Experimental and numerical investigation into RC beams subjected to blast after exposure to fire

• Large-scale model tests on RC beams under fire and explosion were carried out.
• Failure modes of fire-damaged RC beams under explosion were revealed.
• An FE model was developed to reveal fire and blast responses of RC beams.
• Influences of fire exposure on blast responses were quantitatively analyzed.

RC structures may be exposed to fire and blast due to accidents or terrorist attacks during the service life. To investigate the performances of RC structures subjected to blast loadings after fire exposure, a series of model tests on RC beams were carried out. The beams were firstly fired on three surfaces following the temperature time history suggested by ISO384 in a furnace and blast tests were then performed by a developed blast test setup. An FE model was developed to further study the heat transfer process and dynamic response of the RC beams after numerical simulation of exposure to fire by software ABAQUS. The developed numerical method was validated against the test data. Experimental and numerical results showed that more and more cracks emerged at the mid-span zone of the beam under blast loadings as the fire duration increased, and the peak and residual displacements of the RC beam increased nearly linearly with the fire duration. RC beams after fire exposure suffered greater blast-induced damage than those were not exposed to fire.