Response of unbonded prestressed concrete continuous slabs under fire exposure

Abstract

Results from fire resistance experiments on nine unbonded prestressed concrete (PC) continuous slabs are presented in this paper. The test variables included concrete cover thickness, load level, effective prestress and degree of prestressing. Data from the experiments are utilized to study the effect of critical parameters on thermal and structural response of unbonded PC continuous slabs. Test results show that concrete cover thickness, load level and fire induced secondary moments have significant influence on the fire resistance of unbonded PC continuous slabs. Fire induced concrete spalling occurred in three continuous slabs and this led to failure of two slabs. Data from fire tests indicate that the degree of prestressing has significant influence on the extent of concrete spalling and the extent of spalling increase with higher degree of prestressing. Results from fire tests are utilized to recommend better reinforcement layout for enhancing fire performance of PC continuous slabs.