To characterize the rate‐dependency and frictional behavior of quasi‐brittle interface material, a coupling rate‐dependent and friction interface model improved from the Park‐Paulino‐Roesler (PPR) cohesive model, is proposed and validated in this paper. Based on the potential function, this novel coupling model forms the basic relationship of traction‐displacement within the interfaces, in which rate effect and friction behavior are considered by constructing a rate‐sensitive item and smooth friction term, respectively. Specifically, governing equations for typical mode I and mode II crack formation, as well as for normal and tangential directions, are established, and the model includes a complete unloading/reloading mode for the complex loading situations. To validate this model, the 3D simplified shear test of the anchor rod and mortar block model and a three‐point bend test of the composite concrete‐FRP beam with different loading rates are established to verify the engineering availability, considering different loading rates and friction coefficients. The results show that shear and tensile behaviors of brittle material in numerical models and laboratory tests are similar in the fracture initiation and propagation characteristics. The proposed model can reflect not only the elastic, softening, and residual stages, but also the strength rate‐related effects and friction effects of interface materials. This provides a comprehensive solution for describing the complex mechanical behavior of quasi‐brittle materials subjected to tensile and shear loads.

中文翻译：

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考虑脆性材料速率相关特性和摩擦行为的改进 Park-Paulino-Roesler （PPR） 内聚模型


为了表征准脆性界面材料的速率依赖性和摩擦行为，本文提出了一种从 Park-Paulino-Roesler （PPR） 内聚模型改进的速率依赖耦合和摩擦耦合界面模型，并进行了验证。基于势函数，这种新颖的耦合模型在界面内形成了牵引-位移的基本关系，其中通过分别构造速率敏感项和平滑摩擦项来考虑速率效应和摩擦行为。具体来说，建立了典型模式 I 和模式 II 裂纹形成以及法向和切向的控制方程，并且该模型包括用于复杂加载情况的完整卸载/重新加载模式。为验证该模型，考虑了不同的加载速率和摩擦系数，建立了锚杆砂浆块模型的三维简化剪切试验和不同加载速率的复合混凝土-FRP 梁的三点弯曲试验，以验证工程可用性。结果表明，数值模型和实验室测试中脆性材料的剪切和拉伸行为在断裂起始和扩展特性方面相似。所提出的模型不仅可以反映弹性、软化和残余阶段，还可以反映界面材料的强度率相关效应和摩擦效应。这为描述受拉伸和剪切载荷的准脆性材料的复杂力学行为提供了一个全面的解决方案。