Seismic risk assessment of natural gas networks with steady-state flow computation

Abstract

Natural gas networks are spatially distributed systems that play a crucial role in the well-being and safety of communities. Most of the works in the current literature analyse natural gas systems only in topological terms. However, the low tolerance on amount and pressure of gas fed to end-users for maintaining serviceability generates the need for a capacitive analysis. The latter includes connectivity and involves computation of the system's operational state, in terms of pipe flows and node pressures. The paper presents a comprehensive methodology for the seismic risk assessment of gas transmission and distribution networks. The seismic hazard, the vulnerability assessment and the evaluation of the system's performance are addressed with a simulation-based approach, accounting for the relevant uncertainties. The use of the capacitive analysis in this scope represents the most important feature of this work: a complete steady-state flow formulation is used, encompassing multiple pressure levels, the pressure-driven mode and the correction for pipe elevation change. The presented methodology has been implemented into an open-source software, OOFIMS, and applied to a realistic benchmark network composed of 135 nodes and 170 edges, thus resulting to be usable by emergency managers and stakeholders engaged in increasing the seismic resilience of communities.