Ja b to le m ca 1. Jack-envir Becau of str high multi and C desig their mana As ou of a p as rub statio with near loads exper In or under and m well d the ra ice lo requi furthe Previ distri back these than c (1) (2 ack-ups hav een no opera o extend the evel ice, ice model tests ca arried out wi INTROD -ups have be ronments, bu use of their r ructures are g ice loads inv i-leg offshore Cook Inlet ( gns are more operational agement, but utlined in Cr platform or a bble build u onary platform several icebr field. Althou s, Croasdale rt judgement rder to exten rstanding of managed ice defined for l atio between oad for the
red, the rela er investigati ious experim bution of ice (sheltered) legs fails in crushing. Sim EXPE O A.B. Ca Delft Univers 2) Delft Unive (3) e been cons ating experie drilling sea loads due to arried out at ith a focus on DUCTION een designed ut to date th relatively low generally no volved. On t e structures u (Cammaert e e massive. T window sho how much i roasdale et a an anchored up. Ice featur m or vessel reakers; one ugh there is s et al state th t”. nd the drillin f managed ic loads on a level ice, wh managed ic rig designer tion between ion. mental and n e loads on m leg of a stru n bending or milar observ ERIMENTA ON AN ARC ammaert (1), sity of Techno ersity of Techn Cecon NL BV structed for n ence under A ason, but wh o managed i HSVA and n managed ic d and constr here has been
w resistance ot sufficiently
the other han used for prod et al, 2011), o make the ould be exten ice managem l, 2009, man vessel in ord res which wo are broken in or more bre some experie hat the “prese
ng season fo e loads is re jack-up stru hile the ice lo e and level i r. Additional n the load on numerical stu multi-leg struc ucture exper shearing rat ations have a AL PROGR CTIC JACK , J.S. Hoving ology, The Ne hnology, The N V, The Nether numerous o Arctic sea ice hile ice load ice are not k
the results o ce parameter ructed to pe n no operati to overturnin y robust in s nd, there is c duction in su where the i use of jack-nded outside ment do we ne naged ice is t der to reduce ould create l nto small pie eaking ice in ence on how ent methods or jack-up st equired. To t ucture is inve oads due to m ice loads ther lly, for situa n one platfor
udies have a ctures. In an rienced lowe ther than cru
also been wi RAM FOR IC K-UP STRUC g (2), and R. etherlands, em Netherlands, e rlands, email: ffshore envi e conditions. calculations known equal f a correspon rs. erform drillin ing experien ng moments evere ice env considerable ubarctic ice e ice condition -ups viable f e the ice-free eed, and und the term giv e ice loads or
loads greater eces to reduc the far field w much mana for managed tructures by this purpose, estigated as managed ice refore yields ations where rm leg and th also attempte n experimenta er loads beca ushing, and th itnessed in th CE LOADS CTURE Vermeulen ( mail: a.b.camm email: j.s.hovin rv@cecon.co ironments, b Ice manage are reasona lly well. Thi nding param ng operation nce under Ar and slender vironments i e experience environment ns are less c for drilling o e season. Thi der what cond
en to ice tha r other effect r than the re ce the ice loa
and one or m agement is re d ice loads a
means of ic the relation ice load calc are not know an initial es
ice manage he global loa
ed to investi al study Tim ause the bro hese failure m he present ser S (3) maert@tudelft. ing@tudelft.nl .nl but to date th ement will be ably well def is paper sum metric study t
ns in numero Arctic sea ice
member siz in order to w with jack-up ts, such as th critical and t operations in is can be do ditions? at has been b ts of ice inte esistance or s ads. This is u more breakin equired to re are empirical ce managem n between lev culations are wn equally w stimation of t ement is not ad on all fou igate the ma mco (1986) n
oken ice enc modes give eries of tests. .nl l here has e needed fined for mmarizes hat were ous offshore e conditions. es, this class withstand the ps and other he Bohai Sea the platform n the Arctic, one using ice
broken ahead eraction such strength of a usually done ng ice in the educe design l and rely on ment, a better vel ice loads e reasonably well. Finding the managed t necessarily ur legs needs agnitude and oted that the countered by a lower load Shkhinek et e . s e r a m , e d h a e e n n r s y g d y s d e y d t
