火灾后铁尾矿砂混凝土梁抗弯性能试验研究

Experimental study on flexural performance of iron tailings concrete beams after fire

为研究铁尾矿砂全部替代天然砂对混凝土梁火灾后抗弯性能的影响,对3根受火45 min和3根非受火混凝土梁进行了静载试验.对比了受火过程中梁内混凝土和钢筋温度分布、梁跨中挠度以及火灾后静载试验荷载-挠度曲线、残余抗弯承载力、破坏形态,验证了平截面假定,分析了铁尾矿砂全部替代天然砂和不同铁尾矿砂混凝土强度对钢筋混凝土梁火灾后抗弯性能的影响.结果表明:铁尾矿砂混凝土梁与天然砂混凝土梁受火过程中混凝土和钢筋温度、跨中挠度无明显差异,受火45 min后满足平截面假定;铁尾矿砂混凝土梁的火灾后残余抗弯承载力与天然砂混凝土梁无明显差异,但破坏时跨中挠度显著增加;不同铁尾矿砂混凝土强度(C30、C40)对梁火灾后抗弯承载力影响不大.

In order to study the effect of replacing natural sand with iron tailings sand on the flexural performance of concrete beams after fire,static load tests were carried out on three concrete beams exposed to fire for 45 min and three concrete beamsnon-exposed to fire.The temperature distribution of concrete and reinforcement in the beam during fire,the mid span deflection of the beam,the load deflection curve of standard post fire static load test,the residual bending capacity,and the failure mode were compared.The plane section assumption was verified,and the influences of all iron tailings sand replacing natural sandand thestrength of different iron tailings sand concreteon the bending resistance of reinforced concrete beams after fire were analyzed.The results show that there is no significant difference in the temperature fieldof concrete and steel bars and mid span deflectionbetween iron tailings sand concrete beam and natural sand concrete beam under fire,and both meet the plane section assumption after 45 minutes of fire.The residual flexural capacity of iron tailings sand concrete beams after fire is not significantly different from that of natural sand concrete beams,but the mid-span deflection increases significantly during failure.The strength C30 or C40 of concrete with different iron tailings has little effect on the flexural capacity of beams after fire.