Hot Rolled Steel Channel Sections for General Engineering Purposes – Dimensions

IS 3954: Scope - Key Specifications & Sectional Properties

Scope (Clause 3.0): Defines terms and rounding rules per IS 2:1960 for test/analysis results.

Sectional Properties (Clause 6.1, Table 6.2)

Notes:

• Rounding: Final values rounded as per IS 2:1960.
• Units: Depth, width, thickness in mm; area in cm²; inertia in cm⁴.
• Flange slope typically 95°.
• Radii at root and toe ensure stress distribution.

Summary

IS 3954 Key References, Tables & Specifications

1. Sectional Properties (Clause 6.1, Table 6.2)

2. Rounding Off (IS 2:1960)

• Final test/analysis values must be rounded off as per IS 2:1960.
• Number of significant digits retained = same as specified values.

3. BIS Information (Clause 6.79)

• BIS is statutory under BIS Act 1986.
• Holds copyright on publications; reproduction requires permission.
• Free use allowed for implementation details (symbols, sizes, grades).
• Contact BIS for copyright issues.

Useful Formula:

• **Section Modulus (Z) = I

IS 3954 - Definitions & Key Sectional Properties

Key Definitions (Clause 3.0 & 3.2)

• X-X Axis: Passes through the centroid, perpendicular to Y-Y axis.
• Symbols:
  • ( a ) = Sectional area (cm²)
  • ( m ) = Nominal mass (kg/m) = (0.785 \times a)
  • ( I_{xx} ), ( I_{yy} ) = Moments of inertia about X-X and Y-Y axes (cm⁴)
  • ( Z_{xx} ), ( Z_{yy} ) = Section modulus about X-X and Y-Y axes (cm³)
  • ( r_x ), ( r_y ) = Radius of gyration about X-X and Y-Y axes (cm)
  • ( C_x ), ( C_y ) = Distance from centroid to extreme fiber in X and Y directions (cm)

Sectional Properties Table (Excerpt from Table 1)

Notes:

• Channel sections are designated as CHG +

IS 3954: Designation & Sectional Properties of Channel Sections

Designation:

• Channel sections are designated as CHG followed by the depth (in mm) of the channel.
  • Example: CHG 16 means a channel with 16 mm depth.

Key Parameters & Symbols (from Clause 3.2):

Sample Sectional Properties (from Table 1):

IS 3954: Dimensions & Sectional Properties of Hot Rolled Steel Channels

Key Specifications (Clause 6.1 & Table 1)

• Designation: CHG + depth (mm), e.g., CHG 40 has 40 mm depth.
• Mass (m): kg/m, calculated as ( m = 0.785 \times a ) (where (a) = sectional area in cm²)
• Sectional Area (a): cm²
• Depth of Channel (h): mm
• Width of Flange (b): mm
• Thickness of Web (w): mm
• Thickness of Flange (t): mm
• Slope of Flange: typically 95°
• Radius at Root (r1): mm
• Centre of Gravity (Cyy): cm from base
• Moment of Inertia (Ixx, Iyy): cm⁴ about X-X and Y-Y axes
• Radius of Gyration (r_xx, r_yy): cm, ( r = \sqrt{\frac{I}{a}} )
• Section Modulus (Zxx, Zyy): cm³ about X-X and Y-Y axes

Example from Table 1 (CHG 40)

Important Formulas

[ m = 0.785 \times a \quad (kg/m) ]

IS 3954 - Tolerances Summary

Key Points on Tolerances (Clause 6.1 & 6.2)

• Rolling and Cutting Tolerances for channel sections must follow IS 1852:1985 (Specification for rolling and cutting tolerances for hot rolled steel products).
• Tolerances apply to dimensions like:
  • Depth of channel (h)
  • Width of flange (b)
  • Thickness of web (w)
  • Thickness of flange (t)
  • Slope of flange
  • Radius at root and toe

Sectional Properties Table (Excerpt)

Important Notes

• For compliance checking, values must be rounded as per IS 2:1960.
• Use IS 1852:1985 for exact dimensional tolerance limits (typically ±1-3% depending on dimension).

Quick Reference: Tolerance Application Flow

flowchart TD
    A[Channel Section Dimensions] --> B{Check Dimensions}
    B -->|Within IS 1852 Limits| C[Accept Section]
    B -->|Outside Limits| D[Reject or Rework]
    C --> E[Round off values as per IS 2:1960]

For detailed tolerance values, refer to

Rounding Off Numerical Values as per IS 3954 referencing IS 2:1960

• Rule: Final observed or calculated values must be rounded off according to IS 2:1960.
• Significant Figures: The number of significant places in the rounded value should match that of the specified value in the standard.
• This ensures consistency and compliance when comparing test/analysis results with standard requirements.

Key Table Extract: Sectional Properties (Clause 6.1, Table 6.2)

Additional Notes:

• Refer to IS 1852:1985 for rolling and cutting tolerances related to hot rolled steel products.
• The standard IS 3954:1991 (Reaffirm

IS 3954: Application and Use - Key Data

Sectional Properties (Clause 6.1, Table 6.2)

Important Notes:

• Slope of Flange: 95° typically for channel sections.
• Radius at Root: Important for stress concentration considerations.
• Moment of Inertia (Ixx): Used in bending calculations.
• Section Modulus (Z): Used to determine bending stress:
  [ \sigma = \frac{M}{Z} ]

Application:

• These channel sections are used in structural framing, supports, and bracing.
• Selection depends on load, span, and deflection criteria.

Rounding Off:

• Follow

IS 3954: Manufacturing and Trade Practices - Key Specifications

1. Sectional Properties of Channels (Clause 6.1, Table 6.2 excerpt)

2. Manufacturing & Trade Practices

• Channels conform to rolling and cutting tolerances as per IS 1852:1985 (hot rolled steel products).
• Designations and dimensions are standardized for uniformity in manufacture and trade.
• Tolerances ensure interchangeability and quality control in production.

3. Important Notes

• BIS holds copyright; free use allowed only for implementation details.
• The standard is updated to reflect current manufacturing practices in India.
• For detailed tolerances, refer to IS 1852:1985 alongside IS 3954.

Summary Diagram: Channel Section Properties

graph LR

IS 3954 Annexures: Key Tables & Specifications

1. Sectional Properties (Table 1, Clause 6.1)

• Use: For design and checking tolerances of channel sections.
• Units: Mass in kg/m, dimensions in mm or cm, moments in cm⁴ or cm³.

2. Rounding Off (IS 2:1960)

• Final test or calculated values must be rounded off as per IS 2:1960 rules.
• Retain the same number of significant figures as the specified value