Numerical Analysis Of Pile-Soil-Structure Interaction In Structural Dynamic

Pile foundations as a mature approach is widely used in construction projects in various fields. The code for seismic design of pile only makes some details of seismic design, but lacks systematization and pertinence. Data show that in the earthquake, there is a highly dynamic interaction between the pile foundation and soil. This paper studys the subject of numerical modeling of pile-soil-superstructure dynamic interaction under seismic load, it is a certain academic significance and value of projects.Several common constitutive models are introduced in the article, Drucker-Prager model is recommended to simulate the material nonlinearity of soil. Advantages and disadvantages of common interface elements are analyzed in the paper, it is recommended that Goodman contact element simulates pile-soil interface. Taking the analysis models of 3*3 group pile foundations under horizontal seismic load as a study target, dynamic interaction in the pile-soil-structure is analyzed by using three-dimensional elastic-plastic finite element method in ANSYS software . Seismic wave and side boundary are simulated by the EL-Centro seismic wave and elastic damping system boundary respectively.By comparison with corner pile, border pile and middle-pile of the distribution of the shearing stress amplitude along the pile, some conclusions are drawn as below : the distribution of shear stress amplitude along the pile is inverse-triangle,and the maximum value at corner column, the less value at border column, and the minimum value at mid-column. When pile spacing vary, shear stress dose not change. While Pile side increase, shear stress decline on the top of pile, and decrease slowly by pile depth increasing. For instance, a 7-floors R.C. frame structure, the dynamic characteristics of structure and foundation interaction is calculated and compared, with the substructure method and integral finite element method. Considering the pile-soil interaction, system of the cycle is larger and the structure of the internal forces reduces 10% 20%.Under seismic excitation, soft and hard soil interface may become the most important controlled section as the top of pile.Under the pile-soil interaction,through the comparison and the analysis of the linear and nonlinear behavior of soil material model,fixed boundary and elastic damping boundary of side boundary, the conclusions show as below: considering the impact of non-linear , system of the cycle is larger, little effect of floor level displacement, the horizontal displacement on piles is larger, column internal force, is smaller, pile internal force is larger at the peak. In elastic damping boundary of side boundary, system cycle is smaller, little effect of floor horizontal displacement, pile horizontal displacement is larger, column internal force is larger ,pile internal force is larger at the peak.