International Journal of Steel Structures最新文献

P110 Cr13S is a new high-performance casing steel, bridging the critical gap in engineering between conventional carbon steel and high-end stainless steel. To investigate the temperature-dependent cyclic plasticity of this material, standard monotonic tension tests and stress-controlled cyclic tests were conducted at various temperatures. The results of monotonic tension tests revealed that P110 Cr13S exhibits an advanced high tensile strength exceeding 800 MPa and its value gradually decreases with increasing temperature. In cyclic loading, the differences between two successive cycles decreased with increase in the number of cycles, and the retention behavior stabilized after approximately 50 cycles. After approximately 450 cycles, the final shakedown stage was reached. The Chaboche constitutive model was further modified based on experimental observations to accurately describe the cyclic plastic behavior of P110 Cr13S, taking into account the factor of temperature. The corresponding finite element formulations were implemented into ABAQUS via a user-defined material subroutine to perform numerical simulations. Comparisons between simulations and experimental results demonstrated excellent agreement, confirming that the proposed model can reliably predict the thermomechanical cyclic plasticity of P110 Cr13S. This study provides a validated constitutive framework for modeling the high-temperature cyclic response of high-strength casing steels, offering valuable insight for design and life prediction under varying thermal–mechanical conditions.

This paper develops a unified method to predict the compressive strength of fixed-ended lipped channel columns. Using numerical data from different authors, novel design curves are calibrated for isolated buckling modes failure—local (L), distortional (D|) and global (G) buckling – as well as L-D and L-D-G interactive failure modes. The basis of the method is similar to the Direct Strength Method’s L-G treatment, in which the resistance related to each buckling mode affects the slenderness rate of the next mode to be verified. The main difference are the order of the modes for the calculations, from the mode with most post-buckling reserve (L) to the mode with least post-buckling reserve (G), and the inclusion of the distortional mode in the process. The proposed design curves are then compared to a large data of failure loads from numerical simulations. The preliminary results for 1493 numerical columns show that the proposed set of equations are reliable (average results for f_{u, numerical}/f_proposed are 1.014 ± 0.067, resistance factor ϕ = 0.914) and provide a unified procedure to obtain the ultimate strength of columns undergoing different failures modes.

Steel modular buildings are increasingly applied across various building types; however, effective fireproofing design remains a challenge, particularly for mid-rise structures. Conventional fire protection methods focus on individual structural members (e.g., columns, beams, and walls), leading to constructability limitations and material inefficiencies. Existing fire-resistance standards are not well-suited for modular systems. This study proposes a module-unit fireproofing method that eliminates the need for member-level treatment. Full-scale fire tests were conducted for 1-hour and 2-hour ratings. Results confirmed that steel frame temperatures remained below the average limit of 538 °C, and insulation criteria of 165 °C were satisfied. A 3D finite element thermal model was also developed and validated against test data. The model showed strong agreement with the experimental results, demonstrating its potential as a predictive tool for future modular fireproofing design.

The roofs of long-span grid structures are particularly sensitive to wind effects when subjected to wind loads. The present study demonstrates wind-induced response variations due to wind load on the grid structure through CFD (Computational Fluid Dynamics) simulation. In the present study, models with different wind incidence angles (0°,30°, 60°, and 90°) as well as models with varying positions of viscous-elastic dampers are investigated. The results indicate that accounting for fluid–structure interaction affects both wind direction and speed. In the mid-span area of the grid structure, where wind-induced response is significant, fluid–structure interaction has a pronounced impact. Furthermore, the addition of viscous-elastic dampers can reduce the wind-induced response of the existing grid structure, and adding them at positions where the wind-induced response is larger has a more obvious damping effect, resulting in a vibration damping coefficient of 29.09% for the center node displacement.

This study investigates the ultimate strength and deformation behaviour of tubular T-joints, often used in offshore structures, reinforced with collar plates and external ring stiffeners. The nine T-joints for three different β values, 0.25, 0.5 and 0.75 and with two different strengthening techniques (1) external ring stiffeners and (2) collar plate, were studied under brace compression. The effects of key parameters such as β (brace-to-chord diameter ratio), γ (chord slenderness ratio), and stiffener configurations on joint performance were analysed. Finite Element Analysis (FEA) results demonstrated close agreement with experimental data, showing a variation of less than 4%. Reinforcements significantly enhanced load-carrying capacity, with ring stiffeners increasing strength by up to 36% and collar plates by 39%. The optimal parameters, including β = 0.75 and γ = 20, improved stiffness and minimised deformation. Finite Element Analysis (FEA), and EC3 code predictions were compared, demonstrating close agreement with R² values of 0.9726 and 0.9577 for collar plate and ring-stiffened joints, respectively. These findings highlight the effectiveness of reinforcements in improving joint strength and structural integrity of offshore platform.

