Response of Underground Pipelines Subjected to Partially Coherent Seismic Excitation

Analyses on the basis of seismic array records have confirmed that spatially distributed earthquake ground motions are neither fully coherent nor independent, but partially coherent. It has not yet been fully addressed how the partially coherent nature of seismic ground motions affect the seismic response of underground pipelines. In this paper, the impact of auto power spectrum density, pipe cross-sectional radius, and wall thickness, local effect, and coherency effect on pipeline responses are analyzed by calculating the longitudinal and lateral seismic responses of continuous pipelines in a homogeneous medium using a pseudoexcitation algorithm of the random vibration theory. A numerical integration technique is developed by converting infinite integration into a series with limited terms. Sufficient precision is achieved when integration steps are sufficiently small. The method provides a simplified way for practical professionals to analyze response of underground pipelines to earthquakes. (C) 2013 American Society of Civil Engineers.