Date of Award

Spring 1992

Document Type


Degree Name

Doctor of Philosophy (PhD)


Civil & Environmental Engineering


Civil Engineering

Committee Director

Duc T. Nguyen

Committee Member

Leon R. L. Wang

Committee Member

Chuh Mei

Committee Member

Gene Hou

Committee Member

Nahil Sobh


The overall approach is to employ the finite-element method along with specified material models to account for material nonlinearity. This study includes two different applications: truss structures and slabs-on-grade.

Procedures for materially nonlinear analysis of truss structures, which apply for both determinate and indeterminate cases are proposed. The proposed procedures are simple and can handle a variety of different stress-strain functions, and the applied load does not have to be incremental. Proposed procedures results are verified with the output of NASTRAN.

A finite-element model for slab-on-grade is introduced. The concrete slab is represented by eight-node brick elements, and the joints and the subgrade are represented by boundary (spring) elements. The boundary elements are non-tension elements in order to represent the warping effect. A general approach for nonlinear analysis of slab-on-grade based on finite element is developed.

The field test was conducted on floor slabs. The test focused on the warping of floor slabs and edge loading of a warped slab. Twelve floor slabs were included in the test.

The theoretical finite-element results for the slab-on-grade problem are compared with the experimental measurements. The effects of temperature and moisture gradients, the concrete slab thickness, the modulus of the subgrade reaction, and the concrete modulus of elasticity on the warping of floor slabs are studied. Different joint conditions are also covered in this study. A parametric study is performed on the edge and corner loading of a typical floor slab.