钢筋混凝土梁火灾下抗剪性能的试验研究

Experimental research on shear behavior of reinforced concrete beams in fire

对5根足尺钢筋混凝土简支梁进行了标准火灾试验,研究了钢筋混凝土梁火灾下的抗剪性能,得到了火灾中梁内混凝土的温度分布、纵筋和箍筋的温度变化、梁的竖向挠度、梁端的轴向变形以及梁的破坏模式,对比分析了不同混凝土保护层厚度、剪跨比对梁耐火极限的影响。结果表明:与常温下不同,提高混凝土保护层厚度可以显著提高钢筋混凝土梁火灾下的抗剪性能。受火条件下,随着剪跨比的减小,梁发生斜截面剪切破坏的耐火极限逐渐增加,但破坏时的脆性特征更加明显。

In order to study the shear behavior of reinforced concrete beam in fire,five full-scale simply supported reinforced concrete beams are tested.The distribution of concrete temperature,variation of rebar temperature,vertical displacement,axial deformation,and failure mode of the beams are analyzed.The effect of concrete cove thickness and shear-span/depth ratios on the fire resistance of the beams are compared.The results show that the shear capacity of fire-damaged reinforced concrete beam is obviously improved with the increase of cover thickness,which is different from that at room temperature.Under fire conditions,with shear-span/depth ratios decrease,the fire resistance of beam with shear failure is improved,but the failure characteristics of the beam become more brittle.