Title : Repairing and strengthening of concrete structures damaged by extreme loading (fire and earthquake)
Abstract:
The past experience from real fires shows that it is exceptional for a concrete building to collapse as a result of fire and most fire-damaged concrete structures can be repaired economically rather than completely replacing or demolishing them. In this connection an experimental study was conducted to investigate the effectiveness of fibre reinforced polymer jackets for axial compressive and seismic shear performance of post-heated columns. This study also investigates the effectiveness of ferrocement laminate for the repairing of post-heated reinforced concrete columns A total of thirty-five reinforced concrete columns were constructed and then tested after categorising them into three main groups: un-heated, post-heated and post-heated repaired. The post-heated columns were initially damaged by heating (to a uniform temperature of 500°C). The post-heated columns were subsequently repaired with unidirectional glass or carbon fibre reinforced polymer and ferrocement jackets.
The experimental programme was divided into two parts. The columns of experimental part-1 were tested under axial compressive loading. The columns of experimental part-2 were tested under constant axial and reversed lateral cyclic loading to simulate earthquake loading. The circular sections benefited more compared to the square cross sections with glass and carbon fibre reinforced polymers for improving the performance of post-heated columns in terms of compressive strength and ductility tested under axial compression. The glass fibre reinforced polymers (GFRP) and carbon fibre reinforced polymers (CFRP) jackets performed in an excellent way for increasing the shear capacity, lateral strength, ductility, energy dissipation and slowed the rate of strength and stiffness degradation of fire damaged reinforced columns. However, the effect of a single layer of glass or carbon fibre reinforced polymer on the axial stiffness of post-heated square and circular columns was negligible. The use of a ferrocement jacket for the repairing of post heated square and circular columns enhanced the axial stiffness and ultimate load carrying capacity of columns significantly.
