Methods of tests for wood poles

IS 1900: Scope - Key Formulas, Tables, and Specifications

Scope Overview

IS 1900 specifies testing methods and data requirements for wood poles used in overhead power and telecommunication lines.

Key Formulas (Clause 5.2.3.9)

Where:

• ( P ) = load at failure or applied load (kg)
• ( l ) = corrected lever arm (cm)
• ( C_a ) = circumference at ground or break point (cm)
• ( I ) = moment of inertia at ground line (cm⁴)
• ( Y ) = deflection at load point (cm)
• ( D_0 ), ( D_1 ) = diameters at ground and load points (cm)

Data Sheet (Appendix A)

• Species and class
• Temperature & humidity during testing
• Moisture at fracture
• Pole dimensions: total length, butt to ground line, ground line to top, load point to break point
• Cross-section dimensions & average taper
• Maximum load, deflection, and deviation
• Maximum fibre stress at break

Testing Setup (Clause 5.2.3.1)

• Fixed concrete crib or portable crib arrangements
• Schematic layouts provided in Figures 1, 2, and 3 for test setup

Summary Table: Key Parameters

IS 1900 Key References, Formulas & Data Sheets

Appendix A: Data Sheet for Testing of Poles

• Details to record:
  • Species, class
  • Temperature & humidity during test
  • Moisture at fracture
  • Pole dimensions (total length, ground line to top/load/break points)
  • Cross section & taper
  • Maximum load & deflections (r, X)
  • Maximum fibre stress at break

Appendix B: Minor Tests on Small Clear Specimens (Butt Portion)

• Compression parallel to grain (cross-section area, crush strength)
• Shear strength (radial and tangential)

Key Formulas (Clause 5.2.3.9)

Notes:

• Circumference (C) measured at ground line or break point.
• Moment of inertia (I) for circular cross-section:
  [ I = \frac{\pi}{64} d^4 ] where ( d ) = diameter at ground line (cm).

Contact & Publications

• ISI Handbook (1972) contains detailed standards.
• Indian Standards Institution offices available across major cities for standards procurement.

flowchart TD
    A[Testing Data Sheet] --> B[Species, Class]
    A --> C[Environmental Conditions]
    A --> D[Dimensions & Cross Section]
    A --> E[Load & Deflection]
    A -->

IS 1900 - Key Formulas & Specifications for Definitions

1. Maximum Fibre Stress at Ground Line (Clause 5.2.3.9a)

[ F = \frac{P \times l}{Z \times C_a} ]

• F = max fibre stress at ground line (kg/cm²)
• P = load at failure (kg)
• l = corrected lever arm (cm)
• Z = section modulus = (\frac{\pi d^3}{32})
• C_a = circumference at ground line (cm)

2. Maximum Fibre Stress at Break (Clause 5.2.3.9b)

[ F_p = \frac{P \times l}{Z_a \times C_a} ]

• F_p = max fibre stress at break (kg/cm²)
• l = distance from break to load point (cm)
• Z_a = section modulus at break point
• C_a = circumference at break point (cm)

3. Modulus of Elasticity (Clause 5.2.3.9c)

[ E = \frac{P \times l^3}{4 \times I \times Y \times D_1} ]

• E = modulus of elasticity (kg/cm²)
• P = applied load (kg)
• l = corrected lever arm (cm)
• I = moment of inertia at ground line (cm⁴)
• Y = deflection at load point (cm)
• D₁ = diameter at load point (cm)

4. Calculation with Tip Reaction (Clause 5.2.4.8a)

[ F = \frac{(T + 2t) \times 0.098 \times d^3}{} ]

• T = tip reaction from superimposed load (kg)
• t = tip reaction due to dead weight (kg)
• d = diameter at load point (cm)

5. Modulus of Elasticity with Supports (Clause 5.2.4.8b)

[ E = \frac{4 L^2 A B (

IS 1900 - Condition at Test: Key Points

Recommended Test Conditions (Clause 4.1.1, Table 4)

Additional Test Parameters

• Curvature of pole as per IS 876:1970 Clause 8.3.
• Temperature and humidity at testing time must be recorded (Clause 8.3).

Minor Tests (Clause 3.1.2)

• Moisture content & specific gravity
• Static bending strength
• Compression parallel to grain

Notes:

• Testing in green condition means testing poles soon after cutting, retaining natural moisture.
• Air dry condition implies drying poles to equilibrium moisture content in air.
• Treated poles are tested after preservative treatment.
• Alternate wetting and drying simulates weathering effects.

