4 - Memorial University of Newfoundland DAI

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Such s model is called a dynamically similar or hydrrrelastic model. This troatiar deals with thc dcsign, construction, instrumentation and testing of such a model lo carry out Structural Inlegrily Monitoring. To achicvc thia objective, a 1130th scale hydmeiastic model (made from ABS plastic) was constructed to simulate the dynamic behavior d a typical 13 m (240 it), lour lo& offshore tower. Themodel was tested in awave tank quipped with a paoudo random wavcmakingfscility. Ocean wave conditions were~imulated with regular and imgulsr waves. For the irregular warn, two direrent input wave spectra were used: I) a JONSWAP spectrum, and 2) a while noisc spectrum. A very extensive PORTRAN computer program (using a mmbination of w~ve mechanics and stcuctud mechanics) was written to simulate the expcrimentai conditions, and to obtain theoretical estimate8 of the dynamic bohaviar of tho model structure; ao a comparison bet- experiment and thmry could be made. Regarding inlegrity moniloring to detect damageof subsurface structural eo!nponcnt(a), global monitoring was uaed.' Global Monitoring ia based on an mlorometrie unit located on the deck of the structure excited by ambient vibration. Homver, to got n better picture of the global motion, and to increase thescnsitivity/resolution in the resonant frequency variations resulting fmm damaged member(#), three accelerometers were also installed along the jacket. One was plnced at tha node where the jacket and the deck nmet (i.e..at the mean watcr level),and two were installed (below the water) nt tile top and bottom of the bay containing themember(a)~hosen tosirnulato - 'An erannple of permanent global monitoring is on the BARBARA pl8tform in the Adriatic Scn, in 70 m ol valcr. Rum the analyra 01 the dala milmted, lour -"ant peak. wsrc dclmted, although Lllry were out or range of the wrur lwquendu [q.
structural damap. Stnctural damn@ wns simulated by pl~yaierlly anw- cutting the member(=) under consideration in the exporimonlnl n~odei. (171 the computer model, damage was simulated by making thc nmn~ber(s) tmndcr conaideration inactive in the analyses.) Eotirnates of modal pnmn~clcts--i.c., remnant frequencies, damping, ets.-fmm the nmbient strueturnl rrspottw data were attained using the mntly developed Marplc nlgorill~m with llnc Maximum Entropy Method (MEM). 1.2.2 Estimation of Modal Parameters Ertimatez of resonant frequencies and damping rntia obtained from tilo un- bient mponse spectra of a otrttcltmre by con~ventianal FFT rncthocl. (Rinck. man and Tukey [4]), have been shown lo bc inhcrcntly limited in rranl~otiu~m [la, 121. Thir mults because oi tho required tr!tncnlion el the extismt
Page 5 and 6: NOTICE The quallty of this microfor
Page 7 and 8: I*I Et"" :lbL="*"" k.. bpilmsa7d Di
Page 9 and 10: Acknowledgements I should like lo t
Page 11 and 12: Abstract As a result of the increas
Page 13 and 14: Contents List of Figures xii List o
Page 15 and 16: 4.6.3 Fnbrieatiox of tllc Rcduced M
Page 17 and 18: A Selected Algoilthma 278 A.1 Diago
Page 19 and 20: 4.5 Member Configuration at level #
Page 21 and 22: 7.21 Dynamic Mode # 6 (Intact Model
Page 23 and 24: 7.49 Typical Measured lnput Wnve Sp
Page 25 and 26: 7.66 hulls fmm Accelerometer A2 due
Page 27 and 28: D.ll DynamicMode # I (Intact Model)
Page 29 and 30: List of Tables 4.1 Symbols, Units a
Page 31 and 32: 8.9 Pacent Changes in Resonant Frrq
Page 33 and 34: List of Symbols d(k) .i(k) A A(L1 1
Page 35 and 36: autosp~trni density of r(t) cms-spe
Page 37 and 38: 0,1,2
Page 39 and 40: [@I a Pu. P. P:,," P.. o2(k) instan
Page 41 and 42: een recorded, then it is beneficial
Page 43: Associated with every vibration mod
Page 48 and 49: presenlcd. Chapter 3 contains the t
Page 50 and 51: al frequcncic. occurred when member
Page 52 and 53: detwM from the data roeorded (later
Page 54 and 55: y Duggan d a!. [a]. This study inve
Page 56 and 57: ~~lidity of the results war rompsro
Page 58 and 59: nic~~~aan:immcdiateiyuseful, they a
Page 60 and 61: tlncayatem hehavior oftrusswork pla
Page 62 and 63: Chapter 3 Theoretical Modelling Tll
Page 64 and 65: 3.2 Wave Theories Works by earlier
Page 66 and 67: F;-RY% WAVE THEORY) 1/20 I "w/Lw DE
Page 68 and 69: DIRECTION OF WAVE PROPAGATION FIG.
