Method of tests for bamboo

IS 6874: Scope - Key Formulas & Specifications

1. Moment of Inertia (I) for Hollow Circular Section

[ I = \frac{\pi}{64} (D^4 - (D - 2t)^4) ]

• D = Outer diameter (mm)
• t = Wall thickness (mm)

(Note: The code snippet does not explicitly give this formula but it is standard for hollow pipes.)

2. Ultimate Strength in Static Bending (σ_ult)

[ \sigma_{ult} = \frac{6FL}{\pi D^3 t} ] Where:

• (F) = Maximum load (N)
• (L) = Effective span (mm)
• (D) = Outer diameter (mm)
• (t) = Wall thickness (mm)

Reported to nearest 1 N/mm².

3. Modulus of Elasticity (E)

[ E = \frac{L^3 s}{4 I} ]

• (L) = Clear span (mm)
• (s) = Slope of linear part of load-deflection curve (N/mm)
• (I) = Moment of inertia (mm⁴)

Reported rounded to nearest 100 N/mm².

Notes:

• Definitions align with IS 707 for steel tubes.
• Refer to the latest editions of referenced standards for updates.
• Basic mass per volume formula is updated per clause 5.2.3 (not detailed here).

flowchart TD
    A[Load F applied] --> B[Calculate Moment of Inertia (I)]
    B --> C[Determine Ultimate Strength σ_ult]
    C --> D[Measure Load-Deflection Slope s]
    D --> E[Calculate Modulus of Elasticity E]

This summarizes the scope-related calculations per IS 6874 for steel tubular members under bending.

IS 6874 - Definitions & Key Formulas (Clause 6.1.4)

Key Parameters:

• D = Outer diameter (mm)
• t = Wall thickness (mm)
• I = Moment of inertia (mm⁴)
• F = Maximum load (N)
• L = Effective span or clear span (mm)
• s = Slope of linear part of load-deflection curve (N/mm)
• E = Modulus of elasticity (N/mm²)
• σ_ult = Ultimate strength in bending (N/mm²)

1. Moment of Inertia (I)

[ I = \frac{\pi}{64} (D^4 - (D - 2t)^4) ]

Note: This formula calculates I for hollow circular sections.

2. Ultimate Bending Strength (σ_ult)

[ \sigma_{ult} = \frac{6FL}{\pi D^3 t} ]

Or as given (rearranged for circular sections): [ \sigma_{ult} = \frac{6 F L}{I D} ]

Reported to nearest 1 N/mm².

3. Modulus of Elasticity (E)

[ E = \frac{L^3 s}{4 I} ]

Reported rounded to the nearest 100 N/mm².

Additional Notes:

• Definitions align with IS 707 (1976) - Timber technology glossary.
• Basic mass per volume formula updated as per Clause 5.2.3 (refer IS 6874 for exact formula).

flowchart TD
    A[Load Test Setup] --> B[Measure F, L, Deflection]
    B --> C[Calculate I using D, t]
    C --> D[Calculate σ_ult = 6FL / (I D)]
    C --> E[Calculate E = L³ s / (4 I)]
    D --> F[Report σ_ult]
    E --> G[Report E]

This summary provides essential formulas and references for calculations per IS 6874 definitions.

IS 6874 - Marking, Felling and Conversion (Clause 4.2)

• Marking:

  • Mark a ring with paint on the bamboo culm at 1 m height from ground.
  • Mark other details above the ring.

• Felling:

  • Follow standard harvesting practices.
  • Remove unusable parts:
    • Bottom: crooked portion with short internodes.
    • Top: very low diameter and thin walls.

• Conversion:

  • Measure remaining culm length after trimming.
  • Cut culm into 2 or 3 parts.
  • For static bending tests, specimen length ≥ 30 × outer diameter + 1 m.
  • Mark each part at the lower end with a ring and label as B (bottom), M (middle), T (top).

• Specimens for Testing:

  • Prepare from freshly felled bamboo for properties like basic density and shrinkage.

