考虑锈蚀损伤的黏结滑移本构模型

为合理反映钢筋锈蚀后黏结滑移性能劣化对钢筋混凝土(RC)结构抗震性能的影响，在既有黏结应力分布模式的基础上，推导得到钢筋应力-滑移关系，进而通过分析锈蚀对混凝土与钢筋界面黏结滑移机理的影响，建立考虑钢筋锈蚀损伤的黏结滑移本构模型。基于已有拉拔试验结果，与仅考虑纵筋锈蚀率影响的Cheng模型进行对比，验证所建模型的合理性与准确性。基于OpenSees有限元平台，采用纤维梁柱单元和零长度截面单元串联的方式，将所建钢筋黏结滑移模型嵌套于零长度截面单元的钢筋本构中，建立可考虑黏黏结滑移的锈蚀损伤纤维梁柱模型，并通过6根锈蚀RC柱拟静力试验结果验证模型的准确性，结果发现所提考虑黏结滑移的锈蚀RC纤维梁柱模型计算所得滞回曲线与试验滞回曲线吻合良好，累计耗能最大误差不超过15%。此外，通过参数分析研究影响锈蚀钢筋滑移量的因素，结果表明屈服滑移量与极限滑移量随体积配箍率的增大而明显减小，随混凝土保护层与钢筋直径之比(c/d)增大而变化的幅度较小。

Bond-slip constitutive model considering corrosion damage

To reasonably reflect the influence of bond-slip performance degradation of corroded steel bars on the seismic performance of reinforced concrete (RC) structures, stress-slip relationship of steel bars was deduced based on an existing bond stress distribution model. Then, a bond-slip constitutive model considering the corrosion damage of steel bars was established by analyzing the influence of corrosion on bond-slip mechanism between concrete and steel bars. Based on existing pull-out test results, the rationality and accuracy of the proposed model were verified by comparing it with the Cheng model by only considering the influence of the longitudinal reinforcement corrosion rate. Based on the finite element platform OpenSEES, fiber beam-column and zero-length section elements were connected in series. The bond-slip model proposed in this paper was nested in the steel bar constitutive model of the zero-length section element; thus, a corrosion damage fiber beam-column model considering bond-slip was established. The accuracy of the proposed model was verified using quasistatic test results of six corroded RC columns. These results show that the hysteresis curve calculated by the proposed corroded RC fiber beam-column model considering bond-slip agrees well with the experimental hysteresis curve, and the maximum error of cumulative energy consumption is not more than 15%. In addition, factors affecting the slip of the corroded steel bar were studied using parameter analysis. The results show that yield and ultimate slips obviously decrease with increasing volume stirrup ratio and slightly change with an increasing ratio of concrete cover to steel bar diameter.