International Journal of Steel Structures最新文献

This study introduces a sleeve fuse system to improve the cyclic performance of steel end-plate connections. A specially designed steel sleeve, placed between the end plate and nut/washer, disrupts the load path and enhances ductility. Experimental models from the literature were used for model validation, ensuring high accuracy in the numerical analysis. Simulations of various sleeve geometries, using a validated finite element model, demonstrate the system's effectiveness. A comparative analysis with reduced beam sections (RBS) and standard connections highlights the superior performance of the sleeve system, a key novelty of this study. A hybrid design combining the sleeve system with RBS is also proposed. Results show that the sleeve system improves rotational capacity, acting as a structural fuse during seismic events by enhancing ductility and energy absorption. Increased bolt elongation further boosts rotational capacity, enhancing frame robustness. The proposed system offers a superior alternative to conventional methods with improved ductility and energy dissipation.

This study evaluated on the strain caused by the release of residual stress induced by welding as a fatigue crack initiates and propagates. The change in the strain in the unloading condition owing to fatigue crack initiation and propagation was confirmed by fatigue tests conducted on box-type specimens with vertical stiffeners and out-of-plane gusset welded-joint specimens. Next, a strain monitoring system employing small IoT datalogging equipment was demonstrated by detecting the change in strain owing to crack propagation during a fatigue test. Finally, the weld residual stress in the out-of-plane gusset welded-joint specimen was reproduced using a finite element analysis to confirm that the residual strain at the weld toe changed owing to the propagation of a fatigue crack.

A support-type shear connector for basement composite walls was developed, and a push-out test and a finite element analysis (FEA) were performed to evaluate structural performance. For the support-type shear connector specimens, the ratio of the yield load to the nominal strength without applying the reduction factor was 0.83 and the ratio of the maximum load was 1.43. The ratio of the yield load to the nominal strength, to which the reduction factor was applied, was 1.38 and the ratio of the maximum load was 2.39. Thus, if the length of the support-type shear connectors is 35 mm to 100 mm, it can be designed with the nominal strength without the reduction factor applied. Additionally, the initial stiffness and maximum load of the support-type shear connector can be predicted using FEA with an error margin of within 10%.

Liquid storage tanks are essential components widely used across various industrial sectors. In addition to the internal liquid pressure and weight, these tanks are influenced by several external factors, such as wind, seismic activity, and temperature. The sloshing problem, which arises from the combined or individual effects of these external factors, presents a significant challenge for liquid storage tanks. This study aims to investigate sloshing phenomena by focusing on prominent studies in the literature. In the initial sections of the study, sloshing behaviour and key parameters are briefly introduced, followed by a discussion of the methods related to the modelling of sloshing. Subsequently, literature studies focusing on cylindrical and rectangular upright tanks related to sloshing are compiled under the headings of analytical, numerical, and experimental research. In the section presenting the experimental studies, works related to mitigation of sloshing effects are examined as a separate topic. As a result of the review conducted, topics that have received significant attention in the literature and other areas suitable for new research have been discussed.

Cantilever-type longitudinally tapered structures are frequently used in high-rise steel structures. The current paper presents a fault identification technique for differently tapered beams that are elastically restrained and having a tip mass. For this purpose, a method is proposed for identifying the modal parameters of an intact beam by applying continuity and boundary conditions. Then, an equivalent bending rigidity for a beam with a crack is introduced and a characteristic equation is established to estimate the natural frequency change caused by the damage. An experimental study is conducted to verify the presented method. A baseline model is updated for the intact beam before detecting the crack by updating the rotational and translational spring constants. Crack identification is then carried out experimentally based on the neural network technique. The training patterns for the network are composed of the natural frequencies calculated from the derived characteristic equation for cracked beams, along with their corresponding crack sizes and locations. The cracks are identified using the trained neural network, and those are found to be reasonably well identified. The practicality and usability of the presented technique for health monitoring of the differently tapered cantilever-type structures elastically restrained having a tip mass could be thus verified.

This study investigates the effect of post-weld heat treatment (PWHT) on the dissimilar welding joint of AA304 and P92 steels with filler ER90S-B9. The PWHT was conducted at three distinct temperatures, 780 °C, 810 °C, and 840 °C, on the welded specimens. The heterogeneity in mechanical behavior and grain structure was evident, particularly in the HAZ of the P92 side, which experienced more pronounced changes than the SS304 side. The Coarse-grained HAZ (CGHAZ) exhibited an average grain size of 72 ± 8 µm post-PWHT, while the fine-grained HAZ retained finer prior-austenite grain boundaries. Microstructural analysis revealed a higher presence of δ-ferrite and martensite in the as-welded state, accompanied by a coarser grain structure in the HAZ, rendering the sample more susceptible to failure in this region. The hardness values decreased with increasing PWHT temperature, with the CGHAZ recording 276.52 HV, 268 HV, and 245 HV under PWHT_780 °C, PWHT_810 °C, and PWHT_840 °C, respectively. The HAZ and WFZ of the P92 side observed tempered martensite, while the HAZ of SS304 did not respond to PWHT. The UTS of the welded joints without PWHT was observed as 511.27 MPa, while after PWHT at 780 °C, 810 °C, and 840 °C the UTS of the welded joints were increased as 534.14 MPa, 545.96 MPa, and 569.38 MPa respectively.