al, 20 durin betwe In th sched 2. The c carrie Germ the in from the st The m identi mode possi thickn and ic Durin jack-u the fi Subse distri obtain 6/10th secon runs. are th 009, investig ng which leg een the legs w he following, dule of the te TEST DE campaign to ed out in th many. Due to nteraction be a towing car tationary ice model tests w ified as a sin el orientation ble combina nesses, as w ce concentra Test-series 10000 20000 30000 40000 50000 60000 Test-runs x1010 x1020 x1011 x1012 x1021 x1022 ng each test up model wa irst passage equently, the buting the r ned, allowin h ice concen nd passage. F Note here th hus not consi
gated the ice g sheltering, were observe , we will fir est campaign ESCRIPTIO o determine he ice tank o o the impract etween the ja rriage and th cover. were divided ngle test-seri ns, every te ations of ice well as the m ation for each Table 1. D 1st te 2nd te 3rd te 4th te 5th te 6th te Table 2. C D Le Le Man Man Man Man day, 6 exper as pulled thro through the e remaining remaining ice ng for a seco ntration was Figure 1 sho
hat only leve idered. loads on a st non-simulta ed. rst discuss t . ON experimenta of the Hamb ticability of m ack-up mode hen pulling th d over 6 test-ies as shown st-series, an e thickness a model orienta h run are give
Ice thicknes Description est day - 14/0 est day - 17/0 est day - 19/0 est day - 21/0 est day - 25/0 est day - 28/0 Carriage vel Description evel ice, 1/2 evel ice, 2/2 naged ice, 1/ naged ice, 2/ naged ice, 3/ naged ice, 4/ riments were ough a new tank, 20% o level ice wa e floes over ond passage obtained by ows the three el ice and m
tructure with aneous load
the model co
ally the inte mburgische S moving ice t el and the ic he model thr days spread n in Table 1. nd therefore and model o ations are giv
en in Table 2 ss and mode Mo 09 /09 /09 09 09 09 locity and ic Mo /4 /4 /4 /4 e performed, level ice she of the ice wa as cut into r r the length through the y disposing o e different ic managed ice c h four legs by peaks in the onfiguration raction of ic chiffbau-Ve toward and t ce is simulate rough the ice
over a time . As we have
each day of orientation. T
ven per test-2. el orientatio Ice thickn odel scale 0.033 0.033 0.016 0.016 0.033 0.016 ce concentra Velocity odel scale 0.09 0.18 0.09 0.18 0.09 0.18 , starting wit eet with the s as cut from t rectangular p of the ice ta e tank. For t of 25% of t ce concentrat conditions ar y means of a e leg and ja
and the tes
ce with a 4-rsuchsanstalt through a sta ed by suspen e by moving span of 3 we e considered f testing, rep The tested m -series in Ta n per test se Paramete ness [m] Full scale 1.1 1.1 0.5 0.5 1.1 0.5 ation per test
Paramete y [m/s] Full scale 0.5 1.0 0.5 1.0 0.5 1.0 th a passage specifications
the level ice pieces of var ank, an 8/10 he third pas he ice floes tions in the i re simulated a finite differ amming of i st set-up, as -leg jack-up t (HSVA) i ationary stru nding the jac
the towing c eeks. Every d 2 ice thickn presents 1 o model and fu able 1. Carri eries ers M orie e 0 2 2 4 4 0 t run ers conce e lev lev 8 8 6 6 over the tan s given in Ta e sheet and d rious sizes. A 0th ice concen ssage through that remain ice tank prio d and that rid
rence model, ce rubble in well as the p model was n Hamburg, cture model, ck-up model carriage over test-day was nesses and 3 out of the 6 full scale ice age velocity Model ntation 0.0° 22.5° 22.5° 45.0° 45.0° 0.0° Ice entration vel ice vel ice /10th /10th /10th /10th nk where the able 1. After disposed off. After evenly ntration was h the tank a ned after the r to the test-dge ice loads , n e s , , l r s 3 6 e y e r . y s a e -s
Addit Starti carria m/s. was c differ 3. The m winte opera diame mode jack-u depic Figu 4. Each load conne were legs a mean top o defin came Fig tionally, dur ing with a ve age accelerat By doubling chosen to be rent ice veloc MODEL model const er ice conditi ating in open eter of 7 m a el was ultima up model h cted in Figure
ure 2a. Dim scale MEASUR of the four l cells were b ecting the ja well-connec at their inter ns of a 6-com of the model nition camera
eras. The mea
gure 1. Ice c ring each pas elocity of 0.0 ted at 1/3rd o g the velocity e equal for cities yields L CONSTRU tructed for th ions in the C n water, the and a 50 m c ately chosen as a leg dia e 2a. mensions of t and in mod REMENT E legs was equ bolted to the ack-up legs w
cted, the tri-a rface. Furthe mponent load was equippe as and 1 re asurement eq oncentratio ssage through 09 m/s, whic f the tank len y at 1/3rd of both velocit the 6 test-run UCTION he tests is b Chukchi Sea. Arctic jack-u centre-to-cen n as 32.0 to s ameter of 21 he jack-up i del scale EQUIPMEN uipped with a e model fram with the mo axial load ce ermore, the c d cell, measu ed with a dua gular video quipment wa
