International Journal of Steel Structures最新文献

There is a rising urgency to balance the sturdiness and economic feasibility of wind turbine towers due to the global shift towards renewable energy. This paper suggests an innovative approach for a 5 MW wind turbine tower with the triangular cross-section. The aim is to study behavior and the issues encountered with old circular towers regarding geometry and structural effectiveness. The tower’s behavior under dead load, aerodynamic thrust, wind pressure, and other applied loads were evaluated using a detailed finite element model and analysis. To validate the model’s reliability, comparative validation was conducted with standard cylindrical tower models and for that Computer Aided Engineering Tools (CAE) were used. Stress distributions, top deflection, and modal frequencies were computed for the triangular tower. Simulations showed that triangular towers maintained structural performance within safe limits, offering comparable stress and deflection levels to conventional cylindrical towers while potentially reducing material and construction costs.

Corrosion-induced reduction in clamping force threatens the integrity of friction-type bolted connections in steel bridges. This study proposes a non-destructive method for evaluating the condition of corroded high-strength bolts based on X-ray diffraction (XRD) analysis. Traditional techniques, such as ultrasonic testing or strain gauges, require precise bolt geometry or bolt removal, making them impractical for in-service structures. A finite element (FE) analysis was first conducted to examine how bolt-head thinning affects stress distribution. The results showed that reductions in head height, rather than width, significantly influence stress distribution and clamping force evaluation. To validate these findings, XRD measurements were performed on bolt-head surfaces with different levels of head height reduction. A strong correlation was observed between surface stress and clamping force, with the slope of this relationship changing according to the degree of thinning. Based on the experimental results, a calibration equation was developed to evaluate the clamping force while accounting for head thinning. The method demonstrated an evaluation accuracy within ± 40 kN, which is comparable to conventional methods used for new bolts, although variability remains due to initial residual stress. A major source of variability is considered to be the residual stress present from manufacturing. Despite this, the proposed method enables non-destructive evaluation of bolt condition and is primarily suitable for screening and maintenance planning of large-scale bridge structures.

Second-order effects (P–(Delta ) and P–(delta )) play a central role in the stability assessment of steel frames and require nonlinear analysis procedures that remain reliable near critical states. This paper presents a certified second-order framework in which mathematically guaranteed two-sided bounds for the smallest eigenvalue of the global tangent stiffness are embedded in a corotational stability-function formulation. The upper bound is obtained from a Rayleigh–Ritz approximation on low-dimensional trial spaces, whereas the lower bound is constructed using Temple/Kato-type estimates together with residual-based certification and enforced spectral separation. The resulting certified interval ([mu -delta ,mu ]) provides a rigorous measure of the margin to loss of positive definiteness and remains stable with respect to solver tolerances and moderate roundoff effects. These certificates are combined with a goal-oriented, drift-aware load-stepping strategy and a standard backtracking line search within the Newton procedure. Numerical examples involving portal and multi-story moment frames demonstrate reliable path tracing and tight eigenvalue certificates with modest subspace dimensions. The associated computational overhead is quantified in the numerical study and remains small relative to the nonlinear equilibrium solution cost. The formulation retains the exact axial-force coupling inherent in stability functions, is consistent with Direct Analysis Method terminology, and offers a practical basis for certified stability assessment and adaptive step-size control in steel frame analysis.

