Vibration analysis of undersea pipelines with arbitrary bedding conditions

![CDATA[Offshore pipelines have been used extensively to transport hydrocarbons across seabeds. They serve as a critical link between storage units and offshore fields. The consequences of pipeline failure would be severe both economically and environmentally. Offshore oil and gas pipelines are being subjected to deeper water depths, more extreme environmental conditions, and harsher operating requirements than ever before. Given these conditions, free spanning pipelines are becoming more common and are often unavoidable during pipeline installation. Free spans occur as a result of irregular seafloor topography at installation or during pipeline operation as a result of vibration and scour. The pipeline with tree span or regional and local scour will suffer fatigue damage due to oscillatory loads induced by vortex shedding. In this paper, a general solution of the vibration of a pipeline system with arbitrary type of discontinuity at arbitrary number of locations is presented. The pipeline on the seabed is simplified as a simply supported beam on elastic foundation. Two parameters are used to describe the scour or free span in the pipeline that are the central location of the scour or span and the width of the scour or span. Due to the generic nature of the solution and the problem, the present method can be utilized in structural health monitoring of the underwater pipeline system.]]