Numerical, experimental and fragility analysis of urban lifelines under seismic wave propagation: Study on gas distribution pipelines in the greater Tehran area

Dependency of urban life and modern industries on civil infrastructure and lifelines urges the stake-holders and authorities to consider the resilience of lifeline systems as a crucial decision-making factor. In this paper, the performance of a complex urban gas distribution network, under the effects of wave propagation, in a city with more than 12 million residents is assessed. In the first phase, the inputs for soil-pipe interaction analysis in the Greater Tehran Area (GTA) are identified and quantified. Finite element models of the GTA pipelines are developed and the performance of the network is investigated. The second phase of the study consists of an experimental program, aimed at further studying the performance of buried pipelines in wave propagation and verification of the numerical models. Previous studies are consulted to define limit states and develop fragility curves for the steel buried pipeline network in the Greater Tehran Area. A damage distribution map is produced for the GTA buried gas distribution steel pipelines by synchronization of different performance assessment inputs, identified in the study, over the GTA area. The study also provides fragility distribution maps for steel buried pipelines in the GTA for use as a decision-making tool. Countermeasures are proposed for mitigation of wave propagation-induced damage and risks on the gas distribution network. The framework used in the presented study can be adopted for performance assessment and risk mitigations for similar urban infrastructure and lifelines.