2015 crw - setting up for success
TRANSCRIPT
Outrigger Pads for Mobile CranesRules – StandardsRules of ThumbSizing Recommendations
Setting Up For Success
Objectives Disclaimer
Share information to assist you in making better decisions
Agree on Basic Definitions
Identify the Rules & Standards that apply to:
Ground Conditions
Blocking Cribbing & Pads
Identify & evaluate different industry “Rules of Thumb”
Sizing Advice
2
3
Focus on Outrigger Enabled Equipment
Float, Foot, Pontoon, Pad
4
Pad, Mat, Blocking, Cribbing,
5
Mobile CraneApplicable Rules & Standards
6
OSHA• 1926 Subpart CC Section1402 • Definitions
ASME B30.5 Mobile & Locomotive Cranes• 3.2.1.5 • Moving the Load• 3.4.6 • Footing
7
What's Important to Note About OSHA Regulations
BASIC RULE: You must not assemble or use a crane unless ground conditions are firm, drained, and graded to a sufficient extent so that, in conjunction (if necessary) with the use of supporting materials (such as blocking, mats, cribbing, or marsh buggies), the equipment manufacturer's specifications for adequate support and degree of level of the equipment are met.
8
What's Important to Note About OSHA Regulations
OSHA does not have a rule regulating the construction, design, or materials used as foundation support. (pads, mats, blocking or cribbing)
9
Abbreviated Inspection Checklist
1. Determine the adequacy of ground conditions beneath the equipment set up area such as the support/foundation matting, cribbing, blocking, etc.
https://www.osha.gov/OshDoc/Directive_pdf/CPL_02-01-057.pdf
OSHA 1402 Ground Conditions “Summarized”
10
Equipment must stay within manufactures specifications for support and level.
Use supporting materials (blocking, mats, cribbing) to accomplish this
Controlling entity is responsible for ground conditions. Including underground hazards
If there is not a controlling entity, then the responsibility shifts to the employer.
Crane company & operator are responsible for evaluating the ground conditions. They must notify others of inadequate ground conditions before beginning or continuing operations.
ASME B30.5-2011
11
3.2.1.5 Moving the Load
(i) When outrigger floats are used, they shall be attached to the outriggers. Blocking under outrigger floats, when required, shall meet the following requirements:
(1) sufficient strength to prevent crushing, bending, or shear failure.
(2) such thickness, width, and length, as to completely support the float, transmit the load to the supporting surface, and prevent shifting, toppling, or excessive settlement under load.
Not Sufficient Strength (Physical Failure)
12
Not sufficient rigidity (Functional Failure)
13
14
ASME B30.5-20113.2.1.5 Moving the Load
Blocking under outrigger floats, when required, shall meet the following requirements:
(3) Use of blocking only under the outer bearing surface of the extended outrigger beam
15
http://www.elcosh.org/document/1488/748/d000104/selection.html
(3) use of blocking only under the outer bearing surface of the extended outrigger beam
5-3.1.3.3 Responsibilities of Crane Operators.
(b) knowing what types of site conditions could adversely affect the operation of the crane and consulting with the lift director concerning the possible presence of those conditions.
16
ASME B30.5-2011
17
Know Your Ground Conditions (Waikato)
Industry Rules of Thumb
18
19
Industry Rules of Thumb
• Estimating Outrigger Reaction Force • Estimating Ground Strength
• Estimating Pad Sizing
20
Outrigger Reaction Force = Pressure
PRESSURE(PSF)
21
Common Outrigger Load Rules of ThumbCapacity x 85%Rated Capacity (lbs.) of the Crane x 85% = Outrigger Reaction Force
International - (Referenced in European and Australian standards)(Total Crane Mass (lbs.) + Load(lbs.)) x 65% = Outrigger Reaction Force
22
Outrigger Load Rules of Thumb ExampleGrove RT890E
Capacity x 85%180,000 x 85% = 153,000 Lbs
International(Mass + Load) x 65% = Outrigger Reaction Force(117,235 + 180,000) = 297,235 x 65% = 193,200 Lbs
Difference = 40,200 Lbs
23
Outrigger Load Rules of Thumb Example
24
Outrigger Load Rules of Thumb ExampleGrove GMK 5276• Rated Capacity = 220 Tons, 440,000 Lbs• Total crane mass = 150,000 Lbs
Capacity x 85% Example –• 440,000 lbs. x 85% = 374,000 lbs.
25
Outrigger Load Rules of Thumb ExampleGrove GMK 5276• Rated Capacity = 220 Tons, 440,000 Lbs• Total crane mass = 150,000 Lbs
International Example –• (Total Crane Mass + Load) x 65%• 150,000 Lbs + 440,000 Lbs = 590,000 Lbs
• 590,000 Lbs x 65% = 383,500 Lbs
26
Outrigger Load Rules of Thumb Example
Outrigger Load Rules of Thumb ExampleWhat is the Maximum Outrigger Reaction Force (MORF) for your crane?
