Meso-scale response of concrete under high temperature based on coupled thermo-mechanical and pore-pressure interface modeling

This work proposes a meso-scale approach for modeling the failure behavior of concrete exposed at elevated temperature inducing thermal damage. The procedure accounts for a thermo-mechanical and pore-pressure based interface constitutive rule. More specifically, the model represents a straightforward extension of a coupled thermo-mechanical fracture energy-based interface formulation, accounting now for damage induced by the temperature dependent pore-pressure effects in concrete. The nonlinear response of the proposed fully coupled interface model for porous cohesive-frictional composites, like concrete, is activated under kinematic, temperature and/or hydraulic increments (with or without jumps). A simplified procedure is proposed to consider the temperature dependent pore-pressure action. After describing the updated version of the interface model, this work focuses on numerical analyses of concrete failure response under high temperature tests. Particularly, meso-scale analyses demonstrate the predictive capabilities of the proposed formulation.