ssc-367 - Ship Structure Committee

More documents

Recommendations

Info

TOP[C U.K.DEPARTMENTOF ENERGY(OEn) AMERICANPETROLEUMINSTITUTE GENERALCONSIDERATIONS o Fatiguelife Life*~Servlce Life Life> 2x Serv~ceLife o FatigueLoading o FatigueAnalyslsjDes~gn All cyclicloads(Ref.21.2.1OC) (Ref.5.2.5) - SimplifiedMethod No Yes,allowablestressmethod appl~cableto Gulfof~exlco (GOM) (Ref.5.1.1) - DetailedAnalysis Recommended Recommendedfor: waterdepth~400 ~t (122m),or * lifeshouldnotbe 620years - platformperiod> 3 see,or andan additionalfactoron - environmentharsherthanGOM Ilfeis recommendedwhen (Ref.5.1.2) structuralredundancyis ln~dequate(Ref.21.2.10f) DETERMINATIONOF STRESSES o Ob.ject~ve To determinecycl~cstressranges To determineCYCIICstresses (j.e.,meanstressesare neglected- properlyaccountingactualj Ref.21.2.11) distributionof waveenergyover entirefrequencyrange,spectral analysistechniquesare recommended. o Modeling No spectficreference Spaceframeanalysistoobtaln structuralresponseandstress distribution(Includlngdynnmlc effects) o Analysis A detailedfatigueanalyslsallowln9 Typically,spectralanalysisto eachcrltlcalareato be considered. determinestressresponsefor each sea state. J Page1 of 5 . Figure4-7 Comparisonof Recommendations U.K.GuidanceNotesandAPI RP 2A
~ AMERICAN ETPOLEUMlNSTITUTE )tiotSpotStress RangeIs theproductof the nom~na~ RangeIsohtalnedby multiplyingthe stressrangeIn the braceandthe nominalstressrangeat’tubular SCF. ItIncorporatesthe effectsof jointby SCF. overalljointgeometrybut.omitsthe stre<strong>ssc</strong>oncentratingInfluenceof theweld itself. iTRESSCONCENTRATION ‘ACTORS(SCFs~ } Scf ho referencesgiven SCFSdefinedarebaseduponmodl~led Kelloggformulas forchord and Marshallformula[ forbrace 1 (Ref. C5.1,Table5.1.1-1) ISimpleJoints- Nodal JEmpiricalEquations OtherJoints iTRESSHISTORY Nonedefined Noned~flned SCFSdefinehot spotstresses Immediatelyadjacentto the olnt intersection(0.25”toO.1d from weldtoe,Ref.C 5.4) K, T, Y andX jointsdefinedfor axial,In-planeandout~ofplane loading Recommendsa braceSCF~6 (Ref.5.5) )WaveClimate Page2 of 5 i Figure4-7 Comparisonof Recommendations U.K.GuidanceNotesandAP1fW 2A Waveclimatesmay be derivedfrom bothrecordeddataandhlndcasts. Aggregateof allsea statesto be expectedoverthe longterm condensedIntorepresentativesea states. A sea state,characterized by wave energyspectrumandprobabilityof occurrence,may be definedby: o Twoparameterscatterdiagrams o Directionalscatterdiagrams o i)lrectlonalscatterdiagramswith spreading
Page 1:
SSC-367 - FATIGUE TECHNOLOGY ASSESS
Page 4 and 5:
SHIP STRUCTURF COMMllTFF The SHIP S
Page 6 and 7:
—.--— 1. Report No. 2. Gowotnmr
Page 8 and 9:
FATIGUE TECHNOLOGY Assessment AND D
Page 10 and 11:
6. FATIGUE STRESS HISTORY MODELS 6,
Page 12 and 13:
APPENDICES A. REVIEW OF OCEAN ENVIR
Page 14 and 15:
D. VORTEX SHEDDING AVOIDANCE AND FA
Page 16 and 17:
LIST OF FIGURES (cent.) FIGURE TITL
Page 18 and 19:
HOT-SPOT STRESS . The hot-spot stre
Page 20 and 21:
QA/Qc : Quality Assurance/QualityCo
Page 22 and 23:
1. INTRODUCTION 1.1 BACKGROUND The
Page 24 and 25:
general assessmentof fatiguewhile t
Page 26 and 27:
2. OVERVIEW OF FATIGUE 2.1 FATIGUE
Page 28 and 29:
2.2 FATIGUE ANALYSIS 2.2.1 Anal.vsi
Page 30 and 31:
● Loads generated as affected by
Page 32 and 33:
