Factors governing the fire response of bonded prestressed concrete continuous beams

Results from fire resistance experiments on nine bonded prestressed concrete (PC) continuous beams are presented in this paper. The test variables included concrete cover thickness, load level, degree of prestressing and effective prestress. Data from the experiments are utilized to study the effect of critical parameters on thermal and structural response of bonded PC continuous beams under fire conditions. Test results show that concrete cover thickness, load level, degree of prestressing and fire induced secondary moments have significant influence on the fire resistance of bonded PC beams. Specifically fire induced secondary moments increase the total moments at intermediate supports by as much as 1.6 times of that due to imposed external loading under ambient conditions. It is also shown that the fire resistance of PC continuous beams is significantly higher than similar PC simply supported beams. These critical factors are to be considered for evaluating the fire resistance of PC continuous beams under fire conditions.