Numerical Analysis of Buried Pipelines with Right Angle Elbow under Wave Propagation

AbstractPipelines are often referred as “lifelines” and this demonstrates that pipelines play an important role in human's life. Due to huge length and wide geographical distribution of pipelines, they are subjected to more seismic hazards. Seismic wave propagations affect the operation of buried pipelines which influence safety of these systems during and after earthquakes. Wave propagation causes out-of-phase displacements through pipe's longitudinal axis. As a result of more gradient and concentration of stresses and strains, damages increase in bend areas. Considering this subjects, it is crucial to study the buried pipelines’ behavior especially in elbow regions. The interaction between soil and pipe has been evaluated by using nonlinear springs as suggested by American Lifeline Alliance which can consider slipping between pipe and soil. In 3D finite element models used in this study, applied wave is distributed spatially as a sine wave over the longitudinal leg of elbow. Results showed that mechanical properties of soil can affect the response of pipe in elbow region. In the presented paper, in addition to using beam model, a beam - shell hybrid model is used to find the pipe response in the elbow region and the results of these two methods are compared