Aug 2026· Ömer Halisdemir Üniversitesi Mühendislik Bilimleri Dergisi· Vol 18· 0 citations· 15 references
Abstract
This study aims to experimentally investigate the buckling behavior and load-bearing capacities of cold-formed steel (CFS) omega-section columns under axial load. Within the scope of the research, 11 omega column specimens with thicknesses ranging from 1.75 mm to 3 mm were integrated with corrugated silo wall sheets of various thicknesses and subjected to axial compression tests. The experiments were designed to analyze the effects of lateral restraint conditions and column thickness on load-bearing capacity, post-elastic behavior, and failure modes. The findings fill a significant gap in literature by demonstrating the interactive performance of omega sections with secondary elements like silo walls. This study provides critical data for the design of these thin-walled members in modern construction applications.
Stainless steel built-up I-profile are frequently designed with webs significantly more slender than their flanges and greater material strength in the flanges in case of hybrid sections. Given the fundamental load case of pure compression or bending, the compressed flange can develop significant postlocal-buckling strength, approaching its fully plastic capacity, whereas the web reaches only its local buckling resistance, a long-overlooked failure mechanism not currently captured by current design approaches. The effect is particularly pronounced in stainless steel, whose nonlinear stress–strain response and pronounced strain hardening further enhance this reserve capacity. In this paper, experiments are first used to validate a finite element model of such behavior. Following validation, a parametric study is conducted to evaluate the influence of geometric and material parameters on the ultimate strengths. The study includes both homogeneous and hybrid built-up sections, where the homogeneous sections are made of four grades (EN 1.4062, EN 1.4462, EN 1.4307, and EN 1.4404), and the hybrid sections are made using four hybrid combinations covering a wide range of cross-sectional slenderness. A total of 1,325 homogeneous and 955 hybrid FE models are developed, focusing solely on strong flange behavior. The performance of the codified Effective Width Method (EWM), Direct Strength Method (DSM), and Continuous Strength Method (CSM) is evaluated against the numerical results. The comparison highlights that element interaction and local buckling strength reductions cause I-sections with slender webs and stocky flanges to exceed the codified strength predictions. A modified Direct Strength Method (mDSM) approach is then proposed. By introducing two new parameters,
Ω
and
α
, to distinguish between cross-sectional behaviors and better account for strong flange effects, we address the limitations of traditional “whole section” methods while retaining their inherent simplicity, providing greater accuracy and less scatter than any of the codified methods. A reliability assessment provides evidence that the new equation achieves the codified target for acceptable probability of failure when combined with the current resistance factor.
Usman Ali, Gregory A. Langone, B. Rossi· Journal of Structural Engine...· 0 citations
As a lightweight load‐bearing member for aerospace truss structures, thin‐walled metal tubes require improved buckling resistance without additional mass. To this end, this paper innovatively designs a thin‐walled metal inflatable tube structure. The axial compressive behavior of the proposed tube and the influence of internal pressure are preliminarily investigated through experiments and numerical simulations. Axial compression buckling tests were conducted on two sets of specimens under 0 and 2 bar to evaluate the pressure‐induced changes in axial stiffness, critical buckling load, and buckling mode. Concurrently, a finite element model was established using material parameters obtained from independent tensile tests. The model was validated against the experimental results at 0 and 2 bar and was subsequently employed to numerically investigate the axial compressive response over a wider pressure range. In addition, initial local dimple imperfections were introduced into the finite element model to examine the imperfection sensitivity of pressurized thin‐walled tubes. Combining experimental and numerical simulation results reveals that pressurization significantly increases the buckling critical load of thin‐walled tubes and improves buckling morphology, thereby suppressing the occurrence of abnormal deformation. The numerical results also indicate that internal pressure can reduce the sensitivity of thin‐walled tubes to local dimple imperfections.