A deterministic method is sometimes
Page 34 and 35:
1 APPLICATION OF NUMEROUS CYCLIC ST
Page 36 and 37:
I MOBiLEANDSTATIONARY MARWE STRUCTU
Page 38 and 39:
3. FATIGUE DESIGN AND ANALYSIS PARA
Page 40 and 41:
and in-plane/out-of-planeangles,and
Page 42 and 43:
the general quality of fabrication,
Page 44 and 45:
3.2 REVIEW OF FATIGUE ANALYSIS PARA
Page 46 and 47:
frequencies of interest, requiring
Page 48 and 49:
● Reqular Waves in FrecjuencvDoma
Page 50 and 51: The finite element models of increa
Page 52 and 53: The stressmodel parametersdiscussed
Page 54 and 55: While API S-N curves are applicable
Page 56 and 57: DESIGN Osn40H rAnNsirsR8 FAMcA~ M P
Page 58 and 59: Primarily Affect .--------+’ & In
Page 60 and 61: MOTIONS MODEL — .—. ● ;LOADS
Page 62 and 63: loa 1 10 -— — — -t-i-nT 1[ -t
Page 64 and 65: 4. GLOBAL REVIEW OF FATIGUE 4.1 APP
Page 66 and 67: An allowable stress method, also co
Page 68 and 69: esults of work covering assessment
Page 70 and 71: location. Thus, the method should b
Page 72 and 73: 1. SDectral FaticlueAnalvsis Althou
Page 74 and 75: 2. Weibull AtIDroach The Weibull sh
Page 76 and 77: energy about the central direction
Page 78 and 79: Although considered to be an emergi
Page 80 and 81: many design rules implement this ap
Page 82 and 83: Detailed Anal.vsisMethods The detai
Page 84 and 85: The DnV X-curve and the DEn Guidanc
Page 86 and 87: ending restrictions. Cruciform and
Page 88 and 89: period, are also designed tomeet th
Page 90 and 91: incorporates inspection-strategy(Re
Page 92 and 93: ‘Thereare numerous finite element
Page 94 and 95: LOCATIONs oF FATIGUE CMCKS Figure 4
Page 96 and 97: TW=’T ——— ———___ __ r
Page 98 and 99: 1 —. — — — — -.. - .. - .
Page 102 and 103: :1 U.K.DEPARTMENTOF ENERGY(DEn) AME
Page 104 and 105: TOPIC U.K.DEPARTMENJOFEIWRGV(oEn) O
Page 106 and 107: 5. FATIGUE STRESS MODELS 5.1 REVIEW
Page 108 and 109: ● The water particle kinematicsar
Page 110 and 111: “radiation pressure” of waves,
Page 112 and 113: influence on the applied loading. H
Page 114 and 115: their function, selecting appropria
Page 116 and 117: hydrostatic stiffness is introduced
Page 118 and 119: structure is unique and an allowabl
Page 120 and 121: loads directly. Since the diffracti
Page 122 and 123: typically from 0.6 to 0.8 and 1.5 t
Page 124 and 125: therefore be defined uniformly alon
Page 126 and 127: load analysisof adetailed three-dim
Page 128 and 129: esponsesare required , or where con
Page 130 and 131: either multiple stick elements (for
Page 132 and 133: Braces may have stubs or cones, whi
Page 134 and 135: Whatever the basis for an empirical
Page 136 and 137: The SCF equations currently in use
Page 138 and 139: life. During the comprehensive desi
Page 140 and 141: ?.s I z - ]LEvE~ ~ 1,5 \ i i+ 11 Is
Page 142 and 143: -. Figure 5-5 Comparison of Detaile
Page 144 and 145: ( -t ) ( T-JOINT Y-JOINT ( \ I / K-
Page 146 and 147: SMEDLEY-WORDSWORTH 0 d =— = D 600
Page 148 and 149: Wave Records Older wave and wind in
Page 150 and 151:
In many cases wind informationmay b
Page 152 and 153:
q = 3.3 s = 0.07, for f< fm s = 0.0
Page 154 and 155:
Seasonal Variation The annual wave
Page 156 and 157:
4. ~arpkaya spreading. (Reference 6
Page 158 and 159:
~. \“ life of a structure,cannot
Page 160 and 161:
6.3 TIME-DOMAIN ANALYSES Nonlinear
