Seismic Performance And Vulnerability Analysis Of Steel Frame-precast Reinforced ECC Infill Wall

Steel structure is more and more widely used in all kinds of building structure forms.However,ordinary steel frame structure is prone to collapse under earthquake due to its small lateral force stiffness.Due to the small lateral stiffness of steel frame structure and the large structural deformation under earthquake action,the steel frame structure can be improved by setting an inner filled concrete wall.However,the concrete wall is easy to crack,and its working ability with steel frame structure is poor,and it is easy to quit the work early under the earthquake action,resulting in structural failure.Engineered Cementitious Composites（ECC）is a material with high toughness and ductility.In order to improve the deformation ability of RC lateral wall filled in steel frame,this paper proposes to install ECC lateral wall in steel frame to improve the shortcoming of brittle failure of concrete and improve the cooperative working ability with steel frame structure,so as to improve the seismic performance of the whole structural system.Therefore,the research work of this paper is as follows:（1）Firstly,the experimental study of steel frame-assembled ECC wall structure is carried out.One-storey and one-span full-scale steel frame specimen（SF）,steel frame-fabricated concrete lateral wall specimen（SPW-C）and steel frame-fabricated ECC lateral wall specimen（SPW-E）were designed respectively.Horizontal reciprocating loading tests were carried out to study the failure mode,hysteretic behavior,stiffness degradation and other quantitative indicators.The improvement of reinforced ECC lateral wall to steel frame is analyzed in detail.The results showed that the peak bearing capacity Pmax of SPW-C and SPW-E is 9%and 25%higher than that of SF,respectively,and the initial stiffness is 3.21 and 3.02 times of SF,respectively.Compared with SPW-C,the peak bearing capacity of SPW-E is increased by about15%,and the wall spalling is less during the test loading process,and the hysteretic curve is more full,so it has better energy dissipation performance.（2）The finite element analysis of SPW-C and SPW-E was carried out.From the comparison of the results show that the hysteresis curve and skeleton curve agree well with the test.From the failure mode,the model can capture the damage location of the wall well and predict the local buckling behavior of the steel frame well.And on this basis,the wall internal force are obtained,and the relationship between the wall of the internal force distribution,the results show that more than 60%of the lateral force is provided by the wall.When the displacement Angle is 1.5%,the RC wall fails rapidly due to cracking,and the percentage of lateral force provided by the RC wall is only 5%,while the percentage of lateral force provided by the ECC wall remains above 50%at the same displacement Angle,indicating that the ECC wall continues to provide effective lateral force and can work effectively under large displacement.And it has good synergistic characteristics with steel frame.（3）The nonlinear time-history analysis is carried out for steel frame structure and ECC wall structure filled with steel frame,and the comparison is made in terms of the displacement at the top of the structure,the displacement response of floor and the base shear.The results show that the interlayer displacement response of steel frame-prefabricated ECC wall structure is significantly reduced.Due to the existence of ECC wall,θ_max of steel frame structure decreases from 1/71 to 1/121 under rare earthquakes.The deformation of weak layer is more effectively reduced,indicating that the steel frame-prefabricated ECC wall structure has better seismic performance.（4）On the basis of nonlinear time-history analysis,the IDA method was used to evaluate the collapse performance of steel frame structure and steel frame-assembled reinforced ECC infill wall structure.the vulnerability analysis was also carried out to analyze the exceedance probability of the two structures at different performance levels.The results show that the vulnerability curve of steel frame-prefabricated ECC wall structure increases slowly.The collapse probability of steel frame structure under rare earthquake is 16.38%,while the collapse probability of steel frame-prefabricated ECC wall structure is only 4.87%,which indicates that the collapse failure probability is low and the structure has good collapse resistance.