ons in the ice h the ice tan ch correspon ngth to a vel f the tank len
ties. Thus, c ns per test-se
based on an . Instead of t up is fitted w ntre leg spaci
suit actual m 19 mm and in full NT a tri-axial loa me at one si odel frame. T
ells were giv complete jac uring the tota
al axial acce camera abo as calibrated e tank: level nk the velocit nds to a full s ocity of 0.01 ngth, the dur considering 3 eries given in Arctic jack-the truss-styl with 4 enclo ing. The geo material sizes a centre-to-Figure 2b o ad cell, with de and to th To ensure th ven the same ck-up model al loading on elerometer. A ove water, 2 through open ice, 8/10th a ty of the tow scale velocit 18 m/s, i.e. a ration of the 3 different ic n Table 2. up design c le legs that a sed cylindric metrical scal s and leg spa -centre leg s
b. The jacku rientation in
a maximum he cylindrica hat the load
e diameter as was connec n the jack-up All tests were 2 underwate n water tests and 6/10th. wing carriage ty of 0.5 m/s full scale ve ice-structure ce concentra concept for u are common cal legs with ling factor o acing. Conse spacing of 1 up model at n level ice. m capacity of al leg on the cell and the s the cylindr cted with the
p model. In a e documente er cameras a s. e was varied. s, the towing elocity of 1.0 e-interaction ations and 2 use in early-for jack-ups h a full scale of the scaling equently, the 1565 mm as 22.5º 500 N. The e other, thus jack-up leg rical jack-up e carriage by addition, the d by 2 high-and 2 photo . g 0 n 2 -s e g e s e s g p y e -o
5. As th were Arcti chose ice co Durin samp flexu situ b ice w comp thickn place The i passa meas runs t test s made Befor was d comp a suit from streng could streng comm actua occur 6. Durin domi first t bendi for th and S “pure ICE PRO he intention i chosen to r c that is a v en to represe onditions in t ng the test-ru ples taken fro ural strength bending tests was extracted pressive stren ness of 0.03 ed in the com ice thickness age of the ja uring the we to obtain the eries, where e along the le Test-series 10000 20000 30000 40000 50000 60000 re commenci determined f pressive stren
table ice stre the measure gths for the t d not be mea gths, it is un mencing the t ally represent rrence of unw FAILUR ng most of nated the ru two ice shee ing was pred hese four she Sodhi (1983) e” failure mo OPERTIES is to be able represent ear viable candid ent a full sca
the Arctic an uns the prop
om the leve of the ice w s along the le d from the ic ngth could on 3 m. Thin ic mpression test s was measur ack-up mode eight and vol e 8/10th ice c the given va ength of the b Table Me thickn 3 3 1 1 3 1 ing the first from flexural ngth can be f ength was co ed ice propert thick ice shee asured for th
clear whethe test runs. Co ted the early wanted failur RE MODES the tests it un, however ets, the pred dominant and eets crushing ). They stated odes. to extend th rly-winter ic date for the ale ice streng nd normal co
erties of the el ice sheet a was determine evel ice sheet e sheet to m nly be measu ce with a mo t equipment. red from the el through th lume of piece oncentration alues for the basin. e 3. Measure ean ice ness [mm] 32.6 34.5 17.9 17.8 31.0 16.5 passage of th l strength tes found by mu onsidered rea ties in Table et proves to b he thin ice sh er or not the onsequently, y-winter ice re modes wa was observ incidental a ominant fail d for the fifth g occurred a d that the pro
he drilling sea ce conditions use of jack gth of 1.8 M onditions in t e ice were de at different ed by measu t. Next to me measure its co ured for the odel scale ice . e track behin he ice sheet es of the leve n. The measu different ice ed ice prope Mean i density [k 914.8 n/a 893.2 896.0 889.7 866.1 he jack-up m sts; by exper ultiplying the ached when t e 3, the factor be between heet and we thin ice shee it is doubtfu conditions f as investigate
ved that the alternation w
lure mode w h sheet buck as well. Mixe
obability of m
ason for jack s in the Chu -ups. A targ MPa, which ty temperate are etermined by locations alo uring the requ easuring the ompressive s thick ice she e thickness o
nd the jack-u t. Finally, th el ice sheet t ured ice prop e properties a
erties for eac ice kg/m3] C st 8 2 0 7 1 model throug rience it is ex e flexural stre the flexural s r between the 1.1 and 1.2 i re therefore ets were at th ul whether the
for the Chuk ed.
