Gorgon Project, Barrow Island LNG Plant
Contract No: 68500019
Job No 6300
Design Basis For Land Transport Analysis
Document No: G1-TE-S-0000-PDB0002
Revision: 0
Issue Purpose: IFD
SUMMARY OF DOCUMENT REVISIONS
Rev.
No.
Date
Revised
Section
Revised
A
31 July 09
-
Issued for Client Review
0
06 Oct 09
-
Issued for Design (incorporating CVX comments)
Revision Description
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Gorgon Project, Barrow Island LNG Plant
Contract No: 68500019
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Design Basis For Land Transport Analysis
Document No: G1-TE-S-0000-PDB0002
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Issue Purpose: IFD
TABLE OF CONTENTS
1.
GENERAL
4
1.1
1.2
1.3
4
4
4
5
5
5
5
1.4
1.5
2.
3.
4.
5.
Background
Scope of Document
Applicable Documents
1.3.1 Project Documents
1.3.2 Codes and Standards
Abbreviations
Definitions
DESIGN DATA & ASSUMPTIONS
6
2.1
2.2
2.3
2.4
2.5
6
6
6
6
7
Criteria & Assumptions
Steel
Computer Analysis Model
SPMT
Quarantine
PROCEDURE
8
3.1
3.2
3.3
3.4
8
8
8
9
Outline
SPMT Orientation
SPMT Arrangement & Forces
Structural Analysis
COMPUTER MODEL
10
4.1
10
Support Conditions
STRUCTURE LOADS
11
5.1
5.2
5.3
5.4
5.5
5.6
11
11
12
13
14
15
Weight and CG
Tilt
CG Adjustment
SPMT Vertical Reactions
Longitudinal Force
Wind Loads
6.
BASIC LOAD CASES
16
7.
DESIGN VERIFICATION
17
7.1
7.2
7.3
17
18
18
Intermediate Load Combinations
Combinations for Code Checking
Code Checks
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Gorgon Project, Barrow Island LNG Plant
Contract No: 68500019
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Design Basis For Land Transport Analysis
1.
GENERAL
1.1
Background
Document No: G1-TE-S-0000-PDB0002
Revision: 0
Issue Purpose: IFD
The Modules, PARs and PAUs for the Gorgon LNG Plant will be transported by sea
from the fabrication yards to Barrow Island, Australia.
The modularised structures addressed by this Design Basis will be loaded out at the
fabrication yard onto the sea transport vessel using self-propelled modular transporters
(SPMT). On reaching Barrow Island, these structures will be off-loaded from the vessel
and moved to their design locations in the facility using the same SPMT. The offload
and moving operations can also be referred to as ‘load-in’ and ‘road transport’.
For the purpose of Gorgon structural analysis, these operations are collectively known
as Land Transport.
For Load-out, load-in and road transport, the structure is supported on the flat SPMT
decks atop the hydraulic suspension of the SPMT, which exert a determinate set of
forces on the structure; the trailer arrangement will be the same for all operations.
During road transport, the load will have to climb and descend on the haul road from the
MOF to final location. In the load-out and load-in operations, the load is kept essentially
horizontal via the SPMT suspension system as it is moved onto and off the transport
vessel.
The analysis will include the effect of the slope and thereby cater for both operations.
1.2
Scope of Document
This Design Basis describes the procedure to be used for the structural analysis of the
modularised structures for Land Transport operations.
The purpose of the analysis is to obtain forces and deflections in the structure for input
to primary member and joint design. The Design Basis gives the principles and
methods for determining forces on the structure, the modelling and analysis method,
and defines the load combinations for code checking.
This Design Basis gives guidelines for estimating the number and arrangement of SPMT
units. This leads to a statically-determinate SPMT arrangement and is acceptable for
performing the load-out design analysis. The final SPMT arrangement will be the
responsibility of the Contractor who will be appointed later, and who will use the final,
as-weighed weight and CG of the module.
Land Transport is one of several design conditions for the structure. Other design
conditions are covered in Reference [2] and referenced documents.
