Sectional model for the fire evaluation of reinforced concrete columns subjected to biaxial bending

Abstract

[EN] In this work a simplified model for evaluating the cross-sectional capacity of RC columns subjected to biaxial bending and fire is presented. In order to build the simplified model, a fiber based numerical model is developed as a tool to obtain the cross-sectional interaction diagrams in 2D or 3D. For the determination of the temperature field of the section during fire exposure the finite differences method is employed. The fiber model is validated against experimental and numerical data for RC short rectangular columns and their predictions are compared with those given by a numerical model. The influence of the concrete compressive strength, the concrete cover, the reinforcement ratio and its arrangement on the fire capacity of RC columns subjected to combined axial and biaxial bending is investigated through a parametric study. Finally, the simplified model based on the Bresler¿s equation is developed and validated, and its straightforward application for daily practice is illustrated by means of a worked example.