Footings are structural elements designed to carry the load from all elements above them. Such structural elements include beams, columns, slabs, walls, staircases, and others.
Here is a series of step-by-step instructions to estimate the quantity of reinforcements in footings.
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Table of Contents
Estimate Footings Foundation Reinforcements
The following is a series of step guides on how to estimate footings, foundation reinforcements to consider:
Determine Possible Parameters
Let’s assume the footing dimensions:
- Footing size = 2m x 2m x 0.45m
- Reinforcement spacing = 160mm
- Concrete cover = 50mm
Calculating the Number of Spacings
Calculating the number of spacing includes deducting the concrete cover, i.e 50mm at both ends.
- Effective plan size = Total length – Concrete cover at both ends
- Therefore, Effective plan size = 2 – (2 x 0.05) = 1.9m
- Effective depth = 0.45 – (2 x 0.05) = 0.35m
Determine Bar Arrangement
- Number of bars in each direction = (effective length/spacing) + 1
- Therefore, the Number of bars = (1.9 / 0.16) + 1
- Number of bars = 13 approx.
- Please note: the footing is square, both sides have 13 numbers = 2 x 13 = 26 numbers
Determine the Total length
- The cutting length = effective length + (2 x effective depth)
- Therefore, cutting length = 1.9 + (2 x 0.35) = 2.6m
Total Number of bars
- Total number of bars = (cutting length x numbers of bars)/12
- Total number of bars = (2 x 26)/12 = 4.3 full-length bars approx.
Summary: Footings Foundation Reinforcements
From above, to form reinforcement of a footing (2m x 2m x 0.45m) requires 4.3 numbers of full 12m lengths. Normally, you won’t get 4.3 bars; what you will get is 5 full bars.
It should be noted that the calculations above help the Engineer know the number of reinforcement bars they need in their work.
