Optimal Proactive Seismic Rehabilitation of Gas Pipeline Networks

Critical infrastructure systems, such as gas pipeline networks, are essential to the modern community’s survival. In severe seismic hazard zones, earthquakes can cause catastrophic damages to gas pipeline networks. The damages disrupt the gas supply, resulting in various direct and indirect losses to the utilities that serve the community. Resource constrained proactive rehabilitation of these pipelines under seismic uncertainty presents a challenge for gas utilities. Existing seismic susceptibility assessment models of gas pipeline networks have evaluated connectivity loss (CL). However, there is limited research that determines the optimum rehabilitation policy that minimizes connectivity loss within resource constraints. This study aims to identify critical pipes of a gas pipeline network for rehabilitation minimizing the network’s connectivity loss when only a limited length of pipes can be rehabilitated. With this aim in mind, four specific tasks are completed: (1) characterization of spatial seismic hazards in terms of peak ground velocity, (2) determination of pipe repair rate using the empirical fragility curves, (3) evaluation of gas pipeline network’s connectivity loss, and (4) minimization of the expected value of connectivity loss using a genetic algorithm (GA). A simulation-based approach is used to evaluate the seismic hazard, network-level seismic susceptibility assessment, and evaluation of the gas pipeline network’s connectivity loss while accounting for relevant uncertainties. Monte Carlo simulations were carried out to emulate the stochastic nature of the damages to the gas pipeline network. The methodology’s application has been illustrated on a reference network to identify the critical pipelines of that gas pipeline network. The outcomes were compared with the rehabilitation policies determined from a length-based rehabilitation approach. The comparison demonstrated significant improvement in connectivity loss while using GA-based rehabilitation approach. The proposed approach is expected to assist the gas utilities in making rehabilitation decisions to reduce connectivity loss of the gas pipeline networks.