Static and Quasi-static Seismic Analyses of Buried Pipelines. (Seismic Vulnerability, Behavior and Design of Underground Piping Systems)

摘要

Currently available static and quasi-static analyses for the seismic response behavior of buried pipelines are summarized to evaluate the adequacy of existing pipelines and to aid in the design of future systems. The analyses employed include the upper bound--both simplified and quasi-static approaches; static-beam on elastic and elastic-plastic foundation models; and quasi-static elastic and elasto-plastic analyses. Upper bound analyses are simple but conservative, and the bounds are used as a basis of normalization of results. Static analyses are a higher level of analysis for the response behavior of buried pipelines. Quasi-static analysis constitutes the highest level examined. Results indicate that: (1) the seismic response behavior of buried pipelines is controlled by ground displacement characteristics, not by ground accelerations; (2) pipe strain and relative joint displacements are jointly taken up by the imposed earthquake bound displacement; (3) responses are larger under softer soil conditions; (4) responses are higher when there is not slippage between soil and pipe; and (5) a longer pipe segment produces high pipe strain and larger relative joint displacement for segmented pipelines.