Comparison of Damage Models of Reinforced Concrete Columns and Research on Improved Stiffness Model

Based on the test data of reinforced concrete (RC) columns published in Pacific Earthquake Engineering Research Center (PEER) database, three existing typical seismic damage models are studied, and the distribution law of damage index of the same member calculated by energy dissipation model, stiffness degradation model and Park-Ang model are summarized. The relative stiffness with the yield stiffness as the reference is constructed, and the stiffness model is improved to solve the problems that the original stiffness model is too sensitive to the initial damage and the calculation accuracy is not high. The data show that the new model has high accuracy in calculating the damage index of components under earthquake. Comparing the damage index calculated by the model with the apparent damage phenomenon of each stage of the specimen, and comparing the damage development index of different models, it is found that the stiffness model is the most accurate to evaluate the damage. The damage grade evaluation standard based on stiffness degradation is proposed, and the damage indexes under three different damage states of Concrete Cracking, Significant Concrete Spalling and Long Bar Buckling are analyzed. The results show that the damage index calculated by the damage assessment method based on stiffness degradation has good correlation under different damage states.