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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.