THE EFFECTS OF WIND ON CRANES AND THEIR LOADS

Matt Gardiner, P.E.

Houston Business Roundtable – Feb. 12, 2013

PRESENTATION OVERVIEW

1. Wind Effects

2. Standards & Regulations

3. Wind Related Accidents

4. Lift Planning Considerations

5. Questions

Houston Business Roundtable

Wind Effects1

About wind…

• Wind speeds are measured at 33 feet above ground

• Wind speed increases with height

• Gusts can be a bigger problem than sustained winds

• Look for obstructions to wind

• Look for potential areas that funnel or redirect wind

1 WIND EFFECTS

How does wind affect a lift?

• Wind applies forces directly to the load (sail effect)

• Wind applies forces directly to the crane

• Drift can cause tip-overs or side-loading

• Drift can eliminate clearances with boom or other obstructions

• Drift (inward) can cause backward instability

• Wind on load can cause load control issues

1 WIND EFFECTS

Standards & Regulations2

• Crane manufacturers, OSHA and ASME provide wind requirements

• §1926 Subpart CC– §1926.1403(h)(12) and §1926.1435(b)(4)(iii): Wind effects must be

considered during A/D ops for mobile and tower cranes

– §1926.1410(c)(1): Power line drift from wind when working inside Table A distances

– §1926.1417(h): Equipment securement requirements from storm warnings

– §1926.1417(n): Capacity adjustment requirements due to wind

– §1926.1431(k)(8)(i): Personnel hoisting requirements – 20 mph at the platform?

– §1926.1435(e)(6)(v) and §1926.1437(e)(3): Wind indicators required on tower cranes and cranes on barges

– §1926.1437(m)(1)(ii): Load charts must consider 40 mph winds for cranes on barges

– §1926.1437(n)(1)(i): Rated capacity reduction requirements (as applicable) due to wind for cranes on barges

2 STANDARDS & REGULATIONS OSHA Regulations

• ASME B30.5 - 2011– 5-3.1.3.2.1(h)(2): Site Supervisor responsible to ensure potential effect of

wind is addressed

– 5-3.2.1.5(b)(5): The effect of wind on the load and crane has to be noted and considered

– 5-3.4.5.4(g): For operations within a FULLY ERECTED/EXTENDED BOOM LENGTH of Table 5-3.4.5.1-1 (same as OSHA Table A), horizontal and vertical power line drift due to wind shall be added to the minimum clearance distance in the Table

• Also requires consultation with utility owner to get specific clearances

2 STANDARDS & REGULATIONS ASME Standards

LIFT PLANNING CONSIDERATIONS4

LIFT PLANNING CONSIDERATIONS4

What does the manufacturer say?

• Most manufacturers recommend capacity reductions above 20 mph

• Most manufacturers set maximum allowable wind speeds for operations

• Always consult the operations manual for instructions

LIFT PLANNING CONSIDERATIONS4

What is the wind forecast?

• Check with reliable sources (NWS, NOAA, official stations)• Look for peak projected sustained and gust speeds AND wind

direction(s)• Speeds tell you how much force can be applied• Direction tells you how the crane and load will be loaded by wind• Remember that wind forecasts are at a height of 33 feet and your

cranes and loads may be much higher

LIFT PLANNING CONSIDERATIONS4

Food for thought

• Will the wind generate enough force to significantly move the load?

• Will the wind generate enough force on the crane’s boom to jeopardize stability?

• Can the wind cause load control problems?• Are there nearby buildings that can funnel or redirect wind flow?• Has the Operations Manual been consulted for limitations?• Is there anything nearby that can be affected by wind that could

interfere with the lift?• Are there any on-site weather stations or anemometers?

LIFT PLANNING CONSIDERATIONS4

References

• OSHA Regulations• ASME Standards• Crane

Manufacturer (Operations Manual)

• Cranes and Derricks, by Howard Shapiro

QUESTIONS?5