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 Props
Double Prop
These props are consisted of two short and long arms and they
are used to plumb the formwork. They are made from pipes and
threaded bars at the head and bottom to adjust the length. A
kind of these props is used as a load-sustaining element to
sustain the concrete hydrostatic pressure. They are connected to
the ground and soldiers from both ends by bracket anchoring.
 
Prop
Props are used to support slabs and beams formwork. They are the
most suitable and economical component for carry out light slabs
and beams.
Props are available in different heights like 3.2, 3.6, 4, 4.2,
and 4.5 meters and are made of pipes with 5 and 6 centimeters in
diameter, which have holes for adjusting the height. These props
are recommended for heights of 3 to 4.5 meters. For higher
ceilings, prefabricated scaffoldings are suggested. T-props are
made according to the clients’ needs.
Prop Calculation
Prop made from two parts that adjustable in length, up
and down parts. The lower part is made of a pipe with a diameter
of 60 mm and a thickness of 2.5 mm the upper part is made of a
pipe with a diameter of 50 mm and a thickness of 2.5 mm.
For example if the height of the prop is 3.50 meter, the design
is as follows:
For Safety in design, you can use pipe with a diameter of
50 mm
|
Type |
L1 |
L2 |
L(max) |
L(min) |
|
3.20
3.40
3.60
4.00
4.20
4.50 |
149
149
149
200
200
200 |
200
225
250
235
250
300 |
320
340
360
400
420
450 |
215
265
265
250
265
300 |
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For slenderness ratio of 195, the allowable stress is:
The end of prop must be fixed.
There are many reports on formwork failure as a result of out of
alignment
of props during concrete pouring.
By using prop brace, you can decrease unbraced length and
increase allowed stress and loading capacity of props.
In the first example if you brace the prop in the middle, the
slenderness ratio will change to 97 and allowed stress will
increase to 904 Kg /Cm2.
Finally the loading capacity will increase to 3.5 Ton. So, in
here if you brace the prop in the middle of the length, the
loading capacity of the prop will be more than twice.
Accordingly, you can calculate allowed load for props with
different lengths.
|
Prop Loading Capacity |
allowed pressure stress |
Slenderness Ratio |
Prop Unanchored Length |
|
2.86
2.47
2.20
1.98
1.82
1.70
1.64
0.87
0.77
0.68
0.61 |
768
661
591
531
788
457
440
234
206
182
162 |
113
127
141
155
169
184
195
212
226
240
254 |
2
2.25
2.5
2.75
3
3.25
3.5
3.75
4
4.25
4.5 |
T-Head
By using this element, we can change simple props to T-Props.
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