Experimental and Analytical Study of Connections in Steel MRFs Composed ofDouble Section Columns

Chapter ten of Iranian National Building Code recognizes a certain type of connection between I beam and double section built up column to be used in ordinary and intermediate MR frames. The behavior of this type of connection and its panel zone are studied by testing three full scale specimens under cyclic loading and finite element modeling. The first specimen is tested under cyclic lateral loading and the other two are tested under axial loading in addition to cyclic lateral loading. All specimens have sufficient strength and stiffness and are categorized as rigid connection. They also show sufficient ductility for being used in intermediate MR frames. The panel zoe behavior in this type of connection is different from that of an ordinary connection of I beam to H column, mainly because the webs of beam and column are not in the same plane. The results of this research demonstrate that the behavour of the connection is mainly affected by the I section comprising of column cover plates and vertical continuity plates. Due to high stress concentrations produced in full penetration and fillet welds, if fracture in welds occurs early, full plastic hinge may not form in beams as desired. Hence provision of criteria for design of column cover plates in connection region is a prerequisite for satisfactory performance of the connection for seismic application.