Page 162 and 163:
The wave environmentdefinitionsbase
Page 164 and 165:
.,..,, ....- ., ;., .. .... .- .. .
Page 166 and 167:
● Fatiguetest data should be care
Page 168 and 169:
assessmentis typically identifiedas
Page 170 and 171:
damage accumulation similar to that
Page 172 and 173:
“FabricationRestrictions Fabricat
Page 174 and 175:
Fatigue strength of a tubular joint
Page 176 and 177:
Current recommendations,rules and s
Page 178 and 179:
n NB=T 1 [p=+pi Ei . ‘c where: NB
Page 180 and 181:
(2) Damage computation does not acc
Page 182 and 183:
DNB = (f. T/K) (2/2 U)m r (f+ 1) wh
Page 184 and 185:
interactionof multiple fatigue crac
Page 186 and 187:
amplitude loading and loading seque
Page 188 and 189:
n“ CAP PASSES ROOT = * { A A 4 I
Page 190 and 191:
It should be pointed out that the e
Page 192 and 193:
v= flow velocity normal to the cyli
Page 194 and 195:
8.4 METHODS OF MINIMIZING VORTEX SH
Page 196 and 197:
Ra < S REGIME OF UNSE?ARATE~ FLOW 5
Page 198 and 199:
ages. The designer has no control o
Page 200 and 201:
failure data on various structures,
Page 202 and 203:
connections, knife edge crossings,
Page 204 and 205:
9.3.1 Fabrication Effects The fatig
Page 206 and 207:
● Controlled Erosion An alternate
Page 208 and 209:
after a given number of stress cycl
Page 210 and 211:
A second pass with polishingdisc is
Page 212 and 213:
others. Extensive analytical and ex
Page 214 and 215:
d) Stress SDectrum Hot-spot stresse
Page 216 and 217:
Cumulativefatiguedamagecomputations
Page 218 and 219:
as a parametric study intended to i
Page 220 and 221:
Additional areas requiring further
Page 222 and 223:
GROUP Modification of Weld Profile
Page 224 and 225:
400 ‘,, . . 350 - I I 300r [ ~ ,0
Page 226 and 227:
TOPIC SUBJECT INVESTIGATOR COMPLETI
Page 228 and 229:
3.1 Soyak, J. F., Caldwell, J. W.,
Page 230 and 231:
4.12 Daidola, J.C., and Basar, N.S.
Page 232 and 233:
5.4 Papanikolaou,A. and Zaraphoniti
Page 234 and 235:
5.21 -”’ ” ”---”---”
Page 236 and 237:
“7.2 Jordan, C.R., and Cochran, C
Page 238 and 239:
7.19 Niemi, E.J., “FatigueTests o
Page 240 and 241:
9.1 Skaar, K.T., “ContributingFac
Page 242 and 243:
COMMllTEE ON MARINE STRUCTURES Comm
Page 244 and 245:
U.S.Department of Transportation Un
Page 246 and 247:
Member Agencies: United States Coas
Page 248 and 249:
‘ METRIC CONVERSION FACTORS Appro
Page 250 and 251:
APPENDIX A REVIEW OF OCEAN ENVIRONM
Page 252 and 253:
The most distinctive feature-of a r
Page 254 and 255:
s(w) = 2*(4*112) - For a “height
Page 256 and 257:
common probability distributions, t
Page 258 and 259:
T: v. Visually Observed Period, or
Page 260 and 261:
The characteristic wave heights of
Page 262 and 263:
H~ is the significantwave height, a
Page 264 and 265:
a = 0.09, for UJ>wm The U value of
Page 266 and 267:
H~ is the significant height, ‘m
Page 268 and 269:
If the wind duration is less than t
Page 270 and 271:
Sample Wave scatter Diagram s 12 +.
Page 272 and 273:
Nm is the total number of waves in
Page 274 and 275:
turbulence largely a function of te
Page 276 and 277:
Applied Wind Speed Vz(t) ft/s (m/s)
Page 278 and 279:
A.1O REFERENCES A*I Mechanics of Wa
Page 280:
APPENDIX B REVIEW OF LINEAR SYSTEM
Page 283 and 284:
Awhite noise function-may be used t
Page 285 and 286:
Multiplication of the wave spectrum
Page 287 and 288:
