Seismic Damage And Fragility Assessment Of Buried Gas Pipelines

Lifeline is an engineering term denoting those systems that are necessary forhuman life and urban infrastructure. Lifelines are usually used to transport water,sewage, fuel, energy, information, oil, natural gas and other material. This thesisfocuses on the seismic damage and fragility assessment of pipeline network systemstransporting natural gas. The need to avert the dire consequences of an out-of-servicepipeline system located in a seismic region is pivotal for countries. Therefore, thisproject considers the analysis of the interaction of earthquakes with pipelinesdistributing and transporting natural gas for industrial and civil use. In light of the above,specific emphasis was devoted to: detailed study and data collection on the Almatyregion; estimate response of buried pipeline to8-earthquakes using static and seismicanalyses; estimate damage states; and make the fragility curves.For this purpose, a large data of seismic information was presented and analyzed,classified on the basis of selected geotechnical, seismological and structural parameters.Special emphasis was devoted to continuous pipelines under ground shaking, which isthe geotechnical consequence due to transit of waves in soil. The ABAQUS softwarewas chosen to simulate response of the pipeline system when subjected to earthquakes.It was chosen as a method of simulation because of its comprehensive material library.It simplified representation of the problem in to a3D simulation comprising of soil andpipeline; shell and solid elements; and pipe-soil interaction.This thesis provides deterministic fragility curves based on numerical (FEM)analyses for the seismic risk assessments of continuous natural gas pipelines underwave propagation. Different factors affect the response of continuous pipelines understatic and seismic loads and many of those such as material, diameter, boundaryconditions, soil characteristics, were considered in the simulation of a pipeline-soilfinite element model. The numerical model was validated with the real case of a steelpipeline located in Kazakhstan, subjected to the effect of8-earthquakes.For a natural gas pipeline, the most likely damage would be in clay soil with hingeboundary conditions depending on other type of soil.In this thesis, an analysis was made of a pipeline under static and seismic forces,in order to find the damage state and the fragility curves for the pipeline network systemtransporting natural gas from Kazakhstan to China, in order to identify hazardouslocation in the system and prevent losses.