Crane manufactures provide this information
Newer software solutions from manufacturers & others Manitowoc - Compu-Crane Liebherr - Liccon Software Link Belt – Technical specifications Tadano – Online request tool? 3-D Lift Plan
27
28
Grove GMK5275 220 Ton Crane Full Cwt
Outrigger Load Rules of Thumb ExampleGrove GMK 5275 220 Ton CraneCompu-Crane Output
29
Know What Lifts Generate the Highest Pressures Picks=126k (126psi) vs. 875 (104psi)
30
31
Outrigger Load Rules of ThumbDICA Advice –
Don’t use a rule of thumb to determine the maximum outrigger reaction force.
Know the Maximum Outrigger Reaction Force of your crane.
Why – MORF drives the Strength Requirements of your Pad
32
Ground Strength Rules of Thumb
Bearing Capacity of Soils
Determining the bearing strength of the ground and soils is an extremely complex combination of science, engineering and art. Seek the advice of a geotechnical engineer.
33
Bearing Capacity of SoilsUltimate bearing capacity (UGBC) is the theoretical maximum pressure which can be supported without failure.
Allowable bearing capacity (AGBC) is what is used in geotechnical design, and is the ultimate bearing capacity divided by a factor of safety.
In the case of temporary structures the typical FOS = 1.5 - 2
34
Ground Bearing Capacity – Shear Failure
35
How To Prevent Shear Failure
Improve the Ground Compaction Bring in rock or other dense inorganic materials to increase ground bearing capacity Remove un-compacted surface layers If wet, allow time for moisture to evaporate
36
How To Prevent Shear FailureReduce the Pressures Imposed into the Ground Increasing the contact area to the ground using load spreading tools such as Pads, Mats, Blocking, Cribbing
37
How To Prevent Shear Failure“It might make sense to do some of both…”
Keith Anderson. Rigging Engineering Basics, 1st edition
38
39
Ground Strength Rules of ThumbVisual Analysis –
• Reference a generally accepted Ground Bearing Pressure Chart based on the soil type and condition
Roll Tests• Know the Pressure exerted by the tires of your crane.• Measure the compaction of the ground under the tires• Develop a plan to identify the ground strength based on ground
compaction
Generally AcceptedGround Bearing Pressures
40Shapiro Cranes & Derricks, fourth edition
Know Your Ground ConditionsDynamic Cone Penetrometer The DCP procedure is currently standardized by ASTM D 6951-03. (Good for depths up to 6’)
41
42
Ground Strength Rules of Thumb - DangersLittle Jack Horner Sat in a corner, eating his Christmas pie, he put in his thumb, & pulled out a plumb, & said, what a good lad am I!‘
43
Ground Strength Rules of ThumbDICA Advice –
• Use Caution at All Times• Understand Specific Site Information from the Controlling Entity• Reference Geotechnical Information Whenever Possible• Monitor the Ground During All Operations
44
Ground Strength Rules of ThumbDICA Advice –
Know what Ground Strength Your Pads are Designed For
Why – Ground Strength is Key to Determining Pad Area
45
Pad Sizing Rules of Thumb
Pad Sizing Rules of Thumb3x The AreaArea of the Float x 3 = Area of Matting
Shapiro MethodCapacity of the crane in Tons / 5 = Area of Matting
Duerr - Simple Mat Sizing (Capacity x 1,100) / Soil Bearing Capacity = Area of Matting
Square Root Method√ capacity / 4 = Area of Matting
46
Other Pad Sizing MethodsEqualization Method (soil bearing capacity method) Outrigger Load/ ASBC = Area of Matting
Duerr – Effective Bearing Length of Crane Mats Evaluation of the material being used to meet the matting objective.
47
Sizing Methods Evaluated
• 3x The Area
• Shapiro Method
• Duerr - Simple Mat Sizing (SMS)
• Square Root Method
• Equalization (Soil Bearing Capacity) Method
48
Crane Specific Rule of Thumb Evaluation Assumptions
• Crane MORF is the Load to be fit for
• Weight of the mat is not included in the calculations.• Steel pads generally add 50 – 100 Psf
• Pad size results are rounded up to the nearest foot.
• Allowable Ground Bearing Capacity of 5,000 Psf is used, when applicable.
49
Generally Accepted Ground Bearing Pressures
50Shapiro Cranes & Derricks, fourth edition
Grove RT650 E 50 Ton Crane
51
Link-Belt 3140 140 Ton Crane
52
Grove GMK6350 350 Ton Crane
53
54
Confused, Don’t Use Any Pads
Outrigger Pad Sizing Rules of Thumb Analysis54 Total Cranes Evaluated
Not every crane was evaluated in every method due to unconfirmed data.