Page 70 and 71: liero, d and ita wlocity component
Page 72 and 73: and and a+ "=-. OY = wA~inl~IW(1+ s
Page 74 and 75: FIG.3.4 ARBITRARILY ORIENTED CYLIND
Page 76 and 77: ~i n long c mtd wave is being conai
Page 78 and 79: inrther. Ultimately, the resulting
Page 80 and 81: equcncia and mode shapes, equalion
Page 82 and 83: Toestablish tho relationship betwee
Page 84 and 85: Furthermore, from equation (3.56),
Page 86 and 87: lG.3.6 SIMULATED 3-D AND STICK MODE
Page 88: 1. priam&tic heam members, 5. sir d
Page 92 and 93: The equation of motion for each ele
Page 94: From tho ~tatic dispiaeemont muita,
Page 97 and 98:
instance, the non-dimensional equal
Page 99 and 100:
functional relationship relating th
Page 101 and 102:
whcre F, 't iinstantanmua force at
Page 103 and 104:
Table 4.1 Symbols, Unit. and Dimens
Page 105 and 106:
thc Buckinghm r-Thmrem (i.c., I2 te
Page 107 and 108:
That is, equations (4.28) and (4.29
Page 109 and 110:
C. Ilence, if the dynamic amplifica
Page 111 and 112:
where (2) is the general gmmdric or
Page 113 and 114:
the prolotype. Damping is dcfincd b
Page 115 and 116:
2 LEVEL # 7 1 28956DO NOTE: ALL DIM
Page 117:
Mataial= Structural Steel, E = 206.
Page 122 and 123:
LEVEL C6 NOTE: ALL DlMENStONS IN m
Page 124 and 125:
Table 4.5 Relevant Materiel Propert
Page 128 and 129:
FlG.4.9 COMPLETED STRUCTURE. 89
Page 132 and 133:
Since the de& sertioo of the struct
Page 134 and 135:
% FINITE ELEMENT ANALYSIS (COMPUTER
Page 136 and 137:
3 53 I CONTROL RM SECTION A-D. MEZZ
Page 139 and 140:
I I SERVO CONTROLLER MODEL 408.1% j
Page 141 and 142:
LEGEND FI B F2 FREE VlBllTlDN INITI
Page 144 and 145:
5.1.4 Response Circuit Data acquisi
Page 146 and 147:
I ~T.UG~U~E LEGEND: DYIIYT I., 10 A
Page 150 and 151:
the basis upon which the irregular
Page 152 and 153:
then manipulated by the computer ro
Page 154 and 155:
,.. G STRUCTURE IN STILL WATER STRU
Page 156 and 157:
dter every set of hen wave excitati
Page 158 and 159:
To gather spectral information fmm
Page 160 and 161:
is the timelag between silrnplev~l~
Page 162 and 163:
ics, with a lew notable exceptions,
Page 164 and 165:
If bath aides of the dove cguntion
Page 166 and 167:
Conversely, r(1) can be estimated b
Page 168 and 169:
quires ahout N(M + 1) + 9Y1 arithme
Page 170 and 171:
So equation (6.18) become: I, i = C
Page 172 and 173:
At each resonant frequency, the hdl
Page 176:
6.5 Impact Testing Impact testa wer
Page 179 and 180:
Chapter 7 Theoretical and Experimen
Page 181 and 182:
Table 7.1 Natural Wequeney Comparis
Page 188:
Therefore, with the natural freluen
Page 199:
Pi7 Be: kD! SF:& iid id . -5 i#@ Ba
Page 204:
