The effects of plastic yielding and tension on suspended pipelines
Serpas, Raymond Joseph
Wilhoit, James C.
Master of Science
In this thesis, a method for determining the shape of an underwater pipeline suspended under tension together with the forces acting on it is derived for the purpose of evaluating the effect of yielding on the pipeline. This yielding may occur either before the pipe is suspended from a lay barge or in the suspended portion. The method employs a trilinear approximation to the experimental nonlinear moment versus curvature diagram for the pipe in order to account for any yielding. A Taylor's Series approach along with a finite element, initial value method, is used to solve the nonlinear shape description equation for the pipe. A 16-inch O.D. pipe is used as a test case. It is concluded that yielding of the pipe has no significant effect on the depth attainable, and a small amount of horizontal tension can be used to eliminate the yielding and also control the moment distribution in the pipe.