Comparison of seismic capacity/demand ratios of two kinds of foundation schemes of Taizhou Bridge

Pile group foundation and caisson foundation are two common foundation schemes of long span bridges, and the seismic performances of the two kinds of foundations are different. Taking Taizhou Bridge as an example, which is the first kilometer level three pylon two span suspension bridge in the world, two foundation schemes are designed for the middle pylon, and two whole bridge models with two different foundation schemes of the middle pylon are established respectively in this paper. The effects of foundation soil interaction are simulated by equivalent linear soil springs whose stiffnesses are calculated according to m method. Seismic capacity/demand ratios of the two models are calculated. The following conclusions can be drawn: the weak positions of the two schemes are not the same; if caisson foundation is adopted for the middle pylon, the weak position is the bearing capacity of the middle pylon foundation, while if pile group foundation is adopted for the middle pylon, the weak position is the bearing capacity of the side pylon foundation.