Abstract
Though several designing and fabricating methods of exterior diaphragms for RHS columns were recommended, the current types, in which the width of the beam flange is in creased, have rarely been adopted for the practical design of steel structures for several reasons . In this paper, a new type of square ring-type exterior diaphragm is proposed. The simple tension tests of the connection were carried out to know its elasto-plastic behavior, changing the thickness of RHS columns, the size of the diaphragms, the connected position and the width of the beam flange, and welding type between an RHS column and the diaphragm. The design strengths, stiffness and the formulation of the restoring force characteristics for this type of diaphragm are presented
