Fender Design Trelleborg Doc

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  • Fender Design

    Trelleborg Marine Systems

    Ship TablesBerthing ModesCoef cientsBerth LayoutPanel DesignMaterialsFender TestingRef. M1100-S12-V1-3-EN

    Section 12

    www.trelleborg.com/marine

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  • FENDER DESIGN

    M1100-S12-V1-3-EN

    Trelleborg AB, 2011

    122

    Fenders must reliably protect ships, structures and themselves. They must work every day for many years in severe environments with little or no maintenance.

    As stated in the British Standard, fender design should be entrusted to appropriately qualifi ed and experienced people. Fender engineering requires an understanding of many areas:

    Ship technology Civil construction methods Steel fabrications Material properties Installation techniques Health and safety Environmental factors Regulations and codes of practice

    Using this guide

    This guide should assist with many of the frequently asked questions which arise during fender design. All methods described are based on the latest recommendations of PIANC*

    as well as other internationally recognised codes of practice.

    Methods are also adapted to working practices within Trelleborg and to suit Trelleborg products.

    Further design tools and utilities including generic specifi cations, energy calculation spreadsheets, fender performance curves and much more can be downloaded from the Trelleborg Marine Systems website (www.trelleborg.com/marine).

    Exceptions

    These guidelines do not encompass unusual ships, extreme berthing conditions and other extreme cases for which specialist advice should be sought.

    Codes and guidelines

    ROM 0.2-90 1990 Actions in the Design of Maritime and Harbor

    Works

    BS6349 : Part 4 : 1994 1994 Code of Practice for Design of Fendering and

    Mooring Systems

    EAU 1996 1996 Recommendations of the Committee for

    Waterfront Structures

    PIANC Bulletin 95 1997 Approach Channels A Guide to Design

    Supplement to Bulletin No.95 (1997) PIANC

    Japanese MoT 911 1998 Technical Note of the Port and Harbour

    Research Institute, Ministry of Transport, Japan

    No. 911, Sept 1998

    * PIANC 2002 2002 Guidelines for the Design of Fender Systems :

    2002 Marcom Report of WG33

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  • GLOSSARY

    M1100-S12-V1-3-EN

    Trelleborg AB, 2011

    123

    Symbol Defi nition UnitsB Beam of vessel (excluding beltings and strakes) mC Positive clearance between hull of vessel and face of structure mCB Block coeffi cient of vessels hull CC Berth confi guration coeffi cient CE Eccentricity coeffi cient CM Added mass coeffi cient (virtual mass coeffi cient) CS Softness coeffi cient D Draft of vessel mEN Normal berthing energy to be absorbed by fender kNmEA Abnormal berthing energy to be absorbed by fender kNmFL Freeboard at laden draft mFS Abnormal impact safety factor H Height of compressible part of fender mK Radius of gyration of vessel mKC Under keel clearance mLOA Overall length of vessels hull mLBP Length of vessels hull between perpendiculars mLS Overall length of the smallest vessel using the berth mLL Overall length of the largest vessel using the berth mM Displacement of the vessel tonneM50 Displacement of the vessel at 50% confi dence limit tonneM75 Displacement of the vessel at 75% confi dence limit tonneMD Displacement of vessel tonneP Fender pitch or spacing mR Distance from point of contact to the centre of mass of the vessel mRF Reaction force of fender kNV Velocity of vessel (true vector) m/sVB Approach velocity of the vessel perpendicular to the berthing line m/s Berthing angle degree Defl ection of the fender unit % or m Hull contact angle with fender degree Coeffi cient of friction Velocity vector angle (between R and V) degree

    Rubber fender Units made from vulcanised rubber (often with encapsulated steel plates) that absorbs energy by elastically deforming in compression, bending or shear or a combination of these effects.

    Pneumatic fender Units comprising fabric reinforced rubber bags fi lled with air under pressure and that absorb energy from the work done in compressing the air above its normal initial pressure.

    Foam fender Units comprising a closed cell foam inner core with reinforced polymer outer skin that absorb energy by virtue of the work done in compressing the foam.

    Steel Panel A structural steel frame designed to distribute the forces generated during rubber fender compression.

