受火后钢筋RPC简支梁受力性能试验研究

Experimental study on mechanical properties of simply supported reinforced RPC beams after fire

为了研究受火后活性粉末混凝土(RPC)构件的力学行为及其变形性能,完成5根受火后钢筋RPC简支梁受弯试验,获得了梁的正截面剩余承载力、荷载-跨中位移曲线及裂缝发展规律,考察了配筋率、荷载水平、受火时间等因素对受火后钢筋RPC简支梁受力性能的影响,并将试验结果与常温下受力性能进行对比分析。结果表明:配筋率为2.20%~5.13%、受火时间135 min时,受火后钢筋RPC简支梁均保持为适筋破坏,且配筋率越大,剩余承载力越高,荷载水平越高、受火时间越长,剩余承载力越低;通过简化计算模型得到受火后钢筋RPC简支梁正截面剩余承载力计算值,与试验值吻合较好;受火后配筋率不低于3.94%的各试验梁剩余承载力与常温下相比降低了10%左右,钢筋RPC简支梁受明火作用后的承载力损失较小。

In order to study the mechanical behavior and deformation performance of reactive powder concrete(RPC) members after fire, the flexural test of five simply supported reinforced RPC beams after fire was completed. The residual bearing capacity of normal section, load-mid-span displacement curves and cracking propagation were obtained. Meanwhile, the effects of reinforcement ratio, load level and fire duration on the mechanical properties of simply supported reinforced RPC beams after fire were investigated. The test results were compared with the mechanical properties at room temperature. The results show that when the fire duration lasts for 135 min, and the reinforcement ratio is from 2.20% to 5.13%, the post fire reinforced RPC beams show a ductile failure as under-reinforced beam. The increase of the reinforcement ratio can effectively increase the post fire residual bearing capacity of the reinforced RPC beams. The residual bearing capacity decreases with the increase of load level and fire duration. The calculated residual bearing capacity obtained through the simplified calculation model is in good agreement with the test result. The residual bearing capacity after fire of the tested beams with a reinforcement ratio of not less than 3.94% is reduced by about 10% than that at room temperature, which shows a small loss of bearing capacity of simply supported RPC beams under fire.