Prof Awad S. Hanna

8/14/2019 Prof Awad S. Hanna

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Prof Awad S. Hanna

Boobs work


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Prof Awad S. Hanna

FORMWORK- Aakriti vermaSanskriti tiwaryNeha awasthiRicha bhatt


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Prof Awad S. Hanna

Form work for concrete


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Prof Awad S. Hanna

Objectives of FormBuilding

0 Forms mold the concrete to desired size and.shape and control its position and alignment

0 ;But formwork is more than a mold it is a

:temporary structure that supports0 +its own weight0 +the freshly placed concrete0 ( ,construction live loads including materials


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Prof Awad S. Hanna

Objectives of Form Building

asic objectives in formuilding are three fold :0 - ,Quality In terms of strength, ,rigidity position and dimensions

of the forms0 -Safety for both the workers and

the concrete structure0 -Economy the least cost consistent

with quality and safetyrequirements


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INDIAN STANDARDS

0Size of formwork for a span of4.5mt & for a height of 3.5mt

0Sheeting for slab bottom ,beamand column sides -25-40 mmthick

0Joists , ledges (for supportingsheathing of slab)- cross-section

area varies from 50 *50 50*75

0Ballies min. diameter 100 at mid-length & 80 at thin end


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0Ballies should be supported by a

soleplate or wooden wedges -40

mm th.

0Posts cross-section 75*100 100*100

0Column yokes c/s 50*75 75*100

0Studs c/s 50*100 150 * 150

0Size of column yoke bolts- 16-

22mm dia

0Distance between column yokes- .3 -.5 m

0 FORM WORK & CENTERING FOR UPPER


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Formwork for Beams and Slabs


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Formwork Materials

0Wood

WEither all-wood or some wood

components0Plywood

0Aluminum

0Steel0Plastics


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Lumber

0 Designated by Cross Sections, NominalDimensions (prior to finishing)

W After cut length wise, finishing operations

reduces actual dimensions

` 2 x 4 Plank 1 1/2 x 3 1/2 2 by 4 inS4S

W Lengths are multiples of 2 ft (8, 10, 12, 14, 16,)

W Specified by type and grade

`Type: pine, oak, fir`Grade: Selected (A, B, C, D) and Common (1, 2,

3, 4)

` Selected (A best, D poor quality)

W Cost Kind, grade, size, length, milling, quantity,

freight



Plywood

04 ft wide - 8, 10, 12 ft long

01/4, 3/8, 1/2, 5/8, 3/4 inch thick



Plywood Orientation

Face Grain Direction Face Grain Direction

Weak Orientation of Plywood( )Face grain parallel to span

Strong Orientation of Plywood( )Face grain perpendicular to span



Aluminum

0Pure aluminum chemicallyattacked by wet concrete

0Light weight allow larger formingunits

0High reuse value

Aluminum beam - nailer type



Steel

0For heavy concrete work

0With reasonable care will last

indefinitely0High initial cost and high handling

cost



Estimating Issues

0Normally, the forms are used more than

once

0More usage of forms reduce the price0Wood forms have less usage potential

than aluminum or steel forms

0Complicated shapes of concrete aremore expensive because of labor cost

and reuse of forms.



Effect of Reuse on Concrete FormworkCost

Number of usesCost per square foot

of contact area

1 1.002 0.62

3 0.50

4 0.44

5 0.406 0.37

7 0.36

9 0.32



Estimating Issues (Formwork)

0Do not deduct

W Intersection of beams

W Intersection of beams & columns &walls

WAny opening < 100 sq. ft.



Formwork0Unit of Measurement Square Foot Contact Area

SFCA0Measure just contact area, not

area of formwork

Contact Area= 2h(L+B)

Concrete

L

B

h



Additional Costs0 Nails

W For first use, 10 - 20 lb. Per 1000 fbm

W Additional used, 5 - 10 lb. Per fbm

0 Form OilW 300 - 500 ft2/gal

0TiesWTies keep forms apart and resist bursting

pressure of concrete

W Stay in concrete, pull out

WTypes:` Steel bands

`Rods

Threaded

`w/ Nuts and clamps



Design and Estimating ofForms

0Design determine Sheathingthickness, stud size, wale size, tiesize

0Use of design tables0Watch for

1. Rate of pour

2. Temperature and weather 3. Proportions of mix and

consistency

4. Method of placement and



Workshop Example

0Estimate the cost of formwork forconcrete wall (96 x 254)

0The rate of placing concrete = 4ft/hour

0Maximum temperature of concrete

= 70F



Concrete Footing

9

6

Walltie

/ 3 4 plywood sheathing - 2 x 4 x 10 0 stud- 2 2 x 4wale

- 2 x 4 x 10 0- brace @ 6 0

2 x 4 sill

25 4

Side ElevationSection through the Wall

- 2 x 4 x 3 0- Stake @ 6 0


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Documents

Prof Awad S. Hanna