【作者】 丁蔚；

【导师】 张建仁； 王磊；

【作者基本信息】 长沙理工大学 ， 桥梁与隧道工程， 2012， 硕士

【摘要】 在材料老化、不利环境以及使用不当等多种因素的综合作用下，既有钢筋混凝土(RC)构件在服役期间抗力不断退化，其安全性和耐久性受到严重影响。随着对服役桥梁维修加固的增多，以及桥梁倒塌事故的不断出现，既有钢筋混凝土桥梁的耐久性问题越来越引起国内外研究人员的重视。而在引起RC构件抗力退化的诸多因素当中，钢筋锈蚀是其最为重要的原因，因此正确地评估锈蚀环境下的钢筋混凝土构件的抗弯和抗剪承载力就显得尤为重要。本研究项目在国家自然科学基金项目“既有RC桥梁构件抗剪性能退化模型及可靠性研究（50878031）”和湖南省优秀研究生创新基金项目“考虑弯剪失效的RC梁桥时变可靠度计算（CX2011B355）”的支持下，主要针对氯盐环境下的锈蚀钢筋混凝土构件，研究了不同类型钢筋性能退化和构件弯剪抗力衰减等相关问题，主要工作如下：（1）基于已有钢筋锈蚀研究，模拟了钢筋在局部锈蚀情况下的面积和屈服强度退化曲线，探讨了保护层厚度对钢筋面积和屈服强度退化速率的影响规律。（2）采用基于修正钢筋-混凝土变形协调关系后的锈蚀梁抗弯承载力计算公式，结合锈蚀钢筋的面积和强度退化模型，提出了锈蚀梁抗弯承载力的退化概率模型，通过参数敏感性分析确定了混凝土保护层厚度对抗弯承载力退化速度影响最为显著。（3）对比分析了基于修正钢筋-混凝土应变关系和钢筋-混凝土粘结强度损失两种不同方法所建立的抗弯承载力退化模型的差异，结果表明两种退化概率模型所得出的结果最大相差12%。（4）对比了以现行规范公式为基础所建立的抗剪概率退化模型的差异，其抗力退化计算结果相差不超过3%。通过参数敏感性分析确定了箍筋保护层和氯离子浓度对抗剪承载力退化的初始时间影响较大；斜筋保护层和氯离子浓度对抗剪承载力退化速度影响较大。（5）对比分析了RC梁在100年内的抗弯承载力和抗剪承载力退化曲线，结果表明在63年以前构件的受剪抗力退化率高于受弯抗力的退化率，而在63年以后受弯抗力退化率却要高于受剪抗力的退化率。更多还原

【Abstract】 Severely affected by material aging、poor environment and misapplication，theresistances of reinforced concrete（RC）beams deteriorated so that the safety anddurability decreased. With the increase of collapse、maintenance and reinforcementfor bridges, the durability of corroded RC components were focused by researchers.The steel-bar corrosion is the overriding reason in all factors that lead to theresistance degradation of RC beams. Therefore, the accurate assessment ofresistance of corroded RC beam is very important .This research project is supported by National Natural Science Fund of Chinaunder the Project No. 50878031“research on shear capacity deterioration modeland reliability of existing RC bridge”and Excellent Postgraduate Innovation Fundof Hunan Province under the Project No. CX2011B355“the time-variant reliabilitycalculation of RC beam bridge with considering the resistance deterioration”. Thispaper focused on the resistance degradation of RC components in chlorideenvironment. The main research works included as follow:(1) Based on the existing research on steel-bar corrosion, the sectional area andyield strength degradation curves of reinforcements were plotted for local corrosionand the impact of concrete cover on sectional area degradation was discussed.(2) The flexural capacity formula of corrosion beam was adopted based onimproved strain relations between reinforcement and concrete. Combined with thedegradation models of corroded reinforcement for area and strength, the probabilitymodel of flexural capacity degradation for corroded RC beam was presented. Incomparison of the parameter sensitivity analysis, the results showed that the impactof concrete cover on the flexural capacity degradation rate was the most significant(3) The difference between the flexural capacity degradation models that basedon the improved strain relations and bond strength loss were comparativelyanalyzed. The calculation results showed that the maximum difference of flexuralcapacity degradation was 12%.(4) The probability models of shear capacity degradation that based on theexisting codes were compared. The result showed that the maximum difference was 3%. In comparison of parameter sensitivity analysis, the thickness of stirrup coverand chloride concentration had more impact on the degradation initiation time.However, the thickness of diagonal reinforcement cover and chloride concentrationhad more impact on the shear capacity degradation rate.(5) The degradation curves of shear and flexural capacity in 100 years wereplotted and compared. The results showed that the shear capacity degraded fasterthan flexural capacity but slower than that after the 63rd year.更多还原