Civil Engineering Study 81-2
INTRODUCTION A. General During the period of October 1968 through September 1980, the 1968 Edition of the AISI Specification was used for the design of steel deck webs that could withstand web crippling and combined web crippling and bending. (1) The design formulas used to prevent web crippling were developed primarily on the basis of tests conducted in the 1940's and 1950's at Cornell University. (2-4) Recently, new types of cold-formed steel sections have been developed and used in building construction. The use of unusual geometric configurations has complicated the design of such members. In order to develop new design criteria, additional studies of the crippling strength of beam webs have been made in several countries. (5-22) Since 1973, a research project on a study of beam webs has been carried out at the University of Missouri-Rolla (UMR) under the sponsorship of American Iron and Steel Institute. Based on the available test data obtained from research at Cornell and tests recently conducted at UMR, modified AISI design formulas for web crippling have been proposed in Ref. 21. Because these modified formulas are based on the test data of channels, I-beams, and hat sections having vertical webs with relatively small R/t and N/t ratios, these proposed design provisions mayor may not be fully suitable for the design of steel decks when they have inclined webs with large R/t and/or large N/t ratios. In addition, various types of embossments and indentations are usually formed in the webs of the steel decks to be used for composite slabs. These deformations may affect the web crippling strength of steel decks. For this reason, a research project was initiated in 1979 at the University of Missouri-Rolla to study the web crippling strength of steel decks. This project was cosponsored by Steel Deck Institute, American Iron and Steel Institute, and H. H. Robertson Company. B. Purpose of Investigation The objectives of the investigation were (1) to establish experimentally the web crippling strength of a selected group of steel decks, (2) to determine the effect of bending on web crippling load, and (3) to demonstrate the validity of the proposed design formulas for preventing web crippling of steel decks. C. Scope of Investigation In order to achieve the first objective mentioned above, a total of 84 web crippling tests of steel decks were conducted at the University of Missouri-Rolla during the period of September 1979 through March 1980. During these tests, 40 specimens were subjected to interior one-flange loading, and the remaining 44 specimens were subjected to end one-flange loading. Details of the first phase of the experimental study are presented in Articles II and III of this report. Comparisons between the test data and predicted web crippling loads are also included in these two articles. In the second phase of the study, 56 specimens having relatively long spans were tested as simple beams and continuous beams to determine the effect of bending on the web crippling strength of steel decks. The test data have been used to determine the validity of the AISI interaction formulas that are used for the design of steel beams subjected to combined web crippling and bending. Details of the second phase of the -study are presented in Articles IV and V. Finally, the recommendations for future research are discussed in Article VI.
Civil, Architectural and Environmental Engineering
Wei-Wen Yu Center for Cold-Formed Steel Structures
American Iron and Steel Institute
H.H. Robertson Company
Steel Deck Institute
Missouri University of Science and Technology
© 1981 Missouri University of Science and Technology, All rights reserved.
Report - Technical
Yu, Wei-wen, "Web crippling and combined web crippling and bending of steel decks" (1981). Center for Cold-Formed Steel Structures Library. 187.