International Journal of Steel Structures最新文献

The inclined façades of irregular tilted-midsection buildings, which midsections are intentionally designed to be inclined, generate eccentric loads on each floor. In addition, lateral loads, such as earthquakes, and self-weight induce overturning moments, causing lateral displacement in the inclined direction of the structure. To compensate for this structural instability and disperse the overturning moment, the lateral displacement needs to be controlled by applying multiple cores, or by adding a lateral force-resisting system, such as an outrigger system. In this study, the lateral force resistance performance of an irregularly shaped 60-story building with the midsection tilted by approximately 12.1° was investigated according to the change in core placement. The analysis modeling was classified into single–core and dual–core models, and consisted of six models where the core position was shifted horizontally along the tilted direction (X–axis). Eigenvalue and seismic response analyses were performed, and the structural characteristics were analyzed by comparison with the regular analysis model. The analysis results showed that as the core was placed in the inclined direction of the structure, the structural responses of the irregular tilted building under the load combination of vertical load seismic loads decreased. In addition, an analysis model with the best seismic resistance was evaluated for each core placement, and the location of the outrigger system that could effectively reduce the story drift ratio and maximum lateral displacement was investigated through static and time history analyses. This study can be used as a guideline for core placement and the number and location of outrigger systems installed in the planning and initial design stages of irregular tilted-midsection structures.

This study investigates the collapse mechanism of a half-through truss bridge, focusing on its structural reserves beyond the first failure under different damage conditions. Addressing the challenge of predicting collapse behavior in the presence of localized corrosion, a series of progressive collapse analyses were conducted using a three-dimensional finite element model. The findings reveal that the collapse mechanism is primarily governed by the instability of the upper chord system, even when the stress level is well below yielding. These results were validated using an equivalent two-dimensional upper chord system analytical solution. Furthermore, localized deterioration was shown to significantly reduce the bridge’s load-carrying capacity, potentially causing sudden catastrophic failure. The study provides a unique insight into the collapse mechanisms of corroded steel bridges, filling a critical gap not addressed in previous research. The key contributions include a comprehensive nonlinear analysis of progressive collapse, explicit modeling of localized corrosion effects, and the validation of findings using both 3D and 2D models.

This study aimed to elucidate the degradation mechanism of the mechanical properties of Q235B steel under the coupling action of axial tension and local cyclic corrosion. A custom stress corrosion testing apparatus was designed and fabricated for this purpose. Accelerated tests were conducted with varying corrosion durations (1, 3, and 5.5 days) and stress ratios (0.4, 0.6, and 0.8). The corroded steel plates underwent three-dimensional scanning and static ultimate tensile testing. The study revealed that steel plates with a corrosion rate exceeding 30% displayed characteristic necking, and their cross-sectional integrity was significantly diminished. There was a significant positive correlation between the corrosion rate of steel plates and stress ratios, and the mean cross-sectional loss rate in the corroded areas corresponded to the level of stress corrosion. Additionally, the decline in the nominal mechanical properties parameters (f_yⁿ, f_uⁿ) of the corroded steel plates was directly proportional to their corrosion rate. Two models predicting the corrosion-induced degradation of steel’s mechanical properties, incorporating stress ratio variables, were developed using multivariate linear regression analysis.

Trapezoidal corrugated web beams (CWB) have been the subject of extensive research. However, there is a noticeable gap in the literature concerning the determination of moment resistance in slender corrugated web beams with slender flanges (SCWSF). Previous studies, both experimental and numerical, have shown that the SCWSF bending resistance model outlined in EN1993-1-5 (Eurocode 3: Design of steel structures—Part 1-5: Plated structural elements, CEN, 2007) often leads to unsafe resistance predictions. This study investigates the moment capacity of SCWSF using a combination of theoretical, numerical, and experimental approaches. A numerical and analytical investigation is being conducted in the current part to analyze the moment resistance of SCWSF beams. Based on previous results from the experimental studies of SCWSF, a novel formulation has been developed to align with the failure modes and guidelines outlined in ANSI/AISC 360-16 (Specification for Structural Steel Buildings, Chicago, 2016) for the design of steel I sections to resist flexural strength. A new methodology has been developed to assess the moment resistance of SCWSF, considering factors such as flange slenderness, the ratio of flange width to beam height, and various loading conditions. This approach builds upon existing proposals for flat and corrugated web girders, incorporating numerical findings for further validation. The results suggest that all models demonstrate a conservative nature and lack accuracy across the full range of SCWSF beams. The recommended approach offers more accurate estimations compared to existing standards and proposed designs.

The double composite beam system with drop panels is a structural system developed for high-rise buildings with long spans. This system aims to reduce floor height by decreasing the depths of flexural members while minimizing deflection through the incorporation of stiff drop panels at both ends of the span. For a double composite beam system with drop panels, it is essential to assess whether the frame can exhibit adequate flexural and deformation performance under repeated lateral loads, such as those induced by earthquakes, given the varying cross-sections of the flexural members. Experimental results on flexural strength indicate that all specimens demonstrate sufficient flexural performance, with smooth load transfer between members. When predicting deflection using the elastic load method, the results showed good agreement with the experimental outcomes, confirming the method’s validity for predicting negative moment-induced deflection.

