Method of tests for timber props for mines

IS 6346: Scope & Key Specifications for Testing Small Clear Timber Specimens

Scope Summary:

• Applies to testing small clear specimens of timber for mechanical properties.
• Covers compression parallel to grain, static bending, moisture content, and density.
• Reporting format specified in Appendix A for uniform data presentation.

Key Reporting Parameters (Appendix A Pro Forma):

• Species, Supplier, Condition (Air dry/Green/As received)
• Average diameter, Weight, Length/Diameter ratio, Eccentricity
• Test results for:
  • Compression parallel to grain (major & minor tests)
  • Static bending
  • Moisture distribution (Peripheral, Intermediate, Core zones)
• Moisture content and specific gravity at test & oven dry conditions.

Important Measurement Rules:

• Dimensions measured to nearest 1 mm
• Weight measured to nearest 0.1 kg

Typical Test Data Tables:

Formula for Compressive Stress:

[ \sigma_c = \frac{P}{A} ]

• (P) = Maximum load (N or kgf)
• (A) = Cross-sectional area (mm² or cm²)

Moisture Content Zones:

This standard ensures uniform testing and reporting of timber mechanical properties for reliable structural use.

flowchart TD
    A[Timber Specimen] --> B[Measure Dimensions & Weight]
    B --> C{Condition?}
    C -->

IS 6346 - Definitions & Key Specifications

• Reference for Definitions: Clause 2.1 states definitions from IS 6346 and IS 707-1968 (Timber use in coal mines) apply.

• Specimen Measurements (Clause 4.1):

  • Dimensions measured nearest 1 mm
  • Weight measured to 0.1 kg

• Testing Pro Forma (Appendix A):
  Includes parameters like:

  • Species, supplier, condition (air dry/green)
  • Average diameter, weight, length/diameter ratio, eccentricity
  • Test results for compression parallel to grain, static bending, moisture content, etc.

Key Formulas for Compression Stress

[ \text{Compressive Stress} = \frac{\text{Max Load (kg)} \times 9.81}{\text{Cross-sectional Area (m}^2)} ]

• Convert load to Newtons (1 kg = 9.81 N)
• Cross-sectional area in m² (convert cm² to m² by dividing by 10,000)

Moisture Content Calculation

[ \text{Moisture %} = \frac{\text{Weight}{\text{wet}} - \text{Weight}{\text{oven dry}}}{\text{Weight}_{\text{oven dry}}} \times 100 ]

Typical Test Parameters Table (Simplified)

flowchart LR
    A[Specimen Preparation] --> B[Measure Dimensions & Weight]
    B --> C[Determine Moisture Content]
    C --> D[Perform Compression Test]
    D --> E[Calculate Compressive Stress]
    E --> F[Report in Pro Forma (Appendix A)]

References:

• IS

IS 6346 — Classification of Tests for Timber Props

1. Test Categories (Clause 3.1)

• Major Tests (Full-size props):

  • Compression parallel to grain
  • Moisture content distribution
  • Weight of prop
  • Eccentricity of prop
  • Length/diameter ratio

• Minor Tests (Small clear specimens from butt portion):

  • Compression parallel to grain
  • Static bending
  • Moisture content

2. Key Test Parameters & Reporting (Appendix A, Clause 7.1)

3. Formulas for Stress Calculations

• Compression Stress Parallel to Grain:

[ \sigma_c = \frac{P}{A} ]

Where:

• ( \sigma_c ) = Compressive stress at max load (N/mm² or MPa)

• ( P ) = Maximum load (N)

• ( A ) = Cross-sectional area (mm²)

• Modulus of Rupture (Static Bending):

[ f_b = \frac{3PL}{2bd^2} ]

Where:

• ( f_b ) = Bending stress (MPa)
• ( P ) = Load at failure (N)
• ( L ) = Span length (mm)
• ( b ) = Width of specimen (mm)
• ( d ) = Depth (height) of specimen (mm)

4. Moisture Content & Specific Gravity

• Moisture content (%) and specific gravity at test and oven dry conditions are recorded to assess timber condition.

5. Summary Table for Minor Tests (Example)

IS 6346: General Provisions for All Timber Tests

Key Specifications (Clause 4)

• Measurements & Weights (4.1):

  • Dimensions measured to nearest 1 mm.
  • Weight measured to nearest 0.1 kg.

• Distribution of Test Specimens (4.2):

  • 25% tested as received (green if > fibre saturation point).
  • 50% tested air dry (kept in shade, ventilated for 1 month).
  • 25% tested wet (immersed in water for 1 month).

