Study On Seismic Performance And Mechanism Of Precast Shear Wall With Vertical Energy-dissipating Connection

The development of precast buildings is not only an important revolution in the construction way,but also an important measure to advance the supply side structural reform and the development of new urbanization.Specifically,shear walls are commonly adopted as the primary lateral force-resisting component for multi-storied and high-rise frame-shear wall or shear wall structures,due to the higher in-plane stiffness and strength of shear wall under the action of earthquakes.At present,the assembled monolithic shear wall structures are popular based on the design concept of cast-in-situ emulation,in which the mechanical behavior of the precast shear wall with vertical and horizonal connections are close to that of the cast-in-situ shear wall structure.However,because the stress concentration mainly appears at the horizontal connection of shear walls owing to the large in-plane stiffness of walls,the shear wall will sustain brittle failure in an earthquake,resulting in the increased repairing difficulty and cost.In order to effectively improve the deformation ability and control the damage of shear wall structure,the X-shaped metal damper(XMD)and lead viscoelastic damper(LVED)are used in the vertical connection between precast wall panels,which can enrich and develop high-performance precast shear wall structure system.Based on the experimental study,theoretical analysis and numerical simulation,the mechanical behavior of the dampers was revealed and the theoretical method of the dampers were established firstly.Then,the mechanical mechanism and seismic performance of precast and self-centering shear wall systems with vertical energy-dissipating connection were studied systemically.There are three innovative keys in this thesis: 1 The elastic stiffness and yield shear force calculation methods for the X-shaped metal damper and visco-elastic damper were proposed.Meanwhile,pseudo-static tests were conducted on full-scale precast and self-centering shear wall with vertical dampers,and the mechanical behaviors of the precast shear wall with vertical energy-dissipating connections were revealed;k The elastic stiffness and bearing capacity calculation methods for precast shear wall with vertical energy-dissipating connections were proposed based on the continuous connecting link method and design theory of normal section bearing capacity,respectively.Additionally,the load-displacement restoring force model for self-centering shear wall with vertical energy-dissipating connections were established.2The force-based and displacement-based seismic design methods for the precast and self-centering frame-shear wall structure with vertical energy-dissipating connections were established.Based on the main innovative keys,the main research contents are drawn as follows:(1)The hysteretic behaviors of XMDs and LVEDs were studied.Firstly,thirteen XMDs and eight LVEDs were tested to investigate to the hysteretic behaviors of dampers.The test results show that the XMDs and LVEDs had better energy-dissipating capacity and bearing capacity,and the steel stiffeners can effectively restrain the out-of-plane deformation.Subsequently,the elastic stiffness and strength calculation methods for the XMD and LVED were proposed based on experimental results.The theoretical results were in agreement with the experimental results.Finally,the proposed finite element analysis(FEA)models were established using the software ABAQUS,which can effectively predict the hysteretic behaviors of dampers.(2)The seismic performance of precast shear walls with vertical energy-dissipating connections(PSWEC)was investigated experimentally.Two full-scale shear wall specimens were designed,in which the number of dampers for specimens PSWEC1 with XMDs and PSWEC2 with LVEDs were determined based on the design principles of similar peak strength for wall specimens.The seismic performance of specimens PSWEC1 and PSWEC2 was evaluated and compared in terms of the failure mode,bearing capacity,stiffness,energy-dissipating capacity and ductility,et al under cyclic loadings.The test results show that specimens PSWEC1 and PSWEC2 had flexural failure,implying the better deformability and energy-dissipating capacity.In addition,the contribution ratio of energy dissipation of dampers on the precast shear wall decreased with the increasing of horizontal displacement.The dampers can be served as the first seismic line to dissipate seismic energy.Compared with the X-shaped metal damper,the excellent cooperative working performance between the wall panels and viscoelastic dampers was observed.(3)The seismic performance of precast shear walls with vertical energy-dissipating connections was investigated theoretically and numerically.Based on the test results,the elastic stiffness and bearing capacity calculation methods for PSWEC were proposed based on the continuous connecting link method and design theory of normal section bearing capacity,respectively.The reliability and versatility of the simplified calculation method were validated based on the experimental and simulation results.Then,the FEA model for the shear walls was proposed by the software Open Sees,and the parameter study for PSWEC was studied based on the simplified calculation method and FEA model.Finally,the recommended ranges of the critical parameters for PSWEC were also proposed based on the above results.(4)The seismic performance of precast self-centering shear walls with vertical energy-dissipating connections was investigated experimentally.Four full-scale self-centering shear wall specimens were designed while varying critical parameters,including the number of XMDs,layout of energy-dissipating components and initial PT forces.The seismic performance of specimen was evaluated and compared in terms of the bearing capacity,energy-dissipating capacity,stiffness and self-centering capacity,et al under cyclic loadings.The research results show that the self-centering shear walls had obvious characteristics of repairability and replaceability.The self-centering ratio of the shear walls can reach above 0.9 when the restoring force was enough.Compared with specimen PSWEC1,specimen PSWEC3,which was designed with post-tensioned tendons replacing the side columns in wall panels,showed lower stiffness,strength and energy dissipation,but larger residual displacement.(5)The seismic performance of precast self-centering shear walls with vertical energy-dissipating connections was investigated theoretically and numerically.Based on the test results,the elastic stiffness and bearing capacity calculation methods for self-centering shear walls were proposed at the decompression point,softening point,ultimate point and failure point,respectively.In addition,the trilinear mechanical analysis model of self-centering shear walls was established based on the above calculation methods.Subsequently,the FEA model for the self-centering shear walls was proposed by the software ABAQUS.After validating the reliability of the FEA model,the parameter study was conducted to investigate the influence of the number of dampers,oblique angle of XMDs and lead diameter of LVEDs on the seismic behavior of the self-centering shear walls.Finally,the recommended ranges of the critical parameters for the self-centering shear walls were also proposed based on the above results.(6)The seismic design methods for the precast and self-centering frame-shear wall structure with vertical energy-dissipating connection were established.The stiffness characteristic value and coupling rate were selected to propose the force-based seismic design method for the precast frame-shear wall structure with vertical energy-dissipating connection.The dynamic elastic-plastic time history analysis using the FEA model,which was established by Open Sees,was conducted to compare the dynamic response of the frame-shear structure with and without vertical energy-dissipating connections.The results show that the frame-shear structure with vertical energy-dissipating connections had better seismic performance.Subsequently,the displacement-based seismic design method for the self-centering frame-shear wall structure with vertical energy-dissipating connection was proposed by controlling the target drift ratio and base bending moment at the softening point.The reliability and accuracy of the proposed seismic design method was validated by the static nonlinear analysis and dynamic elastic-plastic time history analysis results.