Abstract To explore the nonlinear bond behavior between ribbed bar and concrete, considering frictional resistance and the mechanical interlocking between rebar and concrete as well as the surface characteristic of crescent ribbed bar, a 3D meso-scale modelling approach is established. Comparisons between the simulation and experimental results indicate that the meso-scale method can provide good predictions of the interface behavior between concrete and deformed steel bar under confinement conditions. The bond failure mechanism and the propagation of internal crack of specimen were clearly studied and revealed based on the 3D simulations. Moreover, the influences of concrete strength gradation, ratio of cover thickness to bar diameter as well as stirrup confinement on bond stress-slip behavior, concrete failure mode and rebar stress were explored. The simulation results indicate that the meso-scale modelling method can well describe the bond failure process at the steel bar/concrete interface. It is found that increasing the concrete strength can delay the internal crack of the specimen and may change the failure mode of the specimen from splitting failure to pull-out failure. As concrete strength increases, the bond strength increases linearly, whereas the peak slip decreases slightly. The shape of bond stress-slip curve and the concrete failure modes are closely associated with the lateral confinements such as concrete cover thickness and the stirrup confinement. When the cover thickness and the stirrup confinement index reach a certain value, the bond failure would no longer be affected. In addition, the strain of stirrups increases continuously, the bond stress provided by stirrups increases first and then decreases.

中文翻译：

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带肋钢筋和混凝土之间界面行为的 3D 中尺度建模

摘要 为探讨带肋钢筋与混凝土之间的非线性粘结行为，考虑摩擦阻力、钢筋与混凝土之间的机械联锁以及月牙形带肋钢筋的表面特性，建立了一种3D细观尺度建模方法。模拟和实验结果之间的比较表明，细观方法可以很好地预测约束条件下混凝土和变形钢筋之间的界面行为。基于3D模拟清楚地研究和揭示了粘结破坏机制和试样内部裂纹的扩展。此外，探讨了混凝土强度级配、保护层厚度与钢筋直径之比以及箍筋约束对粘结应力滑移行为、混凝土破坏模式和钢筋应力的影响。仿真结果表明，细观建模方法可以很好地描述钢筋/混凝土界面处的粘结破坏过程。研究发现，提高混凝土强度可以延缓试件的内部开裂，并可能使试件的破坏模式从劈裂破坏转变为拉拔破坏。随着混凝土强度的增加，粘结强度线性增加，而峰值滑移率略有下降。粘结应力滑移曲线的形状和混凝土破坏模式与混凝土保护层厚度和箍筋约束等侧向约束密切相关。当覆盖层厚度和箍筋约束指数达到一定值时，不再影响粘结失效。此外，箍筋的应变不断增加，