Abstract
During tendon towing the pipe is floating in a horizontal plane parallel to the sea-surface unlike the usual vertical slender members like risers, mooring lines, etc where the pipe/cable is perpendicular to the sea-surface. This change in projection of the surface of the pipe to the current and wave direction requires that the drag force, lift force and other forces acting on the pipe be considered to suit the horizontal profile, unlike the usual riser/mooring line model. Software are available to solve more conventional slender members, however the validity of the software for analyzing tendon towing has to be checked by comparing the results with that of another established software or theory. In this dissertation a simple analytical method (tensioned string model) is developed to analyze selected simplified sub-surface tow examples under static and dynamic loads using ORCAFLEX. The effect of the in-line (tangential) component of the drag force, which is usually neglected in the slender members like risers/mooring lines standing in the vertical direction, is estimated. Also the effect of different current direction on tendon profile is studied. Two independent software, WINPOST and ORCAFLEX are used to analyze a simple horizontal pipe model to validate the results against each other. Also to facilitate more general understanding of the problem, different towing methods for slender members have been briefly discussed and the methods are compared for their suitability for tendon towing.
Mendon, Perdoor Mukthi (2002). Analysis of sub-surface towing of tendons and comparison of results using WINPOST and ORCAFLEX. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -2002 -THESIS -M85.