Seismic Evaluation of Buried Pipelines

This paper presents two methods of analysis for buried pipelines subjected to seismic wave propagation effects, temperature load, and internal pressure. The use of closed-form equations for analysis of a single bend with arbitrary bend angle subjected to seismic ground strain, temperature load, and internal pressure is first presented. For pipelines with complex geometries, such as horizontal and vertical bends, compound bends, vertical risers, tees, and attachments to large structures, a finite element analysis procedure is developed to predict the seismic behavior. The three-dimensional finite element model can account for the pipe-soil interaction, joint slack, and other material non-linearities, such as, concrete tensile softening and steel yielding. The analysis is performed for combined effects of seismic wave propagation, temperature load, pressure load, equipment load, and permanent ground motion. As an example, the use of finite element analysis in predicting the seismic behavior of a circulating water concrete pressure pipe in a power plant is presented.