Hybrid finite element thermal modelling of fire protected structural elements strengthened with CFRP laminates

A hybrid formulation of the finite element method, based on the independent approximation of the temperature and heat flux fields, is used in the simulation of the thermal response of a reinforced concrete (RC) beam strengthened with carbon fibre reinforced polymer (CFRP) laminates subjected to the ISO-834 Standard Fire. Domain decomposition is strictly dictated by the adequate representation of geometry and thermo-physical properties, while the approximation of the state variables in each finite element is mainly constrained to adequately simulate the thermal response of the system. This uncoupling of the geometry mapping from the finite element approximation leads to a naturally p-adaptive formulation, well suited to parallelization, which can be implemented on unstructured, coarse meshes of high-degree elements to obtain accurate and numerically stable solutions.