The strong interest in very large floating structure (VLFS) is a result of a need to utilize effectively the ocean space for transportation, industrial use, storage, habitats, and military bases, among others. The VLFS has great width and length and relatively small flexural rigidity, therefore, investigation of its hydroelastic behavior including fluid-structure interaction is of greater importance than studies of its motion as rigid bodies. In addition to the most important wave-induced responses, the operation of the VLFS also requires determination of its dynamic responses with respect to the effect of unsteady external loading due to intense traffic, load movement, takeoffs and landings of airplanes, missile takeoffs, etc. Therefore, the transient responses of a VLFS to impulsive and moving loads must be studied by a reliable calculation method. In this study, a finite element procedure developed directly in time domain for solution of transient dynamic response of the coupled system consists of a VLFS and a fluid domain subjected to arbitrary time-dependent external loads is presented. The hydrodynamic problem is formulated based on linear, inviscid, and slightly compressible fluid theory and the structural response is analyzed under the thin plate assumption. For numerical calculations, a scaled model of the Mega-Float is exemplified. Three tests—weight pull-up test, weight drop test, and weight moving test which idealize the airplane landing and takeoff—are carried out and compared with published experimental data. The overall agreement was favorable which indicates the validation of the present method.

1.
Kashiwagi
,
M.
, 1999, “
Research on Hydroelastic Responses of VLFS: Recent Progress and Future Work
,”
Proceedings of the 9th International Offshore and Polar Engineering Conference
, Brest, France, May 30-June 4, ISOPE, pp.
17
26
.
2.
Kim
,
J. W.
, and
Webster
,
W. C.
, 1996, “
The Drag of an Airplane Taking Off From a Floating Runway
,”
Proceedings of the 2nd International Workshop on Very Large Floating Structures
, Hayama, Japan, Nov. 25-28, SRI, Japan, pp.
235
241
.
3.
Yeung
,
R. W.
, and
Kim
,
J. W.
, 1998, “
Structural Drag and Deformation of a Moving Load on a Floating Plate
,”
Proceedings of the 2nd International Conference on Hydroelasticity in Marine Technology
, Fukuoka, Japan, Dec. 1-3, SRI, Japan, pp.
77
88
.
4.
Watanabe
,
E.
, and
Utsunomiya
,
T.
, 1998, “
A Response Analysis of a Very Large Floating Structures by FEM and a Sponge Layer for the Unbounded Domain
,”
IUTAM Symposium on Computational Method for Unbounded Domains
, Colorado, July 27-36,
Kluwer Academic
, Dordrecht, The Netherlands, pp.
295
304
.
5.
Ohmatsu
,
S.
, 1999, “
Time Domain Analysis of Hydroelastic Behavior of VLFS
,”
J. Kansai Soc. Nav. Archit.
1346-7727,
184
, pp.
223
230
.
6.
Endo
,
H.
, and
Yago
,
K.
, 1999, “
Time-History Response of a Large Floating Structure Subjected to a Dynamic Load
,”
J. Kansai Soc. Nav. Archit.
1346-7727,
186
, pp.
369
376
.
7.
Endo
,
H.
, 2000, “
The Behavior of a VLFS and Airplane During Take-Off/Landing Run in Wave Conditions
,”
Mar. Struct.
0951-8339,
13
, pp.
477
491
.
8.
Kashiwagi
,
M.
, 2000, “
A Time-Domain Mode-Expansion Method for Calculating Transient Elastic Responses of a Pontoon-Type VLFS
,”
J. Mar. Sci. Technol.
0948-4280,
5
, pp.
89
100
.
9.
Lee
,
D. H.
, and
Choi
,
H. S.
, 2003, “
Transient Hydroelastic Response of Very Large Floating Structures by FE-BE Hybrid Method
,”
Proceedings of the Thirteenth International Offshore and Polar Engineering Conference
, Hawaii, May 25-30, ISOPE, pp.
100
105
.
10.
Kashiwagi
,
M.
, 2004, “
Transient Responses of a VLFS During Landing and Take-Off of an Airplane
,”
J. Mar. Sci. Technol.
0948-4280,
9
, pp.
14
23
.
11.
Qiu
,
L.
, and
Liu
,
H.
, 2005, “
Transient Hydroelastic Response of VLFS by FEM with Impedance Boundary Conditions in Time Domain
,”
China Ocean Eng.
0890-5487,
1
, pp.
1
9
.
12.
Sommerfeld
,
A.
, 1949,
Partial Differential Equations in Physics
,
Academic
, New York.
13.
Chapman
,
D. C.
, 1985, “
Numerical Treatment of Cross-Shelf Boundaries in Abarotropic Coastal Ocean Model
,”
J. Phys. Oceanogr.
1520-0485,
15
, pp.
1060
1075
.
14.
Orlanski
,
I.
, 1976, “
A Simple Boundary Condition for Unbounded Hyperbolic Flows
,”
J. Comput. Phys.
0021-9991,
21
, pp.
251
269
.
15.
Israeli
,
M.
, and
Orszag
,
S. A.
, 1981, “
Approximation of Radiation Boundary Conditions
,”
J. Comput. Phys.
0021-9991,
41
, pp.
115
135
.
16.
Hamilton
,
J. A.
, and
Yeung
,
R. W.
, 2003, “
Spectral Shell and Perfectly Transparent Open-Boundary Condition for Unsteady Wave-Body Interactions
,”
ASME J. Offshore Mech. Arct. Eng.
0892-7219,
125
, pp.
9
16
.
17.
Zienkiewicz
,
O. C.
, and
Taylor
,
R. L.
, 2000,
The Finite Element Method
,
5th ed.
Butterworth-Heinemann
,
Oxfod, UK
.
18.
Blayo
,
E.
, and
Debreu
,
L.
, 2005, “
Revisiting Open Boundary Conditions From the Point of View of Characteristic Variables
,”
Ocean Modelling
,
9
,
231
252
.
19.
Sturova
,
I. V.
, 2002, “
Unsteady Behavior of an Elastic Beam Floating on Shallow Water Under External Loading
,”
J. Appl. Mech. Tech. Phys.
0021-8944,
43
(
3
),
415
423
.
20.
Hilber
,
H. M.
,
Hughes
,
T. J. R.
, and
Taylor
,
R. T.
, 1977, “
Improved Numerical Dissipation for Time Integration Algorithms in Structural Dynamics
,”
Earthquake Eng. Struct. Dyn.
0098-8847,
5
, pp.
283
292
.
You do not currently have access to this content.