This paper describes how the design of a catenary riser can be formulated a
s an optimization problem by ruing riser costs as the criteria function, de
sign requirements in terms of maximum allowable stress and buckling capacit
y as constraints, and riser dimensions as free variables. The theory has be
en implemented in a computer program that can generate an optimized riser d
esign for given design parameters such as water depth, diameter, pressure,
and platform excursions. The developed software consists of a conventional
program for two-dimensional riser analysis and a set of standard routines t
o minimize a nonlinear function subjected to general constraints. A case st
udy where design parameters and requirements have been varied is also prese
nted The importance of buckling versus allowable equivalent stress as the m
ost critical constraint has been investigated for varying water depth. The
conclusion of this work is that optimization is a useful tool for riser des
ign, and that the proposed strategy for selection of design variables and c
onstraints will enable an engineer to identify designs with minimum costs i
n art efficient way.