Second-order analysis of steel sheet piles by pile element considering nonlinear soil-structure interactions

Comparing to other supporting pile walls, steel sheet piles with a lower flexural rigidity have a more obvious and significant second-order effect with the large deformation. Also, the nonlinear Soil-Structure Interaction (SSI) can highly influence the efficiency and accuracy of the deformation and buckling of the steel sheet pile. Currently, some empirical methods with linear assumptions and the discrete spring element method are always used for the design of steel sheet piles in practical engineering. However, these methods are normally inaccurate or inefficient in considering the nonlinear SSI and the second-order effect. In this paper, a new line element, named pile element, is applied to analyze the structural behaviors of the steel sheet pile. In this new element, the soil resistance and pressure surrounding the pile as well as the pile shaft resistance are all integrated into the element formulation to simulate the nonlinear SSI. The Gauss-Legendre method is innovatively introduced to elaborate the realistic soil pressure distribution. For reducing the nonlinear iterations and numerical errors from the buckling behavior, the proposed numerical method and Updated-Lagrangian method will be integrated within a Newton-Raphson typed approach. Finally, several examples are given for validating the accuracy and efficiency of the developed pile element with the consideration of the realistic soil pressures. It can be found that the developed pile element has a significant advantage in simulating steel sheet piles.