Multi Objective Seismic Performance Evaluation Method Based On Global Damage Theory

Performance-based seismic design is the mainstream trend of today’s seismic design.Its core idea is to meet different performance goals under the action of earthquakes with different risk levels.Through multi-objective,multi-level seismic design to meet the "individuality" of the structure.With the continuous research of various scholars,on this basis,the concepts based on the displacement behavior spectrum and the damage behavior spectrum are proposed.In this context,this paper uses the damage behavior spectrum as the main line to study its characteristic parameters,analyzes the influence of each characteristic parameter on the nonlinear displacement increase coefficient in the damage behavior spectrum,and conducts the behavior leveling of the reinforced concrete frame structure.To express the overall damage index of the structure,a static elastoplastic analysis of the structure based on the overall damage of the reinforced concrete frame structure is used to establish a capacity spectrum,and the multi-objective seismic performance evaluation of the structure is carried out based on the comparison of the structure capacity spectrum and the demand spectrum.According to the established damage behavior spectrum combined with the principle of nonlinear displacement increase coefficient,the multi-objective seismic design of reinforced concrete frame structure based on damage behavior spectrum is carried out,and the two methods are compared.The main research contents are as follows:（1）According to the summary and analysis of the research status of performance-based seismic design at home and abroad,the theory of damage behavior spectrum is combined with performance-based seismic design.（2）Based on the theoretical basis of the seismic performance design,the elastic response spectrum is selected to establish the damage behavior spectrum through the equivalent linearization method.According to the research on the nonlinear displacement increase coefficient at home and abroad,the nonlinear displacement in the damage behavior spectrum is calculated.Increase the coefficient for discussion.Analyze the damage behavior spectrum and its characteristic parameters,such as the characteristic period,ductility coefficient,structural damping ratio,and the influence of elastic response spectrum on the nonlinear displacement increase coefficient.（3）Through static elastoplastic analysis and dynamic time history analysis of reinforced concrete frame structures,the structural capacity curves and dynamic time history capacity curves under different loading modes are obtained,and the capacity curves are compared and the structural capacity curves under suitable loading modes are selected.According to the Ghobarah structure’s overall damage model and the division of reinforced concrete structures under different behavior levels,the overall damage index of the reinforced concrete structure under different behavior levels is expressed.（4）Perform static elasto-plastic analysis of the multi-layer reinforced concrete frame structure to establish the structural capacity spectrum.According to the overall damage model of the structure combined with the structural capacity spectrum curve,the displacement under different overall damages of the structure is determined,and the displacement between the different overall damages is obtained.relationship.The dynamic time history analysis method is used to iterate the structure repeatedly to achieve the determined displacement target under different overall damages of the structure.Then calculate the seismic demand spectrum of the structure under different overall damage.The static elastoplastic capacity spectrum and the demand spectrum under different overall damage of the structure are expressed on the same diagram,combined with the division of the overall damage index of the structure under different behavior levels,to judge the seismic capacity of the structure.Through time history analysis,the relationship between the structure and the seismic acceleration under different overall damages is obtained.According to the maximum seismic acceleration corresponding to large,medium and small earthquakes under the fortification intensity,the overall damage and displacement of the structure corresponding to the fortification intensity are determined,and its capacity is determined The value of the spectrum and the seismic demand spectrum is compared,and the relationship between the capacity spectrum and the demand spectrum under the fortification intensity is compared to complete the multi-objective seismic performance evaluation based on the overall damage of the structure.（5）Expand the nonlinear displacement increase coefficient,and determine the relationship between the overall damage of the structure and the nonlinear displacement increase coefficient from the damage behavior spectrum according to the selected vibration characteristics of the reinforced concrete structure.The elastic time history analysis of the structure is performed to obtain the elastic displacement of the structure.The elastoplastic displacement of the structure is determined by the nonlinear displacement increase coefficient and the elastic displacement of the structure.Design for comparative analysis.