Structural loading of cross deck connections for trimaran vessels
Abstract
This work investigates the fundamental relationships of wave loading on cross deck structures for trimaran vessels. In contrast with a monohull ship, trimaran vessels experience several possible structural loading cases including: longitudinal bending, transverse bending, torsional bending, spreading and squeezing of hulls, inner and outer hull slam pressures, wet deck slam pressures, loading from ship's motions, and whipping of slender hulls. This work investigates wave loading cases that result in transverse and torsional bending of the cross deck structure. The wave loading cases investigated include: side hull troughing and cresting in longitudinal waves, side hull torsion in longitudinal waves, and transverse hogging and sagging. For each of these load cases, a design load using a fully statistical sea state was derived using an analytical model of a trimaran represented by rigidly connected box barges. The design loadings with a reliability index of 5 for almost 500 trimaran configurations were calculated varying main hull length, side hull length, side hull transverse placement, and side hull longitudinal placement. The design loadings were curve fit to a fourth order polynomial in the three independent variables. The load predictions of the analytical box model of a trimaran were applied to a trimaran vessel with a realistic hull form using the finite element ship structural analysis program MAESTRO. Given the number of approximations and assumptions in the analytical model, the forces predicted by analytical model agreed closely with the finite element model's results. The fitted curve of design loadings allows an initial design stage loading estimate for cross deck structural loading, given general characteristics of length and spacing of a trimaran's hulls.
Description
CIVINS (Civilian Institutions) Thesis document
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.Related items
Showing items related by title, author, creator and subject.
-
Sensitivity analysis of the seakeeping behavior of trimaran ships
Kurultay, Aziz Alper (Monterey, California. Naval Postgraduate School, 2003-12);The dynamic response of the ship while operating in different sea conditions is one of the design parameters of a hull form. The objective of this thesis is to analyze the seakeeping response of trimaran hulls. A ... -
Sensitivity and trade-off analysis of wave making resistance and stability of small water plane area trimarans
Boudreau, Brian R. (Monterey, CaliforniaNaval Postgraduate School, 2007-09);Recent concept ship designs have called for a vessel with the capability to lift and transport multiple medium displacement combatant boats, approximately 40 to 100 tons, at high speeds over thousands of nautical miles. ... -
Orthotropic shell analysis of a ship's bottom section
Johnson, G. L. (Cambridge, Massachusetts; Massachusetts Institute of Technology, 1962-05);In the interest of developing more thorough methods of analyzing ship structures, an entire bottom section extending from side to side and from one bulkhead to another is analyzed as an orthotropic shell of variable ...