IS 2502 — Code of Practice for Bending and Fixing of Bars for Concrete Reinforcement

IS 2502: Scope - Key Formulas, Tables & Specifications

Scope Summary (Clause 3.1 & 3.1.2)

• Applies to bent bars used in reinforced concrete.
• Bars with shapes not covered by standard tables must be fully dimensioned.
• Use standard bending dimensions and symbols from Tables III to IX.
• Avoid special shapes requiring complex dimensioning.

Important Tables & Formulas:

1. Standard Reinforcement Schedule (Table I)

• Specifies format: Location, Mark, Size, Number, Length, Shape.
• Mark designation example: C4 4R 25N (4 round bars of 25 mm diameter, set 4 times).

2. Hook and Bend Allowances (Table II)

• k values depend on steel type and bend complexity.
• Hook allowance example: For k=2, H=9d; for k=6, H=17d.
• Bend allowance example: For k=2, B=5d; for k=6, B=7d.

3. Measurement of Bending Dimensions (Tables III to V)

• Bar length measured along centerline.
• Dimensions like A, C, E, H, B refer to straight lengths, hook, bend allowances.
• Special hooks indicated as "hook up" or "hook down".
• Internal radius R specified if different from standard.

Key Notes:

• Use standard bend dimensions to minimize calculation.
• Fully dimension non-standard shapes in schedules.
• Follow the prescribed method of measurement for accuracy.

flowchart TD
    A[Bar Shape] -->|Standard| B[Use Tables III to IX]
    A -->|Non-standard| C[Fully Dimension Bar]
    B --> D[Apply Hook & Bend Allowances (Table II)]
    D --> E[Measure Length Along Centre Line]
    C --> E

IS 2502: Form of Schedule - Key Points, Tables & Formulas

1. Standard Reinforcement Schedule Format (Clause 2.1, Table I)

• Mark Designation: Format - Number of bars + R (round) + diameter (mm) + ID number.
• Schedule size: Recommended column widths (left to right): 25, 20, 15, 15, 15, 15, 15, 75 mm (total width ~ A4 size).

2. Hook and Bend Allowances (Table II)

• Hook Allowance (H) and Bend Allowance (B) depend on bar diameter (d) and steel type.
• Formula for allowances:

• Values rounded to nearest 5 mm.

3. Measurement of Bending Dimensions (Tables III, IV, V)

• Bar length (L) measured along centerline.
• Standard methods (Ref No. A, B, C, etc.) define how to sum straight lengths and allowances (H, B).
• Example for simple bent bar (Ref A):

[ L = \text{Sum of straight lengths} + \text{Hook or Bend Allowance} ]

• Hooks at right angles marked as

IS 2502: Bend Dimensions and Symbols – Key Points

• Bend Angles:

  • Default bend angle = 90° unless specified otherwise (Clause 3.1.1).
  • Avoid specifying bends with arbitrary angles in degrees.

• Dimensioning Procedure:

  • Use Fig. 1 and Tables II to IX (p. 7–14) for standard bend shapes and dimensions.
  • Minimize calculations by adopting these standard dimensions for marking and machine setup (Clause 3.1).

• Standard Shapes & Symbols:

  • Refer to Table 3 (Clause 3.1.2) for bend dimensions and symbols for common shapes.
  • For bars combining multiple standard shapes, measure bends as per standard shapes.
  • For special shapes not covered, fully dimension and specify measuring methods in the schedule (Clause 3.1.2).

• Reinforcement Schedule Format (Table I, Clause 2.1):

  • Includes: Location, Mark designation, Size/type, Number of sets, Number per set, Total number, Length, Shape.
  • Mark designation example: C4 4R 25N means 4 round bars of 25 mm diameter, 4 sets, identification number N.

Typical Bend Dimensioning Example (from IS 2502)

Summary Diagram of Bend Dimensions

graph TD
A[Straight Bar] --> B{Bend}
B --> C[90° Bend]
B --> D[U-Bend]
B --> E[Custom Shape]
E --> F[Full dimensioning required]

Recommendation: Always use standard bend shapes and dimensions from IS 2502 Tables II-IX to simplify fabrication and avoid errors. Fully dimension any special bends in the reinforcement schedule.

IS 2502 Key Points on Bending Radii:

1. Minimum Bending Radii (Clause 4.1 & Table X)

• Bars specified to be bent to radii greater than values in Table X need not be bent physically; curvature can be achieved during placing.
• Typical minimum bending radii depend on bar diameter (d) and steel type.

2. Hook and Bend Allowances (Table II)

• Hook Allowance (H):
  ( H = k \times d ) where
  ( k = 9, 11, 13, 17 ) for hook values 2, 3, 4, 6 respectively, rounded to nearest 5 mm, minimum 75 mm.
• Bend Allowance (B):
  ( B = k \times d ) where
  ( k = 5, 5.5, 6, 7 ) for bend values 2, 3, 4, 6 respectively, rounded to nearest 5 mm, minimum 75 mm.

