slotted sections

IS 8081: Scope - Key Formulas, Tables & Specifications

1. Safe Working Loads & Factor of Safety (Clause 7.1)

Safe working load (SWL) is calculated as:

[ \text{SWL} = \frac{\text{Failure Load}}{\text{Factor of Safety (FOS)}} ]

2. Safe Load for Beams (Clause 7.3)

• Determine safe load by both strength and deflection criteria.
• Use the lesser of the two as the safe working load.
• Loads based purely on deflection limits should be distinctly marked.
• Design loads must not exceed safe working load limits.

3. Tolerances on Flange Dimensions (Clause 8.1)

Summary Diagram:

flowchart TD
    A[Determine Failure Load] --> B[Divide by Factor of Safety]
    B --> C[Calculate Safe Working Load]
    C --> D{Beam Safe Load?}
    D -->|Strength| E[Safe Load (Strength)]
    D -->|Deflection| F[Safe Load (Deflection)]
    G[Select Lesser of E & F] --> H[Safe Working Load for Beam]

Note: Manufacturer is responsible for providing accurate safe working load values (Clause 6.6.2.1).

This concise overview covers the scope related to design loads, safety factors, and dimensional tolerances per IS 8081.

IS 8081: Key Definitions, Formulas, and Specifications

1. Permissible Loads & Factor of Safety (Clause 7.1)

Safe working load (SWL) is calculated as:

[ \text{SWL} = \frac{\text{Failure Load}}{\text{Factor of Safety (FOS)}} ]

2. Steel Grades for Slotted Sections (Clause 3.1)

3. Flexural Rigidity & Bending Moment (Clause 7.1 & Fig 3)

• Maximum permissible deflection ratio (span/deflection) is defined.
• Bending moment formula for simply supported beam under load (W):

[ M = \frac{W L}{4} ]

• Flexural rigidity related to modulus of elasticity (E) and moment of inertia (I):

[ \text{Deflection} \propto \frac{W L^3}{E I} ]

4. Testing & Reporting (Clause 6.6.1 & 6.6.2.1)

• Independent supervising engineer must report:
  • Test conditions
  • Failure loads
  • Yield stress (0.2% proof stress for aluminium)
• Manufacturer responsible for safe working load values.

flowchart TD
    A[Failure Load] -->|Divide by FOS| B[Safe Working Load]
    B --> C[Design Use]
    D[Steel Grades] --> E

IS 8081: Key Materials Specifications & Formulas

1. Steel Grades for Slotted Sections (Clause 3.1, Table 1)

• IS 513: Cold rolled carbon steel sheets
• +IS 1079*: Hot rolled carbon steel sheets
• #IS 4030*: Cold rolled carbon steel strip

2. Minimum Yield Stress (N/mm²) (Clause 6.1.4, Table 2)

3. Factor of Safety (Clause 7.1)

4. Yield Stress Correction Formula (Clause 6.1.4)

[ \text{Reduced Failure Load} = \text{Failure Load} \times \frac{\text{Min. Yield Stress of Material}}{\text{Yield Stress of Test

IS 8081: Manufacture and Workmanship – Key Formulas & Specifications

1. Safe Working Load (SWL) Calculation

Safe working loads are derived by dividing the failure load by the minimum factor of safety (FOS):

[ \text{SWL} = \frac{\text{Failure Load}}{\text{Factor of Safety}} ]

2. Factors of Safety (Clause 7.1)

3. Safe Load for Beams (Clause 7.3)

• Calculate SWL based on strength and deflection criteria.
• Use the lesser of these two values as the safe working load.
• Deflection-based loads must be distinctly marked (different color or print).
• Design loads must not exceed SWL limits.

4. Manufacturing & Workmanship (Clause 6.6.2.1 & 6.1.5)

• Manufacturer is responsible for SWL values and related info.
• Stitching bolt pattern and pitch for compound sections must follow manufacturer's standard practice.

