钢纤维掺量对变形钢筋与超高性能混凝土黏结性能影响

Effect of Steel Fiber Content on the Bond Behavior between Deformed Steel Bar and Ultra High Performance Concrete

为研究钢纤维掺量对变形钢筋与超高性能混凝土(UHPC)黏结性能的影响,设计、制作了6组18个中心拔出试件,钢纤维体积掺量为0%~5%,室外养护28 d后进行中心拔出试验,观察试件的破坏形态、黏结应力-滑移曲线、最大黏结强度及其对应的滑移等。试验结果表明:随着纤维掺量的增加试件的破坏形态从脆性破坏转变为韧性破坏;纤维掺量对黏结强度影响不大,各组黏结强度均处于60 MPa左右,峰值滑移随着纤维掺量增加而增大;纤维掺量为3%时黏结强度最大,黏结应力-滑移曲线下降段最平缓,韧性最大。建立了黏结强度与抗压强度之间的关系;建议直径16 mm的HRB500型钢筋,在UHPC中最小锚固长度试验值取2.5d;最后给出了黏结应力-滑移曲线上升段计算模型。试验结果可为UHPC材料的工程应用提供参考。

In order to investigate the effect of steel fiber content on the bond behavior between deformed steel bars and Ultra High Performance Concrete(UHPC),6 groups of specimens,fiber volume content range from 0% to 5%,were designed and made,after 28 days of field curing,pull-out test was performed.The failure modes,bond stress-slip curves,bond strength and corresponding slip were investigated.Test results showed that:with the increase of fiber volume content,the failure modes transformed from brittle to ductile,and the slip corresponding to bond strength increase;however,the bond strength of all groups is about 60 MPa,and is less influenced by the fiber content;when the fiber content is 3%,the highest bond strength and toughness are achieved,and the slop of the descending branch of the bond stress-slip curves is slower than other groups.The relationship between bond strength and compressive strength is developed.The minimum experimental anchorage length for HRB500 with a diameter of 16 mm is 2.5d;finally,the calculation mode of ascending branch of the bond stress-slip curve is developed.Test results are worth referring for the application of UHPC.