钢筋与粗骨料超高性能混凝土粘结性能试验研究

Experimental Study on Bonding Performance Between Rebar and Coarse Aggregate Ultra-High Performance Concrete

为了研究含粗骨料超高性能混凝土(UHPC)与带肋钢筋的粘结性能,对6组钢筋-粗骨料UHPC中心拉拔试件进行了加载测试,研究了钢筋直径、保护层厚度、粘结锚固长度对粘结应力的影响,基于厚壁圆筒理论和拉梅解答分析了保护层厚度的影响.采用回归分析的方法得到了极限粘结应力的计算公式,并采用其他文献的试验结果验证了该公式的有效性.研究结果表明:粗骨料UHPC与钢筋的粘结锚固破坏模式与活性粉末混凝土(RPC)相似,有“刮犁破坏”和“劈裂破坏”两种模式;粗骨料UHPC所需钢筋的最小保护层厚度略大于RPC,粘结锚固长度与RPC相近;保护层厚度、粘结锚固长度存在相互影响,粘结锚固长度足够时可适当减小保护层厚度;提出了带肋钢筋在粗骨料UHPC中保护层厚度和锚固长度的建议值.

To investigate the bonding performance between the reinforcement and coarse aggregate UHPC(ultrahigh performance concrete),six sets of pulling out specimens were tested.The effect of reinforcement diameter,cover layer thickness,and anchorage length were quantitatively studied,and further analysis based on the classic thick-cylinder theory and Lame Formula were conducted to obtain the influence of cover layer thickness.The formula for estimating the peak bonding stress was obtained through regression analysis,which was validated with the several physical tests.According to the results,the bonds between the reinforcement and coarse aggregate UHPC have similar failure modes with that of RPC(reactive powder concrete),including“wipe failure”and“split failure”.The thickness of cover layer in coarse aggregate UHPC is a little larger than that in RPC,while the demand of anchorage length is almost the same.The cover layer thickness and anchorage length have interactive effect on each other,meaning that sufficient anchorage length can reduce the requirement of cover layer thickness.Finally,the suggested anchorage length is presented.