This paper presents methods for determining the fatigue failure analysis of dissimilar welded joints by applying automatic opening doors in city buses. The paper focuses on the problem of determining and evaluating the fatigue life of selected types of welded joints by the application. The study shows the extent to which the simplest method based on the amplitude of nominal stress can be used for calculating fatigue life based on two selected types of joints with different asymmetry coefficients, R =  − 1. Three groups of welded models, MS-SS, SS-GI, and MS-GI specimens were designed according to ASTM E466 standard. The FEM model is developed for dissimilar metal welded joints. The present study aims to experimentally investigate the high cycle fatigue strength of dissimilar welded joints subjected to tension–compression loading and Full capacity uniaxial fatigue machine with load 40% YS for MS-SS, MS-GI, and SS-GI dissimilar welded joint conducted. Numerical model developed in high cycle fatigue failure for dissimilar welded joint subjected tension–compression. The numerical results of the welded joint model have been validated with available literature. It shows that the present mathematical model agrees with Shigley & Mischke (2004). Also, parametric studied the effect on fatigue strength by changing: the welded length and welded thickness. The fatigue failure of dissimilar load cycles has been recorded for different models, MS-SS = 230,830 cycle, MS-GI = 166,362 cycle, and SS-GI = 173,867 cycle respectively. The SEM and EBSD observations in the distinct microstructural features, depending on the extent of mixing of both base metals.

This study investigates the axial compression behavior of lightweight concrete-filled circular aluminum alloy tubular (LCFAT) stub columns for structural lightweighting applications. Nine groups of specimens with varying parameters were tested to examine the effects of the cross-sectional aluminum ratio and a confinement factor on the load-carrying capacity, axial stiffness, and failure modes. To induce ideal failure patterns under axial loading, the specimens were locally wrapped with carbon fiber reinforced polymer (CFRP) at both ends solely to provide end restraint and ensure uniform load transfer; the CFRP was not part of the load-carrying system. The experimental program is complemented by calibrated three-dimensional finite element analyses, which were further employed to conduct parametric studies on concrete strength, alloy yield strength, and tube wall thickness. Based on classical concrete-filled steel tubular (CFST) theory, a strength design model tailored to the aluminum–lightweight concrete interaction is formulated by introducing an elastic modulus reduction factor and a lateral confinement reduction factor. The proposed model captures the key characteristics of the axial response, and the numerical simulations were used to replicate the observed failure patterns and load–displacement curves, supporting an interpretation of the confinement mechanism and behavioral phases. These results provide a theoretical basis for engineering application and design optimization of lightweight composite columns.

This study investigates the impact of different erosion environments on the shear performance of stud connectors. A series of push-out tests were conducted to systematically analyze the degradation of shear performance in stud connectors of various diameters under the influence of artificial seawater immersion and wet-dry cycling erosion. By examining failure modes, load–displacement curves, ultimate shear capacity, and peak displacement, the trends and mechanisms of shear performance degradation due to artificial seawater erosion were revealed. The experimental results show that with prolonged erosion time, the failure mode of stud connectors transitions from shear failure to concrete crushing failure, accompanied by a significant reduction in shear capacity and peak displacement. Notably, after 56 days of immersion erosion, the shear capacity of the specimens decreased by 50–60%. Compared to immersion erosion, wet-dry cycling erosion had a more significant impact on the stud connectors, with the shear capacity of specimens under wet-dry cycling conditions being approximately 70% of that under immersion erosion. Moreover, the peak displacement of the specimens decreased significantly under wet-dry cycling erosion, indicating a greater degradation of plasticity and ductility of the bolt connections. Based on the experimental results, this study provides a quantitative assessment for evaluating stud performance degradation in structural engineering design.

The column ends’ stiffness is released due to the connection to corner foot joints by bolts or nesting. It makes the actual effective length factor μ of this column higher than the calculated value μ₀ according to equations in existing standards and codes. A correction factor γ is proposed and multiplied by μ₀. The factor β describes the relative flexural stiffness of each column end. Based on elastic buckling analysis of 2156 sidesway uninhibited columns and 2475 sidesway inhibited columns with different β values, relations between γ, β, the flexural stiffness ratio between beams and columns in each end (K₁ and K₂) are fitted as equations. The high accuracy of these equations has been proven by the coefficient of determination (r²) and the root mean square error (RMSE). Furthermore, the end connection can be treated as rigid when the flexural stiffness of the column ends is no less than 80 times the flexural stiffness per unit length of column i_c for sidesway uninhibited columns, or 200i_c for sidesway inhibited columns.

Reinforced concrete-steel composite systems often rely on headed stud shear connectors to transfer forces in solid slab applications. These components play a significant role in structural integrity, especially in scenarios involving high loads. This study collects 224 experimental test results to develop statistical and data-driven methods that predict the shear capacity of headed studs. In this database, the mean shear capacities ranged from approximately 62 kN to nearly 319 kN. Within the study context, a total of 14 machine learning models, including traditional linear and advanced ensemble regressors, are investigated. The study results indicated that advanced ensemble models demonstrate better predictive accuracy than linear and regularized approaches. The best-performing models achieved R² values as high as 0.98 on the test subset and root mean square errors below 11 kN. The feature importance analyses highlighted the diameter of the stud shank and the diameter of the weld collar as primary factors influencing capacity predictions, while the tensile strength of studs showed lower relevance. The partial dependence plots confirmed nonlinear relationships between input variables and predicted capacities. The comprehensive framework and findings of this study are expected to guide and help scientists and engineers understand and predict stud shear performance.