Any re-sizing of members and joints arising from the Land Transport analysis must be
done in conjunction with the results of the other design conditions.
1.3
Applicable Documents
The applicable CVX, KJVG and consultants’ documents, Codes, Industry Standards and
Government Regulations are referenced below.
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Gorgon Project, Barrow Island LNG Plant
Contract No: 68500019
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Design Basis For Land Transport Analysis
1.3.1
Document No: G1-TE-S-0000-PDB0002
Revision: 0
Issue Purpose: IFD
Project Documents
The following are referenced or associated Project Documents:
1.3.2
1.
G1-TE-S-0000-SPC0001
Design Requirements for Wind Loads
2.
G1-TE-S-0000-SPC2001
Module Structural Design Criteria
3.
G1-TE-T-0000-SPC0002
Loadout and Seafastening Specification
4.
G1-TE-Z-0000-REP1006
Module Weight Report
5.
G1-TE-Z-0000-REP1014
PARs and PAUs Weight Report
6.
G1-TE-S-0000-PDB0001
Design Basis for Structural Analysis Computer Model
7.
G1-TE-T-0000-PDB0005
Design Basis for Structural Primary Joints
Codes and Standards
Structural design shall be carried out in accordance with the following codes and
standards:
1.4
1.5
8.
AISC 360-05
Specification for Structural Steel Buildings [Allowable Stress Design]
9.
API RP 2A-WSD
Recommended Practice for Planning, Designing and Constructing Fixed
Offshore Platforms – Working Stress Design – 21st Edition
Abbreviations
ASD
Allowable Stress Design
ASF
Allowable Stress Factor
BWI
Barrow Island
CG
Centre of Gravity
MOF
Material Offloading Facility
SHLV
Semi-Submersible Heavy Lift Vessel
SPMT
Self-Propelled Modular Transporter
WSD
Working Stress Design
Definitions
Definitions of Primary/ Major/ Secondary and Tertiary Steel are given in Table 1 of
Reference [2].
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Gorgon Project, Barrow Island LNG Plant
Contract No: 68500019
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Design Basis For Land Transport Analysis
Document No: G1-TE-S-0000-PDB0002
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2.
DESIGN DATA & ASSUMPTIONS
2.1
Criteria & Assumptions
SPMT operated by Mammoet have been assumed as the basis for this analysis.
The following design criteria are used here:
2.2
•
Maximum slope uphill/ downhill = 7%
•
Maximum transverse camber = 3%
•
Longitudinal dynamic force = 0.05 g - for low speed operation
•
Transverse dynamic force = 0.02 g - for low speed operation
•
Vertical impact = 0%
•
Maximum axle-line load 30 tonne payload + 4 tonne trailer self weight = 34 tonne.
Steel
Steel material properties for analysis and design shall be as given in Reference [2].
2.3
Computer Analysis Model
The Computer Analysis Model shall be developed in accordance with the requirements
of Reference [6].
2.4
SPMT
Basic SPMT dimensions are shown in Figure 2-1.
Figure 2-1 TYPICAL SPMT DATA (6- and 4-axle units)
SPMT will bear on the underside of the lower deck girders. A typical arrangement is
shown in Figure 2-2.
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Gorgon Project, Barrow Island LNG Plant
Contract No: 68500019
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Design Basis For Land Transport Analysis
Document No: G1-TE-S-0000-PDB0002
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Figure 2-2 TYPICAL SPMT ARRANGEMENT
RAILERS
SPMT
ELEVATION
TRAILERS
SPMT
PLAN
2.5
Quarantine
A special case has been identified for the Gorgon LNG Plant, in the event that
significant wind arises after a structure’s arrival on BWI, and while it is being held in the
quarantine area before it can be taken to its final location.
An additional analysis may be required, where the structure is expected to sustain a
significant wind force while supported on the SPMT. Particular attention will need to be
directed to stability of the structure and the SPMT assembly in this case.
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Gorgon Project, Barrow Island LNG Plant
Contract No: 68500019
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Design Basis For Land Transport Analysis
3.
