端锚CFRP-混凝土界面剥离全过程解析模型

端部锚固是一种控制CFRP-混凝土黏结界面剥离和提高界面承载力的有效措施。为研究端部锚固下CFRP-混凝土黏结界面的剥离过程,引入指数型界面黏结-滑移本构,推导了黏结界面剥离全过程的解析模型,得到了黏结界面滑移、黏结应力、CFRP应变和应力分布表达式,上述解析模型得到了试验结果的良好验证。基于解析模型,给出了黏结界面的最大黏结力、有效黏结长度和剥离荷载的计算方法,并分析了不同黏结长度对界面剥离全过程受力行为的影响。分析表明:相比纯外贴黏结界面,端部锚固黏结界面的有效黏结长度有所增加,且剥离荷载随黏结长度的增加而降低,并趋近于纯外贴黏结界面的极限承载力;当黏结长度较长时,其剥离荷载与最大黏结力相差不大,此时端部锚固力很小;当黏结长度较短时,端部锚固会更早地参与承担荷载,其剥离荷载接近CFRP拉断荷载。

Analytical models of the whole debonding process of CFRP-to-concrete interface with end anchorage

End anchorage is an effective measure to control the debonding of CFRP-to-concrete bond interface and improve the interface bearing capacity. To study the debonding process of CFRP-to-concrete interface with end anchorage, the exponential bond-slip model was introduced to establish analytical models. The distribution expressions of interfacial slip, bond stress, CFRP axial strain and stress were obtained. The proposed models were well verified by experimental results. Based on the analytical models, the calculation methods of the maximum bond force, effective bond length, and debonding load were established, and the influence of different bond lengths on the mechanical behaviors of the interface during the debonding process was analyzed. Results show that the effective bond length of the bonded interface with end anchorage was longer than that of the external bonded interface. The debonding load decreased with the increase of the bond length, approaching the ultimate bearing capacity of the external bonded interface. When the bond length was long, there was little difference between the debonding load and the maximum bond force, and the end anchoring force was small. When the bond length was short, the end anchorage would bear the load earlier, and the debonding load was close to the CFRP breaking load.