ice sheets with another was crushing. kling was the ed failure mo mixed failure k-ups in the A ukchi Sea. T get crushing ypically corr eas. y doing meas ong the leng uired force t flexural stre strength. Unf eets, i.e. thos of 0.016 m w
p model that he ice densit hat were disc perties are sh
are the averag
ch test series Compressive rength [kPa 60.3 57.7 n/a n/a 47.5 n/a gh the level ic xpected for ic ength with a strength was e measured c nstead. As th derived from he target com e ice propert kchi Sea. To had a distin failure mode . In the third predominan odes were al e modes is h Arctic, the ic This is a loc strength of responds to surements on gth of the ic to break the ength in-situ, fortunately h se with a mo was simply to at remained a ty was deter carded after hown in Tabl ages of the m s e a] Fle streng 5 5 2 3 4 3 ce sheet, the ce in the ice factor of 1.5 s 40 kPa. As compressive he compressi m the measu mpressive str ties used in th check its in nct failure m e also occur d, fourth and nt failure mo lso experien higher than o ce properties cation in the 60 kPa was early-season n several ice ce tank. The ice from in-, a sample of however, the odel scale ice oo thin to be
after the first rmined from the level ice le 3 for each measurements exural gth [kPa] 51.2 50.9 28.6 38.8 43.5 39.6 e ice strength tank that its 5. Therefore, can be seen and flexural ive strengths ured flexural ength before hese tests do nfluence, the mode which rred. For the d sixth sheet ode, however ced by Kato ccurrence of s e s n e e -f e e e t m e h s h s , n l s l e o e h e t r o f
Comp exper gover the fu thickn that t meas and th other ice b (1994 Scalin due t to lev the p loads 7. For e force chann comp the pr fit for Four metho metho 7.1 In thi assum 7.2 It is dynam case arithm conta 7.3 This filtere differ legs. (extre annua A fitt identi distri alway maxim paring our i riments ice m rning factors ull and mode ness itself ha the flexural ured ice prop he ice thickn r failure mod by lowering 4). ng of ice pro to a differenc vel ice and th possibly inco
s due to level ASSESSM each test-run,
s on each of nels for the puter on boar
resentation a r analysis an alternative ods are expl ods follows. MAXIMU is method th mes the maxi AVERAG possible tha mic amplific the highest metic mean ( ain at least 5 DISTRIB method invo ed data. Firs rence betwee The ISO 1 eme-level ice al maximum ted Weibull d
ify if the tes bution. Also ys fit well to mum load. ice propertie may have be s for modelli el scales. Bla as an influen strength of perties from ness also inf des besides c the ice tem
operties influ ce in load lim hose due to m orrect scaling
l ice and thos MENT OF T , the measure f the 4 legs i accelerome rd the towing and analysis nd whether an methods to lained in brie UM PEAK L he design loa imum possib GE OF 5 HIG at a measure cation in the local maxim (“average”) o peak events BUTION FIT olves fitting st histograms en the loads 19906 code e event) actio m, a probabilit distribution a st data fits to o the local m o the Weibu es to the fai een modelled ing, which in anchet et al. nce on the fai
f the ice is Table 1 with fluence the o crushing can perature and uences level miting mech managed ice g of the leve se due to man TEST DATA ements were in x-, y- and eters in x- a g carriage wi of the obtain ny test-runs, obtain a d ef and the as LOAD (MET d is taken as ble load is cau
GHEST MAX ed peak load
measuring sy ma in a samp of these valu
and the aver TTING AND of a Weibull s are used to from the 6-specifies an ons. As the i ty of exceeda appears as a o the CDF fu maxima are ull distributio ilure map by d erroneously n our case le (1989) state ilure mode. A an importa h the observ occurring fail be avoided d thus the b l ice loads, w hanisms. Con are influenc el ice into ac anaged ice tha
A
e recorded th d z-direction, and y-directi ith a samplin ned test data,
or segments design load ssumptions m THOD I) s the maximu ught in the m XIMA (MET d is higher ystem, a me ple contain o ues. For now
rage of these D PROBABIL l cumulative show typica -component n annual ex ce condition ance of 10-2 straight line unction. It al used instead on. In this c y Timco (19 y. Timco us eads to diffe ed that not o Additionally ant aspect fo ed failure m lure mode. C by increasin brine volume
