| Summary: | 碩士 === 國立中央大學 === 土木工程學系 === 103 === Knee braced moment resisting frame (KBRF) has been developed in recent years. The KBRF system possesses higher stiffness than the moment resisting frame (MRF) and larger ductility than the concentrically braced resisting frame (CBRF), thus is a suitable structural form for earthquake-resistant purposes. However, when the KBRF is subject to heavy cyclic load, the knee braces that contribute to the structural strength will reach the buckling stage, causing major loss in structural performance. In order to improve the structural performance of the KBRF system, a modified design using dual self-centering mechanisms in the knee brace members and the beam-to-column connections was proposed in this study. A set of copper plates were used in the beam-to-column connections to dissipate energy through friction mechanism. A series of cyclic loading tests were conducted on the multi-bay-multi-story KBRFs to evaluate their performance.
It was found from the tests that the strength, stiffness and energy dissipation capacity of KBRF with dual self-centering mechanisms was higher than the MRF with equivalent dimensions. Test results also showed that the major structural members, including beams and columns, remained intact when the structural was subject to large drift, which justified the effectiveness of the proposed method. Further comparisons on the structural performance suggested that the ratio of joint decompression strength between lower and upper stories be approximately 1.5 so that higher structural performance could be achieved.
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