This ensures realistic strength and durability assessment under varied field conditions.

IS 1900: Test Methods Key Points

• Minor Tests (Clause 6.1 & 3.1.2):
  Conducted on butt portions (unstressed) of poles.
  Specimen size: minimum 5 cm × 5 cm clear section.
  Tests include:

  • Moisture content & specific gravity
  • Static bending strength
  • Compression parallel to grain

• Reference Standard:
  Minor tests conform to IS 1708-1969 methods.

• Data Recording:
  Use datasheet format from Appendix A.
  Tabulate results as per Appendix B.

Typical Test Formulas & Parameters

• Where:
  • (P) = Load at failure (N)
  • (L) = Span length (mm)
  • (b) = Width of specimen (mm)
  • (d) = Depth of specimen (mm)

flowchart TD
    A[Select Butt Portion] --> B[Cut 5x5 cm Specimen]
    B --> C[Perform Minor Tests]
    C --> D{Test Types}
    D --> E[Moisture Content & Specific Gravity]
    D --> F[Static Bending]
    D --> G[Compression Parallel to Grain]
    E & F & G --> H[Record Results Appendix B]
    H --> I[Analyze & Approve]

This summary aligns with IS 1900 clauses and IS 1708-1969 for test execution and reporting.

Determination of Weight of Full Pole (IS 1900)

• Clause 5.1:
  • Weigh the full pole directly on a suitable weighing machine (nearest kg).
  • If unavailable, take two 20 cm specimens from each end after testing, weigh each, average the weights, and extrapolate for full pole weight.

Key Formulas for Pole Analysis

• (F) = max fibre stress (kg/cm²)
• (T) = tip reaction due to superimposed load (kg)
• (t) = tip reaction due to dead weight (kg)
• (d) = diameter at load point (cm)
• (b) = distance from load point to butt support (cm) |

| Modulus of Elasticity (E) |
[ E = \frac{4 \times L \times A \times B \times (aL - Bb)}{T \times \delta} ] |

• (E) = modulus of elasticity (kg/cm²)
• (a, b) = distances from ground line to tip/butt support (cm)
• (L = a + b) (cm)
• (A, B) = radii at ground line and tip support (cm)
• (T) = tip reaction (kg)
• (\delta) = observed deflection (cm) |

Notes:

• Weighing specimens method ensures accuracy when full pole weighing is impractical.
• Use circumference and diameter measurements at ground and break points for stress calculations (see Clause 5.2.3.9 for detailed max fibre stress and modulus formulas).

flowchart LR
    A[Full Pole] --> B[Weigh full pole directly]
    A --> C[If no weighing machine]
    C --> D[Cut 20cm specimens at each end]
    D --> E[Weigh specimens]
    E --> F[Average weights]
    F --> G[Calculate full pole weight

Here are the key formulas and specifications for Static Bending from IS 1900 (Clause 5.2):

1. Maximum Fibre Stress at Ground Line

[ F = \frac{P \times l}{2 \times C_a^3} ]

• F = max fibre stress at ground line (kg/cm²)
• P = load at failure (kg)
• l = corrected lever arm (cm)
• C_a = circumference at ground line (cm)

2. Maximum Fibre Stress at Break

[ F_p = \frac{P \times l}{Z_a \times C_a^3} ]

• F_p = max fibre stress at break (kg/cm²)
• P = load at failure (kg)
• l = distance from break to load point (cm)
• Z_a = section modulus (cm³)
• C_a = circumference at break point (cm)

3. Modulus of Elasticity (E)

[ E = \frac{3 I l}{Y P D_1 D_g} ]

• E = modulus of elasticity (kg/cm²)
• I = moment of inertia at ground line (cm⁴)
• l = corrected lever arm (cm)
• Y = deflection at load point (cm)
• P = applied load (kg)
• D_1, D_g = diameters at load point and ground line (cm)

4. Alternate Formula for Max Fibre Stress at Ground Line

[ F = \frac{(T + t) \times 0.098 \times 2 \times d^3}{L} ]

• T = tip reaction due to superimposed load (kg)
• t = tip reaction due to dead weight (kg)
• d = diameter at load point (cm)
• L = distance between tip and butt support (cm)

5. Alternate Modulus of Elasticity

[ E = \frac{4 L^3 A B (a L - b b) T}{\delta} ]

• E = modulus of elasticity

IS 1900 - Initial Measurements (Clauses 5.2.2 & 5.2.4.2)

Key Points:

• Initial measurements are mandatory before placing the pole in the testing apparatus.
• Measurements recorded on a data sheet (Appendix A) include:
  • Pole dimensions (length, diameter, taper)
  • Weight and material properties
  • Initial deflections or deviations
  • Any visible defects or anomalies

Specifications:

• Use the data sheet format from Appendix A for consistent recording.
• Record corrected load readings, deflections, deviations, and failure positions during testing (Clause 5.2.3.7).
• Photographic documentation of failures is recommended.

