# PARAM VISIONS

All about civil construction knowledge- PARAM VISIONS

### Bar bending schedule (BBS) of a Chajja (sunshade). Type-1 / Calculating the cutting length & weight of reinforcement in a window projection (sunshade).

Let us make BBS of the Chajja or RCC sunshade as shown below.

Given data:

Lintel beam width = 230mm.

Lintel beam depth = 350nmm.

Main bar = 10∅ @ 150c/c.

Distribution bar = 8∅ @ 150 c/c.

Lintel beam cover = 25mm.

Calculation:

A. Cutting length:

1. Cutting length of the main bar

= [{sunshade thickness - (2nos. × cover)} + (sunshade width - cover) + {2nos.×  (lintel width - cover)} + 100mm. + (100mm. - lintel cover) - (3nos. × 90° bend.) ]

=  [{75mm. - (2nos. × 20mm.)} + (900mm. - 20mm.) + {2nos.×  (230mm. - 20mm.)} +100mm.+ ( 100mm.- 25mm.) - (3nos. × 2 × 10mm.) ]

=  [{75mm. - (40mm.)} + (880mm.) + {2nos.×  (210mm.)} +100mm.+ ( 75mm.) - (60mm.) ]

= [ 35mm. + 880mm. + 420mm. + 115mm.]

= 1450mm.

= 1.45m.

2. Cutting length of distribution bar

= [ 1500mm. - ( 2nos. × 20mm.)]

= 1460mm.

= 1.46m.

B. No. of bars:

1. No. of main bars

= [{sunshade length - (2nos. × cover)} ÷ c/c distance ] +1

= [{1500mm. - (2nos. × 20mm.)} ÷ 150mm. ] +1

= [ {1460mm.}  ÷ 150mm. ] +1

= 9.73 +1

= 10.73

By rounding off = 11 nos.

2.  No. of distribution bars

= [{sunshade width - cover - main bar dia} ÷ c/c distance ] +1

= [{900mm. - 20mm. - 10mm} ÷ 150mm. ] +1

= [ {870mm.}  ÷ 150mm. ] +1

= 5.8 +1

= 6.8

By rounding off = 7 nos.

If you want to know how to prepare BBS of lintel beam, Go through the article👇

Now, let us prepare a BBS table for the Chajja or sunshade.

 Sl. No. Type of Bar Dia. in mm. Nos. Length in m. Total length in m. Weight in Kg/m. Total  bar wt. in kg. 1. Main bar. 10 11 1.45 15.95 0.612 9.76 2. Distribution bar. 8 7 1.46 10.22 0.395 4.04 3. Total weight of steel bars = 13.80 4. Add 3% wastage = 0.414 5. The grand total wt. of rebar's in sunshade = 14.21

Go through the article 👇

👀. Bar bending schedule (BBS) of a sunshade. (Type-2)

Thank you for going through these calculation steps. Have a good day 😄.