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1.0

- Building (Construction Regulations (1990).

- BS 5975:Code of Practice for Falsework, 1996

- Formwork - A Guide to Good Practice, Concrete Society.

2.0

Re-propping for Beams

Width of Beam

"W" (mm)

No. of Row

of Steel Prop

Capacity of

Steel Prop

(kN/Leg)

No. of Floor

Required for Re-

propping

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3.2

Dead Load Floor beam = 4.55 x 24

= 109.20 kN/m

Formwork = 0.50 kN/m

Imposed Load Construction load = 1.50 kN/m

3.3

Minimum spacing of beam > 1000 mm

= 1000 mm

3.4

Concrete strength at 28 days = 35 Mpa

1 37%

4 85%

5 89%

8 100%

9 100%

10 100%

3.5 Load Distribution During construction Stages

Loading:

w1 = 109.2 x 1.4 x 0.3 = 45.86 kN/m (D.L. of beam)

Formwork = 0.50 x 1.4 x 1.00 = 0.70 kN/m (Formwork dead lo

[1.5] = 1.50 x 1.6 x 1.00 = 2.40 kN/m (Construction load)

[0.75 L.L] = 0.75 x 1.6 x 1.00 = 1.20 kN/m

Original design load on beam = 3.6 x 1.4 x 0.3 + 4 x 1.6 x 1.00 = 7.912

(Dead load of slab not included in orginal design load on beam for conservative)

(A live load allowa

incidental load on f

35.0

35.0

29.8

35.0

31.2

Age (Days) % of Strength Achieved Compressive Strength (Mpa)

13.0

Load Width of Beam

Adopt load width of beam

(conservative)

Concrete Strength

Design Load

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No. of Floor

with Scaffold

in Place

2

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ad)

kN/m

nce for

loor)

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Concreting of 24/F

25/F\ Age 0 day

0%

24/F [1.5]

Age 0 day W4 Age 1 day

0% 37%

Scaffold

23/F [0.75 L.L]

Age 4 day W3 Age 5 day

85% 89%

Scaffold

22/F [0.75 L.L]

Age 8 day W2 Age 9 day

100% 100%

Back propping

21/F [0.75 L.L]

Age 12 day W1 Age 13 day

100% 100%

Back propping

20/F [0.75 L.L]

Age 16 day Age 17 day

100% 100%

Back propping

(not required)

19/F [0.75 L.L]

Age 20 day Age 21 day

100% 100%

Back propping

(not required)

18/F [0.75 L.L]

Age 24 day Age 25 day

100% 100%

Back propping

(not required)

17/F [0.75 L.L]

Age 28 day Age 29 day

100% 100%

Back propping

(not required)

16/F [0.75 L.L]

Age 32 day Age 33 day

100% 100%

Back propping

(not required)

15/F [0.75 L.L]

Age 36 day Age 37 day

100% 100%

Back propping

(not required)

Strength achieved

Strength achieved

Strength achieved

Strength achieved

Strength achieved

Strength achieved

Strength achieved

Strength achieved

Strength achieved

Strength achieved

Strength achieved

Strength achieved Strength achieved

Strength achieved Strength achieved

Strength achieved Strength achieved

Strength achieved Strength achieved

Strength achieved Strength achieved

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3.6 Check Capacity of Back Propping (Steel Props)

Maximum scaffold load = 48.96 kN/m

Maximum back propping load = 129.15 kN/m (Factered load)

Provide 1 row 20 kN capaity steel props @ 900 c/c along beam

maximum vertical load per leg of steel prop (working load)

= 129.15 x 0.9 / 1.4 / 1

= 83.03 kN

Capacity of steel prop = 20.00 kN/Leg

> 83.03 kN

Adopt 1 row 20 kN capaity steel props @ 900 c/c along beam

For Beam DP

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