International Journal of Steel Structures最新文献

A circular hollow section steel damper exhibits equivalent structural performance in an external force direction owing to its circular cross-sectional shape. When a circular hollow section steel damper is placed in a building with stud supports, the stud supporting the damper is connected to the upper and lower beams. When an earthquake occurs, the shear force in the in-plane direction acts on the damper through the stud from the beam. However, depending on the three-dimensional behavior of the building and the arrangement of the damper and surrounding members, a load other than that in the in-plane direction might act on the damper. In this study, the mechanical characteristics of a circular hollow section steel damper in the external force direction were analyzed according to the cyclic load in the circumferential direction using finite element analysis. A reliable finite element analysis model was constructed based on the results of a previous study on unidirectional cyclic loading. The analysis results under cyclic loading conditions in circumferential directional cyclic loading were compared with those under unidirectional cyclic loading. The hysteresis curve resulted in a circular shape under circular directional loading. Moreover, the x- and y-direction load–displacement curves showed a similar strength-increasing ratio to unidirectional loading. Under circumferential directional loading, the strain was concentrated at the end of the welded part, similar to that under unidirectional loading. Furthermore, the strain was distributed in the circumferential directional loading, showing a smaller value than that of unidirectional loading.

As railway traffic volumes and train speeds increase, rail maintenance is becoming more crucial to prevent catastrophic failures. This study aimed to develop an artificial intelligence (AI)-based solution for automatic rail flaw detection using ultrasound sensors to overcome the limitations of traditional inspection methods. Ultrasound sensors are well-suited for identifying structural abnormalities in rails. However, conventional inspection techniques like rail-walking are time-consuming and rely on human expertise, risking detection errors. To address this, a hierarchical classification model was proposed integrating ultrasound B-scan images and machine learning. It involved a two-stage approach—model A for fuzzy classification followed by Model EfficientNet-B7 was identified as the most effective architecture for both models through network comparisons. Experimental results demonstrated the model's ability to accurately detect rail flaws, achieving 88.56% accuracy. It could analyze a single ultrasound image sheet within 0.45 s. An AI-based solution using ultrasound sensors and hierarchical classification shows promise for automated, rapid, and reliable rail flaw detection to support safer railway infrastructure inspection and maintenance activities.

The primary objective of this study is to examine the impact of tubular dampers exhibiting yielding behavior within knee braces and to evaluate diverse parameters affecting the efficacy of steel frames. To this end, six novel types of yielding metal dampers were introduced and subsequently analyzed for their performance within steel frames utilizing finite element analysis facilitated by ABAQUS software. Through static analyses conducted under cyclic loading conditions, the influence of various geometric parameters on the mechanical characteristics and energy absorption capabilities of these dampers was investigated. The findings indicate that modifying the damper geometry can result in alterations of up to 6% in ultimate strength and up to 8% in yield strength. Also, the three-tube mesh model showed the highest yield strength among the different configurations that were studied. The study further shows that the model 3PIPE damper developed the highest bearing force, about 371 kN, while the PIPE-2L model damper showed the least bearing force, which is about 24% of that developed by the model 3PIPE damper.

This study addresses the limitations of traditional bridge health monitoring methods by introducing the representative power spectral density (RPSD) approach, which provides a comprehensive analysis of multifrequency vibrations to detect changes in bridge stiffness under various damage conditions. Motivated by the need for more accurate and sensitive damage detection tools, this study applied RPSD to the Giongong_To bridge in Ho Chi Minh City, Vietnam, to monitor structural degradation over time. Our key findings demonstrate that as bridge damage progresses, vibrational energy shifts from high to lower frequencies, indicating a loss of stiffness. This method improves early detection capabilities, offering economic and safety benefits for bridge maintenance in infrastructure management. The RPSD approach therefore represents a valuable tool for real-time structural health monitoring, especially within extensive bridge networks like those in Vietnam.

The objective of this study was to refine the slip resistance formulas for high-strength bolted joints subjected to combined shear and tension forces. Traditional formulas typically assume that the prying force generated at the contact surface does not contribute to the slip resistance. To explore the influences of the prying force on slip resistance, a trial design was conducted based on the Specifications for Highway Bridges and Recommendation for Design of High Strength Tensile Bolted Connections for Steel Bridges, with variations in parameters such as bolt diameter, bolt pitch, joint flange thickness, and joint flange material. Additionally, numerical analyses were performed to validate the design methodology incorporating prying force. The trial design results demonstrated that the slip capacity improved when the prying force was considered, especially in cases where the external force direction ranged between 27.6 and 90 degrees. The maximum observed improvement in slip capacity was a factor of 1.2. Moreover, the slip resistance of joints with thinner flanges was enhanced when prying force effects were accounted for. This increase in slip capacity due to prying force was further corroborated through fine element method (FEM) simulations. Finally, the findings suggest the potential for enhancing joint compactness and slip resistance.

