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1 of 35 Erik Soderberg, S.E. Liftech Consultants Inc. www.liftech.net Seismic Retrofit of Container Cranes
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Erik Soderberg, S.E.Liftech Consultants Inc.www.liftech.net
Seismic Retrofit of Container Cranes
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Historic Seismic Performance
Kobe - Liquefaction
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Crane Evolution
Circa 1970 Modern Jumbo
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50’ Gage Crane CLE Response
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50’ Gage - Close-up
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100’ Gage Crane CLE Response
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100’ Gage Close-up
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Wheel Uplift
0
0.5
1
1.5
2
2.5
3
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Time, s
Upl
ift, i
n
50' Landside
50' Waterside
100' Landside
100' Waterside
WHEEL DISENGAGES FROM RAIL
WHEEL ENGAGED ON RAIL
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-400
-300
-200
-100
0
100
200
300
400
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Time, s
Lat
eral
forc
e, k
ips
/ sid
e
50' Landside50' Waterside100' Landside100' Waterside
Lateral Force on Rail
Note: Wheels engaged with rail. If one side disengages, the shown forces may be up to double at the engaged wheels.
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Tipping Forces
Circa 1970 Modern Jumbo1000k 3000k
300k 1360k
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Tipping Leg Moments
Circa 1970 Jumbo150 k
30'
680 k
680 k
40'
150 k
27,200 k-ft
4,500 k-ftM
omen
t
Mom
ent
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Recent Liftech Design Criteria Changes
Pre 2006 – Force-based design –elastic response for 0.2g lateral loading
2006 to present – Performance-based design – consistent with current wharf design practices
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New Crane Design Criteria
Contingency Level Earthquake:Tipping load – no damage
Ductile yielding – some damage
Isolation – no damage
Operating Level Earthquake:Elastic strains – no damage
Reference:
http://www.liftech.net/LiftechDesignNotebook/designcriteria.pdf
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Design for Tipping
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Design for Ductile Yielding
B
B
A
A
AISC SEISMICALLY
COMPACTA-A
B-B
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Design For IsolationIsolation Between Main Equalizer and Sill Beam
Mitsubishi Heavy Industries
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Design For IsolationIsolation Between Lower Leg and Portal Beam
Liftech
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Isolation DetailIsolation Between Lower Leg and Portal Beam
Liftech
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What about Existing Cranes?
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Some Retrofit Questions
1. How will the existing crane perform?
2. Is significant damage acceptable in an operating level earthquake?
3. At what magnitude earthquake is collapse acceptable?
4. Should different criteria be used for different cranes?
5. Should cranes be upgraded when the wharf is upgraded?
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Cost vs. PerformanceNew Construction and Retrofit
Performance
Cos
t
Retrofit + Damage
New + Damage
Retrofit
NewDamage
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Factors Affecting Seismic Risk
Location – SeismicityRail GageDuctility of the Portal FrameMassPortal Strength Portal StiffnessTrolley Mass
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Rail Gage
50’ Gage 100’ Gage or Larger
1000k3000k
300k1360k
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Ductility
Connection strength > member strength
Close stiffener spacing to limit local buckling.
Ductile weld details FILLETSIZE t/4BUT ATLEASTAWS MIN.t
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Mass, Portal Strength, and Stiffness
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Evaluating Existing CranesSuggested Steps
Check if the portal structure can support the tipped crane
Check if the portal structure can deflect laterally 30” without collapse considering secondary effects and multiple load cycles.
Perform time history analysis
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Retrofit Options
ExpensiveNo damageAdd isolation mechanism
Probability of damage unchanged
Least costly,avoids collapse
Improve ductility and strength by adding stiffeners
May reduce portal clearance or be expensive
Reduces probability of damage
Strengthen structure
ConProOption
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Strengthen Portal to Carry Tipped Crane
Temporary Jacking Frame
Pipe Braces
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Add Plate Stiffeners to Improve Ductility
Original Reinforced
External Angle Stiffeners
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Add Isolation MechanismIsolation Between Lower Leg and Portal Beam
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Other Gantry Structures
Bulk Loader
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Loader DamageAticu, Peru 2001
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Time History Analysis
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Summary
Be aware of seismic risk.
Use state-of-the-art performance criteria when purchasing new cranes.
It is practical to evaluate seismic risk.
Retrofit is an option and is most practical when making other modifications.
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Thank You
This presentation with speaker notes will beavailable for download on our website:www.liftech.net
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Quality Assurance Review:
Principal: Erik Soderberg
Editor: Michael Jordan
Author: Erik Soderberg
Liftech Consultants Inc. file data:N:\Papers & Presentations\!Working\2007_AAPA_Seismic_ES\Seismic_Retrofit_Cranes_06_AD.ppt
Copyright 2007 by Liftech Consultants Inc. All rights reserved.This material may not be duplicated without the written consent of Liftech Consultants Inc., except in the form of excerpts or quotations for the purposes of review.
The information included in this presentation may not be altered, copied, or used for any other project without written authorization from Liftech Consultants Inc. Anyone making use of the information assumes all liability arising from such use.
