Abstract：
Four finite element models of RC frame based on finite element software ANSYS were established to study the seismic behavior of the frame with strengthened by section enlargement method. One model is the ordinary RC frame structure, the others model are respectively strengthened the columns of the first floor, the first two floors and the all three floors. Then, the low- cycle and repeated load was imposed on these models until they failed based on finite element software ANSYS. The bearing capacity, deformability and seismic behavior were compared among these structures. It is shown that all had maintaining good energy dissipation ability, energy dissipation ability and ductility under different amount of strengthening. The structure with more strengthening had more significant improvements on the ultimate bearing capacity, while the ductility had not been reduced. Section enlargement method is a very effective seismic strengthening method.