Typical Data Sheet Fields (Appendix A):

This ensures traceability and accuracy in testing results per IS 1900 standards.

IS 1900: Testing Equipment and Procedure for Wood Poles

Key Specifications:

• Calibration (Clause 4.4):
  All testing apparatus must be calibrated periodically to maintain accuracy within ±1% error.

• Testing Equipment Layout (Clause 5.2.3.1):

  • Fixed concrete crib setup: Refer to Fig. 1 & Fig. 2
  • Portable crib setup: Refer to Fig. 3
    These figures define dimensions (in mm) and arrangement for applying loads and supports.

• Data Recording (Clause 5.2.2.1):
  Use the data sheet in Appendix A for systematic data collection.

• Load-Deflection Curve (Clause 5.2.4.7):
  Critical for evaluating bending behavior; see detailed procedure in Clause 5.2.3.8.

Typical Testing Setup (from Fig. 4):

• Components: Equalizing plate, back anchor & pin, weighing platen, loading screw, scale.
• Load applied transversely; hydraulic weighing cell may be positioned at load or reaction point.

Summary Table: Calibration & Equipment

flowchart LR
    A[Load Application] --> B[Equalizing Plate]
    B --> C[Wood Pole]
    C --> D[Back Anchor & Pin]
    B --> E[Weighing Platen]
    E --> F[Scale/Weighing Cell]

This setup ensures accurate bending tests on wood poles per IS 1900 standards.

IS 1900 - Machine Method Key Points

1. Rate of Loading (Clause 4.3)

• The testing machine's loading rate must not vary ±25% from the specified speed.
• Ensures consistent and comparable test results.

2. Load-Deflection Curve (Clause 5.2.4.7)

• Refer to Clause 5.2.3.8 for detailed procedure.
• Important for determining stiffness and failure point.

3. Machine Setup (Clause 5.2.4)

• Includes components:
  • Equalizing Plate
  • Back Anchor and Pin
  • Weighing Platen (with or without extension wing)
  • Scale Loading Screw
• Hydraulic weighing cell can be placed at reaction or load point for accurate load measurement.

4. Data Sheet (Clause 5.2.2.1)

• Use Appendix A for standardized data recording.

Typical Machine Setup (Fig. 4 schematic)

flowchart LR
    LoadPoint[Load Point]
    EqualizingPlate[Equalizing Plate]
    BackAnchor[Back Anchor & Pin]
    WeighingPlaten[Weighing Platen]
    ScaleScrew[Scale Loading Screw]
    HydraulicCell[Hydraulic Weighing Cell]

    LoadPoint --> EqualizingPlate --> BackAnchor
    LoadPoint --> WeighingPlaten --> ScaleScrew
    WeighingPlaten --> HydraulicCell

Summary Table: Loading Rate Control

Ensure all dimensions and setup follow IS 1900 Fig.4 for wooden poles transverse bending tests.

Key Formulas & Specifications from IS 1900 for Poles Testing

1. Determination of Age & Rate of Growth

• Two discs (5 cm thick) are cut from either side of the failure point.
• Count the number of annual rings per cm on each disc.
• Average the counts to find the Rate of Growth (rings/cm).
• Age = Total number of rings on the disc.

2. Sapwood Percentage

[ \text{Sapwood %} = \frac{R^2 - r^2}{R^2} \times 100 ]

• ( R ) = radius of the disc (cm)
• ( r ) = inner radius (heartwood radius, cm)

3. Moisture Content

• Moisture content is measured from the two discs by weighing before and after oven drying.

[ \text{Moisture Content %} = \frac{\text{Wet weight} - \text{Oven dry weight}}{\text{Oven dry weight}} \times 100 ]

4. Testing Conditions (Clause 4.1.1)

Summary Diagram (Pole Testing Process)

flowchart LR
    A[Pole Failure] --> B[Cut 2 Discs (5 cm thick)]
    B --> C{Measure Parameters}
    C --> D[Count Rings → Age & Rate of Growth]
    C --> E[Measure Radii → Sapwood %]
    C --> F[Weigh Discs → Moisture Content]
    F --> G[Calculate Moisture %]

This concise method ensures accurate determination of Age, Growth Rate, Moisture Content, and Sapwood Percentage for structural pole evaluation per IS 1900.