Key Formula for Static Bending Specimen Length

[ L_{min} = 30 \times D_{outer} + 1, \text{m} ]

Where:

• (L_{min}) = Minimum specimen length
• (D_{outer}) = Outer diameter of bamboo culm

This ensures uniformity in testing and accurate assessment of mechanical properties per IS 6874.

IS 6874: Permissible and Non-permissible Defects in Bamboo

Permissible Defects (Clause 4.1.1)

• Discolouration: Allowed if it does not impair strength.

Non-permissible Defects (Clause 4.1.2)

• Borer attack and decay: Not allowed.
• Splits/cracks and blue stains: Not allowed as they reduce strength.

Key Formulas for Strength Calculations (Clause 6.1.4 & 6.4.4)

• (D) = Outer diameter (mm)
• (t) = Wall thickness (mm)
• (F) = Maximum load (N)
• (L) = Effective span or specimen length (mm)
• (I) = Moment of inertia (mm(^4))
• (s) = Slope of linear load-deflection (N/mm)

Summary Table of Defects

IS 6874: Physical Properties of Refractory Materials

Key Specification:

Clause 5.2 — Basic Mass per Volume (Density)

• The mass per unit volume (density) is a critical physical property for refractories, affecting thermal conductivity and mechanical strength.

Revised Formula for Basic Mass per Volume (Clause 5.2.3):

[ \rho = \frac{W}{V} ]

Where:

• (\rho) = Basic mass per volume (kg/m³)
• (W) = Weight of the specimen (kg)
• (V) = Volume of the specimen (m³)

Typical Physical Properties to Consider:

• Apparent Porosity (%)
• Bulk Density (kg/m³)
• Water Absorption (%)

Common Table (Example values for refractory bricks):

Summary:

• Measure mass and volume accurately for density.
• Use density to infer other physical and mechanical behavior.

If you need mechanical properties or other clauses, please specify!

IS 6874: Mechanical Properties Key Formulas & Specifications

1. Shrinkage Percentage (Clause 5.3.3)

[ \text{Shrinkage %} = \frac{D_i - D_f}{D_i} \times 100 ]

Where:

• Shrinkage along diameter, wall thickness, or length is calculated similarly using initial and final dimensions.

2. Moment of Inertia (I) (Clause 6.1.4 a)

For hollow circular section:

[ I = \frac{\pi}{64} \left( D^4 - (D - 2t)^4 \right) ]

• (D) = Outer diameter (mm)
• (t) = Wall thickness (mm)

3. Ultimate Strength in Static Bending ( \sigma_{ult} ) (Clause 6.1.4 b)

[ \sigma_{ult} = \frac{6FL}{\pi D^3 t} ]

Where:

• (F) = Maximum load (N)
• (L) = Effective span (mm)
• (D) = Outer diameter (mm)
• (t) = Wall thickness (mm)

Report (\sigma_{ult}) to nearest 1 N/mm².

4. Modulus of Elasticity (E) (Clause 6.1.4 c)

[ E = \frac{L^3}{4 I s} ]

Where:

• (L) = Clear span (mm)
• (I) = Moment of inertia (mm⁴)
• (s) = Slope of linear portion of load-deflection curve (N/mm)

Round (E) to nearest 100 N/mm².

flowchart TD
    A[Initial Dimensions] --> B[Calculate Shrinkage %]
    C[Load & Deflection Data] --> D[Calculate Moment of Inertia]
    D --> E[Calculate Ultimate Strength

IS 6874: Static Bending Strength - Key Formulas & Specifications

1. Moment of Inertia (I) for Hollow Circular Section

[ I = \frac{\pi}{64} \times (D^4 - (D - 2t)^4) ]

• D = Outer diameter (mm)
• t = Wall thickness (mm)

2. Ultimate Bending Strength ((\sigma_{ult}))

[ \sigma_{ult} = \frac{6FL}{\pi D^3 t} ]

Or from the code's context (simplified):

[ \sigma_{ult} = \frac{6 \times F \times L}{I \times D/2} ]

• F = Maximum load (N)
• L = Effective span (mm)
• I = Moment of inertia (mm(^4))
• D = Outer diameter (mm)

Report (\sigma_{ult}) to nearest 1 N/mm(^2).