(Refer to full Table II for all sizes and steel types.)

3. Measurement of Bending Dimensions (Tables III, IV, V)

• Bar length is measured along the centerline of the bar.
• Use allowances H and B to calculate total length considering bends and hooks.
• Sketch and dimension details must be clearly indicated in reinforcement schedules.

Summary Formulae:

IS 2502: Bending and Cutting Tolerances Key Points

1. Cutting Tolerance

• Bars to be bent have the same cutting tolerance as straight bars (Clause 5.1.2).
• To accommodate this, at least one dimension of bent bars should not be fixed.

2. Bending Radii

• Bars bent to radii exceeding Table X values (p.15) may be curved during placing without bending (Clause 4.1).

3. Hook and Bend Allowances (Table II)

• H = k × d, where k = 9, 11, 13, 17 for k values 2, 3, 4, 6 respectively, rounded to nearest 5 mm, min 75 mm.
• B = k × d, where k = 5, 5.5, 6, 7 for k values 2, 3, 4, 6 respectively, rounded to nearest 5 mm, min 75 mm.

4. Measurement of Bending Dimensions

• Use dimensioning methods from Tables III to V for total length (L) along the bar centerline.
• Include allowances for hooks (H) and bends (B) in length calculations.
• Indicate hooks as "hook up" or "hook down" if bent out of the plane.

5. Summary Formula Examples

• Total length with hooks and bends:
  [ L = \sum \text{straight lengths} + \sum H + \sum B ]

• For right-angle hooks:
  [ H = 9d \text{ to } 17d \quad (\text{depending on k}) ]

Diagram: Hook and Bend Allowance Concept

IS 2502: Bending of Bars - Key Points & Tables

1. Bending Dimensions & Angles (Clause 3.1, 3.1.1, 3.1.2)

• Bars are bent mainly at right angles (90°) unless otherwise specified.
• Avoid specifying bends in degrees; use standard shapes and dimensions.
• For large diameter bars, ensure the overall length does not exceed theoretical length.
• Use standard shapes and dimensions from Tables II to IX (p.7-14).
• For non-standard shapes, combine standard shapes or fully dimension the bar and specify measurement method.

2. Tolerance for Bent Bars (Clause 5.1)

• Tolerances for overall/internal dimensions are given in Table XI (p.15).
• Unless stated, these tolerances apply to bent bars.

3. Standard Reinforcement Schedule (Table I)

• Specifies mark designation, size, number, length, and shape.
• Mark designation example: C4 4R 25N
  • 4 bars, Round, 25 mm dia, Identification No. N
• Shapes and dimensions must follow IS 2502 standard unless otherwise stated.

Typical Bending Dimension Symbols (Clause 3.1.2, Table 3 excerpt):

Practical Notes:

• Use minimum bend radius as per bar diameter (usually 6-8 times diameter for mild steel).
• Use Tables II-IX for standard bend dimensions (e.g., hooks, bends, stirrups).
• Mark bars clearly with identification per Table I format.

flowchart LR
    A[Start: Bar to be bent] --> B{Is shape standard?}
    B -- Yes --> C[Use dimensions from Tables II-IX]
    B -- No --> D{Can shape be combined from standard shapes?}
    D -- Yes --> E[Combine dimensions accordingly]
    D -- No --> F[Fully dimension bar & specify measurement method]
    C --> G[Check tolerance as per Table XI]
    E --> G
    F --> G
    G --> H[

IS 2502: Fixing Reinforcement - Key Points

1. Reinforcement Schedule (Clause 2.1)

• Use the standard form of reinforcement schedule (Table I) for detailing.
• Includes bar mark, shape code, number of bars, size, length, and bend details.

2. Bend Dimensions and Symbols (Clause 3 & 1.1)

• Standardized bend symbols and approximate bend dimensions ensure clarity.
• Typical bends: hooks, bends at 90°, 135°, U-bends.
• Dimensions depend on bar diameter (d), e.g., hook length = 6d.

3. Fixing Reinforcement (Clause 7.1)

• Maintain precise positioning of bars to ensure design effectiveness.
• Use spacers, chairs, and ties for convenience and accuracy.
• Avoid displacement during concreting.

Typical Bend Dimension Formulae (IS 2502):

Fixing Tips:

• Tie bars at intervals ≤ 300 mm.
• Use mild steel binding wire.
• Ensure cover as per design (minimum concrete cover).

flowchart LR
    A[Cut Bars] --> B[Bend Bars as per IS 2502]
    B --> C[Arrange Bars in Position]
    C --> D[Tie Bars with Binding Wire]
    D --> E[Check Cover & Spacing]
    E --> F[Fix Spacers & Chairs]
    F --> G[Ready for Concreting]

This ensures reinforcement is fixed correctly and remains stable during concreting.