while its effe nsequently, a ced by the ap ccount when at follow fro hrough a tota , 6 channels ion. The me ng frequency , it was neces s of test-runs, from measu made are po um value in measurement THOD II) than the act asurement er one or more it is assume 5 peak load LITY OF NO e distribution al distributio load cell and xceedance pr ns are assume is chosen for e on such a g lso gives a c d of all data case, using a 986), it appe es the aspec erent failure only the aspe y, from the IS or scale mo odes shows t Considering t ng the flexur e, according ect on manag also the ratio pplied scaling n considering
m the test re
l of 20 chann for the 6 com easurement d y of 50 Hz. B ssary to cons , could be ne urements are ointed out. A the filtered t t. tual load. Th rror or a non e outliers, it d that each s s is used with ON-EXCEED n function to ons, the influ d the load fr robability le ed to be repre r use in this m graph which m learer view a points. How a Weibull fit
ears that the ct ratio and s
modes when ect ratio, but SO19906 cod odelling. Com
that the flexu the above it ral strength o
to Timco a
ged ice loads os between th g. Thus, we g the ratios esults. nels; 12 chan mponent loa data was ga Before comm sider which t eglected. e suggested A comparison time series. T This could be n-representat could be us sample is lon th this metho DANCE (ME the local ma uence of filte from the sum evel α = 10 esentative fo method. makes it eas of the tail se wever, the t t may under e ice in our strain rate as n comparing t also the ice de it appears mparing the ural strength appears that of the model and O’Brien s is minimal he loads due have to take between the
nnels for the ad cell and 2 athered by a mencing with test data was
below. All n of the four This method e caused by ive event. In seful to take ng enough to od. ETHOD III) axima of the ering and the m of the four 0-2 for ELIE or at least the
y to visually ection of the tail does not restimate the r s g e s e h t l n l e e e e 2 a h s l r d y n e o e e r E e y e t e
7.4 Anoth assum distri gives where 7.5 The d obtain in run (meth proba The v P(F> the d loads for ob Based metho maxim extrem It sho cell d for al I II III IV 8. As ca factor loads 8.1 The Korzh conta The l and in MEAN + her method mes a norma buted variab s a simple an eas in practic METHOD discussed app ned design l n ‘A’. Natur hod II). For ability of non value of the >X) < 10-2 (m design load b s. Among ice btaining a de d on these c od uses the mum value. mes is not ve ould be noted data is at max ll four metho Max peak Average p P(F>X) < Mean + 2 ICE LOA alculation m rs accounting s first. LEVEL I simplest ap havin’s equa act area, in pl last method ncorporates a + TWO STAN is to take th al distributio ble, 97.7% of nd quick estim ce this is not D SELECTIO proaches are oads are com rally, the ma the samples n-exceedanc e mean + 2 method III). before procee e engineering esign load fro onsideration
actual max The choice ery large for d that for the ximum 10% ods. Ta k T is peaks T to 10-2 T d d std.dev. L F m th AD ESTIMA methods for m g for effects ICE LOADS proach assu ation uses th lane shape an is the formu a global ice p NDARD DE he mean plu on and is a f the values l mate. The dis t necessarily ON e applied to t mpared. The aximum peak s taken over ce (method II standard de From a prac eding with th g scientists a om model sc ns, the averag xima but is of the numb many of the e full structu higher than able 4. Cons This method s the most co This method o number of This method distributed da data. Therefo Less sensitive For very shor maximum pe his method c ATES ACCO multi-leg stru of multiple l ON A SING umes a cons he same app nd the effect ula proposed pressure as a EVIATIONS us two stand common m lie beneath th sadvantage i the case. the results of ratios of res k load (meth r the length II) is always eviations (me ctical point o he compariso and engineer cale data. ge peaks me less sensitiv ber of peaks i e samples, it w ure in level ic the result ba siderations f is very sensi onservative o is sensitive t f peaks in tim is less sensit ata and in par ore this metho e to outliers b rt sample len ak load. For can be up to 3 ORDING T uctures are m legs close to GLE LEG stant global proach but a ts of aspect r in the ISO1 a function of (METHOD dard deviatio method used his value. Th is that the dis
