Zero-thickness interface model for coupled thermo-mechanical failure analysis of concrete

A discontinuous-based thermo-mechanical model for concrete subjected to high temperatures is presented. The model is an extension of a fracture energy-based elastoplastic interface formulation which now includes damage induced by high temperatures and fire. The coupled thermo-mechanical effects due to high temperature fields in concrete are taken into account through a temperature dependent maximum strength criterion and post-cracking law. Thereby, the different characteristics of concrete failure behaviour in mode I and mode II type of fracture are considered by means of specific work softening rules in terms of temperature-dependent fracture energy-based formulations. The temperature effects in the interface strength and its post-cracking behaviour are considered in the proposed constitutive model through a dehydration scaling function. After outlining the mathematical formulation of the constitutive model for interface elements, numerical analysis of available experimental results in the literature are presented to validate its soundness and capability. © 2014 Taylor & Francis Group.