Seismic Performance Of Reinforced Concrete Frames Retrofitted With Concentric Core-steel-frame Bracing

Reinforced concrete frame with core-steel-frame concentric brace is a new type of double lateral force resisting structural system,which possesses large strength,lateral stiffness and good energy dissipation capacity.The best advantage is that the bad damaged infill core-steel-frame brace after earthquake can be replaced because RC frame still keeps its integrality.However,due to the complex interactive action between RC frame and infill core-steel-frame brace,some behaviors are still needed to be researched continually,such as failure modes,transferring mechanism and so on.So the research on the hysteretic behavior of CSFBF structure has important theoretical significance and practical value.CSFBF structure is carried on numerical simulation annlysis based on ABAQUS software,and the main contribution is as follows:(1)Reinforcing bars of RC frame structure are designed under 7 degree seismic fortification intensity by PKPM software.When the seismic fortification intensity is increased to 8 degrees,one-bay,four-story RC frame is retrofitted with different size and section size of core-steel-frame brace.Then,a two-dimensional framework model of RC frame with core-steel-frame brace is established and carried on Pushover analysis based on SAP2000 software.A reasonable range of the core-steel-frame size can be obtained according to brace yields before the beam and column of RC frame.(2)Establish a finite element model of one-bay,one-story RC frame with core-steel-frame brace(BASE specimen)by ABAQUS,analyze the existing related tests and verify the modeling approaches.Compare the hysteretic behavior of RC frame,RC frame with core-steel-frame or cross shaped brace.(3)Discusse the hysteretic behavior,ductility,stiffness degradation and energy dissipation capacity of BASE specimen.Analyze the seismic performance of the BASE specimen under different concrete damage factor.(4)Analyze the effect regular of core-frame dimension,horizontal brace length,vertical brace length on hysteretic behavior,ductility,stiffness degradation and energy dissipation capacity of CSFBF structure.According to the relevant parameters of hysteretic behavior,the design proposal of the reasonable size of the core-frame dimension is given.