Cold-Formed Steel Bolted Connections Without Washers on Oversized and Slotted Holes Phase 1

Abstract

In cold-formed steel construction, bolted connections without washers for either oversized or short slotted holes may significantly expedite the building process and lower the cost. However, the current design specification does not include provisions for such connections, and washers are required to be installed for oversized holes or short slotted holes. The research presented in this report aims to experimentally investigate three typical failure modes in cold-formed steel bolted connections with the non-washer and oversized configurations. The three failure modes have been observed: sheet shear failure, sheet bearing failure, and fracture failure of the net section in the connected sheet. The research project consists of two phases. In Phase 1 the sheet shear and bearing failures will be studied, and in Phase 2 the fracture failure will be investigated. The test matrices include a full range of connection configurations covering various steel sheet thicknesses from 30 mil to 118 mil, different connection types of single and double shear using ASTM A307 and A325 bolt types, and high and low ductile steels.