Seismic Risk Analysis of Buried Pipelines

Abstract

A procedure is described for the seismic risk analysis of buried pipelines that provides an estimation of the annual probability of occurrence of different damage states, called damage indexes, in a component segment of the general network system of buried pipelines. The damage indexes are obtained by combining a damage probability matrix (DPM) with the annual probability of occurrence of different levels of earthquake intensity. The DPM is obtained by finding the probabilities of different damage states, defined with respect to some criterion, due to different levels of earthquake intensity. The expected peak values of stresses at the critical sections of the buried pipeline for each level of earthquake intensity are determined using a random vibration analysis with discrete lumped mass model. The pipe responses are calculated by spectral approach, in which the PSDFs of ground accelerations are defined as functions of earthquake intensity in Modified Mercalli Intensity (MMI) scale. The analysis considers two component earthquake having an angle of incidence with respect to global axes of reference. A numerical study conducted with the help of proposed procedure shows that the pipe end conditions, the types of pipe intersections, the pipe radius, the angle of incidence of earthquake wave, the angle of intersection of pipes, and the type of soil have considerable influences on the damage indexes.