outcome parameters have shown that the suggested model has higher Strength and less Web-crippling compared to other models already in use. Here, the proposed IVDM has improved the web crippling rate by 4% than the compared existing approaches. It has been verified that the introduced model is highly suitable for web-crippling applications.

This paper presents a numerical study on the yield resistance and ultimate resistance of steel beam with random corrosion damage. The corrosion is considered by introducing random cylindrical pits to the intact steel beam, in which the thickness of the beam, both at the section and along the length of the beam is reduced. Altogether 240 corroded beams are numerically studied, wherein the effects of corrosion ratio, corrosion diameter, corrosion depth and corrosion location on the yield resistance and ultimate resistance of steel beam are considered. It is found that for global corrosion scenario, when the corrosion ratio is 4.76%, 9.26%, 13.37%, 18.25%, 22.36%, and 25.76%, due to the random nature of corrosion, the reduction factors of ultimate resistance of steel beam range from 0.9–0.92, 0.81–0.86, 0.77–0.8, 0.71–0.76, 0.64–0.67, and 0.58–0.64, respectively. Moreover, when corrosion distributes only at the bottom flange or top flange of steel beam, the adverse effects of bottom flange corrosion and top flange corrosion on the resistance of steel beam are the same. The corrosion diameter and corrosion depth have limited effects on the resistance of steel beam. The relationship between the reduction factors for the yield resistance and ultimate resistance with the corrosion ratio of the beam is proposed. It is found that for the global corrosion case, the reduction factors of the yield resistance and ultimate resistance of the beam are linearly and negatively correlated with the corrosion ratio. For each 10% increase in the corrosion ratio, the reduction factor of yield resistance and ultimate resistance decrease by 18.9% and 15.1%, respectively. The resistances of the corroded beam with random corrosion pits and uniform corrosion are also compared. The results suggest that by using uniform corrosion model, the resistance of the corroded steel beam will be significantly overestimated. When the corrosion ratio is about 14%, the overestimation on the ultimate resistance of steel beam by using uniform corrosion model is more than 10%.