Reporting Format (Clause 7.1 & Appendix A)

• Use the pro forma sheet for each specimen including:
  • Species, supplier, condition (air dry/green/as received), average diameter, weight, length/diameter ratio, eccentricity.
  • Test results tables for Compression parallel to grain (major & minor), Static bending, and Moisture content.

Important Test Parameters & Formulas

Moisture Content Zones

Average moisture content is calculated over all zones.

flowchart TD
    A[Specimen Preparation] --> B{Condition}
    B -->|25% As Received| C[Green or Normal]
    B -->|50% Air Dry| D[Shade, Ventilated 1 Month]
    B -->|25% Wet| E[Immersed in Water 1 Month]
    C --> F[Measure Dimensions &

IS 6346 — Test Methods for Timber Props: Key Specifications & Tables

1. Test Reporting (Clause 7.1 & Appendix A)

• Use the pro forma for each prop, including:
  • Species, supplier, condition (Air dry/Green/As received)
  • Average diameter, weight, length/diameter ratio, eccentricity

2. Compression Parallel to Grain (Major Test)

3. Compression Parallel to Grain (Minor Test)

4. Static Bending (Minor Test)

5. Moisture Distribution & Average Moisture Content

IS 6346: Test Equipment and Setup - Key Points

1. Calibration of Apparatus (Clause 4.5)

• All testing equipment must be calibrated periodically.
• Accuracy tolerance: within ±1% error.

2. Test Equipment (Clause 5.3.1)

• Use a compression testing machine with a capacity of 100 tonnes.
• Refer to Fig. 2 in IS 6346 for setup details.

3. Measurement & Weights (Clause 4.1)

• Measure specimen dimensions to the nearest 1 mm.
• Weigh specimens to 0.1 kg accuracy.

4. Reporting Format (Clause 7.1, Appendix A)

• Use the pro forma provided for test data recording, including:
  • Species, supplier, condition (air dry/green)
  • Dimensions: diameter, length, cross-section
  • Weight, moisture content, specific gravity
  • Load at failure, compressive stress, failure mode
  • Rate of loading for compression tests

5. Important Parameters & Formulas

• Compressive Stress, σ = Max Load / Cross-sectional Area
  [ \sigma = \frac{P_{max}}{A} ]
• Modulus of Rupture (MOR) and Fibre Stress at Elastic Limit recorded for bending tests.

Summary Table: Calibration & Equipment

flowchart LR
    A[Specimen Preparation] --> B[Measure Dimensions (±1 mm)]
    B --> C[Weigh Specimen (±0.1 kg)]
    C --> D[Compression Test on 100 t Machine]
    D --> E[Record Max Load & Failure Mode]
    E --> F[Calculate Stress = Load / Area]
    F --> G[Report Results in Appendix A Pro Forma]

This ensures standardized, accurate testing and reporting per IS 6346 requirements.

IS 6346: Reporting of Test Results - Key Points

• Rounding Off: Follow IS 2:1960 for rounding final observed/calculated values (Clause 0.5).

• Test Report Format: Use the pro forma in Appendix A (Clause 7.1) with signatures of testing personnel.

Appendix A Pro Forma Highlights

Test Data Tables

• Compression Parallel to Grain (Major Test):

• Compression Parallel to Grain (Minor Test):

| Piece No. | Length (cm) | Cross-Section (cm²) | Weight (g) | Moisture (%) | Specific Gravity (Test & Oven Dry) | Max Load (kg) | Compressive Stress | Failure | Remarks |

• Static Bending (Minor Test):

| Piece No. | Length (cm) | Width (cm) | Height (cm) | Weight (g) | Moisture (%) | Specific Gravity (Test & Oven Dry) | Fibre Stress at Elastic Limit | Modulus of Rupture | Failure | Remarks |

Moisture Content Reporting

Additional Specifications

• Measurements: Nearest 1 mm for dimensions; weight to 0.1 kg (Clause 4.1).

• Calibration: Equipment accuracy within ±1% error (Clause 4.5).

This structured reporting ensures uniformity and reliability in timber testing results per IS 6346.

IS 6346: Pro Forma for Testing of Timber Props (Appendix A, Clause 7.1)

Use one sheet per prop with the following key data:

General Information

• Species of timber
• Supplier name
• Condition: Air dry / Green / As received
• Average diameter of prop (cm)
• Weight of prop (g or kg)
• Length/diameter ratio
• Eccentricity of prop

Compression Parallel to Grain Test (Major Test)

Compression Parallel to Grain Test (Minor Test)

Static Bending Test (Minor Test)

Moisture Distribution & Average Moisture Content