How to calculate the shuttering area of beams?/Estimating the formwork area of beams.

 The shuttering area of the beam is calculated by the formula

= [(2d + b) 🇽 L ]

As you can see in the following drawing, the top surface of the beam is excluded while calculating the shuttering area. This is because the formwork covers only 3 sides & we cast the beam from the top to its required level. 

In some cases like in end beams or in cantilever beams the shuttering area of the closed end should also be taken into account. 

Let us first understand the calculation steps for a single beam having the below-given dimensions.

Given data:

Length of the beam = L = 3.5m.

Depth of the beam = d = 0.45m.

Width of the beam = b = 0.23m. 

Calculation:

The shuttering area of the beam

= [(2d + b) 🇽 L ]

 = [(2 🇽 0.45 + 0.23) 🇽 3.5 ]

= [ 1.13  🇽 3.5 ]

= 3.955 m²

Does this calculation explain all?

NO.😊

The shuttering area of the beam mainly depends upon its type & positioning in the building structure.

Now, let us observe the following drawings. 

The beam B3(a) is a mid beam that has a slab on both sides. The beam B3 is the end beam at the edge of the slab.

Now,

For beam B3(a)

The shuttering area

 = [(2d + b) 🇽 L ] 

But, for beam B3

The shuttering area

 = [(d + d1+ b) 🇽 L ] 

Here, 

d1 = [beam depth + slab thickness]

d1 = [ d + t]

Now,

 let us go through the calculation procedure for the beam B3.

Given data:

Length of the beam B3 = L = 3.5m.

Depth of the beam B3 = d = 0.45m.

Width of the beam B3 = b = 0.23m. 

The thickness of the slab = t = 0.15m.

Calculation:

The shuttering area of the beam B3

= [(d + d1 + b) 🇽 L ]

Here, d1 = (d + t )

               = ( 0.45 + 0.15)

          d1 = 0.60m.

Shuttering area

 = [(0.45 + 0.60 + 0.23) 🇽 3.5 ]

= [ 1.28  🇽 3.5 ]

= 4.48 m²

Now, let us calculate the shuttering area for cantilever beam B1(a).

For cantilever beam B1(a)

The shuttering area

= [{(average depth of tapered vertical face on both sides) + bottom width } 🇽 beam length ] +[ area of beam end surface]

 = [{((d2 +d3) ÷ 2) 🇽 2nos. + b1} 🇽 L1 ] + [{ t +d2} 🇽 b1]

 Let us go through the eg. to understand the theory completely.

Given data:

Length of the beam B1(a) = L 1 = 1.5m.

Depth of the beam B1(a) at outer edge = d2 = 0.15m.

Depth of the beam B1(a) at column end = d3 = 0.35m.

Width of the beam B1(a) = b1 = 0.23m. 

The thickness of the slab = t = 0.15m.

The shuttering area of  beam B1(a)

 = [{((d2 +d3) ÷ 2) 🇽 2nos. + b1} 🇽 L1 ] + [{ t +d2} 🇽 b1]

= [{((0.15 +0.35) ÷ 2) 🇽 2nos. + 0.23} 🇽 1.5 ] + [{ 0.15+ 0.15} 🇽 0.23]

 =  [{(0.50 ÷ 2) 🇽 2nos. + 0.23} 🇽 1.5 ] + [0.30 🇽 0.23]

 =  [{0.25 🇽 2nos. + 0.23} 🇽 1.5 ] + 0.069

  = [ 0.73 🇽 1.5 ] + 0.069

 = 1.164 m²

I think you understood the procedure. If you have any queries you can ask me in the comment section.

Thank you for going through these calculation steps❤. Have a good day 😄.

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