Cross sectional shape effects on the performance of post-heated reinforced concrete columns wrapped with FRP composites

An experimental study was conducted to examine how the cross sectional shape affects the strength and ductility of post-heated reinforced concrete columns wrapped with unidirectional fibre reinforced polymer (FRP). Seventeen columns were tested under axial compression. The main variables investigated were the cross sectional shape of the columns, the presence of heat damage and the type of FRP used for repair. The columns were placed into three groups defined by columns without being subjected to heat, post-heated columns and post-heated and repaired columns. The test results showed that the load carrying capacity of post-heated FRP wrapped columns was significantly affected by the column’s original cross sectional shape. For circular sections the strength of post-heated columns was restored up to, or greater than, its original pre-heated strength. However, the strength of post-heated GFRP or CFRP wrapped square columns was recovered to some extent but not to the level of its original pre-heated strength. It was also found that the increase in the ductility of circular columns was more pronounced compared to square columns after wrapping with FRP. For all damaged columns the use of FRP did not restore the column’s stiffness which was lost due to damage caused by heating.