f the various sults for the d hod I) is alwa of a comple s smaller tha ethod IV) is of view it is ons between rs, no consen thod is chos ve to a sing is of much in was decided ce, the result ased on the s for method s itive to outlie of the four m to the numbe me series. tive to outlier rticular the t od is strongly but generally ngths this me long sample 30% lower th TO THE AR mostly based o each other, pressure ac adds three e
atio and ice 19906 standa f ice strength
IV)
ons, i.e. Fmax
in ice engin he advantage stribution is a s level and m different met ays larger th ete run, the an the averag s typically c easiest to ch theoretical e nsus exists o en as a meth gle outlier th nfluence how to use the 5 ting load bas um of the fo selection. ers. From a d methods. er of peaks us rs. But it assu ail might not y dependent y values are l thod results e lengths this han the maxi CTIC JACK d on a single it is of intere cting on on mpirical coe grain anisotr ard which is and ice dime
x = +μ 2σ . T neering. For e of this meth assumed to b managed ice thods are mo han the avera load resulti ge of peaks close to the v hoose one m estimates an on which me
hod for furth han the use wever. As th
highest load sed on 6-com our leg loads
design point sed to averag sumes Weibu t have a good on the tail sh lowest of all in a value cl s load resultin imum peak l KUP TESTS e leg load m est to focus o ne half of th efficients to ropy (indenta based on fu ensions. This method r a normally hod is that it be Gaussian,
runs and the ostly as seen age of peaks ng from the (method II). value of the method to get nd actual test ethod is best
her use. This of a single he number of d peaks. mponent load . This is true of view it ge over and ull d fit to the hape. l methods. ose to the ng from load. S multiplied by on single leg he cylinder. account for ation factor). ull-scale data d y t , e n s e . e t t t s e f d e y g . r . a
Rega prope calcu samp using appen here i The r orien leg #2 the 4 test ru 14 to F 8.2 Like based multi those The I struct accou for th L S N J The I where simul made arding the IS erties observ ulated using ples. In addit g actual ice p ndix. As the instead of th resulting loa ntation had us 2 and leg #3 5°/Slow/Leg uns at 0° and 41% higher Figure 3a. S ISO19906, LEVEL I many other a d mostly on i-legged stru e used in the ISO 19906 c ture which i unt for the ef he multi-legg Leg interferen Sheltering (le Non-simultan amming (bro ISO proposed e F1 is the s ltaneous failu e in the ISO SO 19906 m ved during th the compre tion the mea properties ar ISO 19906 e other appro ads of the th sable data (1 in the 45° te g1 result is b d 45°, the sin r than the ISO
Single leg loa estimates fo ICE LOADS
aspects of A empirical da uctures is exp ISO code are code gives a is based on ffects of hav ged structure nce (failure m egs behind ot neous failure oken ice accu d method for
single leg loa ure and kj co O code. But method it sho he tests rather essive streng asured mean re compared standard is b oaches. hick sheets a 12 out of 14) est. For these based on very
ngle leg load O load estima ad estimates or 1.0 m thic ON A FOU rctic enginee ata. In this se plained first. e derived. a calculation laboratory t ving multiple . The effects mode is influ ther legs exp
(maximum umulates bet r obtaining th ad, ks consid onsiders jamm it is advised ould be note r than the ta gth and the n thickness o to the estim becoming the are shown in ). The missin e legs, no cru ry short time ds compare r ate. s versus ckness UR-LEGGED
ering, the est ection the IS Then factor method for tests. Multip e legs relativ s arising from uenced by leg perience redu
leg load doe tween the leg he global act
S s n
F =k k
ders interfere ming. For th d that ice jam
d that an att rget ice prop e dimensions of the test ru mate load usi e norm for A n Figure 3a. ng combinati ushing data w e series (arou remarkably w Figure 3b ISO19 D JACK-UP S timation of ic O 19906 app rs based on t the global l lication of t vely close to m the multi-le gs close to ea uced loads); es not occur a gs); tion on a mul 1 j k F
ence and she he values of j mming can tempt is ma perties. The i s of the co un is used. T
ing target ice Arctic structu
Most combi ions are the h was available und 7 sec mo well. For the
