SCT4- b Slide 1 National Urban Search & Rescue Response System Structural Collapse Technician...

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SCT4- b Slide 1

National Urban Search & Rescue Response System

Structural Collapse Technician Training

Module : 4 - Part b

Lifting & Moving Airbags

Lifting Considerations & Stabilization

Calculating Weights

Jan0827Jan09

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High Pressure Air Bags Characteristics

Neoprene/butyl rubberSteel kevlar reinforcedVariety of sizesMaximum capacity is calculated at 1

inch of liftCapacity reduced at max height

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High Pressure Air Bags

ApplicationMaximum stack of two high

Lift is limited to capacity of small bag

Larger bag on bottom

Centers of bags MUST be aligned

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Airbag Lift

Animated Slide (10 seconds)

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High Pressure Air Bags

COLUMN OF AIR

BASE OF SUPPORT

Increased surface area = Increased lifting capacity

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High Pressure Air BagsAIR BAGINFLATED

REDUCED SURFACE AREA CONTACT

BASE OF SUPPORT

COLUMN

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High Pressure Air BagsWeightDimension Capacity Lift Ht.

6”x 6” 1.5 Tons 3” 2 lbs 6”x 12” 3.2 3.5 3 10”x 10” 4.8 5 4 15”x 15” 12.0 8 10 15”x 21” 17.0 9 13 20”x 20” 21.8 11 16 24”x 24” 31.8 13 22 28”x 28” 43.8 16 30 36”x 36” 73.4 20 48

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High Pressure Air BagsManufacture’s I.D. Tag

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High Pressure Air Bags & Cribbing

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Spreading & Pushing

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Structural Collapse Technician Training Lifting & Stabilizing Irregular Objects

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Pipes & Cylinders

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Inflating Air Bags

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Lifting Considerations

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Lifting Or Moving A LoadFunctions to be addressed

Center of GravityLoad Stability

Wedges & cribbing

Estimating Load WeightLifting Functions

Critical angle

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Center of Gravity & Load Stability

Connection point below CG makes object unstable.

Stable Unstable

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Wedges, Shims & Cribbing

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WedgesWedge (mechanics)Technically is a portable double inclined

plane, a wedge is a simple machine used to separate two objects, or portions of objects, through the application of force, perpendicular to the inclined surfaces, developed by conversion of force applied to the blunt end. The mechanical advantage of a wedge depends on the ratio of its length to its thickness.

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Wedges

Use of wedges to change direction

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“Marrying” Wedges (repeated from 2b)Sloped Surfaces Must Be in Full Contact

Full Driven Over Driven Under Driven Best O.K. Wrong

What if one wedge is Upside Down?This is NOT RECOMMENDED. It is better to have the cut surfaces together – more friction & better fit

1” min.

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2x4 Wedges

2x4 wedges are often needed for smaller adjustments than are possible with 4x4 wedges.

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Shims Shims are used to fill space,

opposed to wedges that lift, load or charge objects.

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Shims Note that there are two shims in

this photo.

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Box Cribbing6000 lbs. per contact point

Four point system Nine point system

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Box Cribbing

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4xSolid

Box Cribbing

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Box Cribbing6000 lbs. per contact point

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ObjectMust have full bearing

with cribContact Points

Box Cribbing

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Each cribis only

supporting6000 lbs

Not verystable

Height to width1 to 1

Box CribbingLeast desirable layout

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Can be as little as 1 to 1 with angle situations

Box Cribbing

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Crib Stability

Load should be centered!

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CENTER1/3 ofCRIB

Crib Stability

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Crib Stability Load is not within mid-third at bottom

BECENTER

1/3 ofCRIB

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Change Angle Use of wedges & shims

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Martian Cribbing

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Cribbing

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Calculating Weights

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Weights of Building MaterialsWIDTH x HEIGHT x LENGTH = CUBIC FT Reinforced concrete = 150 pcf

Concrete columns & beams weigh more (16”sq w/ 5% rebar = 170pcf)

Steel = 490 pcf Use Area Method – later slides

Earth = 100 to 125 pcf Wood = 35 pcf (dry) – use 40

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Calculating Weight Concrete Rectangle

WIDTH x HEIGHT x LENGTH x WEIGHT

4’ x 2 ’x 20’ = 160cf x 150pcf = 24,000 lbs.

20 feet

4 feet 2 feet

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Calculating Weights Concrete Round

0.8 DIAMETER2 x LENGTH x WEIGHT

0.8 x 3’ x 3’ x 20’ = 144cf x 150pcf = 21,600 lbs.

3 feet

20 feet

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Calculating Weight Concrete Pipe

Weight of Solid Round – Weight of Hole

0.8 (4’x 4’- 3’x 3’) x 20’x 150pcf 112 cu-ft x 150pcf = 16,800 lbs.

4 feet diameter

20 feet6” thick

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Estimating Steel Weight - Area Method

Steel weighs 490 lbs per cubic ft

Steel 1” thick weighs 490pcf / 12” = 40.8 psf

For steel weight per square foot use:1” thick Use 40 lbs¾” Use 30 lbs½” Use 20 lbs¼” Use 10 lbs

12”12”

1”12”12”

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Area Method Example - 1 What is weight of this 36ft long steel section?

2” Steel = 2 x 40 psf = 80 psfArea per ft = 2 x 3 sq ft + 2 x 1 sq ft = 8 sq ftWeight per ft = 8 x 80 = 640 plfTotal weight = 640 x 36 = 23,040 lbs

Exact weight = 652.8 plf (only 2% off)

Pl 36" x 2"

Pl 12" x 2" ea end

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Area Method Example - 2 What is weight of this 20ft long steel section?

2 Flanges 40 psf x 5” x 2 ft x 2 = 800 plfWeb 40psf x 3.5” = 140Weight per ft = 800 + 140 = 940 plfTotal weight = 940 x 20 = 18,800 lbs

Exact weight = 958.8 plf (only 2% off)

Pl 24" x 5"

Pl 12" x 3.5”

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Calculate Steel Weight

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Structural Collapse Technician Training Review & conclusion of Part b Review

AirbagsLifting Considerations & StabilizationCalculating Weights

Questions? Discussion?

Next: Part c Cranes, Rigging & Bolting

SCT4- b Slide 1 National Urban Search & Rescue Response System Structural Collapse Technician...

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