Finite Element Modelling of Reinforced Concrete Slab Exposed to Extreme Fire Loads

Abstract

Numerical approach using the finite element method has been used to determine the mechanical resistance (criterion R) of a reinforced concrete structure exposed to fire. Geometry of the structure is considered as a simply supported slab in one dimension. Fire load has been defined by a nominal standard ISO 834 fire curve. Both, thermal and structural response are obtained using a finite element method software ANSYS. Temperaturedependent nonlinear thermal and mechanical properties of concrete and reinforcement are adopted in accordance with Eurocode standards. Nonlinear material model Menetrey-Willam with exponential functions for compression hardening (and softening) and tension softening has been used to describe the behaviour of concrete elements. Discrete option of modelling reinforcement has been considered. Mechanical resistance of the slab is determined by reaching the limit mid-span deformation. Results have been compared with simplified method of isotherm 500 °C described in Eurocode.