基于Connector单元的锈蚀RC梁界面粘结性能细观数值模拟

Meso-scale numerical simulation of interfacial bond behavior of corroded RC beams based on connector element

结合随机骨料模型建立了锈蚀钢筋混凝土(RC)梁三维细观数值模型,采用Connector单元捕捉加载过程中界面相互作用变化的方法。利用已有试验数据验证了该模型的合理性。分析了加载过程中锈蚀RC梁界面粘结滑移分布以及变形协调系数的变化规律,探讨了界面粘结退化对RC梁抗弯承载力的影响。研究结果表明:采用Connector单元能描述加载过程中粘结应力以及相对滑移等界面行为的变化,可作为锈蚀钢筋-混凝土界面行为模拟的有效手段;界面的最大粘结应力随锈蚀率的增加而降低,30%的锈蚀率使得极限荷载下RC梁界面最大粘结应力下降71%;锈蚀会加剧荷载作用下锈蚀RC梁界面的相对滑移,界面相对滑移峰值位置由加载点逐渐向剪弯段区域转移;锈蚀会减小界面极限变形协调系数,锈蚀率达到30%时,极限变形协调系数为0.479,抗弯承载力下降55%。

A three-dimensional meso-scale numerical model of corroded reinforced concrete(RC)beams was established by random aggregate model in the present study,and the connector element was used to capture the changes of interaction at the interface during loading.The rationality of the model was verified by experimental data.The interfacial bond-slip distribution and deformation coordination coefficient of corroded RC beams during the loading process were analyzed,and the effect of bond degradation on bearing capacity was discussed.Results show that the connector element can describe the bond stress and relative slip at the interface during the loading process,which is an effective method for simulating the interface behavior between corroded steel and concrete.The maximum bond stress at the interface decreases with increasing corrosion loss,a 30%of corrosion loss leads to a decrease of 71%in the maximum bond stress at the ultimate load.Corrosion can accelerate the relative slip at the interface of corroded RC beams,and the relative slip at the interface moves from the loading point position to the shearflexure section.The ultimate deformation coordination coefficient at the interface decreases with the increase of corrosion loss.When the corrosion loss reaches 30%,the ultimate deformation coordination coefficient is 0.479,and the bearing capacity decreases by 55%.