The form of the bracing layout in braced steel frame structures plays a critical role in determining the lateral stiffness and seismic performance of the structure. This paper proposes a topology optimization method for designing the bracing layout based on Evolutionary Structural Optimization (ESO) and conceptual design principles. Different possible bracing layouts can be described as a string of binary codes where ‘0’ and ‘1’ indicate the absence or presence of a bracing unit, respectively. The bracing layout state is classified according to the structure’s eccentricity, while the internal force of the bracing is adjusted according to the importance of the bracing and the symmetry of the structure, and the bracing units with a small contribution to the structure are gradually removed. Subsequently, an optimization program is employed to minimize structural weight considering multiple loading cases and constraints. The automatic optimization program was successfully applied to optimizing bracing layouts for two different steel frame structures. The results demonstrate that this bracing layout optimization method for high-rise steel frame structures, based on ESO and conceptual design, achieves a reasonable arrangement of bracing and reduces the steel consumption of the structure, which proves its feasibility and effectiveness.

To promote the advancement of steel plate shear walls and tackle the challenge of inadequate shear resistance in traditional shear walls, a double-sided metal plate shear wall, filled with rigid polyurethane foam and equipped with replaceable wall panels, was proposed. Three distinct types of metal plates, namely 0.5 mm Q355 steel plates, 1 mm Q355 steel plates, and 0.5 mm 6063 aluminum plates, were utilized for pseudo-static monotonic loading tests and pseudo-static cyclic loading tests. The study delved into the impact of varying metal plate thicknesses and materials on the shear failure mechanism of the wall. The findings revealed that the horizontal bearing capacity of the double-sided metal plate shear wall hinges on the torsional deformation of the steel plate, frame deformation, and polyurethane deformation. Under cyclic loading, the steel plate undergoes deformation, recovery, and reverse deformation. Through analysis of hysteresis curves and skeleton curves, it was evident that augmenting the thickness of the steel plate enhances its shear resistance, whereas the shear resistance of aluminum plates remains relatively unchanged. Monotonic load–displacement curve analysis indicated that the initial shear stiffness increases with the increase in steel plate thickness but decreases with the increase in aluminum plate thickness. Furthermore, an examination of energy consumption curves indicated that thickening steel plates and aluminum plates enhances their energy consumption capacity.

Various methods, such as increasing the cross-section and attaching reinforcements, are employed for repairing and reinforcing old buildings. However, these methods have disadvantages, such as inefficient workability and poor appearance. Additionally, the aging rate of social infrastructure is rapidly increasing; however, the manpower required for its maintenance and reinforcement is decreasing. Therefore, simple maintenance and reinforcement methods are required. This study aimed to verify the effectiveness of repair and reinforcement using polyurea and honeycomb steel plate reinforcement methods, which were developed in response to these industrial and technical requirements. These experiments were carried out on the five different types of specimens considering reinforcement effects: 1) no consideration of reinforcements (control specimen, CC), 2) steel plate (SC), 3) integrated type honeycomb steel plates coated with polyurea (PHC1), 4) unit type honeycomb steel plates coated with polyurea (PHC2) and 5) carbon fiber (CFC). The column experiment focused on how the column’s behavioral characteristics change according to the type of reinforced material, rather than identifying the inherent behavior characteristics of the column. Therefore, in this study, the reinforcement effect of each specimen was investigated based on the non-reinforced specimen. In the experiment, the reinforcing effect on the column test object appears in the order of SC > PHC1 > PHC2 > CFC.

Steel sections are usually manufactured with geometric defects and deviates from the original ideal shape during rolling process; these defects are called imperfection in international standards. This study is devoted towards investigating local geometric imperfections of steel columns under combined effect of axial load and lateral cyclic displacements which simulates steel columns under seismic events. Ten wide flange sections with two cases for each section: ideal and imperfect. A comprehensive nonlinear finite element model which is validated against available experimental data in literature was employed. A sustained axial load which ranges from 20-100 percent of the maximum axial capacity for the column was applied prior to application of the designated lateral cyclic displacement amplitude. It was found that web local imperfection has a substantial impact on the cyclic response of the columns. It was also revealed that higher axial load ratios impact column response than do lower load ratios. Moreover, drift angle was found more susceptible in stocky than in light sections. The study showed that there is a limiting zone within the slenderness ratios for both of flanges and web should be avoided when considering section design of columns under seismic events because it yields a big difference between ideal and imperfect section.