How to calculate reinforcement rods required for slabs

Slab reinforcement rods calculation

To calculate slab rods,
1. Simplify the slab area into a square
2. Calculate the rods required on one span of the square slab (running through length of slab only)
3. Multiply by 2 for the second span to get the total number for the slab (running through length and breadth of slab).
4. Calculate beam rods separately (Typically 16mm rods)
5. Calculate stirrups for beams

Simplify slab:

Convert irregular slab shape into a square

Slab area= 180 sq.m

Length of one side of square slab (slab is simplified into a square using square root of 180)
=13.42 m

Rods required on one span of the square slab

Add 1 meter at both ends of slab for 1m rod length return at ends
New length = 13.42 + 1m +1m= 15.42 m

Rods Spacing=175mm

Number of rods lines on one span= Length of slab/spacing
15.42m/0.175m= 88.1 rod lines

Rods length for one span= Number of rods lines on one span x Length of slab
=88.1 x 15.42= 1358.5 meters

Length of one rod = 12 m

Number of rods required for one span= Total rod length for one span/Length of one rod
= 1358.5m/12m=113.2 rods

Number of rods required for both spans= 113.2 x 2=

226.4 rods (12 mm)

 

Beams

Total beam rods length= Total length of beam x Number of rods in beam section

= 130 m x 5= 650 m

Number of rods required for beam = Total beam rods length/Length of one rod
= 650m/12m=

54.1 rods (16mm)

 

Links/Rings

Number of rings= Total length of beam/spacing of rings

130m/0.25m= 520 rings

Length of one ring= 1 m

Total length of rods required for rings= Number of rings x Length of rings

= 520 rings x 1m= 520 m

Number of rods = Total length of rods required for rings/ Lenght of one rod

= 520/12=

43.3 lengths

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