Fire resistance test for structures

IS 3809: Scope - Key Specifications & Tables

Scope Overview (Clause 1.5 & 4.1.2)

• Thermocouple Placement:

  • Walls & floors: 1 thermocouple per 1.5 m² surface.
  • Beams: 2 thermocouples per 1 m length.
  • Columns: 2 thermocouples per 1 m height.
  • Minimum thermocouples: 5 per test.

• Minimum Test Specimen Dimensions (Clause 4.1.2):

Temperature Rise Curve (Table 1)

Notes:

• Temperature elevation ( T - T_0 ) follows the standard time-temperature curve for furnace testing.
• Overpressure measurement equipment is specified for walls and floors (Clause 2.4).
• Tolerances for measurements are detailed in Clause 3.1.3.

graph TD
    A[Thermocouple Placement] --> B[Walls & Floors: 1/1.5 m²]
    A --> C[Beams: 2/m length]
    A --> D[Columns: 2/m height]
    A --> E[Minimum 5 thermocouples]

    F[Test Specimen Dimensions] --> G[Walls: 4m span x 2m width]
    F --> H[F

IS 3809: Key Formulas, Tables & Specifications – Definitions and Equipment

1. Equipment for Measuring Overpressure (Clause 2.4)

• Used for testing walls and floors.
• Must measure overpressure inside furnace accurately during fire resistance tests.

2. Standard Heating Conditions (Clause 3.1)

• Furnace temperature follows the Standard Time-Temperature Curve (Fig. 1).
• Temperature elevation ( T - T_0 ) (in °C) as a function of time ( t ) (in minutes) is given in:

3. Measurement of Furnace Temperature (Clause 1.5)

• Thermocouples required:
  • Walls/Floors: 1 thermocouple per 1.5 m² surface.
  • Beams: 2 thermocouples per 1 m length.
  • Columns: 2 thermocouples per 1 m height.
• Minimum total thermocouples: 5.

4. Furnace Specification (Clause 2.1)

• Furnace must simulate standard heating and pressure conditions as per Clause 3.

Summary Diagram: Thermocouple Placement

graph TD
  Walls_Floors -->|1 per 1.5 m²| Thermocouples
  Beams -->|2 per 1 m length| Thermocouples
  Columns -->|2 per 1 m height| Thermocouples
  Thermocouples --> Minimum_5

Use these specifications to ensure accurate fire resistance testing per IS 3809.

IS 3809: Standard Heating and Pressure Conditions

Key Specifications:

• Standard Heating Conditions (Clause 3.1):
  Furnace must subject specimens to specified standard heating per Clause 3.

• Pressure Conditions (Clause 3.2):

  • Over-pressure inside furnace:
    10 ± 5 Pa (equivalent to 1.0 ± 0.5 mmH₂O or 0.04 ± 0.02 in H₂O)
  • Applies during the entire heating period for fire-resistance tests on separating elements.
  • For vertical elements: over-pressure must cover bottom two-thirds height.
  • For horizontal elements: measure over-pressure 100 mm below specimen.
  • For vertical elements: measure at 3/4 height of specimen.
  • Doors, windows, ventilators must be within the over-pressure region.

• Notes:

  • Over-pressure can be created by lowering pressure on unexposed face.
  • Over-pressure not mandatory for first 10 minutes.
  • 1 Pa = 1 N/m².

Measurement Equipment (Clause 2.4):

Use equipment capable of accurately measuring small over-pressures (±5 Pa).

Summary Table:

flowchart LR
    Furnace -->|Heating| Specimen
    Furnace -->|Over-pressure 10±5 Pa| Specimen
    Specimen -->|Measure pressure| Sensor
    Sensor -->|Horizontal: 100mm below| Location1
    Sensor -->|Vertical: 3/4 height| Location2

This ensures consistent fire-resistance test conditions per IS 3809.

IS 3809: Test Specimens - Key Specifications

• Specimen Size (Clause 4.1.1):
  Test specimens must be full size to represent actual conditions.

