Bending strength of hot-rolled elliptical hollow sections

Abstract

The recent emergence of hot-rolled elliptical hollow sections (EHS) within the construction industry has attracted considerable interest from structural engineers and architects. Comprehensive structural design rules are now required to facilitate their wider application. This paper focuses on the bending strength of hot-rolled elliptical hollow sections; the results of detailed experimental and numerical studies are presented and structural design rules for EHS in bending about the major and minor axes are proposed. A total of 18 in-plane bending tests in three-point and fourpoint configurations have been performed. All tested specimens had an aspect ratio of two. Full moment-rotation and moment-curvature histories were derived, including into the post-ultimate range. The experimental results were replicated by means of non-linear numerical modelling. Following careful validation of the models, parametric studies were performed to assess the structural response of EHS over a wider range of aspect ratios (between one (CHS) and three) and cross-section slendernesses. For design, cross-section slenderness parameters have been proposed and a set of classification limits in harmony with those given in Eurocode 3 for circular hollow sections (CHS) has been derived. A new Class 3 limit has also been proposed for both EHS and CHS. An interim effective section modulus formula for Class 4 (slender) elliptical hollow sections based on BS 5950-1 has also been developed. Further investigation into effective section modulus formulations is currently underway.

Flexural behaviour of stainless steel oval hollow sections

“…The relevant section moduli (i.e. Wel,y, Wel,z, Wpl,y and Wpl,z) were calculated by assuming the OHS to have a constant thickness (which was verified by the measurements taken) and numerically integrating along the mid-surface of the ellipse, in accordance with [6]. The notation regarding the cross-sectional geometry used throughout the paper is depicted in Fig.…”

“…As successfully employed in similar previous studies [2,5,6,8,18], the reduced integration 4-noded doubly curved general-purpose shell element S4R with finite membrane strains [32] has been employed in the present study. In order to minimize computational time while still generating accurate results, a mesh convergence study based on elastic eigenvalue buckling analyses was carried out.…”

“…2) was chosen. The same mesh size was deemed suitable in similar modelling applications for both carbon steel EHS [5,6] and stainless steel OHS [18].…”

“…Experimental and numerical results on stainless steel OHS stub and long columns, together with appropriate design recommendations have been presented by the authors in a prior study [18]. The present paper focuses on the flexural response of stainless steel OHS, though comparisons are also made with the experimental results from previous studies on carbon steel EHS [6] and stainless steel CHS [19][20][21].…”

“…Previous research into the structural response of oval and elliptical hollow sections has included analytical and numerical investigations of elastic buckling and post-buckling [1][2][3], experimentation and derivation of slenderness limits [4][5][6] and examination of shear [7] and flexural buckling [8] behaviour. The resistances of EHS under combined loading [9] and with concrete infill [10][11][12] have also been studied, as have a range of EHS connection types [13][14][15].…”