Response of reinforced concrete structural members exposed to high temperature fire and retrofitting of fire damaged structural members adopting R.C jacketing

Abstract

When fire breaks out in a building, the most important criteria is the retention of stability of the fire damaged structure against partial or total collapse. An actual case study has been presented in the current work on the response of structural elements present in a 12 storey RC multi storied building exposed to high temperature during a fire event taken place in it. The rise of the temperature in the structural elements in the event of a fire exposure, causes physio-chemical changes in the materials the structural members are made up of, namely, concrete and reinforcing steel, leading towards the degradation of material stiffness, elastic modulus and decrease in the load carrying capacity of such structural members. In the present work, two compartments at the periphery of the building are exposed to high temperatures of 300 °C, 500 °C and 700 °C, and the structural analysis is carried out with dead load, live load and temperature. Structural response of the structural members is assessed, as well as maximum displacements, internal forces developed in them as a consequence of exposure to high temperature has been recorded. As per observation, a combination of temperature and gravity loads(DL&LL), increases the probability of the structure to undergo a higher degree of damage, as the restrained structural members due to the effect of temperature, undergo nonlinear deformations (buckling of columns and bowing action of beams). Reinforced concrete columns and beams that might have undergone a repairable degree of damage due to different temperatures have been retrofitted adopting the RC jacketing method. It is observed from the results of the present case study that, by adopting RC jacketing to retrofit temperature damaged structural members, present in the structure, an enhancement in the stiffness and overall stability of the structure is observed to further withstand externally applied loads.