b. Multi-leg 9906 for diff STRUCTUR ce loads on m proach to est the obtained limit-stress a the single le each other r egged design ach other; e.g at more legs lti-legged str eltering effec jamming fac be expected ade to use th ice strength ompressive s The ISO1990 e properties ure design it inations of l high velocity e. It should b odel scale tim e 22.5° test, t load estima fferent thick RE multi-legged timate level d data and co action on a m eg load with results in a g n are: g. leg-to-leg at the same t ructure is giv cts, kn accou ctor kj no sug d if L/w < 4 he actual ice parameter is strength test 06 estimates in the same will be used leg-velocity-y sections of be noted that me). For the the loads are
ates versus knesses structures is ice loads on omparable to multi-legged factors that global action cracks; time); ven as: (1) unts for non-ggestions are 4, with clear e s t s e d -f t e e s n o d t n ) -e r
distan with factor to oc availa single distin advic Figur shelte avera only v the m estim simul (3.15 Based three) of ne comb The m This calcu 8.3 Figur the hi tests very 8.3 An ov is sho The t m flo nce L betwee expectations r kj in the tes ccur simultan able it is adv e leg load giv nction betwe ce, the maxim
re 3b compar ering (ks) an
age of the hig valid for the measured mu mates for ks h ltaneous failu ). d on these t ) legs. The u cessity for d bined factor i maximum gl is almost sim ulation. MANAG re 4a and Fig ighest loads did not reach likely the ste
Figure 4 6/1 MANAG verview of th own in Figur thickness has oes are abo
en the legs a s, no jammin sts is therefo neously. Th vised to assu ves a factor en sheltering mum ksn = ksk
res the load r nd non-simul ghest sum of orientation i lti-leg load, have been us ure factor (3 tests it is no use of separa design purpos is used. lobal multi-l milar to the
GED ICE LOA gure 4b show
occurred in h a steady sta eady state loa
a. Managed 10th concent GED ICE LOA
he design loa re 5a. The ma s a major inf out 1 to 5 t nd leg width ng was observ re equal to 1 is is taken ume kn = 0.9 which comb g and non-sim kn = 3.15. resulting from ltaneous fail f leg loads (r in which the for the ISO ed (ks,0 = 2.0 3.27) based o t unlikely th ate factors fo ses. Therefor eg level ice 39.1 MN es ADS w the arithme
the high velo ate and the lo ad will be hig
d ice loads fo tration
ADS VERSU ads (in both aximum of b fluence on th times higher h w. In the A ved in the le 1. The peak v into account 9. Dividing bines both sh multaneous m the ISO si lure factors red bars). Th e maximum m load calculat 0, ks,22.5 = 3. on the tests i hat a maxim or non-simult re no further load in 1.0 m stimate base etic mean of ocity section oads were sti gher but it is or US LEVEL I level and ma both velocity he managed r than the l Arctic Jackup vel ice tests values of the t by the red the sum of eltering and failure can b
ingle leg crus (kn = 0.9) (b he sheltering multi-leg loa tion in 0 deg 5 and ks,45 = is slightly lar
mum load occ taneous failu
investigation
m ice for the ed on the (ic f the 5 highes n of the run. I ill increasing s unknown ho Figure ICE LOADS anaged ice) d sections wa ice loads. B loads for an tests L/w = in the test pr loads on dif duction facto
the four leg non-simultan be made on t shing load es blue bars) to factor ks = 3 d occurs. To gree and 45 d = 3.0). The co
rger than sug
curs simultan ure and shelte n has been d e Arctic Jack e strength p st maxima in It should be g at the end o ow much hig e 4b. Manag 8/10th conce S determined in s used. ased on thes n ice thickn 6.2. Fully in rogramme. T fferent legs a or kn. Witho g loads by th aneous failure this basis. Us stimate mult o the load b 3.5 is a max o enable com degree orien ombined she ggested by th neously at tw ering is not p done on this t k-up design parameter-cor n each run. F noted that so of the run. Th gher.
ged ice loads entration. n paragraphs se tests, the l ness of 0.5 n accordance The jamming are not likely out test data he maximum e effects. No sing the ISO
iplied by the based on the imum and is mparison with tations basic eltering/non-he ISO code wo (or even possible, nor topic and the
is 41.4 MN. rrected) ISO
For all cases, ome of these herefore it is s for s 7.1 and 7.2 loads for 1.0 m for 8/10 e g y a m o O e e s h c -e n r e . O , e s 2 0 0
conce In ma no qu The o both jamm amou trend The a is sev cover result conce conce 9. The p ice lo these than t It is e this p the co This comp struct the ic Based conce ACK This grant Activ The techn Resea REFE Blanc F C Camm in C Croas 2 Hovin B In entration. In anaged ice, uantified rela orientation p between th ming) and in unt of bridgin d or relation c amount of ac verely influe r. It could ted in faster entration we entration. CONCLU presented dat oads due to m loads. Nota the ratios fou emphasized h paper are pre
