A practicing engineer's perspective on nonlinear finite element analysis techniques for reinforced concrete structures.

Abstract

The research demonstrates the continued progress in finite element analysis of reinforced concrete structures. Increasingly, structural engineers will use this method in their designs, and in research into materials and systems.

In this research, commercially available software with nonlinear concrete and steel material models, was used to model reinforced concrete structures near their failure loads. Analysis validation consisted of comparison with either experimental results or classical analyses. An implicit dynamic analysis was performed using ANSYS of a rectangular prestressed concrete beam subjected to point loads, and compared with experimental results. Explicit dynamic analyses were performed using TeraScale's TeraDyn code of a tornado shelter and a floor slab subjected to an impulsive pressure load, and compared to classical analyses.

Present design practice of reinforced concrete structures is principally based on linear elastic material properties. Deflections are generally taken as simple multiples of the elastic analysis. However, structural engineers are becoming increasingly proficient with the finite element method since it is a useful technique in solving nonlinear problems in continuum mechanics. Simplified linear analysis techniques are not suitable in quantifying the behavior of a reinforced concrete structure, especially approaching its failure load. The structure's response is load path dependent due to the presence of nonlinearities.