Calculation of column formwork

If slump = 110-150mm, ß 2 = 1.15 v: speed of casting concrete m/h The column 6.5m high will be cast within 30 minute -> v = 13 The effective pressure height of liquid concrete h = F/γ 4.

SMC Project - Phase 1

I/ Input Data:

1/ Loads

Maximum lateral pressure of concrete when using inner vibrator:

F= 0.227 γ t0ß1β2v½ =0.227 x 2400 x 4 x 1.2 x 1.15 x sqrt(13) = 10,842.96 kg/m2 where

γ: density of concrete = 2400 (kg/m3)

t 0 : Initial setting time of concrete (h)= 200/(T+15) = 4 T: temperature of concrete (35 o C)

ß 1 : Adjusting coefficient due to adding admixture If there is admixture ß 1 =1.2

ß 2 : Adjusting coefficient due to concrete slump If slump = 110-150mm, ß 2 = 1.15 v: speed of casting concrete (m/h)

The column 6.5m high will be cast within 30 minute -> v = 13

The effective pressure height of liquid concrete h = F/γ 4.52 m

2/ Material characteristics Elastic Modulus of steel E= 2,100,000 (kG/cm2

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II/ Calculation and check for formwork system:

1/ Check of plywood:

According to Manufacturer (TEKCOM), the plywood characteristics as below:

Elastic modulus of plywood E= 45887.4 (kG/cm2)

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Distributed load applied on formwork, 1m wide

Maximum moment at midle of span

Appendix 3

FORMWORK CALCULATION FOR COLUMNS

Components

Moment diagram

Steel box 2x(50x50x2)mm Steel box (40x80x2)mm Plywood 18 mm

Plywood will be supported with 3 intermediate ribs 80x40x2.0 (mm) with distance L1

Checking bending deflection

Conclusion: Plywood secure with the arrangement of rib at distance 0.25m

2/ Longitudinal Rib 40x80x2 (mm)

Moment diagram

Maximum distributed load q2 applied on the midle longitudinal rib

Maximum moment at midle of span Mmax=q.L22/10= 43.37183971 kGm Allowable deflection

[f] = L1/400 = 0.100 cm

Checking stress

Checking bending deflection

Conclusion: Longitudinal ribs are secure with the arrangement of crossing brace at distance 0.4m

3/ Cross bracing 2 boxes 50x50x2.0 (mm)

Applied forces

Calculation diagram

Moment diagram The cross bracing boxes are kept by 2 tie rods at distance L3

(Accepted)

The ribs to be supported by crossing braces at spacing L2

M=q2 x L²/10 q2

Converse concentrate loads into distributed load

Concentrate loads from the cross bracing boxes

Conversed Distrubiton load

Maximum moment at midle of span Mmax=q3.L32/8= 176.20 kGm

Độ võng cho phép

Checking stress

σ=Mmax/W = 1491.06 (kG/cm2

Checking bending deflection

Conclusion: Bracing boxes are secure with the tie rods supports at distance 0.65 m

4/ Tie rods:

Loads applied on tie rods

Tensile strength of tie rod steel [σ] 2300 KG/cm2 Required cross section area 0.94 cm2 Select diameter of tie rods 1.6 cm

Accepted

5/ Steel support

Load applied to props ,α = 30 : P3 = P2/sinα1 4337.18 kG Check stability:

Load applied to props ,α = 60 : P4 = P2/sinα2 2504.07 kG Check stability:

Conclusion: Steel supports can bear the loads with arrangement of 2 pieces at each direction.

Using steel props with their characteristics: outer diameter 4.9 cm, inner diameter 4.4 cm,