When bolted connections are used in the wall-column joints of the prefabricated steel frame-composite shear wall system (PSF-CSW structure), connection slip and localized plastic deformation inevitably occur under strong seismic loading, causing the boundary restraint characteristics to deviate from the ideal rigid state. The overall shear walls with such connections form finite boundary restraints, and their system stress mechanisms have not been fully explored. This study is based on the elastic restrained buckling theory and the boundary restraint stiffness theory. Taking the PSF-CSW structure as the research object, the finite restraint imposed by the wall-column on the corrugated steel plate is treated as an elastic rotational boundary. A refined finite element model is established using ABAQUS, which incorporates the connection characteristics of bolted angle connections. The reliability of the model is validated through quasi-static tests, and the failure mode of the PSF-CSW structure is revealed. Furthermore, by integrating the semi-rigid connection theory and the plate buckling theory, the influence of wall-column restraint on the local buckling of the corrugated steel plate and the overall load transfer mechanism is systematically analyzed, starting from the deformation of the structural finite-stiffness boundary under loading and the local buckling of the plate. On this basis, the hysteresis model theory is introduced to reveal the influence of layout parameters on seismic performance. Parametric analyses are conducted to examine the effect of wall-column restraint under different conditions, including with and without wall-column restraint, various axial compression ratios, concrete strengths, and steel strengths. The results show that increasing the axial compression ratio, the addition of wall-column restraint improves structural ductility by 9.2%. Increasing concrete strength leads to an 8.1% increase in peak load and a 16.9% increase in ductility. Increasing steel strength achieves a maximum increase of 20.5% in structural ductility. It is thus demonstrated that wall-column restraint improves the boundary stress conditions of the wall, delays local buckling of the corrugated steel plate, and shifts the structural load transfer mechanism from being dominated by local buckling to a more cooperative global response. The related conclusions provide a theoretical basis for the rational design and optimization of wall-column connections in PSF-CSW structures.

Cold formed steel structures are not extensively used in construction than the usual hot rolled sections, these are available in market as thin sheets and that can be rolled to any required shapes, which forms the essential sections needed. Castellated beams are an modern innovative to cellular beams, in which the depth of the sections can be increased to more times than the usual cellular beams,which is mainly achieved with proper cutting and joining in an efficient way. Since, the cold formed steel castellated beams are of minute thickness, the local buckling of beams are most common, based on the knowledge of previous studies made, the new sections has been introduced with depth of 200 mm and 210 mm for the beam, with stiffeners by providing parallel, perpendicular and both parallel- perpendicular to the web of the beam to limit the buckling, hence this research has been made essentially to study the behavior of such beams in transverse loading with diamond castellation in web and in order to predict the buckling modes, stiffeners are provided to web and flange in different manner to get an efficient section. Numerical analysis has been performed by using ANSYS latest version software to predict the buckling modes and Experimental investigation also made for the efficient section.

The new-type segmental-assembled steel temporary beam buttress in railway construction was taken as the research object. The bending property of this structure was studied through static loading tests of a scaled-down specimen. A theoretical method was put forward to estimate the ultimate bending moment of the splice section. A full solid-element calculation model was established, and the accuracy of this finite element (FE) model was verified through comparison with test results. The effects of the initial joint gap width on bending performance were also studied. The results indicate that the test specimen did not exhibit local buckling or overall instability, demonstrating good vertical bearing capacity. The two splicing sections were identified as the weak areas, and the main failure modes are the tensile failure in the bolt walls of the bottom plates and the bolt shear failure in the web plates. The theoretical method can accurately estimate the bending moment of the splice section. Owing to synchronous changes in the stress state in the same area of the plates near the bolt holes, the load–displacement curve of the FE model showed a “two steps and final strengthening stage” shape. Although the neglection of construction errors in the FE model caused differences between tested and simulated results, the developed FE model accurately predicted the ultimate bending moment. Reducing the initial joint gap width can not only significantly improve the structural vertical bearing capacity under normal service conditions, but also enhance the ultimate bending moment and ductility of the splicing section.

Steel–concrete composite beams are indispensable in modern construction for their high structural efficiency, effectively utilizing the tensile strength of steel and the compressive strength of concrete. Over time, these beams are susceptible to deterioration caused by environmental factors, increased load demands, loading patterns and aging of materials. Fiber-Reinforced Polymer (FRP) composites have emerged as a transformative solution for the strengthening of such structural members. Current study explores the application of FRP materials in strengthening steel–concrete composite beams, highlighting different strengthening techniques such as externally bonded (EB) reinforcements and near-surface mounted (NSM) systems. The findings show that FRP strengthening techniques substantially improve beam performance, with load capacity increase between 26 and 116% and stiffness enhancements from 25 to 126%. The study also discusses failure modes, including FRP debonding, concrete crushing, and steel yielding. It further emphasizes the advantages of using various FRP types in maintaining composite action and enhancing load carrying capacity and parameters that influence structural performance. The performance of strengthened beams depends on FRP thickness, layout, degree of shear connection, and level of prestress. Additionally, the study identifies existing gaps in the current literature in connection to the performance of FRP-strengthened composite beams and outlines the potential future research directions aiming to enhance the understanding of flexural behaviour and failure mechanisms.

