International Journal of Steel Structures最新文献

Cable cranes are increasingly utilized for the accelerated construction of large-span bridges due to their high lifting and spanning capacities, precise positioning capabilities, and adaptability to challenging terrains. However, the complex cable-pulley interaction between the saddle and main cable poses significant challenges for finite element analysis using traditional methods or programs. To address this, the study proposes a simplified method for the finite element analysis of cable cranes to capture the mechanical behavior accurately, accounting for cable-pulley interaction. In this paper, the predominate analytical methods for the cable crane calculation, including the parabolic method and catenary method, are derived and compared through parametric analysis. Subsequently, a simplified analysis method is proposed for facilitating the calculation of the cable crane, based on the principles of equal cable tensions on both sides of the saddle and the constant unstressed length of the main cable. Finally, the proposed method is validated through analytical solutions and field experiments of the cable crane. This research offers an efficient numerical approach and valuable experimental data for the design and optimization of cable cranes in bridge engineering.

This study investigated the effect of corrosion damage on the load-bearing capacity of steel girder ends under varying support conditions. A detailed finite element analysis was conducted using ABAQUS to simulate corrosion at the girder ends, considering different combinations of thickness reductions in the web and vertical stiffeners based on actual damage patterns observed in bridges. Two support conditions, i.e. healthy (rotationally free) and unhealthy (rotation constrained due to deterioration), were modeled to reflect realistic bridge aging scenarios. Corrosion was assumed to occur below the crossbeam near the sole plate, and 72 different corrosion cases were analyzed. Additionally, it was assumed that when corrosion occurs, the result is uniform thinning of the affected members and that corrosion at the support is spread over the sole plate surface. The results indicated that under healthy support conditions, the load is evenly distributed among components, and the capacity is proportional to the remaining effective cross-sectional area of the web and vertical stiffener. In contrast, under unhealthy support conditions, the load is concentrated on the web on the span side, making the location of corrosion critical. The findings emphasize the importance of considering both the extent of corrosion and the support conditions when evaluating the structural performance of aging steel girder bridges.

This work discusses experimental and numerical findings about the behavior of tapered steel girders. The experimental program included the fabrication and testing of six simply supported tapered zigzag and flat web steel girders tested under central load. The tapered girders were classified into two types: zigzag and flat steel web with three web heights: 400 mm, 600 mm, and 800 mm. The total span of each specimen was 1800 mm, and the clear span between supports was 1600 mm. The main variables in the present experimental tests were the shape and height of the steel web girders. The experimental results for tapered flat web girders show that increasing the web height from 400 to 600 mm and 800 mm significantly improves the ultimate load capacity of the girders by 60% and 30%, respectively. Moreover, the zigzag web girders' ultimate capacity increased by (72%, 44%, and 18%) compared to the corresponding flat web girders. The maximum vertical middle of the span deflections of the tapered zigzag web girders were greater than that of the flat web girders (25%, 22%, and 39%). It was seen that the increase in web heights of tapered girders led to an increase in the ultimate vertical middle of the span displacements.

Column removal in structures can rapidly result in progressive collapse. While the progressive collapse response of regular structures has received much attention in the current literature, relatively, rare studies has been performed on the response of setback irregular structures under column removal scenarios. In this vein, this study analyzes 60 setback steel moment resisting frames, considering ductility levels, design earthquake level, and number of stories. First, structures are subjected to gravity loading and column removal scenarios leading to damage percentage calculation and categorization into different groups from almost fully progressive collapse resistant to highly vulnerable. Results indicate a significant impact of the ductility level and design earthquake level on the probability of progressive collapse. The results also indicate that an increase in the irregularity of the structures will reduce progressive collapse resistance. Yet, the irregular structures with low setback irregularity perform better than regular structures. As well, the results indicate that column removal scenarios in upper stories can increase the risk of progressive collapse due to weak design regulations. To mitigate the risk of progressive collapse in setback irregular structures, it is then suggested that the design parameters such as minimum beam dimensions, minimum base shear, the ductility level and design earthquake level should be changed as per the damage percentage.

In this study, efficient finite element modeling concept and application for a sub-assembly structure are presented to assess the progressive collapse resistance performance of a whole structure considering the three-dimensional effect of the slabs, the continuity of the adjacent spans, and the stress redistribution through the alternative path of the upper floors. Three modeling levels were considered based on the degree of lateral behavior simulation by considering the flexural rigidity of columns and girders outside the influenced range. Furthermore, the modeling methods for a sub-assembly structure were evaluated by comparing the load-displacement relationship, girder stress, and plastic hinge locations with those obtained from the simulation of the whole structure model. The results indicate that the sub-assembly structure modeling can significantly reduce time in modeling and analyzing large structures and yield reliable results for appraising progressive collapse resistance performance.

