高强钢筋与高体积率微钢丝钢纤维混凝土黏结性能试验研究

Experimental Study on Bonding Behavior of Microwire Steel Fiber RC with High Strength Steel Bar and High Volume Ratio

为提升混凝土与钢筋之间的黏结性能,充分发挥高强钢筋的强度特性,选用直径0.2 mm的镀铜微钢丝钢纤维制备一种纤维体积掺量高达6%,工作性和强度兼备的高体积率微钢丝钢纤维混凝土,研究其与高强钢筋的黏结性能。参考已有的钢筋-混凝土黏结性试验规程相关建议,设计了高强钢筋-混凝土中心拉拔试验,分别研究高强钢筋与高体积率微钢丝钢纤维混凝土和普通混凝土对比组的黏结破坏过程,获得其典型破坏模式、加载端荷载位移曲线和极限黏结强度,进而得到加载端荷载-位移关系模型,并采用数值模拟方法对试验结果进行验证。试验结果表明,高强钢筋-高体积率微钢丝钢纤维混凝土拉拔试件破坏模式由普通混凝土对比组的混凝土劈拉破坏转变为高强钢筋的受拉屈服破坏,黏结强度较普通混凝土对比组试件提高125.5%以上,充分发挥了高强钢筋的强度特性,黏结性能显著改善,数值分析与试验结果较吻合。

In order to enhance the bonding performance between concrete and rebar,and give full play to the strength characteristics of high-strength rebar,by employing the copper coated microwire steel fiber with a diameter of 0.2 mm,a kind of MSFRC with high volume ratio,which is characterized with fiber volume content up to 6%,good workability and strength,is prepared,and then the bonding property between MSFRC and the high-strength rebar is studied.Referencing to the recommendations of existing test regulations of bonding between rebar and concrete,the central pull-out test is designed to study the bonding failure process of MSFRC with high and strength rebar high volume ratio and that of ordinary concrete.The typical failure mode,the load-displacement curves at loading end,and the ultimate bonding strength are obtained,then the load-displacement relation model at loading end is obtained,and the experimental result is verified by numerical simulation.The results shows that(1)different from the splitting failure of the reference specimens of ordinary concrete,the failure model of specimens of MSFRC with high and strength rebar high volume ratio is the yielding failure of rebar;(2)compared with the reference specimens,the ultimate bonding strength of specimens of MSFRC improved by more than 125.5%,which can take full advantage of the high strength of rebar,thus the bonding performance is improved significantly;(3)the numerical analysis result is coincident with the experimental data.