This study investigates the behavior of self-drilling screwed connections under shear effects through experimental and numerical methods, proposing new design equations. In the experimental study, 32 connections were tested to evaluate the effect of screw diameter, number, spacing, arrangement, and plate thickness on load-bearing capacity and failure modes. Results revealed that the vertical distance between the screw and the corner was the most critical factor for net section failure, regardless of screw diameter. For shear failure, plate thickness and screw diameter were key determinants. Increasing screw diameter and plate thickness enhanced the connections’ load-bearing capacity. The numerical study involved 86 finite element models to validate experimental findings and assess additional parameters, such as screw arrangements and t₂/t₁ ratios. The numerical results aligned with the experiments, confirming that higher t₂/t₁ ratios improved load-bearing capacity. Models with double screws in a row arrangement carried more load than those with screws in separate columns. Comparisons with the AISI S100 standard approach highlighted discrepancies, prompting the development of a new design equation. This equation demonstrated better consistency with experimental and numerical data, providing a more reliable assessment of connection behavior under shear effects.

The corrugated steel web (CSW) sections carry advantages over flat sections in terms of greater lateral stability, a larger strength-to-weight ratio, better energy absorption, and a lesser requirement for vertical stiffeners. The arrangement of corrugations brings anisotropy in the web, which along with the fold profile and geometrical parameters govern the local or global stability. Over the last three decades, many studies have focused on the lateral torsional buckling (LTB) characteristic of CSW girders. While a number of analytical, experimental and numerical models have tried to identify the elastic and inelastic LTB strength for CSW girders, the variation in their estimates and ambiguities with respect to the modified parameters are observed. Analytical expressions for elastic and inelastic LTB based on the modified warping and torsional constants are presented. This review paper summarizes and assesses the global stability behaviour of the CSW girders along with the scope for future research. The influence of various geometric parameters on global stability is also summarized.

The failure mechanisms of hollow steel sections can be divided into six main categories (i.e., chord plastification, chord web failure, chord shear failure, punching shear, brace failure, and local buckling). Chord plastification represents the primary governing factor in these failures and the dependence on chord material yielding imposes limitations on structural efficiency. To overcome these limitations, an innovative strengthening method using internal concrete infill applied to both the chords and bracing elements of hollow sections is investigated in this paper. While there have been many studies concerning the behaviour of concrete-filled chord members, the role of concrete-filled bracing members has yet to be fully investigated; this represents a significant gap in the existing body of knowledge. The objective of this study is to examine how parameters including chord thickness, concrete infill length, and concrete compressive strength affect the overall joint performance. Both experimental and numerical approaches were employed. The testing program consisted of eight specimens with varying infill configurations. All eight specimens were subjected to axial compressive loading applied to the brace member and characterised in terms of strength, stiffness, and failure mode. A finite element (FE) model was developed in ABAQUS and validated against the experimental results. Once validated, the model was used to perform parametric study. The test data show an increase in maximum loads that can be supported by joints of as much as 198% for the bare steel control condition based on geometrically identical sections with different types of infills. A transition in failure mode was also observed, from chord face plastification to localised buckling of the brace member. Additionally, numerical increases were found through the parametric studies where the chord thickness was varied along with the type of infill used. Further evaluation demonstrated that currently available code-based design provisions are not applicable to this composite configuration. Consequently, a new capacity prediction equation for composite T-joint configurations is presented and incorporates terms for concrete bearing on the chord face, chord thickness, concrete infill length, and concrete compressive strength. The predicted capacities obtained from the ABAQUS finite element model, and the proposed equation showed good agreement with the experimental results.