Behaviour and design of fixed‐ended steel equal‐leg angle section columns

Abstract

The mechanical behaviour and design of fixed‐ended steel equal‐leg angle section members subjected to axial compression are addressed in this study. First, the critical buckling behaviour is described. Experimental data on steel equal‐leg angle section columns collected from the literature are then used for the validation of numerical (shell finite element) models, developed within the commercial package ABAQUS. Validation is performed by means of comparisons between the test and numerical results, considering ultimate loads, failure modes and the load‐deformation responses, all of which are shown to be generally in good agreement. A numerical parametric study is then presented considering steel angle section columns with a wide range of slenderness values. The behaviour and load‐carrying capacity of the columns is shown to be dependent on, not only the column slenderness, but also the ratio of the elastic torsional‐flexural buckling load to the elastic minor‐axis flexural buckling load. Finally, the collected experimental and generated numerical results are used to develop a new design approach for fixed‐ended steel equal‐leg angle section columns, reflecting the observations made. The proposed approach offers improved accuracy and consistency in strength predictions compared to the existing codified design rules.

Stability and design of fixed-ended stainless steel equal-leg angle section compression members

“…This contrasts with the existing EC3 design approach, where angle section columns with the same member slenderness have the same member buckling reduction factor because, regardless of the critical buckling mode (torsional-flexural or minor-axis flexural), the flexural buckling curve is always applied. Similar observations have been made by Behzadi-Sofiani et al [2] and [3] for steel equal-leg angle section columns. The vertical spread of data in Figs.…”

“…20a and 21a is caused by the changing post-buckling stability with the N cr,TF /N cr,F,v ratio. The numerically-derived [2] ratios of the immediate elastic post-buckling axial stiffness to the initial axial stiffness k pb /k in for a series of fixed-ended angle section columns are plotted against N cr,TF /N cr,F,v in Fig. 22.…”

“…The material properties were input into ABAQUS in the form of true stress σ true and true plastic strain ϵ true , converted from the measured engineering stress σ and strain ϵ using the following well-known relationships: For the hot-rolled stainless steel angles, a bilinear residual stress distribution with a peak value of 70 MPa, constant with thickness and leg width, was employed [2], as illustrated in Fig. 14, where the negative sign indicates compressive stress and the positive sign denotes tensile stress.…”

“…[43] and Behzadi-Sofiani et al [2], by the double-counting of the same buckling mode in the local and member buckling checks and the failure to recognise the stable post-buckling behaviour in the member-level buckling curves for torsional-flexural buckling. New design proposals are presented in the subsequent section to address and resolve this issue.…”

“…Angle section compression members feature in a range of structures, including towers and trusses, and in the bracing of buildings and bridges. Although angles have been studied since the 1920s [1], their complex mechanical behaviour continues to pose challenges and current structural design provisions in international standards are known to have limitations [2,3,4]. New resistance functions for carbon steel angle section columns in the American [3] and European [2] design frameworks have been recently developed, leading to substantial improvements in the accuracy and consistency of capacity predictions.…”