Unified Bond Model for Externally Bonded Reinforcement

本文提出了混凝土与外粘结加固材料界面的统一局部粘结应力滑移模型(剪切粘结模型)。在拉拔粘结试验加载端应力-滑移关系的基础上，建立了剪切粘结模型，简化了必要的测量，使数据分散问题最小化。剪切粘结模型只需要两个材料常数，即界面断裂能和界面延性系数。将剪切粘结模型扩展为粘结应力-滑移-加固材料应变模型，以描述粘结长度较短的情况。原始剪切粘结模型和扩展剪切粘结模型都考虑了加固材料、粘结材料和混凝土基层的力学性能的影响。在剪切带模型的基础上，给出了给定锚固长度时界面断裂能、有效粘结长度和粘结强度的预测公式。通过计算结果与实验结果的比较，给出了统一剪切粘结模型的可靠性，以及给定粘结长度时的界面断裂能、有效粘结长度和粘结强度的计算公式。对拉伸粘结模型进行了实验检验，发现粘结强度(或界面断裂能)不受粘结材料的刚度影响，这与剪切粘结模型的情况不同。提出了一种表示粘结(剪切和拉伸粘结)混合模式的试验方法。利用该方法，给出了剪切粘结强度与拉伸粘结强度的相互作用图，结果表明，即使在拉伸粘结强度相当于拉伸粘结强度的90%的情况下，剪切粘结强度也只降低了10%。给出了正交粘结加固材料冲压能力的理论计算方法。

This study presents a unified local bond stress-slip model for interface between concrete and externally bonded reinforcing material (shear bond model). The shear bond model was derived based on a reinforcing material stress-slip relationship at loaded end of pullout bond test, so that necessary measurement was simplified and the data scatter problem was minimized. The shear bond model needs only two material constants, interfacial fracture energy and interfacial ductility factor. The shear bond model was expanded to be bond stress-slip-reinforcing material strain model to express cases with a short bond length. Both original and expanded shear bond models consider effects of mechanical properties of reinforcing materials, adhesive materials and concrete substrate. Besides the shear band model, the prediction formula for interfacial fracture energy, effective bond length and bond strength for given anchorage length are presented. Reliability of the proposed unified shear bond model together with the proposed formula for interfacial fracture energy, effective bond length and bond strength for a given bond length is presented by comparing the calculated results with experimental results.Tension bond model is examined experimentally and it is disclosed that the bond strength (or interfacial fracture energy) is not affected by stiffness of adhesive materials, which is different from the cases of shear bond model. A test method to represent a mixed mode for bond (shear and tension bond) is newly developed. Using this method, an interaction diagram of shear bond strength and tension bond strength is presented, which shows that the shear bond strength is reduced only by 10% even under tension bond stress equal to 90% of the tension bond strength. The theoretical method to calculate punching out capacity of reinforcing material externally bonded in orthogonal direction is also presented.