Anti-collapse Performances Analysis On Reinforced Concrete Frame-core Structures With Relatively Small Core

It is stipulated in Code for Seismic Design of Building(GB50011-2001) that the ratio of overturning moment subjected to the core wall to the overall overturning moment of the structure due to earthquake should be more than 50 percent in the reinforced concrete frame-core structures. In some cases, however, the area of the core is less than the requirement of the code because of the limited of the layout of the building. This makes the ratio of overturning moment of the core to the overall overturning moment of the structure less than 50 percent. But the elastic analysis of these structures indicate that such as displacement, torsion, can meet the standards well. Therefore, it is important to evaluate the performances and security as well as the ability of anti-collapse of the structures in rare earthquake, by nonlinear static analysis of these structures.Based on the elastic dynamics analysis and static nonlinear analysis of frame-core structures with different heights and different ratios of overturning moment by the finite element method, the elastic-plastic performances and the failure modes and the ability of anti-collapse of frame-core structures are studied in this paper. The results indicate that: 1. In the process of pushover, the plastic hinges appear in the coupling beams and the frame girders first , then appear in the lower part of the core, the structure fails to collapse after a great quantity of hinges appear in the weak story; 2. It is necessary to subdivided the maximum applicable height of the structure in intensity 7 area, when the ratio of overturning moment of the core is larger than 45 percent, the maximum height can be reach to 120m, and 110m while the value is larger than 40 percent.