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基于我国内陆地区温度变化的预测结果,建立了温度变化概率模型,并研究了其对钢筋混凝土碳化腐蚀电流密度的影响。利用锈蚀钢筋样本,测试了锈蚀钢筋的力学行为,统计了锈蚀钢筋面积损失率,建立了其与失效模式和强度的定量概率模型。结合我国规范弯曲和剪切承载能力模型,考虑钢筋混凝土(RC)梁退化的随机性,建立了大气环境下锈蚀RC梁时变弯曲和剪切抗力模型。利用我国建筑规范楼面梁随机荷载模型,发展了弯曲和剪切时变可靠度模型,基于首次超越概率分析方法,预测了我国内陆地区RC楼面梁的概率性能,使用Monte-Carlo模拟方法,计算了将来90 a内的时变弯曲失效风险、剪切失效风险和组合失效风险。研究表明:对于高CO2浓度地区,结构弯曲失效风险、剪切失效风险和组合失效风险比低浓度地区的分别高6%,18%和7%;在只有箍筋和主筋锈蚀的情况下,弯曲失效是锈蚀RC梁的主要失效行为;保护层厚度为20 mm和水灰比为0.55时的弯曲和剪切失效风险比保护层厚度为40 mm和水灰比为0.45时的分别高122%和57%。
Based on the prediction of the temperature change in inland China, a probabilistic model of temperature change was established and its influence on the corrosion current density of reinforced concrete was studied. The mechanical behavior of corroded steel bars was tested by using corroded steel samples. The area loss rate of corroded steel bars was calculated and a quantitative probability model of the corroded steel bars was established. Considering the randomness of the degradation of reinforced concrete (RC) beams, a model of the time-dependent bending and shear resistance of corroded RC beams under atmospheric conditions was established based on the Chinese model of bending and shearing bearing capacity. Based on the random load model of Chinese building codes, the time-varying reliability model of bending and shear is developed. Based on the first exceedance probability analysis method, the probability performance of RC floor beams in inland China is predicted. Monte-Carlo simulation method The time-varying bending failure risk, shear failure risk and combined failure risk are calculated in the next 90 days. The results show that the bending failure, shear failure and combined failure risk of structures are 6%, 18% and 7% higher than those in low concentration areas respectively in areas with high CO2 concentration. In the case of corroded stirrups and main bars, Failure is the main failure behavior of a corroded RC beam; the risk of bending and shear failure at a protective layer thickness of 20 mm and a water-cement ratio of 0.55 is 122% higher than the protective layer thickness of 40 mm and a water-cement ratio of 0.45 57%.