Yield moment of cold-formed steel beams under different strain rates

It has been recognized that the mechanical properties of sheet steels and t he structural strength of cold-formed steel members can be influenced by st rain rate. For studying the local and postbuckling behavior of stiffened an d unstiffened compression elements under a dynamic loading condition, 60 be ams, which were assembled from the same material, have been tested under di fferent strain rates. To study the structural behavior of hybrid cold-forme d steel beams, a total of 72 specimens was investigated. The results showed that the strength of beams increases with increasing strain rates. The amo unt of increase was found to be dependent on the material yield strength, t ype of steel, stress-strain relationships, width-to-thickness ratio, type o f compression element, and strain rate used in the test. In this research, design procedures were also developed to compute the load-carrying capacity of hybrid beams under different strain rates.