Study the effect of high temperature on behavior of R.C. columns

Exposure to high temperatures due to fire significantly damages the mechanical qualities of the concrete, steel rebars and fibre-reinforced polymer bars in hybrid reinforced concrete (RC) columns. In this study, the behaviour and failure modes of RC columns that were concentrically and eccentrically loaded during high-temperature exposure were investigated. The behaviour of the columns was assessed by determining load–displacement relationships, failure mechanisms, crack patterns and strain distributions at failure. Numerical models simulating the reaction and failure of the RC columns were also developed and validated. The test results showed that the eccentricity ratio, high temperature and rebar type affected the ultimate loads. When the exposure temperature was increased from 25°C to 700°C, the ultimate load of the RC columns decreased. When the eccentricity ratio was increased from 0 to 0.5, the rebars caused a decrease in the ultimate load. Steel rebars were found to be more efficient than glass-fibre-reinforced polymer bars at resisting high temperatures. The rate of strength decrease of RC columns with applied load decreased with an increase in the exposure temperature.