A Continuum Shell-beam Finite Element Modeling of Buried Pipes with 90-degree Elbow Subjected to Earthquake Excitations

  In the current work, the seismic analysis of bent region in buried pipes is performed, and effects of soil properties and modeling methods on pipe’s response are investigated. To do this task Beam, Beam-Shell Finite Element modeling and a Continuum shell FE models of a 90 degrees elbow are employed. In the Beam model, the pipe is simulated by beam elements while combined shell-beam elements are used for the Continuum shell finite element model. The surrounding soil is simulated by nonlinear spring and solid elements; moreover, soil hardening behavior and soil-pipe slippage are considered in the models. In addition, an equivalent boundary condition has been employed at the end of each elbow leg to simulate far field effects more closely. From these analyses, it can be revealed that axial strain at bends is larger in stiffer soil due to smaller slippage. In addition, a full three dimensional soil-pipe interaction using Continuum Shell FE model causes a substantial increase of elbow strain.