Seismic analysis of an integral bridge with retrofitted RC pile foundation in different foundation soils using simplified SSI

Retrofitting of Reinforced Concrete (RC) pile foundation below integral bridges is an important issue concerning functionality of such bridges in earthquake-prone regions. In the present study, the numerically investigated retrofitting method comprises addition of micropiles along the periphery of the pile caps with jet grouting around each new pile. Initially, the original bridge response is compared with the response of the bridge strengthened at abutment foundation only. Subsequently, retrofitting of pile foundation at specific pier locations is considered along with the abutment foundation strengthened earlier. Under a site-specific ground motion, bridge response for the two cases of strengthening are compared with the response of the original bridge model. Additional RC micropiles around the pile cap, embedded in jet grouting, tend to reduce the extent of nonlinear behavior of bridge piers and foundation piles. The lateral bearing resistance of the grouted soil medium also gets enhanced during possible earthquake shaking.