3 Different Crane Manufactures Grove, Link-Belt, Tadano
Range in Lifting Capacity from 8.5 Tons – 300 Tons (Defined Bands) < 50 Ton Cranes = 11 > 50 and < 100 Ton Cranes = 16 > 100 and < 200 Ton Cranes = 12 > 200 Ton Cranes = 6
55
56
Outrigger Pad Sizing Rules of Thumb
57
Outrigger Pad Sizing Rules of Thumb
58
ROT Analysis – Soft Ground (2,500 Psf)
Avoid using a ROT in Soft Ground Conditions
59
Outrigger Pad Sizing Rules of Thumb
60
Outrigger Pad Sizing Rules of Thumb
3x The Area – – Cranes < 100 tons, where ASBC > 5,000 Psf– Small Cranes on Stable, Strong Ground
Shapiro Method– Cranes up to 200 Tons, where the ASBC ~ 5,000 Psf– +/- Changes in actual ASBC Significantly Alter the Results
Square Root Method– Cranes up to 200 Tons, where the ASBC ~ 5,000 Psf– +/- Changes in actual ASBC Significantly Alter the Results
Duerr - Simple Mat Sizing (SMS)– Cranes from 50 – 200 Tons in All ASBC– By Far the Most Accurate Rule of Thumb – Takes the ASBC into account
61
Rule of Thumb Sweet Spots?
Rule of thumb conclusions vary significantly from method to method.
Most rules of thumb do not take ground conditions into account.
Rules of thumb Do Not address pad and mat material, design or construction.
Rules of thumb assume pads and mats are designed and constructed in a way that meets or exceeds the bearing, flex and shear strength needed.
They only output estimated pad area.
62
Rule of Thumb Evaluation Conclusions
DICA Advice –
Avoid use a pad sizing method that does not take defined ground conditions and actual outrigger loads into account.
63
Rule of Thumb Evaluation Conclusions
64
Sizing Advice
What Outrigger Pads and Crane Mats Must Do:
• “The must spread the load from the float/pontoon over a large enough area that the bearing pressure to the ground surface is acceptable.”
• “Provide support to the crane that is stiff enough that the crane will not go out of level as the loads from the crane change during lifting operations.”
David Duerr P.E., 2DM and Associates Inc.
65
Sizing Advice
66
Simple Sizing:“To keep things simple, you may decide for your fleet of outrigger based cranes that, knowing the ground capacity and the max loadings each crane could put down, each crane must always use a particular size mat. That would guarantee keeping within the permissibles at all times and avoid having to recalculate every time.”
Keith Anderson P.E., Bechtel
Sizing Advice
Sizing Advice
1. Know the Maximum Outrigger Reaction Forces for your Equipment.
2. Size the Area Your Pads Based On Defined Ground Conditions.
3. Ensure the Pad You Choose has the Strength and Rigidity you need to Not Fail, and to Distribute the Load.
4. Consult with your Outrigger Pad or Crane Mat Manufacturer Specifically for proprietary materials and construction
67
DICA 3 Step Fitting Process1. Identify the Equipment Data Points
Crane capacity Outrigger Float dimensions Maximum Outrigger Reaction Force
2. Determine the Pad Strength & Stiffness (thickness) necessary to Support & Spread the load.
3. Determine the Mat Area Needed Based On: Outrigger Reaction Force to be FIT for Soil Bearing Capacity to be FIT for
68
69
Example:• MORF= 428,000 Lbs. Outrigger floats 2’ x 2’ = 4 sq. ft. Pressure = 743 Psi• Allowable Ground Bearing Capacity = 5,500 Psf• Mat Area Needed = 78 sq. ft. (428,000 / 5,500 = 78 sq. ft.)• Crush Rating 1,000 Psi > 743 Psi• 10.5’ x 7.5’ = 78 sq. ft. mat with proper material, strength, bending and rigidity
properties
Sizing Advice - ExampleLiebherr LTM 1350-6.1 350 Ton Crane
Know your limitations:Know what Outrigger Load and Ground Bearing Pressure the mats are designed for.
70
Sizing Advice
71
Larger Areas, Require More Rigidity
72
Recommended Resources
73
David Duerr, P.E. - 2DM Associates Book – Mobile Crane Support Handbook Paper – Effective Bearing Length of Crane Mats Presentation - Crane Mats & Ground Bearing Issues
Lawrence & Jay Shapiro Book - Cranes & Derricks, Fourth Edition
J. Keith Anderson, P.E. - Bechtel Book – Rigging Engineering Basics, First Edition
Ron Kohner, P.E. - Landmark Engineering Services, LTD ABC’s of Foundation Loading Under Cranes
This is 100% Preventable
74
Thank You
75