Maintaining Position of Reinforcement (IS 2502)

Key Points from IS 2502:

• Clause 7.1: Reinforcement must be maintained at the designed position throughout construction to ensure structural economy and performance.
• Clause 7.1.1: Reinforcement placement must strictly follow detailed design drawings and be securely fixed. Before concreting, re-check the position if there is any delay.
• Clause 8.1: Proper storage of reinforcement to prevent distortion and corrosion is essential before placement.

Practical Specifications & Tips:

• Use spacers, chairs, and ties to maintain cover and position.
• Secure bars with binding wire at intersections.
• Check cover thickness as per design (typically 25-50 mm depending on exposure).
• For complex shapes, use templates or jigs for precise placement.

Typical Table: Reinforcement Cover (IS 456:2000 Reference)

Diagram: Reinforcement Fixing Concept

flowchart LR
    A[Rebar Cutting & Bending] --> B[Fixing on Chairs/Spacers]
    B --> C[Binding at Intersections]
    C --> D[Check Position & Cover]
    D --> E[Inspection Before Concreting]

Summary: Fix reinforcement precisely as per drawings, secure firmly with ties and spacers, store properly, and verify before concreting to maintain position and ensure structural integrity.

IS 2502: Storage of Reinforcement - Key Points

• Clause 9.1.4 highlights storage conditions:

  • A certain amount of hard rust on reinforcement is acceptable and even desirable.
  • Avoid undue rusting or loose scaling during storage.
  • In corrosive weather, reinforcement stacks must be sheltered to prevent corrosion.

• Storage Recommendations:

  • Store reinforcement bars on raised platforms to avoid ground moisture.
  • Stack bars in bundles with spacers for ventilation.
  • Protect from rain and direct sunlight using tarpaulins or sheds.

Summary Table: Storage of Reinforcement (from Clause 9.1.4)

Additional Notes:

• Reinforcement should be cleaned if heavily rusted before use.
• Proper storage preserves bond strength with concrete.

flowchart TD
    A[Delivery of Reinforcement] --> B[Inspect for rust]
    B -->|Acceptable hard rust| C[Store on elevated platform]
    B -->|Excessive rust/scaling| D[Clean bars]
    C --> E[Stack with spacers for ventilation]
    E --> F[Cover with tarpaulin/shed in corrosive weather]
    D --> C

This ensures durability and structural integrity as per IS 2502 guidelines.

Lapping of Bars (IS 2502 referencing IS 456-1964)

• Lap Length (l₀): As per IS 456, lap length depends on bar diameter (d), concrete grade, and bar stress.

  Typical formula:
  [ l_0 = \text{Development length} = \text{(depends on)} ; \phi, f_{ck}, f_y, \text{and concrete cover} ]

• General Requirements:

  • Laps must be staggered to avoid weak planes.
  • Bars should be overlapped by at least the development length.
  • Bars must be tied securely to maintain position during concreting.

• Tolerances:

  • Cutting and bending tolerances for bars are as per Clause 5.1.2 and Table XI of IS 2502.
  • At least one dimension in bent bars should be left unspecified to accommodate cutting tolerance.

• Dimensioning:

  • Use dimensioning procedure from Clause 3.1, adopting Tables II to IX for bends.
  • Bends and laps should minimize calculation and facilitate marking and machine setup.

Typical Lap Length Values (from IS 456-2000 for HYSD bars):

Note: Exact lap length depends on concrete strength and bar stress.

Summary Diagram of Lap

graph LR
A[Bar 1] -- Lap Length l₀ --> B[Bar 2]
B -- Staggered lap --> C[Adjacent Bars]

References:

• IS 2502: 7.1.2 (Lapping)
• IS 456-2000 (Development length and lap length)
• IS 2502: Table XI (Tolerances)

IS 2502: Marking and Scheduling of Bars - Key Points

1. Standard Reinforcement Schedule (Table I, Clause 2.1)

Note:

• Mark designation simplifies identification; first number = quantity, 'R' = round bar, next number = diameter (mm), last number = bar ID.
• Schedule form fits A4 size (210×297 mm), with recommended column widths (e.g., 25 mm for Location, 20 mm for Mark Designation).

2. Bend Dimensions and Symbols (Clause 3.1, Table III to IX)

• Use standard bend shapes and dimensions from Tables III-IX for ease of fabrication.
• For combined or special shapes, fully dimension bars and specify measurement methods in the schedule.
• Avoid special shapes if possible.

3. Dimensioning Rules

• Dimensions should minimize calculations during marking and machine setup.
• Bending dimensions are measured as per standard shapes (refer IS 2502 Tables III-IX).
• When bars are bent in non-standard shapes, provide complete dimension details.

4. Reference Standards

• Bars conform to IS 432 (Part I & II) or equivalent standards (TIS 1139, TIS 1786).
• Ensure quality and shape compliance as per IS 432.

Summary Table: Mark Designation Example

Visualization of Schedule Columns (simplified):

graph LR
A[Location