Case Study of Strategies for Seismic Rehabilitation of Reinforced Concrete Multicolumn Bridge Bents

Abstract

The paper presents a case study for comparing the seismic rehabilitation of four reinforced concrete multicolumn bridge bents typical of older bridges not designed for current seismic code criteria. The types of intervention included connecting the piles to the pile caps with high-strength prestressing steel bars, widening of an existing strut beam connecting the pile caps, construction of a new reinforced concrete grade beam overlay to connect the pile caps, and carbon fiber reinforced polymer composite jackets for strengthening the columns and cap-beam-column joints. The paper includes the hysteresis curves from in situ experiments in which a lateral quasi-static cyclic load was applied at the cap-beam and comparisons to analytical pushover curves. A comparison of the capacity of the four bents to the demand of several earthquake records including historical and NEHRP design earthquakes is developed. The cost of seismic rehabilitation of the four bridge bents is presented along with the peak maximum lateral load and maximum displacement achieved in the experiments. The cost of the seismic rehabilitation is related to the performance of each bridge bent. The bridge bent with the lowest level of intervention had the lowest cost and met the displacement and base shear demands for the 10% in 50 years NEHRP design earthquake; the bridge bent with the highest level of intervention had the highest cost and met the displacement and base shear demands for the 2% in 50 years NEHRP design earthquake.