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1Challenge the future
Onderhouden of NieuwbouwenProf Han Vrijling/ir drs Jules Verlaan
2Challenge the future
Contents
• Theory of Maintenance• Maintenance in Port Engineering• Life cycle cost• Economic life cycle approach• Life cycle approach to systems• Conclusions
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Mechanical Engineering
Maintenance• Inspection• Repair
• Strategies• Corrective• Failure Repair
• Preventive• Inspection Repair
• Working hours• State
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“bath tub” curvebased on the observation of many actual failures
conditional failure rate h(t) = f(t)/{1- F(t)}
Condit
ional
failu
re r
ate
Time
New Old
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Hydraulic and Port Engineering
• Corrective maintenance• Is not advised in view of the risk involved: partial closure
of the port
• Preventive maintenance• Time based• Use based• Load based• Resistance based
w
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Conditional failure rate Hazard rate
• Pr {R<S} in year n, given survival to n• No deterioration of R
Sea dike
Height dike
Stays the same
If “it” worksfailure rate is dropping
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Are good deterioration models available?
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Dike settlement
• S.L.S. h0-A.Int = h(t)• U.L.S. H(t)-HW
overtopping
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Channel siltation
• S.L.S. d0 - zi = d(t) random walk
• U.L.S. d(t) - dship grounding
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Value of inspection
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The life cycle cost problem
Minimize total cost:•Investment•Inspection•Repair•Risk = pfailure x Consequence
Ctotal = Cinvest + Cinsp + Crepair + pfail x C
Minimize PV{Ctotal}
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Capital dredging → InvestingEcho sounding → InspectionMaintenance d. → RepairPr(grounding) → Risk
Dredging cycle2-5 years
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The economic life cycle problem
More alternatives:1. Repair old structure2. Build new structure
Minimize total cost!
Economic lifetime < Technical lifetime
New structure Old structureWages WagesFuel FuelMaterial MaterialInspection InspectionRepair RepairDepreciation -Interest -Insurance (risk) Integral cost new < Variable cost old
Technical lifetime
Economic lifetim
e
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Economic life cycle approach
Economic point of view:A RevenueB Cost
Not only costs
New structure Old structure
Revenuenew Revenueold
Integral costnew Variable costold
Profitnew > Profitold
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Economic life cycle approach
Planned economic life time>
Real economic life time
-Loss of investment
• Intensify use• Move assets to other location• Reassemble assets for other function• Built in flexibility
Underlying assumption:Technical lifetime > Economic lifetime
Most promising
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Economic life cycle approach of the port system
- deep water channel- Entrance channel- Breakwaters- Port layout + handling- Quays and jetties- (un)Loading equipment- Inland transport
Limiting factor!Revenue orientationChanges in relative costs
Org
aniz
ati
on
port
& t
raffi
c
Focus is on
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•
Cause of value
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Conclusions
Maintenance theory is an aid to life cycle management. Focus on risk of failure
Include the renewal option in life cycle cost management
New opportunities are more important than optimal maintenance
Optimize the port system spending on limiting factors
Do some dismal thinking to find the bright ideas
