"Finite Element Analysis of Thick-Walled RC Structures with Different Nonlinear-Elastic Material Models";
in: "Proceedings of the 2nd International Conference on Computer Aided Analysis and of Concrete Structures", N. Bicanic, H.A. Mang (Hrg.); Pineridge Press, Swansea, 1990, S. 695 - 706.
Finite element (FE) ultimate load analyses of thick-walled structures made of reinforced concrete require suitable constitutive equations for the description of the deformational behavior of triaxially loaded concrete. On the basis of the results obtained from cube tests with nonmonotonic and nonproportional loading, a comprehensive comparative study of nonlinear-elastic and elasto-plstic material models for the pre-peak range was carried out. This is the topic of the first part of the paper.
The second part of the paper deals with finite element ultimate load analysis of thick-walled reinforced-concrete ring, subjected to nonuniformly distributed radial compression. A comparison of analytical and experimental results indicates that the influence of different constitutive models for the pre-peak behavior of concrete if smaller than it has been expected. One of the conclusions of this ultimate load analysis is the fact that the often used assumption of a sudden drop of the concrete strength in case of compression failure is inappropriate. Consideration of the softening behavior in tension as well as in compression is very important for a realistic prediction of the ultimate load.