WAWANCARA CALON

INSINYUR PROFESIONAL
BK SIPIL PII
CONTENT
▪ Profile
▪ Technical Experience I – BP Tortue Project (2019)
PROFILE
 PERSONAL DATA
Profile Education Background
PROFESSIONAL EXPERIENCES

▪ Director
PROFESSIONAL EXPERIENCES
PROFESSIONAL EXPERIENCES
TECHNICAL EXPERIENCE –
BP TORTUE PROJECT (2019)
Lifting Analysis of Trestle-TA
STRUCTURE
OVERVIEW
The purpose of the analysis during my work in Saipem are to
check the adequacy of the Trestle A (TA01/TA02/TA03/TA04) to
sustain the loads that it may experience during the Offshore
lifting from transportation vessel deck to its final position -
covering also the loadout by lifting option (lifting from the
transportation yard to the transportation vessel deck). Two
models are considered in the analysis :
• Trestle with blast wall represent by TA02
• Trestle without blast wall represent by TA04
For this presentation, trestle TA02 are presented
LIFTING DESIGN CRITERIA
Lifting Arrangement Analysis Description (1)
Long Trestle Lifting analyses for marine structure is
▪ One hook Lift performed in accordance with ISO 19902 and
ISO 19901-6. Lifting analysis to be carried out
▪ Match Pair of Slings by using static linier analysis of three-
▪ One Transverse Spreader Bar dimensional space frame computer model
comprising :
▪ The object main structure with the lifting
points offsets,
▪ The slings and the spreader bars if any,
▪ The horizontal springs required for the
numerical stability of the structural model
LIFTING DESIGN CRITERIA
Analysis Description (2) Computer Model (1)

Neither content nor live loads are accounted Structural model for lifting analysis uses the
for lifting analysis. structural model developed for the in-service
Lift loads then result from the combinations analysis with precisions defined hereafter.
built upon the following elements: ▪ Load eccentricities
▪ The lifting gross weight of the object Loads eccentricities introduced by the
including dead weight of the structure and trunnions/ padeyes are modelled by using
present equipment either rigid beams or member offsets
▪ The skew effects (effects of fabrication whichever appropriate for the module being
tolerances and variances in sling length) considered.
▪ The load factors including: ▪ Slings
▪ COG Shift Slings are modelled in order to behave as
▪ DAF tension only members and do not transfer
▪ Consequence Factor end moment or compression load.
LIFTING DESIGN CRITERIA
Computer Model (2) Loads
▪ Spreader bars (if any) For limit states approach, loads are classified
▪ Boundary conditions as permanent and transient (ISO 19902).
The top ends of the sling members (hook points) ▪ Permanent Load = Gravity (Gw)
are fixed. In lack of detailed lifting arrangement
The lifting gross weight of the object
provided by Installation Team, a minimum sling
including dead weight of the structure and
angle will be 60° relative with horizontal will be
assumed.
present equipment.
Dummy horizontal springs are introduced in the ▪ Transient = Effect of Tolerances (skew Effect)
computer model in order to stabilize numerically For a lift system using matched pairs of
the structure and spreader bars during the slings and incorporating a single spreader
analysis. Model is considered as satisfactory bar, a skew load factor SF = 1.05. It means
when the generated reactions on these dummy the skew load is equal to 5% Gw
springs do not exceed 0.1% of lifted weight
LIFTING DESIGN CRITERIA
Load Factors
▪ COG Shift ▪ Consequences Factor
A CoG inaccuracy will be introduced as a A consequence factor will be applied in
global factor applied on the lifted weight order to account for the criticism of the
computed considering a variation of the structural components.
module centre of gravity by 10% of the
object spans; but not less than 1.10
▪ Dynamic Amplification Factor (DAF)
Dynamic Amplifications Factor in air to be
considered are extracted from Table 15 of
ISO 19901-6
LIFTING DESIGN CRITERIA
Load Combination Strength Verification

Load combinations to be used in design are All objects will be checked using the internal
built as per Table 8.2-1 of ISO 19902 force (action effect) resulting from the factored
design actions built as per equation 8.3-1 of
ISO 19902

▪ Max static load provides design loads for

shackles/ slings selection.
▪ Situations 1 and 2 are to be used for
strength checking purposes.
TRESTLE TA-02
OVERVIEW
Trestle TA-02 global dimension is 48m x 14m x 5.8m. A three-
dimensional (3D) computer model using SACS is used to assess
the structural integrity of trestle TA-02 during offshore lifting
operation.
Lifting analysis model is modified from in-place analysis model
to comply lifting operation. The modification is as follow :
• Remove live load, content load, friction load, blast load and
other load that is not applicable during lifting operation
• Remove corrosion allowance
• Additional sling, spreader bar, and hook joint
• Additional spring constant
• Update joint fixity
• Update load combination for lifting operation condition
TRESTLE TA-02
LIFTING CONFIGURATION
TRESTLE TA-02
MEMBER PROPERTIES

Modeled as Dummy Member

LOAD ECCENTRICITIES
The loads eccentricities introduced by trunnion are modelled by using
rigid beams whichever appropriate for the objects being considered.

The trunnion member and joint can check are checked by SACS, but
internal ring stiffener and cap plate are calculated using Finite Element
Analysis
GRAVITY LOAD
LOAD COMBINATION
ANALYSIS RESULT
HOOK REACTION
ANALYSIS RESULT
SLING FORCES

All Slings are Tension Only

ANALYSIS RESULT
SPRING FORCES

Spring Forces are neglected

ANALYSIS RESULT
MEMBER STRENGTH VERIFICATION (CF = 1.30)
ANALYSIS RESULT
MEMBER STRENGTH VERIFICATION (CF = 1.15)
ANALYSIS RESULT
MEMBER STRENGTH VERIFICATION (CF = 1.00)
ANALYSIS RESULT
DISTORTION VERIFICATION

A maximum horizontal displacement of 3.93

cm is observed. Hence, distortion on structure
is negligible.
THANK YOU