Evaluation Of Seismic Damage For RC Frame Structures Based On Improved Park-Ang Model

Earthquake disasters seriously threaten and affect people's lives and property safety.Pre-earthquake prediction and post-earthquake assessment of damage to building structures are particularly important.The existing damage model mainly evaluates the seismic damage of the structure from three levels of materials,components and structures.Park and Ang's two-parameter seismic damage model,which is a linear combination of elastoplastic deformation and cumulative hysteresis energy consumption,is widely used to evaluate the damage state of components,however,the model also has some problems.such as: when the component is in the non-damage state,the damage index is not equal to 0;when the component is completely destroyed,the damage index is not equal to 1;the damage index is larger than the actual damage value.In order to make the damage index calculated by the damage model more representative of the actual damage state,this paper further perfects the traditional Park-Ang model and proposes a improves damage model.(1)In view of the fact that the elastic stage of the concrete member is in a non-damage state,the damage model proposed in this paper uses the maximum displacement and the ultimate displacement minus the yield displacement to eliminate the unreasonable damage value caused by the elastic deformation in the Park-Ang damage model,and at the same time the hysteresis energy minus the elastic strain can improve the energy consumption of the damage model.In view of the theoretical damage value of 1 when the component is completely destroyed,the model introduces a coefficient to correct the displacement damage term.(2)Based on the quasi-static test of reinforced concrete beams and columns,the test results of reinforced concrete specimens were analyzed,and the improved damage index was calculated from the test data.Comparing the damage index of the traditional Park-Ang model and the damage index of the improved model with the upper and lower limits of the damage test of the test piece: it is found that the damage index obtained by the improved damage model is equal to 0 when the component is in the non-damage state;when the component is completely the damage index obtained by the damage model during the damage is larger than the actual damage value.Comparing the finite element analysis with the test results,theimproved damage model reduces the damage value of the Park-Ang model and can better reflect the damage process of the reinforced concrete specimen.(3)According to the current regulations of China's buildings,this paper designs a six-story three-span reinforced concrete frame structure,and evaluates the damage state of the structure under different horizontal earthquakes.Firstly,based on the modified Park-Ang damage model,the floor damage index is calculated by using the weight coefficient of Du Xiuli component,and the floor damage index is calculated by using the weight coefficient of Ou Jinping floor to obtain the structural damage index.Floor damage index can identify the location of the weak component and the weak layer of the structure is identified,the overall damage index can be used to evaluate the failure state of structures under Fortification intensity,determine whether the damage state of the structure meets the corresponding fortification target.According to the elastoplastic analysis results of reinforced concrete frame structure,the improved Park-Ang damage model can evaluate the seismic damage of reinforced concrete frame structure and provide scientific and reasonable guidance for structural seismic design and analysis.