In this work, a new mechanistic interface model is proposed to simulate the nonlinear bond behavior of steel reinforcement in concrete. With the motivations to reproduce the bond response more realistically and uncover the underlying mechanisms responsible for the high nonlinearity, the main characteristics including the damage evolution and frictional features are properly embodied during the establishment of the model. Specifically, the collective bond stress is expressed as the superposition of the mechanical interlocking and the frictional resistance, while the total reinforcement slip is first decomposed into three components, namely elastic slip, plastic slip, and sliding slip. As to the interfacial damage, by introducing a probabilistic method and the concept of cumulative slip, the irreversibility and directionality are emphatically considered. Upon these assumptions, along with mathematical and physical laws governing the developments of interfacial damage, kinematic/isotropic hardenings, and frictional sliding, the model is strictly deduced and numerically implemented within the thermodynamic framework. The numerical illustrations of the model behavior under different loading paths and the independent validations with different test results demonstrated that the proposed model is capable of reproducing the bond responses satisfactorily. The nonlinearity of the bond behavior is the integrative result of the variations of interlocking force and frictional resistance, which is largely attributed to the progressive transformation of the dominated mechanisms at different debonding stages. The presented model constitutes a beneficial addition to the understanding of the nonlinear bond behavior from the theoretical viewpoint.

在这项工作中，提出了一种新的机械接口模型来模拟钢筋在混凝土中的非线性粘结行为。通过更真实地再现键响应并发现造成高非线性的潜在机制的动机，在模型建立过程中适当体现了主要特征，包括损伤演化和摩擦特征。具体地，集体粘结应力表示为机械互锁和摩擦阻力的叠加，而总的增强滑移首先分解为三个分量，即弹性滑移，塑性滑移和滑动滑移。关于界面损伤，通过引入概率方法和累积滑移的概念，着重考虑了不可逆性和方向性。基于这些假设，再加上控制界面损伤，运动/各向同性硬化和摩擦滑动发展的数学和物理定律，可以在热力学框架内严格推导并以数字方式实施该模型。在不同加载路径下的模型行为的数值说明以及具有不同测试结果的独立验证表明，所提出的模型能够令人满意地再现键响应。粘结行为的非线性是互锁力和摩擦阻力变化的综合结果，这在很大程度上归因于主导机制在不同脱胶阶段的逐步转变。