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Linkspan Design Optimization
Company
Transmarine
Ltd. |
Industry
Civil Engineering |
Location
U.K. |
Product Used
COSMOSM™
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Type of Analysis
Linear Static,
Frequency, Fatigue
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More Details
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The 86m long truss bridge or 'linkspan'
is used to carry road vehicles from a floating
pontoon to the shore.
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The Challenge
Transmarine Ltd, Newcastle-upon-Tyne are specialists in the design
and supply of marine cargo access equipment. Transmarine has a
global reputation based on an unrivalled reference list of successful
linkspan installations worldwide.
Transmarine's approach to linkspan
design is to treat the bridge as an 'extension' of the ship's
equipment using direct calculation based on allowable stresses.
Factors of safety and loadings are taken from relevant guidelines.
The structure needs to be optimised
for the particular loadings and environmental conditions while
being lightweight and flexible in design. It is important for
weight to be reduced as far as possible to reduce installation
costs and the dead load to be supported by the floating pontoon.
In this case a fully welded construction in high tensile steel
was developed.
The Solution
The bridge structure was modelled using the COSMOSM package supplied
by CenitDesktop. Stress and fatigue analyses were then performed
and the final shape was modified based on the results.
The use of a modern FEA package has
allowed the detailed design of a lightweight structure capable
of responding flexibly to the wave-induced movement of its supporting
pontoon. The direct calculation approach means that a wide range
of loading types can be combined and assessed relatively easily.
The 490Tonne linkspan was installed
in a single lift by floating crane in November 2001. It was successfully
load tested in June 2002, and has since been in daily service.
Summary and Metrics:
- Simulated vehicle and wind/wave loads
- Calculated fatigue over a 40 year design life
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