Seismic Behavior Analysis Of Unbonded Precast Prestressed Concrete Structure

Unbonded precast prestressed concrete structure has the advantages of fast assembly integration,no wet work on site,less affected by the weather.At the same time,its ductility and deformation recovery ability are better than that of the conventional concrete structures,the residual deformation is small,easy to repair,with good seismic performance.At present,the research on unbonded precast prestressed concrete structure is mainly aimed at the seismic performance test of beam-column joints,while the theoretical analysis of its ultimate bearing capacity and restoring force model are less.In this paper,taking the unbonded precast prestressed concrete structure as research object,using ABAQUS finite element software,through the two parts of the node and the frame,the seismic performance including the ultimate bearing capacity and the restoring force model are studied.The main research contents and conclusions are as follows:(1)Taking the beam-column joints of unbonded precast prestressed concrete structure as research object,the stress and strain of the concrete and the prestressed tendons under limit state are analyzed,and their relationship is discussed.Based on the analysis,a procedure for estimating the moment capacity of the beam-column joint the ultimate bearing capacity is developed.And is verified by using ABAQUS finite element software.The results show that the proposed method can well simulate the flexural ultimate bearing capacity of unbonded precast prestressed concrete beam-column joints.(2)Based on the finite element simulation results of unbonded precast prestressed concrete beam-column joints and combined with the calculation method of ultimate bearing capacity,the factors affecting the ultimate bearing capacity of joints are studied.The results show that the ultimate bearing capacity of unbonded precast prestressed concrete beam-column joints can be enhanced by initial prestress,concrete strength grade and eccentricity of prestressed bars.(3)According to the position of the prestressed joints,the finite element model of the three frame structures of the full assembly frame structure,the beam-column assembly frame structure and the cast-in-place frame structure are established to calculate the response of the structure under the cyclic loading and study its seismic performance.The results show that the prestressed joint can improve the deformation recovery ability and seismic performance of the structure,and the fully assembled frame structure has better seismic performance.(4)For the full assembly frame structure,the finite element simulation results were standardized and regression analyzed,the skeleton curve model and hysteretic rules were established,and the restoring force model of the structure was proposed,and compared with the finite element calculation results.The results show that the proposed restoring force model has a good agreement with the finite element calculation results and has good accuracy,which can better reflect the hysteretic behavior of the full assembly frame structure.