锈蚀钢筋混凝土黏结滑移本构模型及数值模拟应用

Bond-slip constitutive model of corroded reinforced concrete and its numerical simulation application

为研究纵筋与箍筋共同锈蚀对钢筋混凝土黏结性能的影响,采用电渗—恒电流—干湿循环的加速锈蚀方法对25个钢筋混凝土(RC)试件进行锈蚀,进而对其进行拉拔试验,研究了纵筋锈蚀、箍筋锈蚀、保护层厚度和箍筋间距等参数对黏结性能的影响规律。分析了锈蚀对混凝土与钢筋界面间黏结力的影响,将黏结性能退化归因于材料性能退化和约束效应退化,基于试验数据,建立并验证了一个考虑设计参数、纵筋及箍筋共同锈蚀的修正黏结滑移本构模型。结合所提本构模型及微元算法建立了锈蚀纵筋应力-滑移模型,基于OpenSees平台,将所建模型应用于零长度截面单元中,通过串联纤维梁柱单元与零长度截面单元建立了考虑黏结滑移变形的锈蚀RC构件数值模型,根据锈蚀RC柱拟静力试验数据对该模型的准确性进行验证,并采用仅考虑锈蚀损伤的纤维模型进行辅助验证。结果表明:混凝土与钢筋界面间黏结力随锈蚀程度的增加呈先上升后下降的趋势,增加保护层厚度可略微增加黏结强度,而箍筋加密对黏结强度提升明显;与纤维模型相比,所建锈蚀RC纤维模型承载力、累计耗能和极限位移误差分别降低12.8%、23.5%和14.2%,表明所建模型可合理计算钢筋滑移的贡献且准确预测锈蚀RC柱地震整体响应。

To study the impact of corrosion of both longitudinal bar and stirrup on the bonding performance of steel bar and concrete,we fabricated 25 corroded reinforced concrete(RC)specimens by the accelerated corrosion method of electroosmosis-constant current-dry wet cycles.Pull-out tests were carried out on the specimens,and the influences of parameters such as longitudinal bar corrosion,stirrup corrosion,cover thickness,and stirrup spacing on bonding properties were studied.The effect of corrosion on the bonding force between concrete and steel bar was analyzed,and the degradation of the bonding performance was attributed to the reduction of the material behavior and the degradation of the constraint effect.On the basis of the test results,a modified bond-slip constitutive model was established and verified considering design parameters and both corrosion of longitudinal bar and stirrup.A stress-slip model of corroded longitudinal bar was obtained by combining the proposed constitutive model and infinitesimal algorithm.In the OpenSees platform,the stress-slip model was applied to the zero-length section element,and the numerical model of corroded RC components considering bond-slip behavior was established by adopting fiber-based beam-column element and zero-length section element.The accuracy of the model was verified according to the quasi-static test data of the corroded RC column,and the fiber model considering only corrosion damage was used for auxiliary verification.Results show that the bonding force between concrete and steel bar increased first and then decreased with the increase in the corrosion degree.Increasing the cover thickness could slightly improve the bonding force,while the increase in stirrup density could significantly improve the bonding force.Compared with the fiber model,the bearing capacity,cumulative energy dissipation,and ultimate displacement errors were reduced by 12.8%,23.5%,and 14.2%in the constructed fiber model,indicating that the constructed model can reasonably calculate the contribution of steel bar slip and accurately predict the overall seismic response of the corroded RC columns.