Practical Soil-Shallow Foundation Model for Nonlinear Structural Analysis

Moussa Leblouba,Omer Mugheida,Salah Al Toubat,Muhammad Ekhlasur Rahman

doi:10.1155/2016/4514152

Abstract

Soil-shallow foundation interaction models that are incorporated into most structural analysis programs generally lack accuracy and efficiency or neglect some aspects of foundation behavior. For instance, soil-shallow foundation systems have been observed to show both small and large loops under increasing amplitude load reversals. This paper presents a practical macroelement model for soil-shallow foundation system and its stability under simultaneous horizontal and vertical loads. The model comprises three spring elements: nonlinear horizontal, nonlinear rotational, and linear vertical springs. The proposed macroelement model was verified using experimental test results from large-scale model foundations subjected to small and large cyclic loading cases.

Highlights

Several researchers ([1,2,3,4,5], among others) have investigated extensively the subject of soil-structure interaction (SSI)
This paper presents a practical macroelement model for soil-shallow foundation system and its stability under simultaneous horizontal and vertical loads
Note that an appropriate constitutive model could be assigned to the vertical spring; in this paper, the spring is considered linear elastic, but the effect of axial loads is present on the soil-shallow foundation global behavior

Summary

Introduction

Several researchers ([1,2,3,4,5], among others) have investigated extensively the subject of soil-structure interaction (SSI). In a completely different modelling approach, El Shamy and Zamani [26] proposed a new 3D particle-based technique using the discrete element method (DEM) to analyze the seismic performance of soil-foundation-structure systems. To overcome the difficulties in performing complete nonlinear simulations, Seylabi et al [27] proposed an equivalent linearization of nonlinear soil-structure systems considering both the effect of SSI and the nonlinear behavior of the structure on equivalent linear parameters In their model the structure is modelled as an elastoplastic single-degree-offreedom system (SDOF) and the soil beneath the structure is modelled by a discrete model combining different spring and dashpot elements. The nonlinear springs are assigned appropriate nonlinear model of plasticity with material degrading parameters

Proposed Macroelement Model

Shear and Rotational Springs

Verification with Experimental Results

Foundation Stiffness Matrix

Conclusions