| With the development of society,there has been a growing focus on precast shear wall structures in the construction industry.Numerous experiments have indeed highlighted issues with the strength and energy dissipation capacity of connections in precast shear walls,which can lead to the failure mode of "weak joint".Therefore,this dissertation proposed a precast tolerant energy dissipation shear wall,which uses steel connectors to connect precast shear walls and install Low Yield Point(LYP)steel energy dissipators to improve the energy dissipation capacity of the walls.To enhance the bearing capacity of the precast Energy Dissipation Wall(EDW),an embedded steel precast EDW was proposed.Furthermore,to improve the self-resetting ability of precast EDW,a steel-embedded precast Unbonded Post Tension(UPT)EDW was developed,which has good energy dissipation capacity and self-resetting ability,making it a high-performance load-bearing and energy dissipation dual-function wall.The theoretical design method and seismic performance investigation on the proposed precast shear walls were presented in the dissertation.The main research content and conclusions are as follows:(1)To improve the failure mode of the wall and the damage to the concrete at the wall toe,this dissertation proposed a precast tolerant EDW using steel connectors.Based on the capacity-demand theory,theoretical analysis of the bearing capacity of each component and its connections,connection interfaces in the wall system was conducted.Direct shear tests on the connection of precast specimens,quasi-static tests on full-scale precast tolerant shear walls under different axial compression ratios,and quasi-static tests on full-scale precast tolerant EDW were carried out.The test results showed that both cast-in-place(RC)and precast specimens exhibit brittle failure modes,and the ultimate capacity of the precast specimens was 48.4% higher than that of RC specimens.Both RC walls and precast walls exhibited flexural-shear failure modes,and the plastic hinges of the precast walls transferred from the connection zone to the wall panel,achieving the design concept of "strong joint,weak component".With the increase of the axial compression ratio,the bearing capacity of the precast wall was increased.The precast EDWs exhibited a flexural-shear failure mode with " strong joint,weak component ".The peak and yield bearing capacity of the specimens were increased by 37.1% and 29.4%,respectively,compared to walls without energy dissipators.The average equivalent damping ratio was increased by 10.1%,and the cumulative energy dissipation capacity was increased by 9.5-48.7%.The proposed three-linear model for the shear capacity of connection was introduced,and the relevant calculation methods were provided.The rationality of the model was validated by comparing the results of finite element analysis,theoretical calculations,and test results,indicating that the three-linear model can be used as a simplified method for analyzing the shear capacity of interfaces.Through parameter analysis,it was found that the bearing capacity of the specimens was determined by the weak section,and the steel plate area of the steel connectors had little influence on the bearing capacity of the shear wall specimens.The diameter of the bars and the axial compression ratio have a significant impact on the bearing capacity and energy dissipation.An increase in the axial compression ratio leads to a decrease in the displacement ductility of the specimens.Increasing the strength or cross-sectional area of the low-yield-point(LYP)steel can improve the bearing capacity of the EDW.The LYP steel dissipators not only enhance the energy dissipation capacity and bearing capacity of the specimens but also improve the displacement ductility of the shear wall specimens.(2)To meet the higher bearing capacity requirements of precast EDWs,an embedded steel precast EDW was proposed.Quasi-static tests were conducted on fullscale embedded steel precast walls and embedded steel precast EDW.The results showed that the EDW exhibited superior strength,stiffness,and a higher equivalent damping ratio.Compared to walls without energy dissipators,the yield and peak bearing of the EDW were increased by 23% and 22%,respectively,and the cumulative energy dissipation capacity was increased by 15%-55%.By comparing the performance of tolerant EDW and embedded steel EDW,it was found that the embedded steel precast EDW has increased yield and peak bearing capacities of 15.7% and 14.5%,respectively,and an average equivalent damping ratio increase of 40%.This indicates that increasing the amount of steel can improve the bearing and energy dissipation capacity of the specimens.A theoretical analysis for the bearing capacity of embedded steel EDW was proposed,and its rationality was verified through test results.Numerical analysis of the embedded steel precast EDW was conducted using the Open Sees.The results showed that increasing the steel content in the edge components,increasing the axial compression ratio,and the thickness of the LYP steel plate can improve the bearing and energy dissipation capacity of the shear walls while increasing the area of the diagonal angle steel has a limited impact on the bearing capacity of the shear walls.(3)To improve the self-centering and energy dissipation capabilities of the embedded steel precast EDW,a steel-embedded UPT EDW was proposed.Quasi-static tests were conducted on three UPT specimens.The results showed that the residual displacements of the UPT walls were small,indicating good self-centering capability.The hysteresis curves of UPT walls without energy dissipators(PPW1)exhibited a similar bilinear response,while the hysteresis curves of UPT EDWs(PPW2,PPW3)exhibited flag-shaped responses.The yield bearing capacities of the three specimens were 97.5 k N,201.5 k N,and 203.7 k N,respectively.The equivalent damping ratios were 0.048,0.114,and 0.115,respectively.The cumulative energy dissipation of the specimens with energy dissipators was 3.1-4.8 times higher than that of UPT wall without energy dissipators.By comparing the embedded steel UPT walls with the embedded steel precast EDW,it was found that the fixed connection wall had a higher bearing capacity and a fuller hysteresis curve.The UPT EDW had a lower bearing capacity,smaller residual deformation,and better self-centering capability.A theoretical calculation method for the bearing capacity of precast UPT EDW was provided,and the calculated yield force was close to the experimental yield force,verifying the rationality of the calculation method.Through numerical analysis,it was found that the energy dissipation capacity of the UPT walls was mainly influenced by the energy dissipators.Increasing the axial compression,initial prestress,the number of prestressing bars can improve the bearing capacity of the specimens.The embedded steel content and the diameter of the bars had little impact on the performance of the specimens.The eccentricity affects the structure related to the lateral displacement.A simplified four-linear bearing capacity model for precast UPT EDW was proposed and verified by experimental and finite element results.A displacement-based seismic design method for frame-precast UPT EDW structures was proposed,and the response of the structure under seismic action was compared with that of frame-precast UPT shear wall structures,verifying that the structure meets the performance objectives of the displacement-based design method.Nonlinear analysis results showed that the peak displacement at the top of the structure,the peak inter-story displacement drift and residual displacement were smaller than that of frame-UPT wall structure,this indicated that energy dissipators can reduce the seismic response of the structure,increase the resilience of the structure,and improve its safety. |
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