(i.o., at noder 6, 12, 18, 22 and 2
Page 208:
tirne dntn;lis reprcsez~lnlioti of
Page 214:
-CUI~IW~~~ anstmr 9~1sn-mmu3n DL um
Page 218:
the posilivc and nogntivr peaks. Re
Page 224 and 225:
Table 7.7 X-Direction Results From
Page 226:
2 GEhEnnlEO FRDM TdE WrllTE hOISE l
Page 230 and 231:
FIG. 7.53 MEASURED INPUT WRVE FROM
Page 236:
'IUnU133dS 3SIR1 31IHI 9NISn--91 30
Page 244 and 245:
Table 7.9 MEM Damping Estimates fro
Page 246:
7.2.3 Impact Test Results In Chsptc
Page 252 and 253:
(K 01 0 01- OZ- DE- 0,- OBI (KI 09
Page 257 and 258:
Chapter 8 Discussion of Results In
Page 260 and 261:
of rnemhcr removal can he visually
Page 263 and 264:
emoved is a cancellation offecl, an
Page 265 and 266:
Force Variation Along the Jacket. P
Page 267:
fi~t on the lower rrequency end of
Page 271 and 272:
pond approximately to thasc which c
Page 273 and 274:
'Ikble 8.1 Measured Resonant Rsquen
Page 275 and 276:
Table 8.6 Measured Resonant Wequenc
Page 277 and 278:
After a close look at the measured
Page 279 and 280:
Table 8.11 Percent Changes in Reson
Page 281 and 282:
Table 8.16 Percent Changes in Reson
Page 283:
apprmiably. Since the tmnsa of the
Page 286 and 287:
'*~+12 \5 \8 h4 h7 $0 FREOUENCY IHz
Page 288 and 289:
8.2.4 Impact Test Results 'l'incobj
Page 293 and 294:
I able 8.20 Comparison of the Reson
Page 295 and 296:
'Phc invalidity of thc lumped mass
Page 297 and 298:
Chapter 9 Concluding Remarks and Re
Page 299 and 300:
general agreement. 5. An investigat
Page 301 and 302:
mode, br example, might have been e
Page 303 and 304:
References K I'o,lnt~n~. 'A Sludy o
Page 305 and 306:
[21] .I.K. Vandiver, "Structo~ral D
Page 307 and 308:
1431 D.J. Kartewcg and G. d-Vria "O
Page 309 and 310:
1671 I..S. Marplo, "A NCW Autorepes
Page 311 and 312:
(111 J. Zhou "Ocean Wave Simulation
Page 313 and 314:
[Ill M.C. Ilallsm, N.J. Hcaf and L.
Page 315 and 316:
Appendix A Selected Algorithms Tllr
Page 317 and 318:
- M = the total mass of the slructu
Page 319 and 320:
Suhrtituting qualion (A.5) in equal
Page 321 and 322:
..3 Longuet-Higgins and Cokelet Smo
Page 323 and 324:
Appendix B Sample Calculations Typi
Page 325 and 326:
The dcnsity of ABS plsstic (p.,,) i
Page 327:
C.l Calibration and Instrumentation
Page 330:
D.l Mode Shape (Members 70 and 68 R
Page 340 and 341:
D.2 Results for an Impact Initiated
Page 343:
i W 4 P Li I 2: 5: E B '5 2- d :" i
Page 347:
oa m 01 o or- QZ- oe- om Q Z ~ oo a
Page 353:
D.3 MEM Damping Estimates for the D
Page 357:
Table D.4 MEM Damping Estimate. fro
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4 - Memorial University of Newfoundland DAI

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