Date: 02/09/02 Page : 1 de 5

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A / To: Structural Staff De / From: Copie / Copy: Date: 02/09/02 Nos rf./Our ref : Objet / Subject: Lifting analysis : Design basis clarification

1 > Load factors : the here below load factors shall be applied to derive the lifting analysis design factor :

DAF ( Dynamic amplification Factor ) Applicable to all structural members For module lift weight* < 100Mt 1.30 ( offshore lift assumed )For 100Mt < module lift weight* < 1000 MT 1.20 ( offshore lift assumed ) For 1000MT < module lift weight* < 2500MT 1.15 ( offshore lift assumed ) For Module lift weight* > 2500MT 1.10 ( offshore lift assumed )

Note* : Module lift weight includes all tolerances and contingencies on structural weight, equipment and pipings weight )

OTHER FACTORS Applicable to all structural members COG FACTOR : Fcog = 1.03 TILT FACTOR : Ftilt = 1.00 YAW FACTOR : Fyaw = 1.00

Applicable to

CONSEQUENCE FACTOR Pad-eyes

& spreader bars

Members directly connected to pad-eyes

Other members

Consequence Factor : FCF = 1.35 1.15 1.00 Therefore Design factor = DAF x Fcog x Ftilt x Fyaw x FCF = DAF x Fcog x FCF ( Since Ftilt = Fyaw = 1 ) 2 > Skew effects by Slings shortenings : ( actually based on API RP2A-WSD 21st Edition ) Total variation from the longest to the shortest sling shall be taken as follows , whichever is most severe : - of 1% of the sling length or, - 3 inches ( = 76.2mm) Moreover, in order to capture the most severe cases , slings shortenings shall be applied individually , by pair of neighboring slings or diagonally located slings. 3 > COG shifts : ( to account for uncertainty on COG location ) As illustrated here below , the variations of the COG shift shall be taken as 7.5% of the longitudinal and transverse plan dimensions with the center at the estimated nominal COG location, with a minimum value of 1m.

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COG

L1

=

=

= =

7.5%L1

7.5%L2 L2

Therefore , the following 5 load conditions shall be considered in the lifting analysis :

Load Condition # 1 2 3 4 5CoG at nominal position x CoG shifted to North East Corner x CoG shifted to South East Corner x CoG shifted to North West Corner x CoG shifted to South West Corner x

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5 > Allowable stress & Maximum API/AISC Unity Ratios : API basic allowable stress without 1/3 increase shall be considered in the lifting analysis. Recommended members maximum API/AISC Unity Ratios shall be limited as follows :

Member Type/Size

Maximum Unity Ratio (Conceptual

& Preliminary Design)

Maximum Unity Ratio(Final Design)

Tubulars

24" ( 609.6mm ) 24" - 36"

> 36" ( 914.4mm ) Beams

24" Depth ( 609.6mm ) > 24" Depth ( > 609.6mm )

Plate Girders

0.70

0.80

0.85

0.70

0.80

0.80

1.00

1.00

1.00

1.00

1.00

1.00

6 > Rigging model : The modelling of the rigging for lifting analysis shall be carried out as follows :

Define slings diameter according to static force in slings (after a first run). Force includes COG shift and sling shortening effect, COG, tilt and yaw factor. Force doesn't include Dynamic Amplification Factor and consequence factor. Table next page gives sling to be used according to the computed maximum static load

slings of same length and level should be of same size : For instance on Figure page 5, slings number 100 to 103 and 200 to 203 should have same properties, slings number 104 to 108 and 204 to 208 should have same properties, slings number 109 to 110 and 209 to 210 should have same properties.

Input sling properties with axial section equal to 57% of real section and young modulus equal

to 80000 MPa.

Spreader bars are defined as tube (or member with 6 degrees of freedom at each end).

Slings are released at start in moments X & Y, at end in moments X, Y & Z

Boundary conditions on module, spreader bars and hooks are as defined on figure page 5

Spring values used to ensure the module stability are given page 3 : satisfactory rotation of the modules shall be reflected by negligible reactions on these stabilizer springs , which should not exceed 4.5 MT or 0.1% of module weight , whichever is smaller. As an example , for a module of 2000 T, the residual reaction in the stabilizer springs should not exceed Min ( 5Mt, 0.1% x 2000 T ) = 2Mt .

Determination of Slings

Di t ff ti B ki All bl