International Journal of Steel Structures最新文献

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.

The present study illustrates the fatigue behaviour with the presence of welding residual stress for an orthotropic steel deck bridge subjected to a range of traffic loads. The fatigue estimation methodology adopted integrates the concept of fracture mechanics with rainflow counting. Numerical models in commercially available finite element software along with rainflow counting algorithm as per ASTM standards are explicitly developed. Fatigue failure due to welding residual stresses has been reported extensively in the literature, so its evaluation would facilitate understanding the distribution and determining the stress concentrations essential in designing OSD bridge structures. The existing Mingzhu Bay bridge is considered to understand its behaviour under various traffic loads. The results emphasize the need to consider residual stress effects while evaluating the fatigue life of OSD bridges. Results showed that the initial fatigue life of concern points decreased significantly with welding residual stresses, with the fatigue life of OSD dropping from (4.6times {10}^{6}) cycles to (1.0times {10}^{3}) cycles for an initial crack length of 0.1 mm.

The impact of varying fiber orientations and clearances on load sharing by each bolt and displacement in multi-bolt laminated composite joints subjected to in-plane tensile loads is investigated in this paper. A semi-analytical spring model used for evaluating load distribution and displacement through a computational micromechanical approach. Within this approach, the distinct properties of the matrix and fibers are individually considered to assess laminate properties, utilizing a homogenization technique. This approach enables better control over design parameters which helps in evaluating accurate load sharing with optimum computational efforts. The disparity between the maximum and minimum loads borne by bolts serves as a metric for evaluating the load-sharing efficiency of the bolted connection. The impact of bolt-hole clearance is explored across various lamination schemes and volume fiber fractions.

The self-centering (SC) hysteretic damper can effectively enhance the seismic resilience of structures, due to its supplemental damping and recentering capability. Recently, a new SC damper, is developed known as the SC Disc Slit Damper (SC-DSD) was experimentally tested using cyclic loading test. In the proposed damper, the steel slit dampers play the role of energy dissipation (ED) source, while the pre-compressed disc spring stacks form the SC system. The tests have shown that the telescopic configuration of the damper ensures a symmetric cyclic behavior. However, additional analytical and finite element (FE) analyses are required to more deeply explore the effects of the damper's parameters and its local behavior. Based on the working mechanism of the damper, the restoring force models of the ED system and SC system are first derived individually, and then they are combined to obtain the hysteretic model of the damper. In addition, the FE model of the damper is established to provide additional information that is challengeable to observe in tests. The accuracy of the analytical method and FE model is confirmed by the testing results. Further, the parametric analysis is conducted based on the validated FE model, using the key parameters of the length of the steel strips, the width of the steel strips, and the preload of the stacked disc springs. Based on this work, the hysteretic behavior of the damper is further understood, and more importantly, it provides more insights for practical applications of the damper.