EXPERIMENTAL STUDY ON SEISMIC PERFORMANCE OF REINFORCED CONCRETE SPLIT-FOUNDATION FRAME STRUCTURES WITH STEEL BRACES

In order to improve the non-uniformity of lateral stiffness distribution of reinforced concrete (RC) split-foundation frame structures, an RC split-foundation frame structure with steel braces was designed. According to the ratio of 1/4, the substructure of the lower 5 floors of the middle frame along the slope was extracted as the test object. A quasi-static test of RC split-foundation frame specimen with steel braces was carried out to investigate the failure process. And the failure mode of the specimen was compared with those obtained from the RC split-foundation frame tests, and then the seismic performance indexes such as hysteretic performance, ductility and stiffness degradation were analyzed. The results show that the final failure of the specimen was marked by the crushing of the concrete at the bottom of the column at the forth story, the spalling of the concrete at the beam end, the fracture of the bottom reinforcement and the spalling of the concrete at the column top of the top story. Compared with the test results of RC split-foundation frames, the damage of grounding columns of RC split-foundation frame specimen with steel braces was significantly reduced, and the damage distribution at the column ends was more uniform, which avoids the occurrence of "half floor failure mode", thus improving the energy consumption and seismic collapse resistance of the structure. However, the deformation and damage degree of the adjacent upper story of the upper ground story of the specimen was large, so the column ends on that story should be properly strengthened; The overall seismic performance of the RC frame specimen with steel braces is excellent, its hysteretic curve is relatively full, and it has good ductility (the displacement ductility coefficient under positive and negative loading can reach 5.13 and 5.69 respectively). The stiffness degradation curves of positive and negative loading tend to be symmetrical.