Contribution à la modélisation des stuctures en béton armé par la méthode des éléments finis

A computer program is developed for the finite element nonlinear analysis of two-dimensional reinforced concrete structures under monotonie loading. The smeared-crack approach is used and the reinforcement is considered uniformly distributed within the element. An elastic work-hardening plastic stress-strain relationship with nonassociated flow rule is assumed for the concrete in compression and an elastic brittle fracture behavior in tension. The steel is considered as an elastic perfectly plastic material. Nonlinear reversible formulations are used for the tension stiffening and the aggregate interlock while a linear model is adopted for the dowel action of the reinforcement. The overall behavior of a cracked element is obtained by combining the above phenomena in such a way that the normal and tangential effects are coupled. A new solution algorithm is developed, with variable load level, which follows the subsequent cracking of elements. Therefore a better approximation of the behavior of the cracked structure, highly path dependent, is obtained. Numerical examples are presented for three structures and comparison is made with experimental results. A good agreement is observed and many aspects of the behavior of the structures are well represented by the analysis. These applications also showed the improvements to carry out and particularly the use of higher order elements and better models for the phenomena mentionned above.