Study On Evaluation Method For Post Earthquake Performance Loss Of Existing Concrete Frame Structures

Earlier research on seismic engineering focused on how to reduce the collapse of buildings and casualties caused by huge earthquakes.With the Development of Seismic Engineering Research,in addition to ensuring three-level structural design objectives,economic losses caused by earthquakes have gradually become a focus of attention,Therefore,it is necessary to study the evaluation method of earthquake loss on the basis of seismic vulnerability analysis of existing buildings.In this paper,the reinforced concrete frame structure is taken as the research object,and the evaluation method of post-earthquake performance loss of existing concrete frame structure is deeply studied.The main research work and achievements of this paper are as follows:1.The basic principle and analysis steps of incremental dynamic analysis method are discussed.Using Peak Acceleration of Ground Motion PGA as Ground Motion Intensity Index,Maximum Interlayer Displacement Angle ?max as Structural Damage Index.Based on the existing research results of the research group,Four analytical models under different damage states are established by numerical examples,the IDA curves were obtained by IDA analysis.Finally,the seismic performance of the structure under different damage states is obtained.2.Through the lognormal distribution function,the seismic vulnerability curves of structures under different damage states are obtained,and the vulnerability curves under various limit states are analyzed.The seismic vulnerability analysis method based on incremental dynamic analysis is emphatically studied.3.In view of the current seismic vulnerability analysis method is based on the traditional IDA analysis method.The amount of calculation is huge.Therefore,this paper proposes a simplified IDA algorithm SPO2 IDA based on FEMA-P58 documents.Through an example,the results calculated by the traditional method are compared and analyzed.It is found that the SPO2 IDA method not only has high accuracy,but also has small amount of calculation and is suitable for theoretical research and engineering examples.On the basis of vulnerability analysis,an evaluation method of post-earthquake performance loss of concrete frame structures based on PL index is proposed.4.A displacement-based seismic vulnerability analysis method is proposed.The theoretical analysis frame and calculation formula of secant stiffness method in the yield limit state of structures are introduced.Taking reinforced concrete frame with beam hinge failure mechanism as an example,Time history analysis is used to verify the validity.The results show that the secant stiffness method can give accurate evaluation results in the yield limit state.On this basis,the irrationality of secant stiffness method in limit state analysis after yield is avoided.The theoretical framework has been reorganized.A more reasonable two-dimensional equivalent linearization method is proposed.Finally,a numerical example is given to verify the validity of the proposed method.The results show that the two-dimensional equivalent linearization method can give more accurate evaluation results in the post-yield limit state.