How the BBS Generator works
Prepare a bar bending schedule (BBS) for beams, columns, slabs and footings. Enter each bar once with its shape and the number of members; the tool works out the cutting length, total bars, running metres and steel weight for every diameter, plus wastage.
Frequently asked questions
How is the cutting length of a stirrup calculated?
For a rectangular stirrup with 135° hooks: 2(A + B) + 2 × hook − 3 × 2d − 2 × 3d, where A and B are the outer dimensions (member size minus twice the clear cover), d is the bar diameter, and the hook is 10d (common site practice) or 6d with a minimum of 65 mm as required by IS 13920 for seismic detailing.
What bend deductions does the BBS use?
Standard site practice: 1d for a 45° bend, 2d for 90°, 3d for 135° and 4d for 180°, where d is the bar diameter.
How is steel weight calculated?
Unit weight of a bar is d²/162 kg per metre (d in mm). For example, a 12 mm bar weighs 0.889 kg/m and a 16 mm bar 1.580 kg/m.
How do I calculate a crank (bent-up) bar?
Cutting length = straight length + 2 × 0.42D − 4 × 1d for a bar with two 45° cranks, where D is the crank height (slab depth minus top and bottom cover minus bar diameter).
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