Study on finite element model of bridge multi-pile foundation

In order to use finite element software to complete the design or calculation of bridge multi-pile foundation, this paper discusses the finite element model (FEM) of a bridge multi-pile based on the theory and provisions in Code for Design of Ground Base and Foundation of Highway Bridges and Culverts (CDGBFHBC 2007) of china. For the FEM of a bridge-multi pile foundation, cap is regarded as a rigid body, piles are taken as beams, and boundary constraints are a series of horizontal springs and vertical springs. First, the formula of stiffness for horizontal springs and bottom vertical spring is derived according to elastic ground base theory and winkler hypotheses. Secondly, for the friction pile, the stiffness of vertical springs on piles side is derived basis of the principle of friction generated and simplified distribution of pile shaft resistance. Then, the FEM of multi-pile needs pay attention to three issues: the simulation of connections between piles and cap, elastic modulus needs discount, and the weight for pile underneath the ground line (or local scour line) needs calculate by half. Taking pile section bending moment often control the design and calculation of pile into account, this paper gives a simplified FEM of pile. Finally, an example is used to introduce the application of the FEM of bridge multi-pile foundation.