PROCEDURE
3.1
Outline
Document No: G1-TE-S-0000-PDB0002
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The load-out analysis is carried out in three basic stages:
3.2
•
Stage 1: Determine the required SPMT orientation based on the structure
geometry and the load plan for the sea transport vessel.
•
Stage 2: Devise an acceptable SPMT arrangement and calculate the loading it
imposes on the structure, for an envelope of CG locations.
•
Stage 3: Analyse and code-check the structure.
SPMT Orientation
SPMT are aligned in the direction in which the structure is moved to its final In-Service
supports. The alignment must be confirmed explicitly for each structure.
Sketches are to be produced for each analysed structure, showing the SPMT alignment
and orientation.
3.3
SPMT Arrangement & Forces
The SPMT arrangement must be acceptable in terms of the permitted SPMT axle-line
loading and permissible ground bearing pressure. The arrangement must be checked
for practicality of operation and consistency with grillage, sea-fastening and load-on/
load-off operational assumptions.
The hydraulic circuits to the axle lines of the individual SPMT units are linked to
adjacent units to create zones of equal hydraulic pressure. This gives a uniform SPMT
platform height and uniform loading to the structure.
Three such zones are created in a set of load-out trailers, providing a statically
determinate support system for the structure. The CG of the structure must lie within
the stability triangle formed by the hydraulic centres of the three zones, and preferably
within the inner triangle shown in Figure 3-1.
The total load carried by each zone is calculated from static equilibrium, using the
weight and CG in relation to the hydraulic centre of each zone.
The wheel loads within each zone are all assumed equal because the hydraulic
pressure is nominally equal in all units. Therefore the load per axle-line is simply the
total load on a zone divided by the number of axle-lines within that zone.
Thus, a set of uniform axle-line loads is obtained for each zone, shown as P1, P2 or P3 Figure 3-1 (b). (Note: one axle-line = two axles = four wheels.)
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Figure 3-1 LOADING ON SPMT SETS
The loadings applied to the module (F1, F2 … Fn) are then calculated using beam theory.
If the axle-line loads exceed permissible values, a new zone layout or a new SPMT
arrangement must be devised. Sufficient load transfer points must be modelled to avoid
unrealistic racking (torsional) deflections being produced.
The SPMT arrangement used in the design analysis will not necessarily be the one
finally chosen at site. It must, however, be one that satisfies the requirements of
capacity described above. When considering an envelope of CG locations, it may be
necessary to devise different arrangements for each CG position being considered.
The size of the hydraulic zones should be such that axle-line loads are of similar
magnitude in all zones. SPMT are supplied as either 4- or 6 axle-line units, and the
hydraulic zones should be made up of complete units.
The top surface of the unloaded SPMT platform at its lowest position shall not be higher
than 1200 mm from the ground surface; the preferred nominal operating height is
1500 mm, as shown in nominal vertical stroke of ±300 mm (total 600 mm). To maintain
an operational margin, it is recommended that this be kept below ±250 mm.
3.4
Structural Analysis
The structure is analysed for each combination of weight and SPMT reactions.
Allowance is made for CG accuracy and for the effects of tilt.
Wind loads may be ignored for load-on and load-in, as the operation is carried out in
controlled conditions in which calm weather conditions can be chosen.
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Design Basis For Land Transport Analysis
4.
COMPUTER MODEL
4.1
Support Conditions
Document No: G1-TE-S-0000-PDB0002
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The module is supported by the hydraulic forces within the suspension system of the
SPMT (P1, P2, and P3 in Figure 3-1). In the stiffness analysis, the forces exerted by the
trailers are represented as applied forces.
Three notional supports will be applied to make the model statically admissible. An
example is shown in Figure 4-1. Lateral restraints should also be arranged either side
of the trailer longitudinal loads. See also Reference [2].
Figure 4-1 DUMMY SUPPORTS
X
Z
PLAN ON DUMMY SUPPORTS
= VERTICAL SUPPORT
= HORIZONTAL SUPPORT
The SPMT forces will then be factored so that they are in equilibrium with the weight
and CG of the model.
When the SPMT forces are combined with the model weight, the sum of forces and
moments is zero, and the vertical reactions at the notional supports will then be zero.
