| Steel reinforced concrete(SRC)composite structure,as a new type of structural system,is widely used in high-rise and super high-rise structures because of its excellent seismic performance.The key factor of performance-based seismic evaluation theory is the division of structural performance level and the selection of performance index.Because displacement can better reflect the performance of the structure under earthquake,At present,for SRC frame structure,displacement based seismic performance evaluation mainly uses the drift angle as the quantitative index of structural performance level to reflect the deformation of the structure under the action of earthquake.The failure of the structure is caused by the failure of internal components,and the drift angle is not accurate enough to judge the failure of internal components.Based on the angle of component,the distribution of component failure at all levels of performance can be better,and the corresponding relationship between component failure and structural failure can be realized.In this paper,the two parameter indexes of displacement angle between floors and failure ratio of members are used to comprehensively reflect the failure of structures and members.The main research contents are as follows:(1)Referring to the main seismic codes at home and abroad,the seismic performance of the structure is divided into four performance levels and three performance objectives by adopting the multi-level seismic fortification idea and combining with the existing research results of SRC frame structure.The existing test data of several groups of SRC frame structure are analyzed.In the comparison between the macro description of four level performance level and the test phenomenon,the corresponding drift angle data of SRC frame structure are established.The limit values of drift angle corresponding to each performance level of SRC frame structure are proposed,which are 1/440,1/130,1/45 and1/30 respectively,and the probability guarantee is checked.(2)From the perspective of components,through literature research,the corresponding relationship between the overall structural performance level and the component performance level is expounded,the component failure ratio is analyzed,and the importance of components and the judgment of the failure of the weak layer of the structure are considered.IDA incremental dynamic method was selected to reflect the failure characteristics of the structure in different stages,so as to establish the component failure ratio limits at different performance levels of the structure,and the basic steps to realize this performance index were given by using the finite element software performing-3d.(3)Considering the different seismic fortification intensities and heights of the structures,11 SRC frame structure models were designed according to the specifications.Meanwhile,a number of seismic wave records were selected,and the nonlinear analysis was carried out by using Perform-3d software and IDA.According to the analysis results,several IDA curves were drawn to obtain a series of performance points of limit state.Based on the performance point of limit state,the failure ratio of the model in single seismic wave and multiple seismic waves is analyzed and verified.Through the data calculation of all models,the seismic performance index of SRC frame structure based on component is established.(4)Based on the two-parameter failure index of drift angle and component failure ratio,the IDA seismic vulnerability of SRC frame structure model was compared and analyzed,and the corresponding vulnerability curve was drawn according to the performance level of the structure.At the same time,on the basis of the vulnerability curve,through the study of vulnerability index,the vulnerability index results of two different structural performance indexes are compared,it can be concluded that the corresponding vulnerability results of the two performance indexes can better meet the seismic performance requirements of the structure. |
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