Seismic Performance of RC Bridge Column under Repeated Ground Motions

Seismic performance of reinforced concrete bridge column under repeated earthquake ground motions is investigated through shake-table experimentation on a scale model. The specimen is subjected to a series of simulated ground motions at different levels of shaking intensity. The deformation and damage evolution of the test column is addressed in terms of selected mechanical quantities including the effective stiffness, hysteretic energy dissipation, residual displacement, and dominant vibration frequency. The test column, designed according to the AASHTO seismic design specifications, survived successive ground motions by virtue of its outstanding energy-absorption and ductility capacity. Analysis of the experimental data indicates that structural degradation of the column closely correlates with its decreasing effective stiffness and increasing hysteretic energy dissipation. The residual displacement measured at the column top after each shaking event increases with the growth of damage in the column. A frequency-domain analysis of the vibration response of the column during successive ground motions indicates that increase in the structural degradation of the column results in a decrease in the dominant vibration frequency of the column.