Abstract A numerical model to take into account the effect of the stress state on the bond behavior between steel and concrete in reinforced concrete structures is proposed. It is based on a zero thickness element, adapted to large-scale simulations and the use of 1D elements for steel bars. The proposed model also assumes the definition of a bond stress – slip law which includes the confining pressure around the steel bar as a parameter. The implementation of the model is presented and the calibration of the bond law is discussed. A general equation is especially proposed. This evolution law is validated through the comparison to 28 pullout tests. The model is able to reproduce the evolution of the bond stress (especially the bond strength) as a function of the confinement pressure, whatever the configuration (different concrete cover to steel diameter ratios). Finally, the effects at the structural level are investigated on a reinforced concrete tie. The response for different confining pressures is especially studied. It shows the capability of the model to reproduce the “expected” tendencies with an increase of the initial elastic stiffness with increasing pressures and consequently a higher number of cracks in the stabilized nonlinear regime. The “transfer length” is also shown to decrease with increasing confining pressures.

中文翻译：

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钢筋混凝土结构钢-混凝土结合中主动约束效应的结构尺度建模

摘要 提出了一种考虑应力状态对钢筋混凝土结构中钢与混凝土结合性能影响的数值模型。它基于零厚度元素，适用于大规模模拟和钢筋的一维元素的使用。所提出的模型还假定结合应力-滑移定律的定义，其中包括钢筋周围的围压作为参数。介绍了该模型的实现，并讨论了键合定律的校准。特别提出了一个通用方程。通过与 28 次拔出试验的比较，验证了这一演变规律。该模型能够再现作为约束压力的函数的粘合应力（尤其是粘合强度）的演变，无论配置如何（不同的混凝土保护层与钢直径比）。最后，研究了钢筋混凝土拉杆在结构层面的影响。对不同围压的响应进行了特别研究。它显示了模型再现“预期”趋势的能力，初始弹性刚度随着压力的增加而增加，因此在稳定的非线性状态中裂纹数量增加。“转移长度”也显示出随着围压的增加而减少。它显示了模型再现“预期”趋势的能力，初始弹性刚度随着压力的增加而增加，因此在稳定的非线性状态中裂纹数量增加。“转移长度”也显示出随着围压的增加而减少。它显示了模型再现“预期”趋势的能力，初始弹性刚度随着压力的增加而增加，因此在稳定的非线性状态中裂纹数量增加。“转移长度”也显示出随着围压的增加而减少。