Load and resistance factor design of cold-formed steel statistical analysis of mechanical properties and thickness of materials combined with calibrations of the AISI design provisions of unstiffened compression elements and connections

INTRODUCTION This report presents the progress made on the development of the load and resistance factor design of cold-formed steel following the preparation of the First Progress Report. In Article 11.1, the statistical analyses of the tested values versus the specified values on mechanical properties and thicknesses of the steel sheets and strip are discussed. More than 4,000 tensile coupon tests on mechanical properties and 1,400 data on thickness of steel sheets have been collected and analyzed. For the purpose of formulating the procedures to be used for calibration of various provisions of the AISI Specification, the required formulas are summarized in Article 11.2. Article 11.3 contains the calibration of the current and proposed AISI design provisions on unstiffened compression elements. (1,11) The calibrations of the current AISI provisions on bolted and welded connections are presented in Articles 11.4 and 11.5, respectively. Based on the progress made to date, a preliminary summary is presented in Article 11.6. This report is a revision of the Second Progress Report dated November, 1976. This investigation was sponsored by American Iron and Steel Institute. The technical guidances provided by our consultant, Dr. M.K. Ravindra, the AISI Task Group on Load and Resistance Factor Design (K.H. Klippstein, Chairman, D.H. Hall, R.B. Matlock, and D.S. Wolford, members), the advisors for the AISI Task Group (R. Bjorhovde, N.C. Lind, F.J. Phillips, C.W. Pinkham and G. Winter) and the AISI Staff (A.L. Johnson and D.P. Cassidy) are gratefully acknowledged. The data on mechanical properties and thicknesses of steel sheets and strip were supplied by three companies. Their cooperation in this manner is appreciated. Thanks are also due to J.R. Senne for his advice during the project. Special thanks are extended to Mrs. Alice Crangle for typing this report