Structural behavior of perforated web elements of cold-formed steel flexural members subjected to web crippling and a combination of web crippling and bending

PREFACE A study of structural behavior was conducted and design equations were developed that account for the degradation in web crippling capacity caused by web openings for single web cold-formed steel flexural members. The sections were subjected to a concentrated load applied to one flange. The load application satisfied the AISI definition for either End-One-Flange or Interior-One-Flange loading. The research findings enable the current design provisions for sections without web openings to be modified by a reduction factor equation to obtain the web crippling capacity for sections with web openings. The modified capacity is considered for the web crippling capacity in the absence of bending moment. For situations of combined bending and web crippling, the current AISI provisions for interaction are used based on the web opening modified bending moment and web crippling capacities. Simple and practical web reinforcement configurations using material from the same cross section as the member are provided. Use of the web reinforcement configurations, for single web members having web openings, will ensure that the web crippling strength for the same cross section without web openings is obtained for the same key parameters defining the design situation. This report is based on the dissertation of the same title presented to the Faculty of the Graduate School of the University of Missouri-Rolla (UMR) in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Civil Engineering. This investigation was sponsored by the American Iron and Steel Institute (AISI) and the Metal Lath/Steel Framing Association (MLjSFA) Division of the National Association of Architectural Metal Manufacturers (NAAMM). Technical guidance was provided by the ML/SFA-AISI Joint Task Force: J.E. Sullivan (chairman), C. Bissey, R.L. Brockenbrough, C.R. Clauer, E.R. diGirolamo, S.J. Errera, E.R. Estes, Jr., L. Hernandez, A.L. Johnson, K.H. Klippstein, J.P. Matsen, W.R. Midgley, T.B. Pekoz, N. Peterson, G.S. Ralph, R.M. Schuster, T.W. Trestain, and R.A. LaBoube. Thanks are also extended to R.B. Haws, K.L. Cole, AISI staff, and A.L. Sisco, NAAMM staff, for their assistance