Experimental Study On Seismic Performance Of Frame Truss Composite Wall And Finite Element Analysis

In order to improve the stiffness and deformation capacity of the structure,to optimize the layout of lateral resistant nember,forming a good.ductile energy dissipation system,so that the purpose of effectively preventing and mitigating structural earthquake disasters,preventing the continuous collapse of structures and reducing the threat of earthquake to people’s life and property can be achieved.In this paper,a new type of composite wall is proposed and named as a frame truss composite wall.The advantages of this new wall are multi-stage energy consumption,prefabricated assembly and novel modeling,and a quasi static test is carried out on this new wall.The failure modes and failure characteristics of the specimens are mainly analyzed,and the hysteretic properties,skeleton curves,ductility,stiffness and energy dissipation of the specimens are studied through the data obtained from the test.The test process and the experimental results are as follows:Three different truss section form frame truss composite wall resistance unit specimen were produced according to the design scale of 1:2,due to the experimentation of the test,the three specimens under different axial compression ratio have different truss section size,reinforcement ratio and steel ratio also.Through the horizontal low cycle cyclic loading test,the failure process and failure mode of each specimen were summarized,and the failure mechanism was analyzed.The hysteretic curves of each specimen and strain data of reinforcement and steel plate were obtained.Through the analysis of the hysteresis curve data,the skeleton curve and the load displacement curve of each specimen were obtained.The effect of different axial compression ratio and cross section of truss on the seismic performance of the specimen was qualitatively analyzed.The test results showed that three specimens exhibiting such behavior that truss rod component,as the stress component of the first phase,appeared the first crack and yield,then the outer frame wall gradually began to undertake the main stress components,This rule of the three specimens shows that the energy consumption of the new wall is in sequence,so it can reach the target of energy dissipation,The peak load capacity of the three specimens is significantly different due to the different cross-section design of truss members,which indicates that the design of truss members has great influence on the horizontal bearing capacity of the whole wall units;The ductility coefficients of the three specimens are less than 3,which indicates that the failure mode of the new wall can be classified as brittle failure.Therefore,the design of the truss to improve the ductility of the new wall remains to be further studied.The finite element analysis model of the frame truss composite wall with the same size as the test specimen was established and compared with the test results.On the basis of verifying the reliability of the specimen model,the parameters of the model are analyzed,such as axial compression ratio,reinforcement ratio and steel ratio.The effect of different parameters on the seismic performance of frame truss composite wall is studied.The finite element analysis results show that the ductility factor decreases with the increase of axial compression ratio and longitudinal reinforcement ratio,but the ductility factor increases with the increase of concrete strength.The influence of the stirrup ratio on the load displacement curve,the bearing capacity and the ductility of the specimen is less.The biggest impact on the parameters of the load displacement curve of specimens is the ratio of longitudinal reinforcement,followed by concrete strength,then is the axial compression ratio,the smallest impact is the hoop stirrup rate;for the bearing capacity of the specimens,the greatest impact is the ratio of longitudinal reinforcement,followed by the strength grade of concrete,then is the axial compression ratio,the last is the stirrup ratio;for the ductility coefficient,axial compression ratio impact mostly,followed by concrete strength grade,but stirrup reinforcement ratio and longitudinal reinforcement ratio has little effect.On the basis of the test,the four fold line model is used to fit the skeleton curves of the three specimens,and the comparison with the test curves is made.A restoring force model for the new wall is put forward,and the whole loading process and unloading process are described.Through comparison,it can be concluded that the restoring force model agrees well with the experimental results,and can be used as a reference for studying the hysteretic characteristics of specimens under low cycle reciprocating load.