PERFORMANCE EVALUATION OF EMERGENCY SHUTOFF SYSTEM OF CITY GAS SUPPLY SYSTEM IN EARTHQUAKE DISASTER

Abstract

 City gas shutoff system in earthquake disaster can be modeled as a k-out-of-n system activating shutoff when observing SI values exceeding a prescribed criterion. In this study, performance evaluation is carried out in order to better manage trade-off between service continuity and shutoff. Monte Carlo simulations are conducted to generate a set of SI values, resulting shutoff status in accordance with the criterion and corresponding damage ratios using fragility function and pipeline inventory. The generated dataset is analyzed using contingency table and associated indices such as true positive rate, true negative rage, positive predictive value, negative predictive value and ROC. Practical examples suggest that shutoff criterion can be appropriately determined by considering level of earthquake-resistance of low-pressure pipe.