International Journal of Steel Structures最新文献

Corrosion will reduce the threshold for the expansion of existing cracks in steel structures. To establish the criterion for the propagation of existing cracks in corroded steel structures, it is necessary to study the microscopic mechanism of ductile fracture in the crack tip area of corroded steel plate. This paper aimed to investigate the void deformation characteristic in the crack tip region of corroded steel plates based on computational cubic cell models. By setting boundary constraint, the computational cell models considering the crack tip stress states with pit effects could be established. The pit did not change the evolution modes of the crack tip microscopic void, but the pit depth and shape had influence on the closing speed and degree of the micro-voids in the crack tip steel. The fracture initiation criterion of corroded cracked steel plates could be established based on the micro void evolution mechanism in the crack tip region considering pit effects.

This paper investigates the optimization of stiffness distribution in semi-rigid joints within both the plan and height dimensions of steel space frames. To achieve this, advanced structural analysis and optimization techniques, specifically the Practical Advanced Analysis (PAA) method and the Slime Mould Algorithm (SMA), are employed. The PAA method are utilized to effectively capture material inelasticity and second-order structural effects. The structural model incorporates a zero-length element consisting of three rotational springs and three translational springs, with rotational spring stiffness values derived from the Kishi-Chen Power Model. This model is instrumental in predicting the nonlinearity exhibited by semi-rigid connections. SMA, a global optimization algorithm, is then applied to determine the optimal solution. This method has performed very well in optimization problems; therefore, it is being utilized for the first time in this type of problem. In this study, the optimization variables extend beyond the cross-sectional properties of beam and column members to include various types of semi-rigid connections. The results, obtained from analyzing two distinct three-dimensional steel frames—a four-story and an eight-story structure—reveal that connection stiffness is distributed more prominently within the structure’s inside plane compared to its edges and corners. Furthermore, the distribution of joint stiffness within the structure’s height either remains constant or increases. Additionally, a reverse relationship is observed between joint stiffness and column stiffness.

‌The behavior of double diagonal corrugated plate-reinforced flat steel shear walls (SSWs) has been studied in this study. Corrugated double plates were used in this research with 5 angles of 90°, 60°, 45°, 30°, and 0° to the vertical axis. Also, three corrugation angles were used for the trapezoidal corrugated plate, including 30°, 45°, and 60°. The reinforcement corrugated plate was used in three thicknesses of 2, 4, and 6 mm. According to the study’s findings, reinforcing a flat wall using corrugated plates of varying thicknesses and angles improved the wall’s maximum strength by 6.1–40.5%. Also, the initial stiffness of hardened SSWs has increased by a minimum of 1% and a maximum of 47.7% compared to the control sample. The results also showed that the increase in the thickness of the reinforced corrugated plate directly led to an increase in the lateral bearing capacity and initial stiffness. Furthermore, due to the reinforcement of the flat plate, energy absorption has increased between 4.9 and 40%. Also, findings indicate that stiffened materials have a higher equivalent viscous damping than unstiffened samples.

The purpose of the present study is to develop an assessment approach of impact load that can consider the effect of ship bows types and impact angle. The impact procedures between various types of ships and bridge are simulated by using FE ((finite element) analysis. The influence of bridge pier stiffness, bow shapes and impact angle on the impact force are discussed. The numerical results of impact load are compared with that of the existing specifications. The various impact responses of peak force, deformation of vessel bow and impact duration are compared with that of the existing specifications. The impact force of ship having the same displacement tonnage bows are very different for various types bows. The empirical formulae for predicting vessel impact forces with considering the influence of impact angle and vessel types are developed.

Cables are vital load-bearing components in cable-stayed bridges, significantly influencing structural performance. Monitoring natural frequencies is a widely used method for assessing cable conditions. This study examines changes in the natural frequency values of cables on the Phu My Cable-Stayed Bridge over time, focusing on comparisons within strands, between opposing strands, on the same pylon, and across different measurement periods. The analysis highlights variations in tension distribution and the influence of factors such as position, length, and measurement time on cable vibrations. These findings offer critical insights for effective monitoring and maintenance, ensuring the safety and longevity of cable-stayed bridges.

The rib-to-deck weld root crack is located inside the U-rib and is commonly treated using rewelding from the deck surface. Due to the challenge of real-time crack state detection post-repair, ensuring the repair effectiveness is crucial. By conducting rewelding tests, the local strain, fatigue crack size, fatigue life, and the crack propagation behavior of the specimens were analyzed. The impact of welding parameters such as welding length, number of welding passes, as well as processes like inter-pass grinding and impact treatment after rewelding, on the repair effectiveness was discussed. The results indicate that the untreated crack exceeding 150 mm and secondary cracks after rewelding exceeding 50 mm require immediate intervention to mitigate further propagation and structural compromise. The local stiffness of the specimen will decrease, and the specimen cannot be restored to its original stress performance after rewelding. The crack growth rate and crack size after secondary cracking are greater than those in the unwelded state. Increasing the welding length will enlarge the length for rapid crack propagation, reducing the fatigue life of the specimen. A combined approach using multi-pass welding, inter-pass grinding, and impact treatment will achieve a better repair outcome, which is recommended in real bridges.

