Fire-resistant capacity of RC structures considering time-dependent creep strain at elevated temperature

摘要

This paper introduces a numerical evaluation of the fire-resistant capacity of reinforced concrete structures. On the basis of a time-dependent temperature distribution across a section determined from a transient heat transfer analysis considering heat conduction, convection and radiation, a layered fibre section method is adopted to take into account the non-linear material properties depending on the temperature. Furthermore, non-mechanical strains of concrete and steel such as thermal strain, transient strain and creep strain, which increase with elevated temperature variation induced by fire, are implemented into the formulation. Numerical results for structural members are compared with experimental data obtained from standard fire tests to investigate the influence of non-mechanical strains at elevated temperature. Beyond the member level, frame structures exposed to fire are also analysed to evaluate the influence of fire on statically indeterminate structures exposed to practical fire conditions. Finally, consideration of the change in material properties induced by elevated temperature in design practice is emphasised through correlation studies between the resisting capacities evaluated by the introduced numerical algorithm and those determined by the design code EN 1992-1-2.