Three-Dimensional Tests of Two-Story, One-Bay by One-Bay, Steel Concentric Braced Frames

Abstract

Steel concentric braced frames (CBFs) are widely used as systems to resist lateral loads induced from wind and seismic loading. Recent research on full-scale CBF subassemblages has shown that current design provisions fall short of the design intent. Additionally, the effect of imposed out-of-plane deformation on the system has never been evaluated experimentally in this manner. This paper describes the design, test setup and experimental results of two tests performed on a two-story, one-bay by one-bay CBFs, an HSS buckling-brace system in a single-story Xconfiguration, and a buckling-restrained braced frame (BRBF) in a single-diagonal configuration. The design of the gusset plates for the HSS braces followed a balanced design procedure with an elliptical clearance to permit out-of-plane rotation due to brace buckling. The HSS braces fractured at 2% story drift. The BRBF gusset plate design followed current design standards with the BRB cores fracturing at 3.5% story drift prior to any instabilities.