In this study, finite element and frame structure analyses were conducted to evaluate the effect of re-corrosion of thickness-reduced steel plates repaired using patch plates. In the analyses, some elements of the analytical model were eliminated to simulate re-corrosion under dead load. Based on the results of the finite element and frame structure analyses, the shared axial forces of the main and patch plates during re-corrosion were evaluated. It was found that even for re-corrosion of a thickness-reduced steel plate repaired by patch plates, frame structure analysis can be used to evaluate shared axial forces. In addition, cases of re-corrosion with eccentricity were evaluated in this study. Finally, it was shown that a part of the dead load induced in the thickness-reduced plate was redistributed to the patch plates, and the change in the dead load during the redistribution could be estimated by frame structure analysis.

Monitoring the health of critical structures like truss systems has been a key focus for researchers in recent decades due to the growing number of constructed facilities and the associated risks of structural failures. This article introduces a testing method employing a moving source to identify damaged elements within the truss. By analyzing the vibration data collected from each nodal point of the truss, damaged elements are pinpointed through data processing. The technique involves evaluating the Cumulative Damage Index (TDI) values derived from time and frequency domain analyses of nodal velocity responses recorded at upper nodes of the structure. Validation of this damage detection approach is conducted using seismic data obtained from a real truss structure and synthetic data generated through numerical simulations. A three-dimensional truss structure with dual spans is used in the laboratory for this purpose, and various numerical analyses are carried out. The findings demonstrate that the moving source method facilitates precise identification of failure locations and severity levels. Notably, an increase in TDI values at nodes correlates directly with a rise in damage severity within the affected member. However, the TDI pattern varies across different scenarios, with values changing based on the damaged member’s position. Consequently, the TDI parameter serves as a valuable indicator for pinpointing the location and extent of damage throughout the structure during moving source tests.

This study examines the impact of connection types between a beam and a column, as well as between a beam and a shear core, on the optimal design of 3D steel buildings with reinforced concrete (RC) shear cores. Three metaheuristic algorithms, Adaptive Harmony Search (AHS), Biogeography-Based Optimization with Levy Flight (LFBBO), and Dandelion Optimizer (DO), were implemented to minimize the total weight of the steel frame while incorporating geometric constraints. RC shear core dimensions were treated as fixed due to elevator design considerations. The effectiveness of these algorithms was evaluated using two mid-rise steel building models with 20 and 30 stories, with a focus on the impact of varying connection configurations. Results indicate that LFBBO consistently produced the lightest designs. It is noticed that connection types significantly affect the optimum designs. In the 20-story models, the increase in the proportion of hinged beam connections led to a decrease in the optimum steel weight. Conversely, in the 30-story models, more hinged connections resulted in increased weight. Column-to-column (CtoC) and inter-story drift (ISD) constraints dominated the optimum designs in all models. It is necessary to account for connection types and structural drift when designing steel buildings with shear cores.

Cable domes have low redundancy and are prone to progressive collapse. The present study simulated the dynamic responses and collapse modes of a real cable dome structure under the failure of its structural members during a typhoon. Moreover, the structural reliability of the structure was studied based on the Monte Carlo method and the effect laws of the structural reliability by the design parameters, such as the wind speed, component section, initial prestress level and rise–span ratio were analysed. Finally, on the basis of the importance coefficients of the structural members, this study optimised the shape, component sections, and topology of the examined structure by using genetic algorithms. This study found that during a typhoon, failure of key, important, and general members leads to progressive collapse, localised collapse, or non-progressive collapse of the examined structure, respectively. In the simulations, the strength reliability index values of the outer ridge cable and other structural members were 1.7426 and 1, respectively. In addition, the deformation reliability index of the structure was 1.7147, satisfying the serviceability limit state requirement. Member sections, prestress levels, and rise–span ratios had different effects on the strength failure reliability and deformation failure reliability of the structural members. Shape optimisation reduced the importance coefficient of the outer ridge cable, which had the lowest strength reliability among all structural members, from 0.613 to 0.393, with the optimisation rate being 35.7%. On this basis, the effectiveness of optimising component cross-sections on reducing outer ridge cable importance was quite limited. When the structure was completely altered from a Geiger-type to a Levy-type topology (topological structure 1), the importance coefficient of the outer ridge cable was optimised 32.5%. Topological structure 2 demonstrated the optimal comprehensive optimisation, ultimately optimising the importance coefficient of the outer ridge cable by 64.3%.