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30 3B 2010 5 315
30 3B2010 5
pp. 315 ~ 324
Development of a Design Chart for the Initial Design Stage of Very Large Floating Structures
**********
Zi, GoangseupKim, Jin GyunLee, Seung OhLee, Phill-Seung
Abstract
We developed a design chart for very large floating structures through intensive hydroelastic analysis. Using this chart, one can
predict the hydroelastic response of very large floating structures preliminarily at design stage without the cost-demanding
hydroelastic analysis. This paper presents two new design charts based on the theory of VLFS. The purpose of the first design chart
is to determine RAOs of the maximum longitudinal stress of VLFS considering properties of waves and structures. The design
chart I can be applied to any sizes of VLFS in same aspect ratios and dimensionless stiffness parameters. The second design chart is
developed to take into account the actual wave condition by using the Bretschneider spectrum with Beaufort sea state.
Keywords : VLFS, design chart, hydroelastic analysis, wave spectrum, spectrum analysis
.
.
I, II . I
. I
. I II , Beaufort
Bretschneider .
: , , , ,
1.
(Very Large Floating Structure;
VLFS)
, ,
, , LNG ,
. VLFS
MOB (ONR, 1997~2000),
MHP (NFESC, 1998~2004), (TRAM,
1995~2001)
.
1999 , KAIST
2009
(, 2008; KAIST, 2009).
VLFS , ,
. VLFS
VLFS .
.
VLFS 1980
(Ando , 1983; Bishop , 1983).
.
2
,
.
(Webster , 1994; , 2001).
* (E-mail : [email protected])
** () (E-mail : [email protected])
*** (E-mail : [email protected])
**** (E-mail : [email protected])
-
316
VLFS
. VLFS
(Andrianov, 2005) ,
(2006, 2008)
.
, VLFS
VLFS
.
,
,
(characteristic length, c)
(Suzuki, Yoshida, 1996). 100
m (Lw)
100 m 8
. VLFS
50:1 VLFS
(ISSC,
2006; , 2008).
VLFS
,
, .
.
,
2~3 .
,
.
VLFS
,
.
VLFS
.
VLFS ,
.
2. VLFS
2.1
.
, , ,
(Newman, 1994).
I, S,
R .
(1)
,
,
.
.
(a) Laplace :
(b) (z=0):
(c) :
(d) : 0
(e) :
p (Reza , 2006).
(2)
z t , , g
. (2)
F M .
(3)
(4)
, n , r
. (3) (4)
.
(5)
mij, dij, kij , , , aij,
bij, cij (added mass), (damping),
I S R+ +=
2
0=
p gz t=
F pn Sds=
M p r n( ) Sds=
2
mpq apq+( ) i bpq dpq+( ) cpq kpq+( )+ +[ ]qp
j 1=
N
F pexct
=
1. VLFS
-
30 3B 2010 5 317
(hydrostatic) ,
. ,
, ,
.
(6)
, p . p=1
.
,
. (3) (4)
, .
2.2 VLFS RAO
VLFS 1
. VLFS
1
. 1
VLFS
.
(1) (6)
, (6)
p p
.
(7)
(x, y, z) (6) (7) .
(Response amplitude operators, RAO)
(6)
.
(8)
RAO .
4 RAOp
RAO . ,
RAO
RAO .
2.3 VLFS
( ) .
VLFS
, ,
(Riggs , 2007; , 2008;
, 2008; Kim , 2009). ,
.
,
.
3. VLFS
3.1
VLFS
1 . 1
qi
qi
ui up x y z, ,( )qp
p 1=
=
up x y z, ,( )
F iexct
qp up
qp qp0
cos t p+( ) isin t p+( )+[ ]=
RAO x y z, ,( ) up x y z, ,( )qp0cos
p( )
p 1=
2
up x y z, ,( )qp0sin
p( )
p 1=
2
+=
up x y z, ,( ) p x y z, ,( ) Mp x y z, ,( )
2. (RAO)
1.
Lw(T) (wave length)
S(f) (wave spectrum)
Ls, Ws, Ds , , a(f)
(wave amplitude)
T, f , xx
(longitudinal stress)
(wave induced angle)
Mu (ultimate bending capacity)
S (section modulus)
2.
(aspect ratio)Ss
(stiffness parameter)
(dimensionless wave length)
L
3.
-
318
,
. 2
.
(aspect ratio, )
( 3).
VLFS
. (9) Ls
Ws .
(9)
=5 10
.
Ls
Ws------=
4. I, ( =5)
-
30 3B 2010 5 319
VLFS
VLFS
. (10) .
(10)
, Lw (m), Ls VLFS (m)
. .
(11) (Wang
, 2008).
(11)
, T (sec) .
.
Lee Newman(2000)
L
L
LLw
Ls------=
Lw 1.56T2
=
5. I, ( =10)
-
320
(12) .
(12)
, Ss , E , I
, s VLFS , g
, L .
3.2 I:
I,
II . I VLFS
RAO
. I
(wave induced angle, ), (dimen-
sionless wave length, ),
(dimensionless stiffness parameter, Ss)
(aspect ratio, )(Lee, Newman, 2000).
,
. ,
RAO. 0.70106 4.90106
. 0o 90o
. I
RAO
.
4 5 5 10 I
7 . I
7 0o 90o
. I ,
1/4 .
I
RAO .
RAO ,
RAO
. RAO
5 10 RAO
5 .
3.3 II:
,
.
RAO
(ultimate bending capacity,
Mu) .
Bretschneider
. Bretschneider (9)
.
(13)
, H1/3 (m), T1 (average wave
period, sec), f (rad/sec) .
VLFS
.
(13) H1/3 T1
6a 1 12
SsEI
sgL5
--------------=
L
S f( ) 173H1 3
2T1
4f
5exp 692T
1
4f
4( )=
6. Beaufort
7.
-
30 3B 2010 5 321
Beaufort (Journee Massie,
2001).
fi ai (14)
.
(14)
6 VLFS
I RAO
,
Mu (15) .
(15)
, As , Larm
, , , (fi)s RAO
.
8 9 II .
S fi( )df1
2---ai
2=
Mu AsLarm fi( )a fi( )=
8. II : Mu ( =5, Ls=300 m)
-
322
7 II .
VLFS , ,
, VLFS
Beaufort . VLFS
II ,
, (Sreq) .
(Sdes)
VLFS .
.
.
9. II: Mu ( =10, Ls=100 m)
-
30 3B 2010 5 323
4.
. VLFS
5, 300 m, Ss
=2.80106 , VLFS
10 .
Sdes 5.7 m3.
12
.
II
1600103 kNm . 100
MPa Sreq 16 m3
. 400 MPa
4 m3
,
3.30106 ( 8).
1750103 kNm .
400 MPa 4.2 m3
.
II
5% .
VLFS
.
5.
,
. , ,
,
.
10. , 3D
11. II
-
324
,
.
.
. Beaufort Bretschneider
.
.
2010 ()
(2010-0015690)
(: 05B01)
.
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,
, , 18 3, pp. 356-360.
, , , (2006)
, ,
, 16 2, pp. 132-140.
(2008) .
(2001)
,
, , 38 4, pp. 39-47.
, , , , (2008,
, 2008
, , pp. 1123-1127.
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(: 2009.11.30/: 2010.2.3/: 2010.3.11)