Cold-Formed Steel Bolted Connections Using Oversized and Slotted Holes without Washers Phase 2

Abstract

In cold-formed steel (CFS) construction, bolted connections without washers for either oversized or slotted holes may significantly expedite the installation process and lower the cost. The North American Specification for the Design of Cold-Formed Steel Structural Members requires washers to be installed in bolted connections with oversized or slotted holes. A research project (Phase 1) sponsored by American Iron and Steel Institute was recently completed at the University of North Texas (UNT) that investigated the performance and strength of bolted CFS connections with oversized and slotted holes without using washers. The research presented in this report is the Phase 2 project in which the bolted CFS connections were studied in a broader respect in terms of the failure mechanism, the material thickness, and the hole configurations. Combined with Phase 1 results, the Phase 2 report gives a comprehensive evaluation of the behavior and strength of bolted CFS connections with oversized and slotted holes without using washers. Revisions to the existing AISI North American Specification requirements for bolted connections are proposed to account for the reduction in the connection strength caused by the oversized and slotted hole configurations without washers.