This confirms that true equilibrium exists.
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Design Basis For Land Transport Analysis
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5.
STRUCTURE LOADS
5.1
Weight and CG
The Land Transport analysis will use the gross load-out weight and CG from the latest
Weight Report (Ref. [4] [5]). Load cases generated for the analysis will represent this
weight.
Weight and CG information is necessarily approximate while the Project develops.
While the gross weight provides a contingency against future weight growth, a separate
allowance must be made for CG shift.
To cover variation of the CG during design, a CG tolerance envelope will be considered,
as shown in Figure 5-1, where:
•
A = 0.1 LA or 2.0 m, whichever is less
•
B = 0.1 LB or 2.0 m, whichever is less.
The CG envelope is centred on the CG from the Weight Report; later in Detail Design,
the CG envelope will be assigned fixed coordinates.
Figure 5-1 TOLERANCE ON CG POSITION
LA
A
=
=
CG ENVELOPE
FOR CG
VARIATION
X
Z
CG FROM WT
REPORT
5.2
PLAN
Tilt
Moving the structure on an inclined roadway produces an apparent CG shift, Δ, with
respect to the SPMT. The analysis will consider a 7% tilt in the longitudinal direction, for
forward and reverse movement on ramps and road inclines, and 3% transverse [2].
These figures are higher than those specified in Section 2.1. In addition, reference [2]
requires allowances of 5% (longitudinal) and 2% (transverse) for dynamic effects
(including braking).
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Combining this with the CG tolerance envelope we get an overall envelope, shown in
Figure 5-2. The analysis will consider the CG at the nominal location and at the
extreme corner locations A, B, C, D. The CG will be adjusted in the analysis to each
location using unit-moment load cases described in Section 5.3.
Figure 5-2 CG LOCATIONS FOR ANALYSIS
(A) CG SHIFT DUE TO MODULE TILT
A
D
C
OVERALL
ENVELOPE
A
CG FROM WT
REPORT
B
ENVELOPE
FOR WT
REPORT CG
X
Z
(B) OVERALL CG ENVELOPE
(Dimensions ‘A’ and ‘B’ obtained from Figure 5-1. Note: Δ applies only in the direction of tilt.)
The modelled weight and CG must match the Weight Report values.
5.3
CG Adjustment
Two load cases consisting of unit moments about global horizontal axes will be included
in the analysis. These will be combined with the gravity load cases to give the desired
CG in the analysis; see Figure 5-3.
The Figure is indicative; it will be necessary to distribute the ‘dummy’ forces over
multiple structural lines and levels, to avoid large member forces causing spurious overloading of structural elements.
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Figure 5-3 LOAD CASES FOR CG ADJUSTMENT
5.4
SPMT Vertical Reactions
Three unit load cases will be defined to represent the SPMT reactions in the three
hydraulic zones. Each case will consist of total unit load on a zone (set at 1000 kN),
with the forces on the structure calculated according to Section 3.3. The forces are
distributed over the SPMT bearing points on the lower deck girders. An example is
shown in Figure 5-4.
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Figure 5-4 SPMT UNIT LOAD CASES
Y
Z
X
UNIT LOAD CASE - TRAILER LOADS ZONE 1
Y
X
Z
UNIT LOAD CASE - TRAILER LOADS ZONE 2
Y
X
Z
UNIT LOAD CASE - TRAILER LOADS ZONE 3
The unit SPMT load cases will be combined so as to match the target weight and CG.
5.5
Longitudinal Force
The longitudinal component of weight due to tilt or acceleration can be simply applied as
a set of horizontal forces on the underside of the structure, as shown in Figure 5-5.
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Figure 5-5 SPMT LONGITUDINAL FORCES
5.6
Wind Loads
Wind loads are not expected to contribute significantly to structural action during load-on
and load-in operations. Stability should be verified in all cases.
Wind forces may be significant for strength as well as for stability for the Quarantine
case (see Section 2.5). The wind speed is specified as 40 m/s in Reference [2].
Analysis is required for this case. No SPMT movement will take place in these
conditions; the need for additional tie-downs will be investigated.
