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The robustness of steel connections in fire
Last modified: 2012-02-28
Abstract
Connections are key components in framed structures, tying floor beams either directly tosupporting columns or to primary beams. Failure of a connection could cause collapse of the connected beam,which could lead to further buckling of the column as it loses its lateral support, or to progressive collapse offloor slabs. In performance-based fire design, beams are sometimes allowed both to develop very largedeflections and to support the floor by developing large catenary tension forces. The tying capacity ofconnections to transfer these significant forces to adjacent structure when they are already subject to highrotations is essential to maintain structural stability. Traditionally, connections have been studied in terms oftheir moment-rotation behaviour alone. Recently however, some work has been done to investigate thebehaviour of commonly used steel connections subjected to an inclined tying force at elevated temperatures.The effect of co-existent shear force and rotation on the tying capacity has been studied in furnace tests atdifferent temperatures. This paper discusses the results of these tests on four different connection types, andtheir implications. A key objective is to facilitate the inclusion of the major aspects of joint behaviour intoglobal structural analysis for performance-based structural fire engineering design of steel-framed andcomposite structures by means of a component-based approach.
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