Steel buckling‐restrained braced frames with single and dual corner gusset connections: seismic tests and analyses

Abstract

SUMMARY The design of a three‐story buckling‐restrained braced frame (BRBF) with a single‐diagonal sandwiched BRB and corner gusset was evaluated in cyclic tests of a one‐story, one‐bay BRBF subassembly and dynamic analyses of the frame subjected to earthquakes. The test focused on evaluating (1) the seismic performance of a sandwiched BRB installed in a frame, (2) the effects of free‐edge stiffeners and dual gusset configurations on the corner gusset behavior, (3) the frame and brace action forces in the corner gusset, and (4) the failure mode of the BRBF under the maximum considerable earthquake level. The subassembly frame performed well up to a drift of 2.5% with a maximum axial strain of 1.7% in the BRB. Without free‐edge stiffeners, the single corner gusset plate buckled at a significantly lower strength than that predicted by the specificationof American Institute of Steel Construction (2005). The buckling could be eliminated by using dual corner gusset plates similar in size to the single gusset plate. At low drifts, the frame action force on the corner gusset was of the same magnitude as the brace force. At high drifts, however, the frame action force significantly increased and caused weld fractures at column‐to‐gusset edges. Nonlinear time history analyses were performed on the three‐story BRBF to obtain seismic demands under both design and maximum considerable levels of earthquake loading. The analytical results confirmed that the BRB and corner gusset plate achieved peak drift under cyclic loading test. Copyright © 2011 John Wiley & Sons, Ltd.

Out‐of‐plane stability of buckling‐restrained braces including moment transfer capacity

“…Hikino et al [11] carried out shaking table tests on BRB frames, and Okazaki et al [12] suggested stiffness requirements for gusset plates under one-sided buckling considering the loss of restrainer moment transfer capacity and confirmed the requirements by the test results. In addition, the stiffness and strength requirements at connections have also been investigated through several other BRB frame tests [13][14][15][16][17].…”

Compressive behavior of dual-gusset-plate connections for buckling-restrained braced frames

“…A parametric study was conducted to study the effects of plate thickness, plate length, presence of centerline stiffeners, and gusset boundaries on ultimate load. Test results of full-scale one-story BRBFs using dual-gusset-plate connections can be found elsewhere [22]. Test and analytical results of dual-gusset-plate connections in compression are summarized as follows:…”

Effect of non‐moment braced frame seismic deformations on buckling‐restrained brace end connection behavior: Theoretical analysis and subassemblage tests

“…In the frame tests by Aiken et al [13], beam flange and web fracture occurred near the toe of gusset plates because of frame action and BRB end rotation. The frame tests by Lin et al [15], Chou et al [16], and Palmer et al [17] showed that in-plane frame action force at the beam-column-gusset interface was observed. Although no significant influence on BRB hysteretic behavior was found in these studies, concern on the behavior of surrounding connections was still evident.…”

“…The frame tests by Lin et al [15], Chou et al [16], and Palmer et al [17] showed that in-plane frame action force at the beam-column-gusset interface was observed. These findings [15][16][17][18][19][20][21] all highlighted the negative effect of braced frame seismic deformations on the performance of BRB connection zones. The gusset plate design considering the combined effect of brace action and frame action forces was investigated theoretically and numerically [18][19][20].…”