火灾后超高性能混凝土梁斜截面剩余承载性能试验研究

Experimental study on residual bearing capacity of inclined section of UHPC beam after fire

为研究火灾后超高性能混凝土(UHPC)梁斜截面剩余承载性能,开展了12个UHPC梁火灾后静载试验,获得了火灾后UHPC梁破坏模式、裂缝发展、荷载-位移曲线,分析了受火时间、剪跨比、荷载水平、箍筋对火灾后UHPC梁承载性能的影响。结果表明:随着火灾下UHPC梁的受火时间增大、荷载水平升高,试件内部损伤增加,火灾后抗剪承载力下降;剪跨比对火灾后UHPC梁的抗剪承载力影响显著,当剪跨比由2.0增加至3.5时,抗剪承载力降低43%,破坏模式由“剪压破坏”转变为“斜拉破坏”;配箍率由0%提升至0.27%,对火灾后UHPC梁抗剪承载力提高15%;开展的火灾后UHPC梁斜截面剩余承载性能研究为UHPC梁受火后性能评估和加固修复提供了借鉴。

In order to study the residual bearing capacity of ultra-high-performance concrete(UHPC)beams after fire,12 static load tests of UHPC beams after fire were carried out.The failure mode,crack development and load-displacement curve of UHPC beams after fire were obtained.The effects of fire time,shear span ratio,load level and stirrup on the bearing capacity of UHPC beams after fire were analyzed.The results show that with the increase of fire time and load level of UHPC beams under fire,the internal damage of specimens increases,and the shear bearing capacity decreases after fire.The shear span ratio has a significant effect on the shear capacity of UHPC beams after fire.When the shear span ratio increases from 20 to 35,the shear capacity decreases by 43%,and the failure mode changes from‘shear compression failure’to‘diagonal tension failure’.The stirrup ratio is increased from 0%to 027%,and the shear capacity of UHPC beams after fire is increased by 15%.The study on the residual bearing capacity of UHPC beams after fire can provide reference for the performance evaluation and reinforcement of UHPC beams after fire.