Seismic damage evaluation of RC bridge columns based on plastic hinge model

A plastic hinge model has been widely used in bridge aseismic design codes such as Japan, Caltrans, New Zealand and China (revised edition), to evaluate deformation capacity or the displacement ductility factor of RC bridge columns. With the development of bridge performance/displacement based aseismic design, several damage indices have been suggested, such as the ultimate curvature and curvature ductility factor of critical section, maximum strain of confined concrete and reinforced steels, low cycle fatigue damage indices of longitudinal reinforcement etc. To study the accuracy degree of damage indices calculated with plastic hinge models and the main influencing factor, a computer program was developed employing 5 plastic hinge models to compute aforesaid damage indices compared with the test data of RC bridge columns. The study results show that force-displacement curves and residual deformation calculated match the experiment with adequate accuracy, but the strain of longitudinal steel is overestimated and the strain of core concrete is underestimated. The computed ultimate curvature is lower than that of experiment results when shear span ratio is not less than 8. It is also recognized that under the same loading control displacement, loading path hardly affects the aforesaid damage indices.