New Shear Stud Provisions for Composite Beam Design

by W. Samuel Easterling, P.E.,

Abstract: The 2005 American Institute of Steel Construction (AISC) Specification for Structural Steel Buildings (AISC 2005) will contain significant changes to the shear connector provisions for composite beams. Current specification provisions use shear connector strength models that were developed in the 1960s and 1970s. The pending provisions incorporate the data base of test results used to develop the current provisions as well as test results conducted in the interim. The focus of this paper, and indeed the changes to the specification, is on welded headed shear studs. Welded, headed shear studs are by far the most common type of shear connector used in the design of composite members in steel frame construction today. Indeed this has been the case for the last 30 years. Provisions for the design of the shear studs have been a part of the AISC specifications since the 1960s. Yet the subject has been researched and debated extensively for the last 17 years. The primary reason for the continued discussion is that since 1987 the AISC specification equations for shear stud strength have been questioned. Specifically, the equations used to determine the reduction in strength due to the use of cold-formed steel deck have been identified as being unconservative. Papers on the subject have appeared in the literature in the United States, Canada and Europe (Jayas and Hosain, 1988; Robinson, 1988; Mottram and Johnson 1990; Lawson 1992; Lloyd and Wright, 1992; Easterling, et al 1993; Van der Sanden, 1995; Johnson and Yuan, 1998.) The shear stud is one of the fundamental components of any composite member in which it is used. It can therefore be argued that a thorough understanding of the performance characteristics of the shear studs is essential if efficient, reliable design of composite members is to take place. A comprehensive research project conducted at Virginia Tech (VT) has addressed this issue (Easterling, et al 1993; Lyons, et al 1994; Roddenbery, et al 2002.) It has been shown through a combination of elemental (push-out) tests, direct shear tests, composite beam tests and subsequent analytical evaluations of these tests that the current AISC specification provisions (AISC 1999) are not representative of true behavior.

Subject Headings: Composite beams | Studs | Steel construction | Steel structures | Shear strength | Connections (structural) | Shear tests | Steel beams | North America | United States | Virginia | Europe | Canada | Vermont

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