Upper space limitation problems such as floor slabs and decorative panels on the upper part of steel beams, cause difficulties in the actual strengthening OF steel structures. A new type of retrofitting method for articulated joints of steel frames under the limitation conditions was proposed. The models of articulated joints, rigid joints, and rectangular plate-strengthened joints were established. Finite element analysis was employed to investigate the failure modes, ultimate load-carrying capacity, hysteresis characteristics, ductility, energy dissipation capacity, and stiffness degradation of the joints. Additionally, the parameters of the new strengthened joint models are analyzed. It was found that the hysteresis curves of the strengthening joints were fuller and the bearing capacity and seismic performance were significantly improved, When the length-thickness ratio is less than 20, the bearing and energy dissipation capacities increased with increasing the rectangular strengthening plate size.

The current study intends to evaluate various aspects of GTAW of Austenitic stainless steel AISI 316L. Parametric optimization is one of the project's primary goals. There have been attempts at both single and multi-objective optimization. To achieve the aforementioned goal, an experimental plan is developed. The face-centered central composite design of experiments, based on response surface methods, was employed. After welding, visual inspection, X-ray radiography test, tensile test, and micro-hardness test were performed. The results on ultimate tensile strength, yield strength, and % elongation obtained under various welding circumstances are evaluated. The process has been optimized using response surface methodology.

A study on austenitic stainless steel (STS304 TKC and STS316 TKC) square hollow section(SHS) columns subjected to centrally axial compression has been conducted to investigate the buckling behaviors of the compression members with both fixed ends. Main variables are steel type, column length and width-thickness ratio. Buckling modes at ultimate state were classified into two such as local buckling and global buckling. Compressive material properties of SHS members was also investigated through stub column tests in addition to tensile material properties. Stub columns showed local buckling mode. A finite element (FE) analysis model of a stainless steel SHS column considering initial geometric imperfection and compressive material properties was developed, and the validity of the FE analysis procedure was verified through comparison with test results. The test buckling strengths were compared with the strengths predicted by current stainless steel design specifications (American Society of Civil Engineers (ASCE 8–22) and Eurocode (EC3)). As a result, it is found that design strengths with compressive material test data of stub column than those of tensile coupon were close to test buckling strength. The global buckling coefficients of ASCE 8–22 was the values presented for the compression members of open sections, and since it did not sufficiently reflect the buckling characteristics of the closed-section SHS members, some of the buckling coefficients were adjusted upward referring to the AISC 370–21 specification. The EC3 standard presented a value with the adjusted initial imperfection coefficient. It was confirmed that the predicted strength by the design equations with the modified coefficient was close to the test and analysis buckling strength.

The influence of interface sliding is analyzed for the improved composite box girder bridge with corrugated steel webs. The governing differential equation for the slip function is established by using the energy variational method. The analytical expressions of the normal stress, shear lag coefficient and deflection of the simply supported box girder are derived. A finite element model is established to verify the reliability of the theoretical solution. The results show that the theoretical formula is in good agreement with the finite element results. Theoretical parametric studies are carried out to study the influence of various factors on the shear lag coefficient, the maximum normal stress and deflection of this kind of structure. The results indicate that the width-to-span ratio and width-to-depth ratio have a larger influence on the maximum normal stress; the contribution of shear deformation on the total deflection is significant.

Based on the current plans for Urban Air Mobility (UAM) in various nations, there is an increasing need for vertiport infrastructure in urban areas. Offshore floating vertiports have potential as they address the space constraints of land-based vertiports and can integrate with maritime transport. However, their susceptibility to environmental factors such as waves has limited their prior development. This study conducted a conceptual design to establish the physical properties and geometry of a floating vertiport. The design process focuses on ensuring stability against mooring breakage and securing UAM vertical take-off and landing stability, with quantitative target performance criteria. The dimensions of the floater were determined by referencing the vertiport design guideline established by Federal Aviation Administration. The response to wave loads was evaluated through hydrodynamic analysis, and the appropriate mooring system was selected. The selected designs, which meet the target performance criteria, were examined through ({T}_{p}-{H}_{s}) diagrams, confirming that appropriately designed floating vertiports could operate stably under significant wave height of up to 2 m.