Analysis of light gage steel shear diaphragms


INTRODUCTION The stiffening effect on building frames of light gage steel cladding and floor and roof deck has long been recognized by structural engineers. Specific utilization of the in-plane shear strength and stiffness of panelling was suggested more than 18 years ago. In order to take this contribution to stiffness and strength into account in engineering design, it is necessary to have means for predicting the effective shear rigidity and ultimate strength in shear of the steel panel diaphragms. Up to now, engineers have relied upon tests of full-scale panel assemblies, in which the performance of specific combinations of panels, marginal framing members, and connections have been studied on a strictly ad hoc basis. While much has been learned using this approach, no rational theory to describe and predict structural behavior has resulted. On the other hand, testing of large diaphragms is expensive and time consuming, and test results are applicable only to diaphragms using the same panels as tested, with directly equivalent fastening systems. The need for a general method of analysis is clear. The present research is directed toward the development of such a method of analysis. The approach taken is based on the finite element concept, developed in the aerospace industry and now finding many applications in the field of civil engineering structures. In the present case, each of the components of a metal deck diaphragm (i.e., the individual deck panels, the connectors, and the marginal framing members) is taken as a discrete element, the stiffness characteristics of which are established by analysis or small scale testing. The component parts are then combined analytically to establish the behavior of the entire assemblage. The first goal of the present research is to establish, for panels and connectors, a set of simple, standardized test procedures, and to use these test techniques to produce representative stiffness and strength properties for system components. The second goal is to develop the analysis to the point that a general-purpose computer program can be made available to the design profession for the analysis of diaphragms.


Civil, Architectural and Environmental Engineering

Research Center/Laboratory(s)

Wei-Wen Yu Center for Cold-Formed Steel Structures


American Iron and Steel Institute



Publication Date


Document Version


Document Type

Report - Technical

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