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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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Prof Awad S. Hanna
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
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Plywood
04 ft wide - 8, 10, 12 ft long
01/4, 3/8, 1/2, 5/8, 3/4 inch thick
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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
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Aluminum
0Pure aluminum chemicallyattacked by wet concrete
0Light weight allow larger formingunits
0High reuse value
Aluminum beam - nailer type
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Steel
0For heavy concrete work
0With reasonable care will last
indefinitely0High initial cost and high handling
cost
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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.
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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
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Estimating Issues (Formwork)
0Do not deduct
W Intersection of beams
W Intersection of beams & columns &walls
WAny opening < 100 sq. ft.
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Formwork0Unit of Measurement Square Foot Contact Area
SFCA0Measure just contact area, not
area of formwork
Contact Area= 2h(L+B)
Concrete
L
B
h
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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
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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
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Workshop Example
0Estimate the cost of formwork forconcrete wall (96 x 254)
0The rate of placing concrete = 4ft/hour
0Maximum temperature of concrete
= 70F
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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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4
4
4
8 8 8 8
-
9
6
- 25 4
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