Given below, the detailed processes for working out the quantity of steel in RCC slab.
1. Produce a bar bending schedule with the purpose of categorizing various shapes of bars (bent up bar, straight anchor bar, eos bar, curtail bar etc) and diameters.
2. Make a list of all the shapes of bars out of the drawing.
3. Calculate the number of bars for each of those shapes.
4. Now work out the cutting length of each of those bars.
Cutting length of bar = (length of the member – subtraction for cover on both sides) + development length.
5. Then work out the unit weight of each dia bars with the formula given below :
W = d^2/162
Here d stands for the dia in mm and weight (w) in kg.
6. After that compute weight of rebar
Weight of rebar= no of bars x cutting length x unit weight
7. Sum up all the weight to obtain the total steel quantity.
NOTE – 1. Least % of steel as per Indian standard are:
1. Beam (Tension reinforcement):
As = 0.85bd/fy of gross cross-section area.
2. Slab – 0.12% of total area
3. Column – 0.8% of cs area
2. Maximum % steel as per Indian standard are:
1. Beam – 4 % of cross-section area.
2. Slab – 4% of cross-section area.
3. column — 6% of cross-section area.
3. Development Length is normally indicated in the drawings, but if it not mention there, you can compute it as,
D.L = Depth – 2 times cover
4. Binding wire = 10 grams per kg of reinforcement.
5. No. of stirrups = (length of member – 2 x cover ) / spacing + 1