Shear Behavior of Screw Connections for Cold-formed Thin-walled Steel Structures

Self-drilling screws are the primary mean s to fasten cold-formed thin-walled steel members in construction. There are several failure modes for shear connections with self-drilling screws, including screw tilting, hole bearing, edge tearing, tensile fracture in net s ection of connected elements and shear fracture of screws. Meanwhile, the “g roup effect” will exist when a large number of screws are used in a shear connection. A series of tests (75 specimens) on single lap shear connections with self-drilling screws has been carried out and the results report ed in this paper. The end distance, screw spacing, pattern of screws arra ngement and number of screws was varied to determine their influence on shear connection strength. The study focused on the analysis of factors af fecting the shear connection strength, the shear strength estimation of self-drilling screw connections based on different failure modes and the influence of group effect. Finally, a proposed design method and recommendations for Chinese specification GB50018 are presented