Numerical modeling of RC slabs on tensionless elastic subgrade

Mansoor Ali Beg

Civil Engineering

July 1996

Abstract

The problem of slabs resting on elastic soil is tackled by means of developing two nonlinear finite element programs, WINKLER and PSEUDO-3D. The program WINKLER is based on the classical Winkler hypothesis whereas a three dimensional elastic analysis is used in PESEUDO-3D. A tensionless behavior is considered for the subgrade, by assuming that the subgrade reacts only in compression. The existence of sinkholes/cavities underneath the slab is also modeled. The size effect and location effect of such sinkholes on the behavior of reinforced concrete slabs are studied. A new concept of variable subgrade modulus values for a subgrade is introduced in the PSEUDO-3D model. The new model Pseudo-3D is compared and contrasted with the classical Winkler hypothesis. Contours of subgrade modulus as well as dimensionless equivalent subgrade modulus, for slabs on weak, intermediate, and stiff soils are presented.

Numerical Modeling of RC Slabs on Tensionless Elastic Subgrade

by

Mansoor Ali Beg

A Thesis Presented to the

FACULTY OF THE COLLEGE OF GRADUATE STUDIES

KING FAHD UNIVERSITY OF PETROLEUM & MINERALS

DHAHRAN, SAUDI ARABIA

In Partial Fulfillment of the Requirements for the Degree of

MASTER OF SCIENCE

In

CIVIL ENGINEERING

July, 1996