Bidirectional Loading Behavior of Buckling-Restrained Braced Frames

摘要

Bucking-restrained braces frames (BRBFs) are an efficient lateral-load resisting system to meet seismic design requirements. An analytical study was conducted on BRBFs that include columns shared by orthogonal BRBs. It is not clear whether the current codes and design methods adequately address bidirectional loading effects, particularly for shared columns. Therefore, eighteen building frames were designed and analyzed to examine the bidirectional loading behavior and demands for BRBFs. The frames had a rectangular floor plan with a pair of BRBFs framing orthogonally into each corner, and these frames were designed with two different heights, two types of brace arrangements, three response modification factors, and two different design criteria for the shared corner columns. Each three-dimensional, nonlinear BRBF model was subjected to ten sets of bidirectional ground motions. The results are used to discuss the force demands to size the shared columns. The results also suggest that BRBFs designed according to the current codes and provisions may not perform as intended.