Web Crippling Strength of Steel Deck Subjected to End One Flange Loading Onur Avci 1 and W. Samuel Easterling 2 Abstract: Cold-formed steel deck profiles are extensively used in building construction due to their versatility and economy. Web crippling is one of the failure modes of these multiweb profiles. The provisions for web crippling contained in the 1996 AISI Specification for the Design of Cold-Formed Steel Structural Members are believed to be conservative for multiweb deck sections. They are based on unfastened specimens and are limited to the use of decks with certain geometric parameters. The unified web crippling equation of the 2001 North American Specification for the Design of Cold-Formed Steel Structural Members is also limited to certain geometric parameters. Although new web crippling coefficients for different load cases and different end conditions are contained in the specifica- tion, coefficients for the unfastened configuration in the end one flange loading case were used as a conservative solution for the fastened case because there are no test data available in the literature that are applicable to multiweb deck sections. Results of an experimental study on web crippling strength of deck profiles subjected to end one flange loading are presented in this paper. A total of 78 tests were conducted on multiweb deck sections. Test specimens lying inside and outside of certain geometric limitations given in the specification were tested with both unrestrained and restrained end conditions. Test specimens within the specification limitations exhibited conserva- tive results in the prediction of web crippling strength using both the 1996 AISI specification and the 2001 North American Specification. Using the unified web crippling equation of the North American Specification, a nonlinear regression analysis was performed to improve the unfastened case coefficients and derive new fastened case coefficients. A calibration using these coefficients was carried out for both Canadian and U.S. specifications. DOI: 10.1061/ASCE0733-94452004130:5697 CE Database subject headings: Steel decks; Flanges; Webs; Cold-formed steel. Introduction Web crippling is one of the failure modes that must be taken into consideration in cold-formed steel design. Cold-formed steel members experience web-crippling failure due to the high local intensity of concentrated loads or reactions. Design equations in the specifications have always been empirical, developed by curve fitting of experimental data. While AISI 1996 has differ- ent design expressions for different types of cross sections and loading cases, the Canadian Standard CSA 1994 has one ‘‘uni- fied design expression’’ with different coefficients for different section types and loading. In both standards, the web crippling calculations are based on unfastened specimens and are limited to the use of decks with certain geometric parameters. The unified design expression of CSA 1994 was adopted by AISI in the North American Specification for the Design of Cold-Formed Steel Structural Members NAS 2001. In this specification, im- proved coefficients were developed for the unified web crippling design expression. Also, different coefficients were derived for fastened and unfastened end conditions. The web crippling strength of a cold-formed steel section de- pends on several parameters. The major parameters that affect the web crippling strength are section type, cross-sectional properties, bearing length, and loading conditions. Section Types Many cold-formed steel section types are being used in building construction, the most common of which are hat sections, Z-sections, C-sections, and multiweb sections. Even though web crippling occurs in the webs of the members, the interaction of the web elements with the flanges plays an important role in web crippling strength. The rotation of the web under loading depends on the degree of the restraint of the web provided by the flanges, as illustrated in Fig. 1. Because the web-flange interaction is one of the major factors affecting the web crippling strength, different types of cross sections show different behaviors in web crippling failures. In this study, tests were performed for multiweb deck sections. A typical deck section is illustrated in Fig. 2. For web crippling calculations, sections are classified in the applicable specifications as ‘‘Shapes Having Single Webs,’’ ‘‘I-Sections or Similar Sec- tions,’’ or ‘‘Multi-web Deck Sections.’’Additionally, both of the specifications classify some cross sections as stiffened and un- stiffened. 1 Graduate Research Assistant, The Charles E. Via, Jr. Dept. of Civil and Environmental Engineering, Virginia Polytechnic Institute and State Univ., Blacksburg, VA 24061. 2 Professor and Assistant, Dept. Head, The Charles E. Via, Jr. Dept. of Civil and Environmental Engineering, Virginia Polytechnic Institute and State Univ., Blacksburg, VA 24061. Note. Associate Editor: Christopher J. Earls. Discussion open until October 1, 2004. Separate discussions must be submitted for individual papers. To extend the closing date by one month, a written request must be filed with the ASCE Managing Editor. The manuscript for this paper was submitted for review and possible publication on September 10, 2002; approved on February 21, 2003. This paper is part of the Journal of Structural Engineering, Vol. 130, No. 5, May 1, 2004. ©ASCE, ISSN 0733-9445/2004/5-697–707/$18.00. JOURNAL OF STRUCTURAL ENGINEERING © ASCE / MAY 2004 / 697