In the design of tensegrity systems, which are commonly used in large-span structures, the determination of a set of prestress forces is one of the most critical issues. The stability of a tensegrity system depends on a set of prestress forces that ensure the entire structure remains in equilibrium and may need architectural requirements. For a specified geometry, a set of prestress forces that are in equilibrium can be obtained through iteration, and this set of prestress forces is referred to as feasible. This study introduces a novel approach for obtaining a feasible set of prestress forces for desired geometries through nonlinear iteration using the Force Density Method. The proposed method effectively mitigates singularity issues arising from non-invertible force density matrices, thereby enhancing computational robustness and reliability. The methodology is applied to four geometric configurations: a simple model, a Levy dome, and two Geiger domes (with and without inner rings), demonstrating its ability to achieve a set of prestress forces that are consistent with established benchmarks. These results highlight the method's potential as a practical and reliable tool for addressing prestress design challenges in tensegrity structures.

To enhance the seismic performance of super high-rise buildings, this paper proposes a nonlinear seismic response analysis of super high-rise frame core tube structures based on the Bouc–Wen model. Using the Bouc–Wen model as the material model, the stiffness ratio, hysteretic shape parameters, strength degradation and stiffness degradation parameters are solved, the parameters of the Bouc–Wen model are identified through genetic algorithm, and the super high-rise frame core tube structure is designed accordingly. Concrete material model, steel bar, section steel material model and beam-column node element model, and finally the frame-core tube structure model is constructed. Eight seismic waves were selected to simulate the earthquake situation to test the nonlinear seismic response of the frame core tube structure of the super high-rise building. The experimental results show that the super high-rise frame core tube structure can reduce the floor shear, the displacement angle between floors and the floor displacement are small, and the top layer displacement and acceleration of the frame core tube structure are reduced. The super high-rise frame core tube structure based on the Bouc–Wen model has better damping efficiency under large earthquakes than under moderate earthquakes, and exhibits excellent seismic performance to protect more structural members from damage under large earthquakes.

The fixed base approach is widely used to obtain the seismic behaviour of Square Hollow Section (SHS) joints in a lattice girder. However, in some cases where soil-structure interaction (SSI) can be relatively significant, this approach may result in incorrect acquisition of the natural periods and dynamic responses of the lattice girders using welded tubular joints. This situation may negatively affect the safety of the structure by causing an underestimation of the dynamic loads acting on the structure. Therefore, this study evaluates the seismic behaviour of SHS joints in a typical lattice girder exposed to different ground motions considering SSI. A nonlinear finite element analysis software, Abaqus, performs the dynamic analyses considering six earthquake excitations with three different frequency contents (a ratio of peak ground acceleration (PGA) to peak ground velocity (PGV)) and four different soil types. After verifying the numerical model, it is determined that 3D solid elements should be used to capture the actual seismic behaviour of the tubular joints in a steel truss frame with or without SSI. A comprehensive parametric study is then carried out to evaluate the peak displacement and stress values on the SHS joints with and without SSI under different ground motions with different PGA/PGV ratios. The findings show that the stresses are concentrated around the column and bottom chord connection region. Besides, the SSI mechanism significantly affects the peak stress and displacement values of the SHS joints, especially in soft soil types. Furthermore, it is observed that the PGA/PGV ratio significantly changes the seismic responses of the steel truss frame.

Lattice columns are widely used in various metal structural systems, for example, within the telecommunications industry to form the mast that supports the transmission devices or as vertical supports for building roofs. A particularity of these lattices is the large number of elements that conform (e.g., diagonals). As a result, their representation and processing through finite element modeling typically entail a substantial computational cost. The height and slenderness that these lattice columns usually present means that in the event of lateral displacements, they can become sensitive to the applied compression loads, potentially leading to the global buckling of the structural system. In previous work, the authors analyzed spatial lattices of triangular and rectangular cross-sections, obtaining continuous representation models from an energetic approach. In the present work the linear problem of the equilibrium stability of lattice columns is studied. From an energy approach, the analytical expressions are obtained to predict the global critical load for the analyzed lattices. These developed expressions were validated numerically and experimentally, showing excellent performance.

To address the unsuitability of traditional construction formwork for the complex conditions of pipeline corridor projects, and after considering factors such as cost and quality, LFT (Long Fiber Thermoplastic) tempered boards were selected as the face material. These were combined with steel frames of higher structural strength to create a steel frame-LFT glass fiber reinforced tempered surface layer composite formwork. This study includes both experimental testing and numerical simulations of the pipeline corridor system, analyzing the effects of various parameters on performance. The experiment focused on the influence of two variables—support spacing and the number of support points—on the formwork's load-bearing performance, comparing it with traditional steel formwork. The results showed that the failure mode was characterized by unstable bending, with the panel bending and the steel frame bulging, and some specimens showing cracks at mid-span. As the support spacing increased, the ultimate load-bearing capacity and stiffness of the steel frame-LFT glass fiber reinforced surface composite formwork decreased. Fewer support points led to a more significant reduction in both load-bearing capacity and stiffness. Compared to traditional steel formwork, the steel frame-LFT glass fiber reinforced surface composite formwork demonstrated similar load-bearing capacity and stiffness, while being lighter in weight and having a higher turnover rate. The steel frame-LFT glass fiber reinforced surface composite formwork exhibited excellent performance in terms of load-bearing capacity and initial stiffness, meeting the strength requirements for construction formwork. It can replace traditional steel formwork in practical applications, particularly in environments with shorter support distances. Based on the combined results of the experiments and numerical simulations, the optimal support spacing and number of support points were identified. These findings offer valuable insights for the design and application of such formwork systems in future engineering projects.