Symbols & Representation in BBS
A Bar Bending Schedule (BBS) is a detailed tabular document prepared for reinforcement steel used in RCC structures. It provides complete information regarding:
- Bar shape and bending details
- Diameter and spacing of reinforcement
- Number and length of bars
- Cutting length calculation
- Bending dimensions and hook details
- Steel quantity and weight
- Fabrication and placement instructions
Symbols and abbreviations are used in BBS to simplify drawings and ensure uniform understanding between designers, detailers, fabricators and site engineers.
Purpose of Symbols in BBS
Easy Interpretation
Symbols help engineers and workers understand reinforcement drawings quickly.
Reduce Errors
Standard symbols minimize confusion during fabrication and placement.
Fast Fabrication
Steel bending yard can identify bar shapes directly using shape symbols.
Uniform Standards
Symbols are standardized according to IS codes and detailing practices.
Bar Shape Symbols
Straight Bar
Represents reinforcement without bends. Generally used as:
- Main bars in slabs
- Distribution bars
- Temperature reinforcement
Bent / Cranked Bar
Represents reinforcement having bends or inclined portions. Used to resist:
- Shear stresses
- Diagonal tension
- Negative moments
Hook Bend
Hooks are provided at bar ends for anchorage and bond. Common hook angles:
- 90° Hook
- 135° Hook
- 180° Hook
Stirrups / Ties
Closed reinforcement provided in beams and columns to:
- Resist shear force
- Confine concrete
- Prevent buckling of longitudinal bars
Bar Diameter and Spacing Symbols
-
Diameter Symbol (Φ):
Greek letter Φ denotes reinforcement diameter.
Example:- 8Φ = 8 mm diameter bar
- 12Φ = 12 mm diameter bar
- 20Φ = 20 mm diameter bar
-
Spacing Symbol (@):
Represents spacing between bars.
Example:- @150 c/c = bars placed at 150 mm center-to-center spacing
- @100 c/c = bars spaced at 100 mm center-to-center
- c/c (Center to Center): Distance measured between centers of adjacent bars.
Shape Codes in BBS
Shape codes are standardized bar bending shapes used in BBS preparation as per IS 2502 and SP-34.
| Shape Code | Description |
|---|---|
| 00 | Straight Bar |
| 01 | Bar with One Bend |
| 02 | Bar with Two Bends |
| 21 | Rectangular Stirrup |
| 22 | Circular Stirrup |
| 41 | Cranked Bar |
Symbols for Structural Members
| Abbreviation | Meaning |
|---|---|
| Bm | Beam |
| Col | Column |
| FG | Footing |
| Sl | Slab |
| RW | Retaining Wall |
| St | Staircase |
| WL | Wall |
| PC | Pile Cap |
Position and Direction Symbols
EW
Means reinforcement provided in both directions (Each Way). Commonly used in slabs and footings.
Arrow Direction
Indicates direction in which bars extend or continue.
Limit Line
Shows limit or boundary up to which reinforcement is provided.
Main Components of a BBS Table
| Component | Description |
|---|---|
| Bar Mark | Unique identification number for each bar |
| Diameter | Size of reinforcement bar |
| Spacing | Center-to-center spacing of bars |
| Shape Code | Standard bending shape code |
| Cutting Length | Total length required after bends and hooks |
| Quantity | Number of reinforcement bars |
| Total Weight | Steel quantity in kg |
- Accurate steel quantity estimation
- Easy checking of reinforcement drawings
- Reduction in steel wastage
- Faster bar fabrication
- Better communication between site and design teams
- Proper reinforcement placement during construction
- Improved structural safety and detailing quality
Reference Codes
- IS 2502 : 1963 – Code of Practice for Bending and Fixing of Bars
- IS 5525 : 1969 – Recommendations for Detailing of Reinforcement
- SP 34 – Handbook on Concrete Reinforcement and Detailing
- IS 456 : 2000 – Plain and Reinforced Concrete Code
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