Contribution to the Modelling of the Structural Behavior of Reinforced Concrete Walls Under ISO Fire Exposure

In the framework of the international benchmark “Vulcain tests on 3 Walls”, three full scale ISO fire tests on a reinforced concrete wall, simultaneously subjected to a constant uniaxial compressive load, were conducted in CSTB in Paris, France. The duration of these tests exceeded 120 min. In order to assess the capability of available finite elements (FE) models to represent reinforced concrete structural behaviour under fire exposure, IRSN, within the scope of the Vulcain benchmark, set up a modelling with help of Mazars isotropic continuum damage mechanical model (Mazars Application de la mécanique de l’endommagement au comportement non linéaire et à la rupture du béton de structure. PhD Thesis, Univ. Paris 6, ENS Cachan, France, 1984) ran with the CAST3M software (Verpeaux et al. in Fouet, Ladevèze and Ohayon (eds), Calcul des Structures et Intelligence Artificielle, Pluralis, 1988), while a user-defined procedure was used to calculate the concrete properties taking into account load induced thermal strains (LITS). The effect of LITS according to the model of Anderberg and Thelandersson (Stress and deformation characteristics of concrete at high temperatures: 2 experimental investigation and material behavior model, Bulletin 54, Lund Institute of Technology, Lund, 1976) was considered by an explicit term in the strain decomposition. Also, the numerical simulation of three full scale ISO fire tests of Vulcain was carried out with the help of a FE model that takes into account the values of the concrete thermomechanical parameters identified. The numerical model is composed of two different parts, one for heat transfer analysis and the other one for structural analysis based on a three-dimensional FE model including concrete and reinforcing steel meshes. It is illustrated through this numerical investigation that the proposed model can predict the thermomechanical behaviour of reinforced concrete walls under fire exposure.