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# Column formwork check (1200mm side length as an example)

13 Nov 2019

First, the parameter information

1. Basic parameters

Column formwork height: 4.3m ; structural surface requirements: hidden; see the detailed description of the column formwork.

2. Panel parameters

Panel thickness: 18mm ;

Bending design value fm : 31N/mm ; elastic modulus E : 11500N/mm ;

3. Fixed card parameters

Fixed card setting pitch (mm) : 300

concrete formwork side pressure standard value G 4k : 36.952kN / m ;

The standard value of the load generated by dumping Q Q 3k : 2kN/m ;

Second, the calculation of the column formwork panel

The panel is a bent structure and its bending strength and stiffness need to be checked. Here, the calculated width of the panel is 10mm.

The section moment of inertia I and the section resistance moment W of the panel are :

I = 10 × 18 / 12 = mm ;

W = 10 × 18 / 6 = mm ;

(1) The large side pressure G 4k of the new pouring effect on the formwork

Calculate by the following formula and take the smaller of them :

F =0.22γtβ β 1/2

F = γH

Wherein γ - gravity density concrete, taking 24.000kN / m . 3 ;

t -- The initial setting time of the new pouring can be taken according to the actual value of the field. When inputting 0 , the system calculates according to 200/(T+15) and gets 5.714h ;

T - concrete formwork temperature, take 20.000 ° C ;

V - concrete pouring speed, take 1.500m / h ;

H - the total height of the top side pressure calculation position to the top surface of the new pouring, taking 4.300m ;

β -- admixture affects the correction factor, taking 1.000 ;

β -- slump affects the correction factor, taking 1.000 .

Calculated according to the above two formulas:

F =36.952 kN/m 2

F =103.200 kN/m 2

According to a large number of experimental studies at home and abroad, when the height of the formwork is > 2.5m , the large side pressure F = 50 kN/m ;

The new side pressure acting on the formwork is G 4k =min ( F , F , F ) = 36.952 kN / m ;

Effective head height of the helium side pressure: h=F/γ=36.952/24.000=1.540m ;

(2) Standard value of load Q3k generated when dumping sputum

3k = 2kN/m ;

(3) Determine the load combination used

Calculate the deflection using a standard combination:

q=36.952×1=36.952kN/m ;

Calculate the bending moment using the basic combination: q = max ( q1 , q2 ) = 46.661kN / m ;

Combination controlled by variable load effects:

Q1=0.9×(1.2×36.952+1.4×2) ×1=42.428kN/m ;

Combination controlled by permanent load effects:

Q2 = 0.9 × (1.35 × 36.952 + 1.4 × 0.7 × 2) × 1 = 46.661 kN / m ; The column die is unfolded, the pressure of the poured concrete side is loaded, the fixed card (steel strip) bearing is set at intervals of 300 mm , the 8.8 steel screws are arranged one for each steel strip, and the formwork panel is calculated according to the one-way plate (the ratio of long and short sides is greater than 3) ), each span is simplified into a simply supported beam, taking a 10mm calculation unit, q=460661x0.01=0.47KN/m. The calculation diagram is as follows: ### You might also like... ##### Effect of circular column forms...

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