The force-transfer mechanism of a steel–concrete joint (SCJ) in a railway hybrid girder cable-stayed bridge was analysed using model tests and nonlinear finite element analysis (FEA), and the influence of the main design parameters on the load transmission performance was determined. The FEA results were in good agreement with the test results. The SCJ behaved linearly up to even under 2.0 times the design load, and the safety factors of the concrete and steel were not less than 2.02 and 2.55, respectively. The SCJ exhibited excellent deformation performance. Approximately 33.0% of the axial force was transferred from the steel girder to the concrete girder through the rear bearing plate (RBP), indicating that the RBP played an important role in force transfer. The force transmission efficiency of the steel cabin segment was approximately 2.0 times greater than that of the insert segment. The relative slip distribution along the bridge was saddle-shaped with large ends and a small middle. The uneven coefficients of the force shared by the PBL connectors and shear studs were 0.45–4.17 and 0.17–3.15, respectively. The deformation of the RBP was more complex than that of the front bearing plate (FBP), and the perforated plates, longitudinal prestressed tendons and webs strongly influenced the deformation distribution of the RBP. A parameter analysis revealed that the shorter the SCJ was, the greater the force transferred by the bearing plates and the greater the shear force shared by the shear connectors were. The greater the height of the steel cabin was, the greater the proportion of axial force transmitted by both the FBP and RBP was. Decreasing the stiffness of the PBL connectors and shear studs increased the relative slip considerably.

In offshore steel tubular structures corrosion caused by the environment can lead to perforations that compromise their integrity. However, there are still no well-established standards for assessing the reduction in structural capacity considering the damage dimensions. This article aims to investigate, both experimentally and numerically, the strength of tubular structures with oblong perforations under compressive loads, as well as to propose the use of regression to estimate the remaining load capacity. In the experimental analysis, four tubular members with varying length-to-diameter and diameter-to-thickness ratios are used, featuring oblong perforations oriented longitudinally and transversely. A finite element model is also developed using shell elements, and the experimental and numerical results are compared, with the four tested samples being replicated with identical geometry and stress–strain material curves. The numerical model results demonstrate remarkable agreement with the experimental findings, particularly regarding the maximum axial load capacity, validating its applicability to similar configurations. Based on the results, regression was employed to generate an optimized expression, minimizing the error between the predicted values and the numerical data. It is concluded that the size of the perforation in the transverse direction of the tubular element is critical to the loss of compressive strength, whereas the perforation length in the longitudinal direction contributes significantly less.

The production of stainless-steel systems has created a major impact on the advancement of technology and its application in various industries. The failure of stainless-steel machinery and structural components can be attributed to the important role played by mechanical and electrochemical properties. Thus, there is ample room for enhancement in these domains. The powder was compacted using cold compaction through single-action uniaxial pressing; applying a pressure of 600 MPa. Hydrogen sintering produced a refined pore structure, enhancing strength (222 MPa YS, 410 MPa UTS) but reducing ductility (13.9% elongation). Mixed-atmosphere sintering improved ductility (23.5% elongation) but lowered strength (188 MPa YS, 359 MPa UTS). It has been noted that the specimens sintered in a hydrogen sintering atmosphere exhibited a significant increase of 11 and 18% in the ultimate tensile strength and yield strength, respectively, compared to the specimens sintered in a mixed atmosphere. Fractography showed more ductile features in hydrogen-sintered specimens. Corrosion resistance was higher in mixed-atmosphere sintering, with a lower OCP ( − 399 mV). These results highlight the critical role of sintering conditions in material performance optimization.

This paper presents the results of an experimental fatigue behavior study, conducted on round standard specimens, which were machined from T-welded connections, which are extensively employed in the repair of offshore oil & gas structures. For the analysis, two different grinding/wet welding repair conditions were performed. Hence, the tested grinding depths conditions are 6 and 10 mm, which were subsequently filled with wet welding at three immersion water depths of 50, 70, and 100 m. The round specimens were subjected to high cycle fatigue tension tests, and the S–N curves were measured for air-repair an immersion repair condition. The results reveal a decrease of cycles number in the S–N data with water depth increment, compared with air repair condition. For the wet repair condition, the lowest stresses were obtained for the connections with a grinding depth of 10 mm and filled with wet welding at 50 m of water depth, however the stresses where higher to those obtained at repair air conditions. Nonetheless, for the case of a 6 mm grinding depth repaired with wet welding at 50 m of water depth, the stresses were similar to those at air repair conditions, therefore this last grinding-wet welding combined repair condition can effectively restore the original service life of T-shaped connections, damaged and repaired by the combination of grinding and wet welding. In contrast, for water depths of 70 and 100 m, significantly lower fatigue results were observed compared for both grinding and wet welding repair conditions.

The increasing adoption of lightweight, long-span pedestrian walkways has heightened concerns regarding vibration serviceability due to reduced natural frequencies and damping ratios. Traditional evaluation methods, such as root mean square (RMS) acceleration and maximum transient vibration value (MTVV), are widely used in design standards. However, significant discrepancies exist between threshold values specified in guidelines and real-world vibration experiences, leading to inconsistencies in serviceability assessments. This study proposes a probabilistic methodology that evaluates walkway vibrations based on in-situ measurements rather than predefined standard limits. By examining resonance-induced pedestrian discomfort, site-specific discomfort thresholds are established. A weighted MTVV (WMTVV) approach is introduced, integrating probabilistic modeling to enhance accuracy in real-world applications. To validate this framework, an experimental study was conducted on a 52-m span footbridge, incorporating long-term ambient vibration monitoring and controlled resonance experiments. The results reveal that existing vibration assessment methods often yield subjective and overly conservative or inadequate criteria. The study highlights the necessity of data-driven, probabilistic methodologies tailored to structure-specific conditions, thereby improving accuracy, reliability, and practical applicability in pedestrian walkway vibration evaluation.