UHPC-NC组合构件界面行为研究

Study on the interfacial properties of UHPC-NC composite component

随UHPC材料兴起,现已有较多研究表明将UHPC材料应用于结构接缝处可极大程度地增强结构的整体性能,接缝界面处的粘结强度也逐渐引起学术界关注。然而,如何对结合面处进行有效的有限元模拟却始终未见统一有效的方式。文章在广泛的文献调研基础上,总结现有试验数据,对比试验方法,得到3种不同粗糙度界面粘聚力分别为2.24 MPa,2.37 MPa和2.66 MPa,3种界面摩擦系数分别为1.42,1.63和1.64;提出基于粘聚力和抗剪强度的UHPC-NC界面强度计算式;基于接触分离模型分别建立适用于受拉为主构件及压剪为主构件的3D有限元模型,提出适用于光滑界面、中等粗糙界面及粗糙界面的粘聚力参数、接触损伤相关参数;为验证有限元参数有效性,建立多个文献试验有限元模型并与结果对比较为吻合,可为后期有限元计算提供参考。

With the rise of ultra-high performance concrete(UHPC),researches show that UHPC as connection elements in components can improve the performance of the overall structures.The bond strength of the joint interface has drawn increasing attention worldwide.However,there is limited information on the effect model of the interfacial properties between UHPC and normal concrete.In present study,by summarizing existing experimental results and comparing experimental methods on the basis of extensive literature research,three interfacial cohesion values with different roughness were obtained(i.e.2.24 MPa,2.37 MPa and 2.66 MPa),with friction coefficient of 1.42,1.63 and 1.64,respectively.The friction coefficient calculated by direct tension test was generally larger than that obtained by splitting or bending test.The formula of UHPC-NC interface bonding strength based on cohesion and shear strength was proposed.Based on traction-separation model,a 3D finite element model suitable for tensile-dominated components and compressed-shear-dominated components was established.The cohesion and contact damage parameters suitable for smooth,medium rough and rough interface were proposed.Several finite element models of the experiments in past literature were established to verify the validity of the proposed traction-separation parameters.The finite element calculation and experimental results were well fitted,which can provide reference for later FEM study.