Strength curves for web crippling design: first approach for stainless steel hat sections based on numerical analyses

Abstract

Web crippling is a local instability that causes cold-formed sections to become unstable when a concentrated load is applied transversally to the cross-section. The European design rules for stainless steels EN1993-1-4 [1] refers to the standards for carbon steel cold-formed sections EN1993-1-3 [2] to determine the web crippling ultimate capacity in which different expressions are presented according to the cross-sectional number of webs. For the fundamental case of hat sections (cross-sections with two or more webs), a single expression is codified which is in essence an empirical equation based on curve fitting given different coefficients. During the last years, research has been focused on improving this expression but overlooking the philosophy of a ¿( ) strength curve in which are based most of the instability verifications of the European design provisions. Some background related to web crippling of stainless steel cross-sections can be found in [3] and [4]. The purpose of this paper is to assess if this slenderness-based approach is suitable to determine the ultimate resistance of stainless steel hat sections subjected to web crippling. The appraisal will be based on numerical simulations performed in Abaqus and experimental results found in the literature [5]. A comparison of the results with current design rules according to European [2] and American standards [6] is also presented. Two new expressions to predict web crippling strength of ferritic stainless steel hat sections are proposed in the present study.