IS 1900: Minor Tests on Small Clear Specimens

Key Points from IS 1900 & IS 1708-1969

• Specimen size: Minimum clear specimen of 5 cm × 5 cm from butt portion (unstressed).
• Minor Tests Include:
  • Moisture content & specific gravity
  • Static bending
  • Compression parallel to grain

Moisture Content (MC) Calculation

[ MC% = \frac{W_{wet} - W_{dry}}{W_{dry}} \times 100 ]

• (W_{wet}) = weight before drying
• (W_{dry}) = oven-dry weight

Specific Gravity (SG)

[ SG = \frac{\text{Oven dry weight}}{\text{Volume} \times \text{Water density}} ]

Static Bending Test

• Load applied transversely on specimen supported at ends.
• Calculate Modulus of Rupture (MOR):
  [ MOR = \frac{3PL}{2bd^2} ]
• (P) = Maximum load (N)
• (L) = Span length (mm)
• (b), (d) = width and depth of specimen (mm)

Compression Parallel to Grain

• Calculate compressive strength:
  [ f_c = \frac{P}{A} ]
• (P) = Load at failure (N)
• (A) = Cross-sectional area (mm²)

Testing Setup

• Refer to Fig. 4 schematic for bending test setup with equalizing plate, back anchor, weighing platen, and loading screw.

flowchart LR
  A[Specimen Preparation] --> B[Moisture Content Test]
  A --> C[Specific Gravity Test]
  A --> D[Static Bending Test]
  A --> E[Compression Parallel to Grain]
  D --> F{Calculate MOR}
  E --> G{Calculate Compressive Strength}

Note: Refer IS 1708-1969 for detailed procedures and Appendix B of IS 1900 for tabulation format.

IS 1900: Data Sheet & Key Specifications for Testing Wood Poles

1. Testing Setup (Clause 5.2.3.1 & 5.2.4.1)

• Use hydraulic/mechanical testing machine with capacity suitable for pole size.
• Load applied at ground line by movable head.
• Fixed concrete crib or portable crib used for support (see Fig. 1, 2, 3 in IS 1900).
• Dimensions and layout per IS 1900 drawings (all in mm).

2. Specimen for Minor Tests (Clause 6.1)

• Minor tests per IS 1708-1969.
• Take a clear specimen of 5 cm x 5 cm from butt portion.
• Tabulate results as per Appendix B of IS 1900.

3. Load-Deflection Curve (Clause 5.2.3.8)

• Plot load (kN) vs deflection (mm) for each pole.
• This curve is essential to assess flexibility and strength.

4. Typical Data Sheet Fields

5. Schematic Concept (Mermaid.js)

graph LR
A[Pole Setup] --> B[Fixed Concrete Crib]
A --> C[Portable Crib]
B --> D[Load Applied at Ground Line]
C --> D
D --> E[Load-Deflection Curve]
E --> F[Strength & Flexibility Assessment]

Summary:
IS 1900 mandates testing poles with a hydraulic machine applying load at ground line, using crib supports, minor tests per IS 1708, and plotting load-deflection curves. Data sheets must capture dimensions, load, deflection

IS 1900: Minor Tests on Small Clear Specimens from Butt Portion of Poles

Key Points from IS 1900 Clauses:

• Specimen size: Minimum clear specimen of 5 cm × 5 cm taken as a disc from the butt (unstressed) portion.
• Reference standard: Minor tests follow procedures in IS 1708-1969.
• Test purpose: Evaluate wood properties on small clear specimens after major tests on full poles.
• Data presentation: Results tabulated as per Appendix B of IS 1900.

Minor Tests typically include:

• Compression parallel to grain
• Tension parallel to grain
• Shear strength
• Hardness
• Density and moisture content

Typical Minor Test Specimen Preparation:

Example: Compression strength parallel to grain (from IS 1708)

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

• (f_c) = compressive stress (N/mm²)
• (P) = load at failure (N)
• (A) = cross-sectional area (mm²)

Summary Diagram of Testing Process

flowchart TD
    A[Full Pole] --> B[Major Tests on Full Pole]
    B --> C[Cut Disc from Butt Portion (5x5 cm)]
    C --> D[Minor Tests on Small Clear Specimen]
    D --> E[Tabulate Results (Appendix B)]

Note: For detailed test methods and specimen preparation, refer to IS 1708-1969. This ensures uniformity and reliability in minor test results for wood poles.