Summary Diagram

flowchart LR
    A[Failure Load] --> B[Divide by Factor of Safety]
    B --> C[Safe Working Load]
    C --> D{For Beams}
    D --> E[Check Strength-based SWL]
    D --> F[Check Deflection-based SWL]
    E & F --> G[Select Lesser SWL]
    G --> H[Specify Safe Working Load]

Note: Always refer to the specific IS standards cited for detailed material properties and testing procedures.

IS 8081 - Finish and Surface Treatment Key Points

• Clause 5.1: Manufacturer must specify the finish applied on steel sections.

• Clause 5.2:

  • Surfaces must be clean: free from scale, grease, rust, and imperfections before painting.
  • Apply an anti-rust coat prior to paint.

• Clause 5.3:

  • Galvanizing must follow IS 4759-1968 (Hot-dip zinc coatings).
  • Anodizing aluminum sections must comply with IS 1868-1968.

Surface Preparation & Treatment Summary

Related Testing Standards for Steel Sheets & Strips

• Tensile testing: Thickness 0.5 mm to 3 mm
• Bend testing: Thickness < 3 mm
• Light metals tensile & bend tests also referenced (for aluminum)

flowchart TD
    A[Steel Surface] --> B{Clean?}
    B -- No --> C[Remove scale, grease, rust]
    C --> B
    B -- Yes --> D[Apply Anti-rust coating]
    D --> E[Apply Paint Finish]
    E --> F{Galvanized?}
    F -- Yes --> G[IS 4759 Compliance]
    F -- No --> H{Aluminum?}
    H -- Yes --> I[IS 1868 Compliance]
    H -- No --> J[Finish complete]

Summary: Proper surface preparation and adherence to IS 4759 (galvanizing) or IS 1868 (anodizing) ensure durability and corrosion resistance of steel/aluminum sections per IS 8081.

IS 8081: Methods of Test for Strength of Slotted Sections

Key Specifications & Formulas

1. Testing Requirements (Clause 6.1.2 & 6.1.4)

• All sections must be tested per the standard; loading conditions should simulate real practice.
• Yield stress (or 0.2% proof stress for aluminum) is determined from coupons cut from the same strip.
• Failure loads are adjusted by the ratio:

[ \text{Adjusted Load} = \text{Failure Load} \times \frac{\text{Minimum Yield Stress}}{\text{Yield Stress of Test Piece}} ]

• Ignore results if test piece yield stress < specified minimum.

2. Minimum Yield Stress Values (Table 2) for Steel Grades

3. Bending Test (Clause 6.6.1 & Fig. 3)

• Bending moment formula for simply supported beam with central load ( W ):

[ M = \frac{W L}{4} ]

• Flexural rigidity relation:

[ \delta = \frac{W L^3}{48 E I} ]

• Secant modulus to deflection ratio is used to determine max permissible deflection.

Summary Diagram: Load-Deflection in Bending Test

graph LR
A[Load W] --> B[Bending Moment M = WL/4]
B --> C[Deflection δ = WL³/(48EI)]
C --> D[Check max permissible deflection]

References:

• IS 1663-1972 for tensile testing of steel sheets.
• IS

IS 8081: General Design Provisions (Clause 7.1 & related)

Key Formulas & Specifications

1. Safe Working Load (SWL):
   [ SWL = \frac{\text{Failure Load}}{\text{Factor of Safety (FOS)}} ]

2. Factors of Safety (FOS):

3. Material Strength Certification (Clause 6.6.4):

   • Safe load values must be certified by tests per IS 8081.
   • Adjusted for minimum specified yield stress (0.2% proof stress for aluminium).
   • Certification signed by an independent qualified engineer.

4. Typical Load Cases (Clause 6.6.2):

   • Concentrically loaded struts (effective length factor = 1).
   • Simply supported beams with uniform load (see Clause 7.3).
   • Concentrically loaded ties.
   • Bearing strength.

5. Bending Moment & Flexural Rigidity:
   For a beam with uniform load ( W ), span ( L ), modulus of elasticity ( E ), and moment of inertia ( I ):

   [ M = \frac{W L^2}{8}, \quad \delta = \frac{5 W L^4}{384 E I} ]

   (Deflection limit as per secant modulus and permissible ratio of span.)

