Abstract
Infilled RC frames with an open first story are prone to a weak story mechanism under seismic loads due to the irregular distribution of lateral stiffness across stories. To address this challenge, a hybrid improvement strategy is introduced, incorporating damping masonry infill walls (DMIWs) in the upper stories and a novel rotational steel rod damper (RSRD) in the open first story. This paper discusses the configuration of the RSRD, which dissipates energy through the bending-shear deformation of four low-yield-point steel rods with arc-shaped edges. Cyclic quasi-static tests were conducted on two RSRD specimens. The test results reveal that the steel rods fracture at 1/3 and 2/3 of their lengths. Desired cyclic behavior and superior energy dissipation capacity were observed, with an equivalent viscous damping ratio exceeding 0.53. Discussions also cover the rotational strength and overstrength characteristics, highlighting a maximum overstrength factor of 3.0 due to the cyclic hardening effect of low-yield-point steel. Additionally, an RC frame with traditional masonry infill walls was designed and analyzed to compare with the improved RC frame implemented with DMIWs and RSRDs. Nonlinear time history analysis of the two infilled RC frames shows that the improved frame exhibits lower peak story drift ratios and a more uniform distribution of story drifts. Furthermore, peak floor acceleration is also reduced in the improved frame, demonstrating that the hybrid improvement strategy can significantly decrease structural and nonstructural damage, thereby enhancing the seismic resilience of the building.
Published Version
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