orresponding study focuss pared to the e ture given by ce parameter d on these te entration this KNOWLEDG work has be t to the bud vities, Contra authors wou nical and sci
arch Infrastru ERENCES chet, D., Ch Failure Mech CCREL Spec maert, A.B, M n Ice Enviro Conditions, M sdale, K.R., B 0th Int. Conf ng, J.S. Ver Between Leve nt. Conf. on P 6/10 this ran the load inc ation can be d robably has he legs (dete n front of th ng). Howeve could be dist ccumulation enced by the observed th r accumulati ere always USION ta shows a cl managed ice ably, we find und for the th
here that the liminary. Ad g design load ses on obtain estimated loa y ISO 19906 rs is quantifi ests the load s decreases fu GEMENTS
en supported dget of the I act no. 26152 uld also like entific supp ucture ARCT hurcher, A., F hanisms for L cial Report 89 Metrikine, A onments. Pro Montreal, Ca Bruce, J.R. & f. on Port an rmeulen, R., el Ice Loads Port and Oc nged from 1 creases with determined. an influence ermining the he legs (dete er from the t inguished. (jamming a concentratio hat 8/10th c ion. The loa higher than
lear distinctio e; it is now p d that the rati hinner ice sh e data analys dditional plan ds, as well as ning the glob ad based on 6 is in close ed. Qualitati in 8/10 conc further to 9 to d by Europea Integrating A 20. e to thank H ort, as well TECLAB. Fitspatrick, J Laboratory, F 9-5, pp. 77-1 A.V., and Hov
oc. of the 21 nada. Vol. 2 & Liferov, P nd Ocean Eng , Mesu, A.W and Manage ean Enginee to 10 times velocity bu e on clearing e amount o ermining the tests no clear and bridging) on of the ice concentration ads in 8/10th n for 6/10th on between m possible to m ios between heets. sis is current nned data an s Fourier and bal design loa
the ISO 199 agreement w ive descriptio centration eq o 25%. an Communi Activity HY HSVA, espe as the profe J., and Badr First Year an 124. ving, J.S., 20 1st Int. Conf 7. . 2009. Sea I gineering un W. and Cam ed Ice Loads ering under A . ut g, f e r ) e n h h measured ice make a first e level ice loa
ly still on-go nalysis consis d Wavelet an
ad for the te 906 code. Th with the test r ons of the m quals 19 to 5 ity's Seventh YDRALAB I ecially the i essional exec ra-Blanchet, nd Multi-Yea 011. Perform f. on Port an Ice Loads du nder Arctic C mmaert, A.B. on an Arctic Arctic Condit Figure e loads due to estimate of th ads and mana
oing and that sts of a proba alysis. sted conditio he sheltering results. Furth most importan 54% of the le h Framework IV within th ce tank crew cution of the P., 1989. A ar Ice. Work mance of Min nd Ocean En ue to Manage Conditions, L 2013. Expe c Jackup Stru tions, Espoo, 5a: Overvie to level ice an the actual rat
aged ice load
t the results abilistic dete
ons. The leve g factor for a
hermore the nt phenomen evel ice load
k Programme he Transnati w, for their e test progra An Analysis king Groupon nimal Offsho Engineering u ed Ice, 2009. Luleå, Swede eriment-base ucture. Proc , Finland. ew of loads f nd measured tios between ds are larger presented in rmination of el ice load is a four-legged influence of na are given. d and in 6/10 e through the onal Access r hospitality, amme in the of Observed n Ice Forces, ore Platforms under Arctic Proc. of the n. Vol. 31. ed Relations . of the 22nd from tests d n r n f s d f . 0 e s , e d , s c e s d
Kato, R Shkh O Timc 2, Timc R Timc S Verm st 1 , K. and Sod Report 83-25, hinek, K.N. e Ocean Engine co, G.W., 198 , pp. 321-33 co, G.W., 19 Range. Proc. co, G.W. and Science and T meulen, R., tructure, Ma 18 February dhi, D.S. (19 , 35 p. t al, 2009. Ic eering under 86. Ice Load 7. 86. Indentat of the 5th OM d O’Brien, S Technology, 2014. Expe aster’s thesis 2014, Delft, 983): Ice Act ce Loads on a r Arctic Cond ds on Multi-l
ion and Pen MAE Confer S., 1994. Flex Vol. 22, pp. 2 eriment-based s, Delft Univ The Netherla tion on Pairs a Four Leg S ditions, Lule egged Struct netration of E rence, Tokyo xural strengt 285-298, Els d quantifica versity of Tec ands s of Cylindri Structure. Pro å, Sweden. V tures. Proc. I Edge-loaded o, Japan. th equation f sevier. ation of ma chnology - O
ical and Con oc. of the 20 Vol. 43.
IAHR Symp. Freshwater for sea ice. J anaged ice l Offshore and nical Structu 0th Int. Conf. on Ice, Iow Ice Sheets i Journal of C loads on a d Dredging E ures. CRREL on Port and a, USA. Vol. in the Brittle Cold Regions four-legged Engineering, L d e s d
