In previous reports (Part 1 and 2), it is shown that the load carrying capacity of welded T joints are obtained by a simple linear expression approximately. Here, it is tried to apply the results of previous basic model tests to various truss joints, and the relation between the local behavior of joints in actual structure and that of basic model is investigated. First, the trussed beam to column connection is examined, they have the most unfavorable joint for local deformation. At the same time, specimens with joint stffner is tested to evaluate their effect. Common type of truss joint is that two or more branch tubes are connected to chord member, in such case it is guessed that the structural behavior of joint may differ from that of basic model. Nevertheless, by examining several tests on truss joints already reported, it is shown that the results of basic model tests are applicable to common truss joints by using vertical component of axial force in their branch tubes to the chord member. Finally, based on the above investigations, design formulae are proposed by using parameters related to allowable loads of welds of directly welded joints in the present A.I.J. specification.
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