Civil Engineering Study 88-5
INTRODUCTION When cold-formed steel beam webs are subjected to partial edge loading, they may fail by web crippling rather than bending of the beam. Web crippling is caused by a highly localized intensity of the load or reaction. Because of the complexity of the web crippling behavior, empirical expressions are presently used for the design of cold-formed steel beams in buildings and automotive structural components to prevent web crippling. 1,2,3. The research on the structural behavior of cold-formed steel beam webs subjected to web crippling has been conducted at Cornell University and the University of Missouri-Rolla (UMR) under the sponsorship of the American Iron and Steel Institute (AISI).4,5 Since 1982, additional work has been performed at the University of Missouri-Rolla, Inland Steel Company, and Ford Motor Company to investigate the web crippling strength of automotive structural components using high strength sheet steels. 6-9 The research findings of the UMR study were summarized in the Eighth Progress Report. 7 In the UMR Fifth and Eighth Progress Reports, it was noted that if the I-beam specimens are subjected to the end one-flange loading without connecting the beam flange to the bearing plate, the failure of all sections used in the pilot tests occured by cross-bending of the flange about the connector location as shown in Fig. 1 instead of the conventional web crippling. This type of failure will be referred to as a "flange cross-bending" mode of failure in this report. It seems to be dependent primarily on the bend radius, the thickness of the web, the location of connectors and other parameters. Figure 2 shows the failure of an I-beam subjected to end one-flange loading. The tested loads for the specimens having the "flange cross-bending" type of failure were lower than those caused by the conventional web crippling. The purpose of this brief study reported herein was to review the test results described in Ref. 6 for the "flange cross-bending" type of failure of cold-formed steel I-beams using high strength sheet steels and to develop some new design criteria, if possible. Because of the limited number of test results, the present investigation can only be treated as a preliminary study of the problem. An extensive experimental work will be needed for the development of general design criteria. Section II contains a review of the experimental research results described in Ref. 6. In Section III, an analytical study of this type of failure mode for cold-formed steel I-beams is presented by using the finite element method. The development of an empirical expression for predicting the ultimate load is discussed in Section IV. Also included in this section is the comparison of test results and predicted values based on the newly developed equations for "flange cross-bending" failure. In addition to the study of the web crippling strength of I-beams, this report also evaluates the results of 157 beam tests using hat sections. These tests were conducted recently at the Research Laboratories of Inland Steel Company. Section V includes the information on beam specimens 10 and comparisons of the tested and predicted failure loads on the basis of the design recommendations proposed in Ref. 7. Finally, conclusions are drawn in Section VI.
Civil, Architectural and Environmental Engineering
Wei-Wen Yu Center for Cold-Formed Steel Structures
American Iron and Steel Institute
Missouri University of Science and Technology
© 1988 Missouri University of Science and Technology, All rights reserved.
Report - Technical
Lin, Shin-Hua; Hsiao, Ling-En; Pan, Chi-Ling; and Yu, Wei-wen, "Design of automotive structural components using high strength sheet steels structural strength of cold-formed steel I-beams and hat sections subjected to web crippling load" (1988). Center for Cold-Formed Steel Structures Library. Paper 70.