HRBF500级钢筋混凝土梁受火后力学性能试验研究

Experimental research on mechanical properties of HRBF500 concrete beam after fire

以HRBF500级钢筋混凝土梁为研究对象进行了常温下和受火后细晶粒钢筋混凝土梁的力学性能试验。在不同的受火时间作用下进行了5根细晶粒钢筋混凝土梁的明火试验,自然冷却至室温,然后进行静载试验。通过试验,观察其受火破坏现象、静载破坏形态和在不同工况下混凝土梁受火后剩余承载力的变化;进行了2根细晶粒钢筋混凝土梁常温下的静载试验,得到荷载-挠度曲线关系,并与受火后的细晶粒钢筋混凝土梁剩余承载力进行比较。试验结果表明:高温对细晶粒钢筋混凝土梁的损伤很大,受火时间、配筋率、预加荷载对混凝土梁耐火性能有影响;受火时间越长,其剩余承载力越小;配筋率越小,其火灾后的剩余承载力越小;预加荷载降低梁的剩余承载力。

This paper conducts an experimental study on the mechanical properties of the fine grain reinforced concrete beam with HRBF500 at normal temperatures and after fire. The experiments of five fine grain reinforced concrete beams under fire with different time were accomplished. The static loading test was done when the beams were cooled to room temperature naturally. Its macroscopical phenomenon and the static failure modes were investigated through the tests. Hence, the variation of the bearing capacity of the fine grain reinforced concrete beams by the fire was obtained under different conditions. The tests of two fine grain reinforced concrete beams under loads without fire were carried out. The load-deflection curves were obtained and compared with the results after fire. The results show that the concrete beams can be seriously damaged by fire. The effects of the time of fire, bar ratio and preloading on the fire resistance are revealed. Some conclusions are drawn： The longer it is exposed to fire, the weaker its residual bearing capacity is. The smaller the bar ratio is, the weaker its residual bearing capacity is; A preloading will reduce the residual bearing capacity of the fine grain reinforced concrete beam.