Direct Strength Method for Web Crippling of Cold-Formed Steel C-and Z- Sections Subjected to Two-Flange Loading

摘要

Direct Strength Method (DSM) is a design method for cold-formed steel members recently adopted by the North American Specification for the Design of Cold-Formed Steel Structural Members (AISI S100, 2007). DSM uses the elastic buckling solutions and the yield loads of the entire section instead of the effective section modulus to predict the nominal strength of cold-formed steel members. With the help of advanced computation tools such as the Finite Strip Analysis, DSM offers quicker, simpler, and more reliable calculations compared with the traditional Effective Width Method. However, the DSM is currently capable of determining the nominal strength of flexural and compressive strength only. This paper presents an effort to expand the DSM to the web crippling strength of cold-formed steel C- and Z- sections subjected to two-flange loading. The proposed DSM equations use simplified elastic buckling solution and the yield load for the web to predict the nominal web crippling strength. The research shows that the proposed DSM equations have good agreement with industrial standard cold-formed steel C- and Z- sections. This paper proves the concept that DSM can be used to determine the web crippling strength of cold-formed steel flexural members.