Summary Diagram: Load-Deflection Behavior

graph LR
A[Load (W)] --> B[Bending Moment (M)]
B --> C[Deflection (δ)]
C --> D[Check against permissible deflection ratio]

Note: Always verify test reports and material properties per IS 8081 clauses 6.6.1 & 6.6.4 before design.

IS 8081: Dimensional Tolerances Summary

1. Flange Sectional Dimensions (Clause 8.1)

2. Flange Thickness (Clause 8.2)

• Tolerances on flange thickness depend on the steel grade or aluminium.
• Must conform to respective material specifications (refer to relevant steel/aluminium IS codes).

3. End Hole Centre-to-Centre Distance (Clause 8.7.2)

• Tolerance on overall centre-to-centre of end holes = ±1.6 mm

Quick Reference Table:

flowchart TD
    A[Flange Dimensions] -->|Tolerance %| B{Nominal Size}
    B -->|≤40 mm| C[±5%]
    B -->|40-50 mm| D[±4%]
    B -->|50-75 mm| E[±3%]
    B -->|>75 mm| F[±2%]
    G[Flange Thickness] --> H[Material Spec Tolerance]
    I[End Holes Centre-to-Centre] --> J[±1.6 mm]

This ensures dimensional accuracy for structural integrity and proper fitment.

IS 8081 - Marking of Slotted Sections

Key Specifications (Clause 10)

• Manufacturer's Identification Marking:

  • Marked at intervals not exceeding 300 mm on slotted sections.
  • Cutting marks at intervals not exceeding 100 mm.

• Standard Mark:

  • Use governed by Bureau of Indian Standards Act, 1986.
  • Manufacturer may mark the product with the Standard Mark (Clause 10.1.1).

• Responsibility:

  • Manufacturer responsible for safe working load values and design info (Clause 6.6.2.1).

Marking Table Summary (Clause 10.2)

Practical Notes

• Markings ensure traceability and quality assurance.
• Markings should be clear, durable, and visible.
• Standard Mark use requires BIS license.

flowchart LR
    A[Slotted Section] --> B[Manufacturer's ID Mark]
    B -->|≤ 300 mm| C[Marking Interval]
    A --> D[Cutting Mark]
    D -->|≤ 100 mm| E[Marking Interval]
    A --> F[Standard Mark]
    F -->|BIS Licensed| G[Optional]

This ensures compliance with IS 8081 marking requirements for quality and traceability.

IS 8081: Certification and Test Reports - Key Points

1. Test Report Requirements (Clauses 6.1.3, 6.6.1, 6.6.4)

• Reports must include:
  • All test conditions.
  • Failure loads of specimens.
  • Yield stresses (or 0.2% proof stress for aluminium).
  • Any additional relevant info as per test procedures.
• Certification must be signed by an independent qualified supervising engineer.
• Safe load values must be adjusted for minimum specified yield stress.

2. Key Formula for Flexural Rigidity and Bending Moment (Clause 6.6)

• Bending Moment, M:
  [ M = \frac{WL}{4} \quad \text{(for simply supported beam with central load W)} ]

• Flexural Rigidity, EI:
  [ EI = \frac{WL^3}{48 \delta} ] where

  • ( W ) = Load applied
  • ( L ) = Span length
  • ( \delta ) = Deflection at mid-span

• Secant Modulus to Deflection Ratio:
  Maximum permissible deflection ratio (deflection/span) is specified for serviceability.

3. Typical Load-Deflection Graph (Fig. 3)

• Illustrates linear elastic behavior up to yield.
• Shows relationship between load, deflection, bending moment, and flexural rigidity.

Summary Table: Test Report Contents

graph LR
A[Test Setup] --> B[Load Application]
B --> C[Deflection Measurement]
C --> D[Calculate EI and M]
D --> E[Compare with Specified Limits]
E --> F[Prepare