Dahai Zhang, Jiarong Jiang, Pengfei Yan et al.· Advanced Engineering Materia...· 0 citations
The swift advancement of modern construction has established cold-formed steel (CFS) as a prominent structural option owing to its high strength-to-weight ratio and lightweight properties. However, CFS in open sections such as channel and zee sections is heavily restricted by susceptibility to premature instabilities such as local, distortional, and lateral-torsional buckling. The study examines the structural performance, especially the load-deformation behaviour of closed structural sections, to address and resolve these deficiencies and limitations. The main objective of the study is to experimentally determine the load-deformation behaviour of a full-scale roof truss system fabricated from a CFS hollow rectangular section and to compare it with that of a CFS channel section. A full-scale roof truss measuring 4,900 mm in span and 1,100 mm in height was constructed in a Howe configuration type and assembled using 6 mm self-drilling screws. Static vertical load experimental activity was conducted utilising a 100 kN load cell, a hydraulic jack, five linear variable deformation transducers (LVDTs), and seven strain gauges linked to a data logger to record ultimate load capacity, deformation and localised strain actions. The experimental results indicated that the CFS hollow outperforms the CFS channel section, attaining a 52.42% increase in ultimate load capacity and a 21.66% decrease in vertical mid-span deformation. The CFS channel had premature local and distortional buckling at its top chords, but the CFS hollow successfully mitigated early geometric instabilities. Ultimately, the study concludes that CFS hollow serves as a highly efficient, stiff and structurally stable system that is ideal for lightweight and sustainable long-span roofing applications.
M. Sani, C. Tan, F. Muftah· Journal of Building Material...· 0 citations
To study the axial compression performance of steel tube-confined concrete, nine short column specimens were designed for axial compression testing. The parameters are the diameter-to-thickness ratio of steel tubes and the contact treatment method at the steel-concrete interface. The failure mode, load-displacement curve, load-strain curve, and load-lateral deformation of the specimens were comparatively analyzed. The results show that the failure mode is mainly shear failure. The confinement effect of the steel tube is fully activated in the elastoplastic stage. The load-displacement curves of these specimens do not have obvious descending branches. A smaller diameter-to-thickness ratio leads to more significant improvements in both load-bearing capacity and ductility during the later loading stage. The use of film-type materials at the steel-concrete interface enhances the confinement effect of steel tubes on concrete, and this improvement becomes increasingly obvious in the later stage of loading.
Tianhao Li, Dongliang Zhang, Kun Fu et al.· Journal of Physics, Conferen...· 0 citations
Sixteen reinforced concrete beams were tested under symmetric concentrated loading to investigate the mechanical behavior of beams designed using the compressive force path (CFP) method, in comparison with specimens designed according to the Chinese Code for Design of Concrete Structures (GB 50010-2010). The test variables included shear-span ratios (4.0, 3.0, 2.5, and 2.0) and sectional dimensions (150 × 300 mm and 250 × 550 mm). The test process and test results were systematically analyzed. The results show that the stress transmitted along the compressive force path is the main factor governing the shear capacity. The CFP beams achieved peak loads comparable to those of the GB beams while using 5.88–39.99% fewer stirrups, with larger savings observed for smaller shear-span ratios. The CFP method predicted the shear capacity with an error of approximately 10% (ranging from 2.24% to 12.45%). The shear strength of the CFP beams decreased with increasing shear-span ratio and effective depth. Overall, the CFP-designed specimens met the expected mechanical performance requirements, verifying the accuracy and applicability of the CFP method.
The study presents the results of model experimental investigations and nonlinear numerical analyses of thin-walled, two-segment box structures with various configurations of integral corrugated stiffeners. The models for experimental testing were fabricated using additive manufacturing techniques. Five variants of the structure were examined, including a reference configuration without reinforcement. The experimental investigation was carried out using a dedicated test rig. Numerical representations of the investigated models were developed and subjected to nonlinear analyses using finite element method-based software. The adequacy of the numerical results was assessed through comparison with experimental data. The objective of the study was to determine the effect of different forms of the proposed structural solution on the magnitude of the critical load and the nature of post-buckling deformation.
T. Kopecki, P. Mazurek, Aleksandra Tęczar et al.· Advances in Science and Tech...· 0 citations