3. Modulus of Elasticity (E)

[ E = \frac{L^3 \times s}{4 \times I} ]

• L = Clear span (mm)
• s = Slope of linear part of load-deflection curve (N/mm)
• I = Moment of inertia (mm(^4))

Round (E) to nearest 100 N/mm(^2).

4. Test Setup Summary (Clause 6.1.3)

• Specimen supported on saddles on I-beam.
• Load applied uniformly at 0.5 mm/s.
• Deflection measured at mid-span every 500 N load increment.
• Load-deflection curve plotted.
• Measure D and t near load points after failure.

Diagram: Static Bending Test Setup (Fig. 2)

flowchart LR
    A[Load Head] -- Load --> B[Wooden Beam]
    B -- Load --> C[Specimen on Saddles]
    C -- Support --> D[I-Beam Supports]
    C -- Deflection Measurement --> E[Dial Gauge]

This concise summary aligns with IS 6874 Clause 6.1 for static bending strength testing of bamboo specimens.

IS 6874 - Compressive Strength Parallel to Grain (Clause 6.2)

• Definition: Compressive strength parallel to grain (f_c) is the maximum compressive stress a timber specimen can withstand along the grain direction.

Key Formula:

[ f_c = \frac{P_{max}}{A} ]

• (P_{max}) = Maximum load at failure (N)
• (A) = Cross-sectional area parallel to grain (mm²)

Typical Values (from IS 6874 Table for Common Timber Species):

Specifications:

• Test specimens should be conditioned at 12% moisture content.
• Load applied uniformly along grain axis.
• Cross-section measured accurately for stress calculation.

Related Strengths (for reference):

• Tensile Strength Parallel to Grain (Clause 6.3)
• Shear Strength Parallel to Grain (Clause 6.4)

flowchart LR
    A[Load Applied Parallel to Grain] --> B[Specimen]
    B --> C[Measure Max Load (P_max)]
    B --> D[Measure Cross-sectional Area (A)]
    C & D --> E[Calculate f_c = P_max / A]

This ensures accurate evaluation of compressive strength parallel to grain as per IS 6874.

IS 6874: Tensile Strength Key Points

1. Test Specimen (Clause 6.3.1)

• Length: 60 mm
• Width: 10 to 20 mm (flat specimen)
• Thickness: ≤ wall thickness of culm (t)
• One node at the center
• Fibres parallel to specimen length
• Laminated ends allowed for better grip (see Fig. 3)

2. Calculation of Tensile Strength (Clause 6.3.4)

[ \sigma_{ult} = \frac{F_{ult}}{A} ]

• (\sigma_{ult}) = Ultimate tensile strength (N/mm²)
• (F_{ult}) = Maximum load applied (N)
• (A) = Cross-sectional area of specimen (mm²)

Note: Round (\sigma_{ult}) to the nearest whole number.

3. Related Formulas (Clause 6.1.4 for bending, useful for context)

• Moment of inertia (I) for hollow circular section:

[ I = \frac{\pi}{64} (D^4 - d^4) ]

Where:

• (D) = Outer diameter (mm)

• (d = D - 2t) (inner diameter)

• Ultimate bending strength:

[ \sigma_{ult} = \frac{6FL}{D^2} ]

• Modulus of Elasticity:

[ E = \frac{23 s L^3}{196 , I} ]

Where:

• (s) = slope of load-deflection curve (N/mm)
• (L) = span length (mm)

Summary Table

IS 6874 - Shear Strength Parallel to Grain (Clause 6.4)

Key Formula:

Shear strength parallel to grain, ( f_{v} ), is generally expressed as:

[ f_v = \alpha \times f_c ]

Where:

• ( f_v ) = Shear strength parallel to grain
• ( f_c ) = Compressive strength parallel to grain (from Clause 6.2)
• ( \alpha ) = Empirical factor (typically 0.5 to 0.6 depending on wood species and moisture)

Typical Values (Indicative):

Notes:

• Shear strength parallel to grain is lower than compressive and tensile strengths.
• Moisture content and wood defects significantly affect ( f_v ).
• Use Clause 6.4 for specific species and conditions.

flowchart LR
    A[Compressive Strength \( f_c \)] --> B[Shear Strength \( f_v \)]
    B --> C[Shear strength \( f_v = \alpha \times f_c \)]
    C --> D[Design Shear Capacity]

Summary:
Use ( f_v \approx 0.5 \times f_c ) as a guideline. Refer to IS 6874 Clause 6.4 for species-specific factors and detailed tables.

IS 6874 — Test Specimen Preparation: Key Points

1. Specimen Dimensions & Selection

• Bending Test Specimen (6.1.1):

  • Length ≥ 30 × diameter at mid-point + 1 m
  • Free from cracks, crookedness, and taper variation
  • Air-dried and conditioned culms

• Compressive Strength Test Specimen (6.2.1):

  • Length = outer diameter (measured per 5.3.2)
  • Taken from undamaged ends of bending test specimens, from internode
  • Ends flat and perpendicular within 0.2 mm deviation

• Tensile Strength Test Specimen (6.3.1):

  • Length = 60 mm; Width = 10–20 mm; Thickness ≤ wall thickness
  • One node at center; fibers parallel to length
  • Laminated ends allowed for better grip (see Fig. 3)
  • Dimensions accurate to 0.1 mm

2. Testing Machine Setup (6.4.2)

• Specimen rests on two opposite triangular steel blocks at the bottom (from a square block cut diagonally)
• Load applied at the top over the other two independent triangles
• Creates four shear areas for load distribution (see Fig. 4)

Summary Table of Specimen Dimensions

flowchart TD
    A[Test Specimen Preparation]
    A --> B[Bending Specimen]
    A --> C[Compression Specimen]
    A --> D[Tensile Specimen]
    B --> B1[Length ≥ 30×diam + 1m]
    C --> C1[Length = outer diameter]
    D --> D1[Length = 

IS 6874: Testing Machines and Equipment - Key Points

1. Testing Machine Requirements (Clauses 6.1.2, 6.2.2, 6.3.2)

• Load Measurement Accuracy: ±100 N
• Deflection Measurement Accuracy: ±1 mm
• Load Application: Along longitudinal axis; prevent twisting
• Platen: One platen must have a hemispherical bearing for uniform load distribution
• Friction Reduction: For bamboo specimens, use molten sulphur or Teflon + wax layer between specimen and steel platens due to hollow nature

2. Specimen Support & Loading (Clause 6.4.2)

• Use a square steel block cut diagonally into four triangles:
  • Lower end: support on two opposite triangles (fixed)
  • Upper end: load applied on other two independent triangles
• This arrangement creates four shear areas for testing (see Fig. 4 in code)

3. Test Setup (Clause 6.1.2)

• Four-point bending test
• Specimen length: clear span = 30 × diameter at mid-span
• Supports: saddles allowing free rotation, reaction forces transmitted to nodes
• Load applied at nodes via beam resting on saddles, divided into two halves

Summary Table

flowchart TB
    A[Test Specimen] --> B[Lower Support: 2 Triangles (fixed)]
    A --> C[Upper Load: 2 Triangles (independent)]
    B --> D[Steel Block (Square cut diagonally)]
    C --> D
    A --> E[Four Shear Areas]

This setup ensures uniform load distribution, minimal friction, and accurate shear testing of bamboo specimens per IS 6874.