    Commonly used symbols

    De nitions

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  • WHY FENDER?

    M1100-S12-V1-3-EN

    Trelleborg AB, 2011

    124

    10 reasons for quality fendering

    Safety of staff, ships and structures Much lower lifecycle costs Rapid, trouble-free installation Quicker turnaround time, greater effi ciency Reduced maintenance and repair Berths in more exposed locations Better ship stability when moored Lower structural loads Accommodate more ship types and sizes More satisfi ed customers

    There is a simple reason to use fenders: it is just too expensive not to do so. These are the opening remarks of PIANC* and remain the primary reason why every modern port invests in protecting their structures with fenders.

    Well-designed fender systems will reduce construction costs and will contribute to making the berth more effi cient by improving turn-around times. It follows that the longer a fender system lasts and the less maintenance it needs, the better the investment.

    It is rare for the very cheapest fenders to offer the lowest long term cost. Quite the opposite is true. A small initial saving will often demand much greater investment in repairs and upkeep over the years. A cheap fender system can cost many times that of a well-engineered, higher quality solution over the lifetime of the berth as the graphs below demonstrate.

    Capital costs Maintenance costs

    0

    20

    40

    60

    80

    100

    120

    140

    160

    180

    Trelleborg Other

    Purc

    hase

    pric

    eO

    ther

    cos

    ts

    10 20 30 40Service life (years)

    500

    100

    200

    300

    400

    500

    600

    700

    Trelleborg

    Oth

    er

    Purchase price+ Design approvals+ Delivery delays+ Installation time+ Site support= Capital cost

    Wear & tear+ Replacements+ Damage repairs+ Removal & scrapping+ Fatigue, corrosion= Maintenance cost

    Capital cost + Maintenance cost = FULL LIFE COST

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  • DESIGN FLOWCHART

    M1100-S12-V1-3-EN

    Trelleborg AB, 2011

    125

    Functional

    type(s) of cargo safe berthing and mooring

    better stability on berth reduction of reaction force

    Design criteria

    Calculation of berthing energyCM virtual mass factorCE eccentricity factor

    CC berth confi guration factorCS softness factor

    Mooring layout

    location of mooring equipment and/or dolphins

    strength and type of mooring lines

    pre-tensioning of mooring lines

    Assume fender system and type

    Computer simulation (fi rst series)

    Check results

    check vessel motions in six degrees of freedomcheck vessel acceleration

    check defl ection, energy and reaction forcecheck mooring line forces

    Computer simulation (optimisation)

    Calculation of fender energy absorptionselection of abnormal berthing safety factor

    Selection of appropriate fenders

    Determination of:energy absorption reaction force defl ection

    environmental factors angular compression hull pressure

    frictional loads chains etc

    Check impact on structure and vesselhorizontal and vertical loading chance of hitting the structure (bulbous bows etc)face of structure to accommodate fender

    implications of installing the fenderbevels/snagging from hull protrusionsrestraint chains

    Final selection of fenderdetermine main characteristics of fenderPIANC Type Approved verifi cation test methods

    check availability of fender track record and warranties future spares availability fatigue/durability tests

    Operational

    berthing procedures frequency of berthing limits of mooring and operations (adverse weather)range of vessel sizes, types special features of vessels (fl are, beltings, list, etc)allowable hull pressures

    light, laden or partly laden ships stand-off from face of structure (crane reach)fender spacing type and orientation of waterfront structurespecial requirements spares availability

    Site conditions

    wind speed wave height current speed

    topography tidal range swell and fetch

    temperature corrosivity channel depth

    Design criteriacodes and standards design vessels for calculations normal/abnormal velocity maximum reaction force friction coeffi cient desired service life

    safety factors (normal/abnormal) maintenance cost/frequency installation cost/practicality chemical pollution accident response

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  • THE DESIGN PROCESS

    M1100-S12-V1-3-EN

    Trelleborg AB, 2011

    126

    Many factors contribute to the design of a fender:

    ShipsShip design evolves constantly shapes change and many vessel types are getting larger. Fenders must suit current ships and those expected to arrive in the foreseeable future.

    StructuresFenders impose loads on the berthing structure. Many berths are being built in exposed loca