Cyclic Response of Sloped Steel Moment Connections

Abstract

For seismic applications in special and intermediate steel moment frames, the design standard provides a number of prequalified connections. This assumes that the beam frames orthogonally into the column in the elevation and plan of the frame. To provide insight into the sloping effect, two one-sided, full-scale reduced beam section (RBS) moment connection specimens with a 25° slope angle were tested. The specimens had a W36×150 beam connected to a W14×257 column. The RBS dimensions were identical for both specimens, except that the RBS configuration was oriented parallel to the column centerline in one specimen and orthogonal to the beam span in the other. One orthogonal connection specimen was also tested. Defining the heel location as that where the outer face of the beam flange and column flange form an acute angle, testing showed that force concentration there caused brittle fracture. Fracture started from the end of the beam web complete joint penetration weld and the weld access hole. Design recommendations are made based on results from both testing and the associated finite-element simulation. A remedy that aims to reduce force concentration is also recommended.