DYNAMIC SOIL-STRUCTURE INTERACTION ANALYSIS: DETECTING THE RELIABILITY OF MODELLING THE PILES AS A PLATE ELEMENT FOR A MULTISTORY BUILDING RESTING ON DEEP FOUNDATION

Dynamic soil-structure interaction (SSI) is one of the main subjects that has attracted the attention of researchers in the recent decades. Numerous studies were interested in examining the seismic response of buildings supported on pile footings while including SSI. Most of these studies were simulating the problem by two dimensional models in the plane strain to overcome the usual difficulties encountered in 3D models. Commonly, piles were represented by plate elements of infinite length, disregarding the spacing between piles, and thus overestimating its stiffness. Recently, Plaxis – a finite element softwarehas implemented a new feature known as “the embedded pile row”. Although this latter models the pile as a 2D structural element, it allows the definition of an out-of-plane spacing where the soil can flow around the piles upon keeping a continuous mesh. Many researchers have studied the reliability of the embedded row element and verified its validity. The objective of this paper is to define the limitations of employing the plate feature in soilstructure pile interaction analysis. This is achieved by comparing the behavior of the structure and the pile foundation using the plate feature to that of the embedded pile row. In this scope, a series of 2D finite element models consisting of multistory buildings supported on pile footings are generated while varying the soil type, the earthquake frequency content, as well as the out-of-plane piles' spacing. This paper demonstrated that the building response with piles modeled as plate elements is just adequate when the surrounding soil is dense. Yet, regarding the pile response, the plate feature is unable to capture the real behavior for all soil types. Keywords—Plaxis 2D; Embedded Pile Row; Plate Element; SSI; Dynamic Response