Semi-rigid behaviour of stainless steel beam-to-column bolted connections

Abstract

Stainless steel is increasingly used in structural applications but there is still significant lack of experimental evidence on the moment-rotation (M-) behaviour of moment resisting beam-to-column connections. The current paper presents experimental test results obtained from full scale tests conducted on three widely used connection types i.e., double web angle (DWA), top seat angle (TSA) and top seat with double web angle (TS-DWA) connection. Considered beam, column and angle sections were fabricated using austenitic stainless steel plates and M20 high strength bolts were used for connection assembly. M- curves for all connections were carefully recorded and were used to determine initial stiffness (Ki) and moment capacity (M20mrad) for each of the connections. Eurocode 3 guidelines were used to check the classification i.e., whether or not the connections were semi-rigid in nature. Although the considered DWA connection failed to achieve partial-strength, both TSA and TS-DWA connections showed obvious semi-rigid nature despite the connection capacities were limited by bolts. In addition, extensive ductility of stainless steel ensured that all three connection types achieved a minimum connection rotation of 30 mrad, which is specified by FEMA as a requirement for earthquake design of ordinary moment frames.