Ductile steel knee brace with built-in comb-shaped seismic damper

Abstract

The attachment of supplemental knee braces is an efficient seismic retrofitting measure for existing steel buildings. A new ductile knee brace with a built-in comb-shaped damper is proposed in this study. The proposed ductile knee brace is composed of a wide-flange section with multiple slot holes in its web plate, which is designed to plasticize earlier at shear-yielding struts in the comb-shaped web. The isolated knee brace components and subassemblages reinforced by the proposed knee brace were subjected to cyclic loading tests to investigate the cyclic behavior of the knee brace. The test results showed that the knee brace exhibited sufficient deformation capacity. The overall strength and cyclic behavior of the knee brace was estimated using a simple mechanical model. Additionally, it was shown that the experimental low-cycle fatigue life of the knee brace can be predicted using the fatigue curve of notched specimen of the steel and Miner's rule.