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6.
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BASIC LOAD CASES
Basic load cases are shown in Table 6-1.
Table 6-1 BASIC LOAD CASES
Structural Generated Self Weight
ST
Weight
Cond.
Code
A
Structural Non-generated Weight
ST
A
Architectural Weight
AR
A
Mechanical Equipment Dry Weight
MC
A
Electrical Equipment Weight
EL
A
Instrumentation Weight
IN
A
Loss Control Weight
LC
A
Piping Dry Weight
PI
A
Temporary: Permanent Items in temporary location (to be postinstalled in final location)
All
B
Temporary: Rigging, seafastening, voyage protection
All
C
Temporary: Items present for load-out only
All
K
Indicative – cases developed as required
Load
Case
Disc.
Code
Description
601
Zone 1 SPMT reactions ΣFY = 10,000 kN
602
Zone 2 SPMT reactions ΣFY = 10,000 kN
603
Zone 3 SPMT reactions ΣFY = 10,000 kN
610
Longitudinal force due to tilt
621
CG correction, unit ΣMX = 1000 kNm
622
CG correction, unit ΣMZ = 1000 kNm
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7.
DESIGN VERIFICATION
7.1
Intermediate Load Combinations
Initially, and for convenience of checking, the structure weight cases and SPMT loading
cases are assembled into intermediate sets of combinations given in Table 7-1 and
Table 7-2. Load case numbers are indicative.
Table 7-1 INTERMEDIATE COMBINATION 1799 (LOAD-OUT WEIGHT)
Load
Case
Description
Dead: Self Generated Dead Weight
Load cases as Table 6-1.
Dead: Non-generated Structural Dead Loads
Dead: Architectural Dead Loads
Dead: Mechanical and HVAC Equipment - Dry
Dead: Electrical Equipment
Dead: Instrumentation
Dead: Loss Prevention
Dead: Piping - Dry
Temporary: Permanent Items in temporary location
Temporary: Rigging, seafastening, voyage protection
Temporary: Items present for load-out only
Table 7-2: INTERMEDIATE COMBINATIONS
610
621
622
CG
Correction
“
A
1.0
-1.0
a1
b1
1703
“
B
1.0
1.0
a2
b2
1704
“
C
1.0
-1.0
a3
b3
1705
“
D
1.0
1.0
a4
b4
1711
SPMT forces, CG at location
O
c1
d1
e1
1712
“
B
c2
d2
e2
1713
“
C
c3
d3
e3
1714
“
D
c4
d4
e4
1715
“
D
c5
d5
e5
Load-out wt, CG at location
Business
603
1.0
Horiz.
1702
1701
602
O
SPMT Forces
601
Description
Weight
1799
Load
Comb
(Figure 5-2)
COMBINATION FACTORS
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Combinations for Code Checking
Final combinations for code checking are outlined in Table 7-3 below. The engineer
must check that the reactions at the dummy supports are all zero for each combination.
Wind loads in appropriate directions may be added to prepare a complete set of
combinations.
Table 7-3: CODE CHECK COMBINATIONS
7.3
B
1754
“
C
1755
“
D
1715
“
1714
1753
1713
A
1712
“
+
1711
1752
1705
O
1704
CG at location
1703
1751
1701
DESCRIPTION
1702
Combination Factors
LOAD
COMB
+
+
+
+
+
+
+
+
+
Code Checks
The structure will be checked for load combinations in Table 7-3 to the provisions of
AISC-ASD [8].
Allowable Stress Factor (ASF) shall be in accordance with Table 7-4, based on Table 61 of Reference [2].
Table 7-4: LAND TRANSPORT - ALLOWABLE STRESS FACTORS
Allowable Stress Factor
(ASF)
Design Condition
Land Transport
1.0
Target member utilisation ratio shall be in the range 0.80 to 0.90.
Where members need to be re-sized to the target utilisation range, this will be done in
conjunction with results from In-Service and Sea Transport analyses.
‘Dummy’ members – included in the model to represent loading mechanisms – are
excluded from all code checks.
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