The Research On Seismic Behavior Of Steel Frame Super High Performance Concrete Core Tube Structure

Based on the finite element analysis of ultra-high performance concrete shear wall and ultra-high performance concrete coupling beam by OpenSEES software,a 35-story steel frame core tube structure is established to study the vulnerability of the structure based on the incremental dynamic analysis method.(1)On the basis of verifying the feasibility of the models of UHPC shear walls,the test pieces of UHPC shear walls are designed to study the influence of the parameters such as the ratio of height to width,the ratio of axial compression,the ratio of longitudinal reinforcement and the spacing of stirrups on the performance of UHPC shear walls.The results show that the ratio of height to width and the ratio of axial compression have the most significant influence on the shear walls.When the ratio of height to width is 1.0,the brittle failure mode is mainly shear failure;when the ratio of height to width is 2.0 and 3.0,the bending failure mode is mainly bending failure.With the increase of axial compression ratio from 0.1 to 0.3,the bearing capacity and ductility of the specimens increase significantly.The increase of the reinforcement ratio of the longitudinal reinforcement of the concealed column can significantly improve the bearing capacity and ductility of the wall.With the increase of the reinforcement ratio from 2.68% to 5.36%,the bearing capacity of the shear walls is increased by 31.60%,and the deformation capacity of the specimen is improved significantly.With the increase of stirrup,the bearing capacity and ductility of shear walls are improved.With the increase of the reinforcement ratio of the horizontal distribution reinforcement,the bearing capacity of the shear walls is slightly improved,and the ductility of the shear walls is improved.(2)On the basis of verifying the feasibility of UHPC shear wall coupling beam model,design UHPC coupling beam,and study the influence of span height ratio,stirrup spacing,longitudinal reinforcement ratio and reinforcement form on the performance of UHPC coupling beam.The results show that with the increase of span height ratio from 1.5 to 2.5,the energy dissipation capacity and deformation capacity of the specimens increase significantly,while the bearing capacity decreases by 58.9%.With the increase of stirrups,thebearing capacity and ductility of the specimens are improved.The ratio of longitudinal reinforcement has no significant effect on the bearing capacity and deformation capacity of coupling beams.The comprehensive reinforcement forms can significantly improve the bearing capacity of the coupling beam and the deformation capacity of the specimen.(3)The results show that compared with the ordinary concrete coupled shear wall structure,the ultra-high performance concrete coupled shear wall structure has higher bearing capacity,energy dissipation capacity and variability.The results show that the ultra-high performance concrete coupled shear wall has good seismic performance.(4)The models of steel frame ultra-high performance concrete core tube structure and steel frame ordinary concrete core tube structure are established,and the elastic-plastic analysis of the structure is carried out.The results show that the lateral displacement and the maximum inter story displacement angle of the steel frame ultra-high performance concrete core tube structure are lower than those of the steel frame ordinary concrete core tube structure.Based on the incremental dynamic analysis(IDA)method,20 seismic waves suitable for the site conditions are selected to analyze the structural dynamic time history of steel frame super high performance concrete core tube structure,and the corresponding IDA curve cluster and three quantile curves are drawn to determine the five performance points of the IDA curve,and the failure probability curves of the structure corresponding to five states are obtained respectively.The seismic strength index corresponding to 50% failure probability is 0.55 g and 0.79 g respectively when approaching the collapse performance point.The CMR of the structure under rare earthquake is 2.5 and 3.59 respectively,which shows that the steel frame ultra-high performance concrete core tube structure has better safety reserve under rare earthquake.