IS 6874: Calculation & Reporting of Results

Key Formulas (Clause 6.1.4)

1. Moment of Inertia, (I) (mm⁴):
   [ I = \frac{\pi}{64} (D^4 - (D - 2t)^4) ] where

   • (D) = outer diameter (mm)
   • (t) = wall thickness (mm)

2. Ultimate Strength, (\sigma_{ult}) (N/mm²):
   [ \sigma_{ult} = \frac{6FL}{\pi D^3 t} ] where

   • (F) = maximum load (N)
   • (L) = effective span (mm)
   • (D) = outer diameter (mm)
   • (t) = wall thickness (mm)

   Report (\sigma_{ult}) rounded to nearest 1 N/mm².

3. Modulus of Elasticity, (E) (N/mm²):
   [ E = \frac{L^3 s}{4I} ] where

   • (L) = clear span (mm)
   • (s) = slope of linear part of load-deflection curve (N/mm)
   • (I) = moment of inertia (mm⁴)

   Report (E) rounded to nearest 100 N/mm².

Reporting Guidelines

• Round off values per IS 2:1960 "Rules for rounding off numerical values".
• Report ultimate strength to ±1 N/mm² accuracy.
• Report modulus of elasticity to nearest 100 N/mm².

Summary Table

IS 6874: Air-Drying and Conditioning of Bamboo Specimens

Key Specifications (Clause 4.3 & 5.1.2):

• Air-Drying:

  • Dry culms to about 12% moisture content (MC) before testing.
  • Condition specimens at 27 ± 2°C and 65 ± 5% RH for at least 1 week to reach equilibrium MC of 12%.
  • Use minimum 12 specimens per test (2 from each culm).

• Oven Drying Procedure (Clause 5.1.2):

  1. Weigh specimen accurately to 0.01 g (initial mass (m_i)).
  2. Dry in hot air oven at 103 ± 2°C for 24 h.
  3. Continue drying and weigh every 2 hours until weight change ≤ 0.01 g.
  4. Final weight after drying = Oven dry mass (m_0).

Moisture Content Calculation:

[ \text{Moisture Content (MC, %)} = \frac{m_i - m_0}{m_0} \times 100 ]

Where:

• (m_i) = initial mass before oven drying (g)
• (m_0) = oven dry mass (g)

Summary Table:

flowchart TD
    A[Cut Specimen] --> B[Weigh (m_i)]
    B --> C[Air-Dry to ~12% MC]
    C --> D[Condition at

Committee Composition (IS 6874 - Annex A)

The Timber and Timber Stores Sectional Committee, CED 9 is responsible for formulating IS 6874. It includes representatives from:

• Various Government Departments: Forest Departments (Bhopal, Raipur, Bangalore, etc.), Ministry of Defence, Ministry of Environment & Forests, Directorate General of Civil Aviation, Directorate General of Supplies & Disposals.
• Research Institutes: Forest Research Institute (Dehra Dun), Indian Plywood Industries Research & Training Institute (Bangalore), Institute of Wood Science & Technology (Bangalore), Central Building Research Institute (Roorkee).
• Industry Representatives: Federation of Indian Plywood & Panel Industry, Bamboo Society of India, Timber Development Association, Rubber Board.
• Individual Experts: Scientists, Directors, and Chairpersons from related fields.

Key Contacts:

Shear Strength Formula (Clause 6.4.4)

[ \sigma_{ult} = \frac{F_{ult}}{t \times L} ]

• ( F_{ult} ) = Maximum load (N)
• ( t ) = Mean wall thickness (mm)
• ( L ) = Mean length of test specimen (mm)
• (\sigma_{ult}) = Ultimate shear strength (N/mm²), rounded to nearest whole number

Summary

• Committee composition is broad, including government, research, and industry experts.
• Shear strength calculation is key for timber testing.
• Refer to Annex A for full member list and Clause 6.4.4 for shear strength formula.

graph LR
A[IS 6874 Committee] --> B[Government Departments]
A --> C[Research Institutes]
A --> D[Industry Representatives]
A --> E[Individual Experts]