Study On Seismic Performance Of Self-Centering Ductile Structure With Yield Reserve Stiffness

The ordinary self-centering structure enhances the ductility and overall deformation capacity of the structure,and the structure can be restored to the pre-earthquake position after the earthquake.However,when the self-centering structure has large deformation due to the yield of prestressed tendons or prestress loss,it will affect the self-centering performance of the structure and reduce the seismic performance of the structure.Given,Because of the large deformation of the ordinary self-centering structure due to the loss of prestress in the limit state,a self-centering ductile structure with yield reserve stiffness is proposed in this thesis.The stiffness hardening behavior of the damping device is used to provide the reserve stiffness for the self-centering structure and reduce the deformation of the structure in the limit state.The seismic performance is analyzed by finite element software.Under the action of the earthquake,a prestressed steel strand provides stiffness for the structure without energy dissipation.For the energy-based seismic design of ductile structures with yield reserve stiffness,the equivalent velocity spectrum of the equivalent single-degree-of-freedom(SDOF)system can be used to calculate the input energy.At present,the input energy calculation is mostly based on the elastic structure and the bilinear restoring force model,and the influence of parameters such as yield reserve stiffness on the response spectrum is not considered.Based on this,this thesis carries out the following research,specifically:(1)The seismic performance of the damper with yield reserve stiffness and ductile structure with yield reserve stiffness is studied.A new type of damper with yield reserve stiffness is proposed.Six kinds of dampers with different parameters are simulated by finite element software,and the influence of various parameters on their seismic performance is obtained.The research shows that the damper with yield reserve stiffness has good working performance under different horizontal earthquakes.The influence of angle steel size,initial prestress,and damper with yield reserve stiffness on structural performance is investigated by numerical simulation.The analysis shows that the increase of the angle steel size can improve the energy dissipation level of the structure,the increase of the initial prestress can improve the initial stiffness of the structure,the increase the yield strength of the damper,and the influence on the energy dissipation capacity of the structure is more significant.(2)Seismic response analysis of ductile structures with yield reserve stiffness.Using finite element software,the time history comparison analysis of the three-layer ordinary self-centering structure and ductile structure with yield reserve stiffness under a strong earthquake is carried out,and the seismic responses of the two structures are compared respectively.The analysis shows that the ductile structure with yield reserve stiffness improves the structural stiffness and reduces the damage to the main components under seismic action.The seismic response of the ductile structure under strong earthquake is significantly smaller than that of the ordinary self-centering structure.(3)The equivalent velocity spectrum considering the influence of structural parameters,site type,and earthquake type is constructed.120 seismic records of different site types and earthquake types are selected.The influence of five factors,such as postyield hardening stiffness,damping ratio,ductility coefficient,site type,and earthquake type,on the equivalent velocity is analyzed by a self-compiled program.The formula of equivalent velocity spectrum considering the influence of multiple factors is proposed by using a data fitting tool,and its accuracy and validity are verified.An energy-based seismic design method for ductile structures with yield reserve stiffness is proposed.