What is the difference between Part 1 and Part 2 of IS 4924?

Part 1 covers destructive testing to evaluate the ultimate load capacity, while Part 2 covers proof testing where the truss is loaded to a specified non-destructive limit to check serviceability.

How should the load be applied during the proof test?

Load should be applied at panel points (nodes) incrementally, often using suspended dead weights (like sandbags) or a calibrated hydraulic jack system.

What is the main acceptance criteria for this test?

The truss must sustain the proof load for 24 hours without showing signs of failure and must exhibit a specified minimum deflection recovery 24 hours after the load is removed.

IS 4924

: 2000

Method of Test for Nail-jointed Timber Trusses, Part II: Proof Test

CurrentSpecializedTesting MethodStructural Engineering · Building Construction Practices incl. Painting, Varnishing

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This standard specifies the method for proof testing of nail-jointed timber trusses. It details the setup, incremental loading procedures, deflection monitoring, and acceptance criteria to verify structural adequacy without causing destructive failure.

Method of Test for Nail-jointed Timber Trusses, Part II: Proof Test

Quick Reference Values

Proof load duration24 hours

Unloading recovery time24 hours

Deflection measurement least count0.01 mm

Practical Notes

Lateral restraints simulating actual roof purlins must be provided during the test, but they should not restrict the vertical movement of the truss.

Loading should be applied symmetrically and gradually at the node points to avoid eccentric stresses or sudden local failures.

Temperature and moisture content of the timber should be recorded at the time of testing as they significantly affect deflection characteristics.