不同受火方式下混凝土柱耐火性能的试验研究

通过5根高强混凝土柱和2根普通混凝土柱的足尺明火试验,考察了不同受火方式对混凝土柱破坏形态、轴向变形和耐火极限的影响。结果表明:(1)非四面受火柱的耐火极限较四面受火柱有很大提高,同时三面受火柱的耐火极限小于两面受火柱;(2)相同受火方式和相同轴压比下高强混凝土柱的耐火极限远低于普通混凝土柱;(3)相同受火方式下大轴压比普通混凝土柱的耐火极限可能小于中等轴压比的高强混凝土柱。在实际结构的抗火设计中,合理考虑受火方式、混凝土强度等级和轴压比的影响是十分必要的。

Experimental study on fire resistance of RC columns with different faces exposed to fire

Five full-scale high strength concrete(HSC)columns and two full-scale normal strength concrete(NSC)columns were tested for fire resistance.The effect of different types of fire exposure on the failure mode,axial deformation and fire resistance of the columns was investigated.The results indicate that:(1) columns with four faces not all subjected to fire exhibit stronger fire resistance than columns with all four faces in fire,whereas the fire resistance of three-face-under-fire columns is less than that of two-face-under-fire columns;(2) the fire resistance of HSC columns is much less than that of NSC columns with same axial load ratio and same fire exposure;(3) the fire resistance of NSC columns with high axial load ratio may be less than that of HSC columns with moderate axial load ratio.In fire-resistant structure design,it is necessary to reasonably consider the effect of fire exposures,concrete strength and axial load ratio on the fire resistance of RC columns.