Contents
Depth and width of the beam as per thumb rule | dimensions of beam | calculation of beam dimensions |
depth and width of beam is the important concept in structural design. Beam is a horizontal member which is connected in between the column sections. The main purpose of the beam is to transfer the load from slab to column section for the building structure.
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| Beam cross section |
The depth and width of the beam are the major aspects in building design. Without fixing the dimensions of the beam it is not possible to analyze structure under consideration.
The following are the major 3 factors which will effects the dimensions of beam.
- Center to center distance between columns
- Loading condition
- Number of floors
1. Center to center distance between columns
The minimum center to center distance between RCC structures is taken as 8’0“and the maximum value is taken as 15’0”. If the distance between the columns increases then the loading rate increases from the beam to resist that much of load the depth of beam increases. The depth of the beam is directly proportional to center to center distance between columns.
2. Loading condition
Loading condition is the second factor which we need to consider in depth of beam. As we discussed in center to center distance if the load increases the depth of beam also increases. Here is also the loading is directly proportional to the depth of beam.
3. Number of floors
Number of floors is the third important factor we have to take while calculating the dimensions of beam in building design. If the number of floors increases then the dimensions of beam are also increases.
Depth and width calculation as per thumb rule
As per the thumb rule the depth D of the beam is calculated by using below formulae
D= L/16
Where L = Center to center distance between the columns
D= Depth of the beam
So the depth D is directly proportional to center to center distance. If the center to center increases the depth is also increases. From the depth of the beam one can easily calculate the width of beam. Width of the beam is given by below formulae
W= D/1.5
Where W= Width of beam
D= Depth of beam
Examples depth and width of beam as per thumb rule
1. The following image shows the example 1 beam which is supported on two columns. The center to center distance between columns is assumed as 4000mm.
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| Beam example 1 |
Depth = L/16 = 4000/16 =250mm
Width = D/1.5 = 250/1.5 =166.66mm
Approximately take as 250mmX170mm for 4000mm distance beam.
1. The following image shows the example 2 beam which is also supported on two columns. The center to center distance between columns is assumed as 6000mm.
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| Beam example 2 |
Depth = L/16 = 6000/16 =375mm
Width = D/1.5 = 375/1.5 =250mm
Approximately take as 375mmX250mm for 6000mm distance beam.
1. 2. The following image shows the example 2 beam which is also supported on two columns. The center to center distance between columns is assumed as 8000mm.
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| Beam example 3 |
Depth = L/16 = 8000/16 =500mm
Width = D/1.5 = 500/1.5 =333.33mm.
Approximately take as 500mmX340mm for 8000mm distance beam.
The complete concepts are explained in my YouTube channel Civil Engineering by shravan. Please watch from here.
Conclusion of depth and width of beam as per thumb rule
Well now the explained concepts are related to Depth and width calculation as per thumb rule. As per the standards it is having approximately take as 250mmX170mm for 4000mm distance beam, approximately take as 375mmX250mm for 6000mm distance beam and approximately take as 500mmX340mm for 8000mm distance beam.
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