Experimental investigation on cold-formed stainless steel stiffened C-sections under localized interior-two-flange loading

This paper presents a test program to study the web crippling behavior of cold-formed stainless steel stiffened C-sections. A total of 51 specimens having different stainless steel types, web slenderness ratios, flange conditions and bearing lengths were tested under interior-two-flange (ITF) load case codified in American Specification ASCE/SEI 8. The failure modes, load-displacement relationships and web crippling capacities of specimens with unfastened and fastened flanges were obtained and fully reported. It is found that the fastened flanges could significantly enhanced the web crippling capacities of the C-sections, especially for those with high web slenderness ratios. The test results showcased the specimen lengths had significant effects on the web crippling capacities of C-sections under ITF load case. The obtained experimental web crippling capacities were compared with the nominal predictions calculated by the American and European design provisions. It is indicated that the current American design provisions are generally unconservative and unreliable for the cold-formed stainless steel stiffened C-sections under ITF load case, except for austenitic stainless steel sections with flanges fastened. By contrast, the European design provisions are generally quite conservative in predicting the web crippling capacities. The reasons of unsatisfactory predictions by the codified design rules are discussed.