Plastic Hinge Model for Nonlinear Pushover Analysis of Pile Foundations

Plastic Hinge Model for Nonlinear Pushover Analysis of Pile Foundations

For a pile-soil system, the use of the concentrated plastic hinge method in simulating the inelastic flexural behavior of piles usually gives unsatisfactory results because the location of maximum moment in piles may vary due to the effects of soil-structure interaction. To solve this problem, this study suggests adopting a distributed plastic hinge model to trace the propagation of yielding in a pile interacted with nonlinear soils. To construct the rotational property of a plastic hinge, this paper modifies the definition of plastic curvature suggested in ATC-40. This modification is crucial for plastic hinges in simulating correctly the nonlinear deformation of a beam. Besides, to arrange distributed hinges properly, this paper proposes simple formulae to estimate the least range of plastic zone for a pile-soil system, so that the proper intervals of plastic hinges can be determined. To demonstrate the method of modeling proposed, numerical examples of a pile-soil system were analyzed using the computer program SAP2000 with distributed plastic hinge modeling. Results are in good agreement with those from ABAQUS analyses by using nonlinear elements for pile modeling.