B.2.2.2 Response Amplitude Operator
Page 289 and 290:
0.2.3 Wave Spectra The wave spectru
Page 291 and 292:
9 is the acceleration of gravity in
Page 293 and 294:
The following is..a. sample...of..a
Page 295 and 296:
is the damping ratio,..the ratio of
Page 297 and 298:
the set of extreme conditions, and
Page 299 and 300:
A response scatter diagram could be
Page 301 and 302:
2.4 2.2 2 1 ‘Sen &-”Swull$p~ctr
Page 303 and 304:
L ‘2
Page 305 and 306:
o Kuang (ReferenceCl) “ o Wordswo
Page 307 and 308:
C.2 STRESS CONCENTRATION FACTOR EQU
Page 309 and 310:
C.3 PARAMETRIC STUDY RESULTS . C.3.
Page 311:
30. 2s , 20. 15. 10. 5. & wORDSWORT
Page 314 and 315:
ChordSide Brace Side K-Joints SCFU
Page 316 and 317:
Definition of Parameters, Validitv
Page 318 and 319:
-, l— I + ?1 -— I . 4> a ,- I I
Page 320 and 321:
Kuang SCF Computdion 1 L u UI \ f-
Page 322 and 323:
., I , 1- out— FIano SCF m tg n I
Page 324 and 325:
— 6 Smedley-Wordswoti SCF Computa
Page 326 and 327:
T ln— Plan- SCF CrOwn POsltlon o
Page 328 and 329:
C.3.l(C) Kuang Chord SCF’S for T-
Page 330 and 331:
5 Kuang SCF Computation 4 IL u M 3
Page 332 and 333:
C.3.l(d) Smedley-WordsworthChord SC
Page 334 and 335:
. ,i 5 Smedley-Wordsworth SCF Compu
Page 336 and 337:
I I K Out— Plan= SCF —— Saddl
Page 338 and 339:
- 10 Smedley-Wordsworth SCFComputat
Page 340 and 341:
‘\, ?v x out— Plan- SCF ——
Page 342 and 343:
C.3.2(a) Kuang Chord SCF’S for T-
Page 344 and 345:
KuwqSE _im T-joint In%neW UrrdSicko
Page 346 and 347:
C.3.2(b) Smedley-HordsworthChord SC
Page 348 and 349:
T-joint Axial SF Saddle Posiiim
Page 350 and 351:
-— T-joint CtkuHlane ELFSaddlePci
Page 352 and 353:
I 1 1 1 1 ~. l~o ~ ha= 1s0 : ~. ~J
Page 354 and 355:
1 ! ! O.fi ;0.762 %841 0,769 O,= !0
Page 356 and 357:
Ikrdwth-kdlw SF l%quiaiifm K-joint
Page 358 and 359:
hdsmthqwdhy W Camputatim l-joint Ax
Page 360 and 361:
Ejrnnt flkf+lane SF SaddlePmitim ~,
Page 362 and 363:
MAXIMUM PRINCIPAL STRESS SCF = ----
Page 364 and 365:
‘-W, .\ I Ill I : II m -,, !) .
Page 366 and 367:
’ \./ ““’ w~”mm m ““-
Page 368 and 369:
. . I Column L’ Longitudinal Gird
Page 370 and 371:
C.8 Underwater Engineering Group,
Page 372 and 373:
APPENDIX D VORTEX SHEDDING AVOIDANC
Page 374 and 375:
a an b d f“ f ar f~ ‘bmax f~ fn
Page 376 and 377:
D. VORTEX SHEDDING 0.1. INTRODUCTIO
Page 378 and 379:
Vortex Shedding Frequency (f”) fv
Page 380 and 381:
waves. When only isolated members u
Page 382 and 383:
member’s nominal diameter and thi
Page 384 and 385:
\Lf-! of cycles. Thus, the reduced
Page 386 and 387:
s ; J steady current, by substituti
Page 388 and 389:
Step 3: Obtain a new valueof 1/10 b
Page 390 and 391:
vortex shedding will occur, i.e., V
Page 392 and 393:
h. The fatigue life may -be modifie
Page 394 and 395:
NOTE: The relationship given is bas
Page 396 and 397:
CELL C7: KINEMATIC VISCOSITY = U CE
Page 398 and 399:
COLUMN N: THE STRESS AMPLITUDE IS C
Page 400 and 401:
D.8.3 Devices and Spoilers Devices
Page 402 and 403:
D*9 REFERENCES D.1 King, R., “A R
Page 404 and 405:
Fint Insmbility Rtgion I !%mmd Inat
Page 406 and 407:
.—____ *U.S. E.P.O. :1993-343-273
Page 410 and 411:
COMMllTEE ON MARINE STRUCTURES Comm
Page 412:
4!! . ,—.-.,
show all

ssc-367 - Ship Structure Committee

Create successful ePaper yourself

Delete template?

Save as template?