锈蚀钢筋混凝土梁的抗剪承载力分析模型

文章编号：1674-4764（2018）06-0131-08

Shear strength model of corroded reinforced concrete beams

Yu Bo， Chen Bing， Liu Yang

（School of Civil Engineering and Architecture; Key Laboratory of Disaster Prevention and

Structural Safety of Ministry of Education; Guangxi Key Laboratory of Disaster Prevention

and Engineering Safety， Guangxi University， Nanning 530004， P. R. China）

Abstract：The accuracy of traditional shear strength models for corroded reinforced concrete （RC）beam are far from satisfactory， since these models generally belong to the empirical methods which are lack of theoretical basis and do not take into account the various influential factors comprehensively. Hence， a shear strength model of corroded RC beam which takes into account the influences of corrosion on key factors including the critical diagonal crack angle， the effective shear cross-sectional area， the reinforcement ratio and the stirrup ratio was established based on the modified compression field theory （MCFT）. The accuracy of the proposed model was validated by comparing with 85 sets of experimental data and several existing models. Analysis results show that the proposed model is of good accuracy and small discreteness.

Keywords：reinforced concrete beam; corrosion; shear strength; critical crack angle; shear span ratio; modified compression field theory

受混凝土碳化和氯鹽侵蚀等腐蚀环境作用的影响，在役钢筋混凝土（RC）结构的梁往往发生钢筋锈蚀。董卫等[1] 通过锈蚀RC梁的四点受弯加载试验，分析了钢筋锈蚀对RC梁承载机理的影响，发现锈蚀RC梁的承载机理为梁效应和拱效应的复合体，钢筋锈损率越高，梁效应向拱效应转化的程度越高;张梦光等[2] 通过外加电流加速箍筋锈蚀，开展了4根锈蚀箍筋RC梁的抗剪性能试验，发现箍筋锈蚀会降低RC梁的抗剪性能和变形能力。由于影响锈蚀RC梁抗剪性能的因素较多，导致其抗剪承载力分析较为困难。霍艳华[3] 在未锈蚀RC梁的抗剪承载力模型基础上，分别引入经验影响系数φ和γ′来考虑钢筋锈蚀对混凝土和箍筋的抗剪承载力贡献的影响，建立了锈蚀RC梁的抗剪承载力模型;赵羽习等[4] 引入经验影响系数 P  v来考虑箍筋锈蚀的影响;李士彬等[5] 考虑钢筋锈蚀对箍筋屈服强度和梁有效抗剪截面积的影响，建立了锈蚀RC梁的抗剪承载力模型，但忽略了钢筋锈蚀对配筋率、配箍率、临界斜裂缝倾角等重要因素的影响;余璠璟[6] 基于试验数据拟合分析，确定了钢筋锈蚀对抗剪承载力的影响系数，但当钢筋未锈蚀或锈蚀率较低时，该影响系数为负值，与实际情况不符;El-Sayed[7] 考虑钢筋锈蚀引起的梁有效抗剪截面积和箍筋截面积改变对抗剪承载力的影响，但忽略了其他重要因素的影响;卢朝辉等[8] 基于欧洲规范的抗剪承载力公式，分别引入了钢筋锈蚀对箍筋和混凝土承担剪力的折减系数。综上所述，现有的锈蚀RC梁的抗剪承载力模型主要是在未锈蚀RC梁的抗剪承载力模型基础上，通过引入经验性的钢筋锈蚀影响系数而建立的，缺乏严密的理论推导，且考虑的影响因素不全面，导致计算精度有限。

1 锈蚀RC梁的抗剪承载力模型

根据修正压力场理论（MCFT）[9-11] 可知，RC梁的抗剪承载力V主要由混凝土和箍筋的抗剪承载力贡献（分别记为V  c 和V  s ）组成。