Behavior of cold-formed steel elliptical hollow sections subjected to bending

Abstract

This paper presents the experimental and numerical investigation on the behavior of cold-formed steel elliptical hollow section beams. In the test program, a total of 20 beam tests was conducted. Four elliptical section series with the nominal cross-section aspect ratio ranging from 1.65 to 3 were bent about the major and minor axes in both three-point and four-point bending configurations. Finite element models were established to replicate the beam tests numerically. Based upon the validated model, extensive parametric study was conducted on 235 beam specimens to study the behavior of cold-formed steel elliptical hollow sections subjected to bending. The results obtained from experimental and numerical investigation were used to assess the existing design methods and to propose modified design methods for cold-formed steel elliptical hollow section beams. It should be noted that the current design codes do not cover the design of elliptical hollow section beams. The flexural strengths of beams were compared with the design strengths predicted by the equivalent diameter and equivalent rectangular section methods proposed by previous researchers, the traditional design methods using equivalent diameter as well as the Direct Strength Method and the Continuous Strength Method. The applicability and reliability of these design methods were assessed. The results indicate that the existing design methods are not capable to predict the flexural strengths of cold-formed steel elliptical hollow section beams in accurate and reliable manner. In this study, the modified Direct Strength Method and Continuous Strength Method are proposed, which provide accurate and reliable flexural strength predictions.