• Specimen Composition (Clause 4.2.1.1):

  • Must include at least one of each representative joint type.
  • May include beams, columns, doors, or glazing integral to the element to test composite behavior.

• Mechanical Strength (Clause 4.3.2):
  Constituent materials should have mechanical strength close to in-service conditions.

• Conditioning (Clause 4.3):
  Specimens must be conditioned to replicate temperature, moisture, and mechanical strength expected in service.

Summary Table: Test Specimen Requirements

flowchart TD
    A[Test Specimen] --> B[Full Size]
    A --> C[Includes Joint Types]
    A --> D[Includes Composite Elements]
    A --> E[Conditioned for Service]
    E --> F[Temperature]
    E --> G[Moisture]
    E --> H[Mechanical Strength]

IS 3809: Test Procedure Key Points

1. Test Conditions (Clause 5.1)

• Test specimens must simulate actual service conditions.
• Mechanical strength of materials should be near in-service strength (Clause 4.3.2).
• Overpressure measurement equipment must comply with Clause 2.4 for walls/floors.

2. Standard Heating & Pressure (Clause 5.3.4)

• Heating duration starts at test commencement.
• Fire resistance time is the period (in minutes) the specimen maintains performance.

3. Performance Criteria (Clause 6)

• The specimen must meet criteria for load-bearing capacity, integrity, and insulation during the test.
• Failure is declared if any criteria are not met within the specified time.

Typical Fire Resistance Time Expression:

flowchart TD
    A[Test Specimen Preparation] --> B[Apply Standard Heating & Overpressure]
    B --> C[Monitor Load-bearing, Integrity, Insulation]
    C --> D{Criteria Met?}
    D -- Yes --> E[Record Fire Resistance Time]
    D -- No --> F[Test Failure]

Summary:
IS 3809 test procedure ensures specimens are tested under realistic mechanical strength and heating conditions, with fire resistance time recorded until failure of load-bearing, integrity, or insulation criteria.

IS 3809: Performance Criteria – Key Points

1. Performance Criteria (Clause 6)

• The duration for which the test specimen meets the specified requirements during heating is expressed in minutes (Clause 5.3.4).
• This duration indicates fire resistance or performance under standard heating.

2. Test Conditions (Clause 5.1 & 3.1)

• Tests are conducted under Standard Heating Conditions (Clause 3.1), simulating fire exposure.
• Heating follows a time-temperature curve as per IS 3809 or relevant fire test standards.

3. Mechanical Strength (Clause 4.3.2)

• For load-bearing elements, materials must have mechanical strength close to that expected in service.
• Ensures test results reflect real-life structural performance.

Summary Table: Key Parameters

Typical Fire Resistance Test Curve (Conceptual)

graph LR
A[Start Heating] --> B[Temperature rises as per standard curve]
B --> C{Specimen maintains integrity?}
C -- Yes --> D[Continue test]
C -- No --> E[Test ends; record duration]

Note: Refer to IS 3809 Annexures for detailed heating curves and specimen preparation.

IS 3809 - Test Report Requirements (Clause 7.1)

The test report must include:

• Testing Laboratory: Name and address.
• Sponsor: Name of the test sponsor.
• Test Date.
• Manufacturer & Trade Name of the product.
• Moisture Content of the specimen (Clause 4.3.1.2).
• Specimen Details: Construction, conditioning, physical & mechanical properties, and drawings.
• Fixing/Support Methods: How specimens were fixed or restrained.
• Load-bearing Specimens: Method of calculating test load and its relation to max permissible load.
• Asymmetrical Elements: Test direction and rationale.
• Observations: As per Clause 5.2.
• Test Results: As per Clause 6.1, including early termination details.

Additional Notes:

• Moisture content must be measured at testing time.
• Test reports validate fire resistance based on time the specimen meets criteria under fire exposure (Clause 1.2).
• Temperature measurements during testing follow the furnace temperature rise curve (Clause 1.5).

Furnace Temperature Rise Table (°C above ambient):

This ensures comprehensive documentation for fire resistance testing per IS 3809.