负泊松比钢筋与UHPC的黏结性能

Bond behavior of negative Poisson’s ratio rebar in ultra high performance concrete

摘要:

为探究负泊松比钢筋（negative Poisson’s patio rebar, NPR钢筋）与超高性能混凝土（ultra high performance concrete, UHPC）的黏结性能,通过对27个拉拔试件进行中心拉拔试验,研究了UHPC种类、钢筋种类和外形、锚固长度以及保护层厚度等参数对NPR钢筋与UHPC间黏结性能的影响规律,并使用声发射技术对NPR钢筋与高应变强化型UHPC间的黏结滑移破坏损伤行为及破坏模式进行分析。试验结果表明:高应变强化型UHPC与 NPR钢筋的黏结性能优于低应变强化型及应变软化型UHPC；随着锚固长度的增加,拉拔试验的极限荷载逐渐增加,荷载-滑移曲线趋势并未发生明显改变；保护层厚度较小时,会导致试件破坏呈现一定的脆性。NPR钢筋与高应变强化型UHPC间的黏结滑移破坏可分为初始、破坏和残余三个阶段,声发射试验可以较好地表征拉拔试验过程中基体损伤的演化进程。

Abstract:

Considering the cooperative working performance of negative Poisson’s ratio rebar (NPR rebar) and ultra high performance concrete (UHPC), central pull-out tests on 27 pull-out specimens were conducted, and the effects of UHPC type, rebar shape, embedded depth, and protective layer thickness on the bonding performance between NPR rebar and UHPC were studied. The damage and failure modes of bond slip failure between NPR rebar and high-strain strengthened UHPC were analyzed by acoustic emission technology. Results show that the bond performance between high-strain strengthened UHPC and NPR rebar was better than that between low-strain strengthened UHPC and strain softened UHPC. With the increase in embedded depth, the ultimate load of the pull-out test gradually increased, and the trend of load-slip curves did not change obviously. When the thickness of protective layer was small, the failure of the specimen was brittle. The bond slip failure between NPR rebar and high-strain strengthened UHPC could be divided into initial, failure, and residual stages. Acoustic emission test could better characterize the evolution process of internal damage in the matrix during the failure process.