In alkaline and near-neutral soil environments, the mechanical and seismic performance of buried steel pipes degrades with deepening corrosion over time. To study the seismic fragility of buried steel pipes of different service ages in these environments, an incremental dynamic time history analysis of typical pipes was carried out with the time-varying constitutive model of steel. A probabilistic seismic demand model for buried steel pipes of different service ages in alkaline and near-neutral soil environments was then established, which can characterize the probability relationship between the ground motion intensity and structural response. Furthermore, on the basis of the tristate criteria, the limits of each ultimate failure state were determined. Time-varying seismic analytical fragility models of the pipes, including pipe units in two different soil environments and four service ages, were then established, which can characterize the probability of different failure states of structures under different earthquakes. The corresponding seismic fragility curves were then drawn. Seismic fragility curves were also obtained under three different diameter ranges based on seismic damage statistics. Results showed that, under the same ground motion, with increasing service time and decreasing pipe diameter, the probabilities of three failure states, namely, basically intact, moderately damaged, and severely damaged, all increased.

在碱性和近中性土壤环境中，随着时间的推移，埋地钢管的机械和抗震性能会随着腐蚀的加深而下降。为研究不同使用年限埋地钢管在这些环境中的地震脆性，采用钢的时变本构模型对典型管道进行增量动态时程分析。建立了不同服役年限埋地钢管在碱性和近中性土壤环境中的概率地震需求模型，可以表征地震动强度与结构响应的概率关系。此外，在三态标准的基础上，确定了每个最终失效状态的极限。管道的时变地震分析脆弱性模型，然后建立了包括两种不同土壤环境和四种使用年限的管道单元，可以表征结构在不同地震下不同破坏状态的概率。然后绘制相应的地震脆性曲线。基于地震损伤统计，还获得了三个不同直径范围下的地震脆性曲线。结果表明，在相同地震动条件下，随着使用时间的增加和管径的减小，基本完好、中度损坏和严重损坏三种失效状态的概率均增加。然后绘制相应的地震脆性曲线。基于地震损伤统计，还获得了三个不同直径范围下的地震脆性曲线。结果表明，在相同地震动条件下，随着使用时间的增加和管径的减小，基本完好、中度损坏和严重损坏三种失效状态的概率均增加。然后绘制相应的地震脆性曲线。基于地震损伤统计，还获得了三个不同直径范围下的地震脆性曲线。结果表明，在相同地震动条件下，随着使用时间的增加和管径的减小，基本完好、中度损坏和严重损坏三种失效状态的概率均增加。