Research On Seismic Behavior Of Ultra-high Performance Concrete Shear Wall Structure

As a new type of concrete material,ultra-high performance concrete(UHPC)has ultra-high strength,high durability and high toughness.The use of UHPC for the shear wall structure will effectively reduce the self-weight of the structure and improve the seismic behavior of the shear wall structure.This paper mainly studies the seismic behavior of UHPC shear wall structure through simulation research and theoretical analysis.The main contents are as follows:(1)The numerical simulation of 12 UHPC shear walls was carried out.By analyzing the load-displacement curve and plastic damage diagram of shear wall,and the influence of factors such as the axial compression ratio,the amount of steel fiber,the characteristic value of the hoops and the aspect ratio on the bearing capacity,deformation capacity and plastic damage of the shear wall was studied.The research results show that as the axial compression ratio increases from 0.1 to 0.5,the peak load of the shear wall increases by 64.6%.As the characteristic value of the hoops increases from 0.1 to 0.4,the ultimate displacement and ductility coefficient of the shear wall increase significantly.The axial compression ratio and the wall aspect ratio have a significant effect on the bearing capacity of UHPC shear walls,and the deformation capacity of UHPC shear walls can be improved by increasing the steel fiber content and the characteristic value of the hoop,and the plastic damage of shear walls decreases with the increase of steel fiber content,aspect ratio and hoop characteristic value.(2)Analyze the three stress states of cracking,yield and peak respectively,and the ways for calculating the normal section bearing capacity of UHPC shear wall was proposed.Based on the theory of simplified truss model,introduce the softening coefficient considering the steel fiber content,the ways for calculating the diagonal-section bearing capacity and deformation of the shear wall are put forward and the calculated values are in good agreement with the test results.Based on the theory of three-fold line model and the law of hysteretic curve stiffness degradation,the restoring force model of UHPC shear wall is proposed,and comparing the restoring force curve with the experimental hysteresis curve.The results show that they are in good agreement.(3)The model of reinforced concrete frame-core tube structure and the UHPC frame-core tube structure were established,and the elasto-plastic time-history analysis were carried out respectively.The IDA analysis of 30 seismic waves is performed on the UHPC frame-core tube structure model,and the IDA curve clusters and 3 quantile curves are drawn.Log-linear regression was performed on the data of IDA curve cluster to calculate the vulnerability probability of the structure and the anti-collapse reserve coefficient,and the vulnerability curve was drawn.The research results show that: compared with the reinforced concrete frame-core tube structure,the maximum inter-storey displacement Angle of the UHPC frame-core tube structure decreases.The curve cluster of incremental dynamic analysis is relatively discrete,but the general trend of the curve is the same.The slope of the curve is high at the beginning and then slowly decreases,reflecting the whole process of the structure from the elastic state to the collapse state under the action of earthquake.Under rare earthquakes,the collapse probability of the UHPC frame-core tube structure is less than 5%,and the structure can meet the seismic design requirements under the action of large earthquakes.The collapse reserve coefficient of the structure corresponding to the rare earthquake reaches 6.32,and the ultrahigh performance concrete frame-core tube structure has strong collapse resistance.