Link points to Internet Archive / others. Not hosted by InfraLens. Details
IS 4924:2000 (Part 1) is the Indian Standard (BIS) for method of test for nail-jointed timber trusses, part i: destructive test. This standard establishes the procedure for conducting destructive tests on nail-jointed timber trusses to determine their ultimate load-carrying capacity, deflection characteristics, and modes of failure.
Method of test for nail-jointed timber trusses, Part I: Destructive test
Overview
Status
Current
Usage level
Specialized
Domain
Structural Engineering — Building Construction Practices incl. Painting, Varnishing
National Design Standard for Metal Plate Connected Wood Truss Construction
Defines quality criteria and test procedures for full-scale trusses, focusing on metal plate connectors.
BS 5268-3:1998British Standards Institution (BSI), UK
HighWithdrawn
Structural use of timber. Code of practice for trussed rafter roofs
Provided detailed prototype testing procedures for trussed rafters very similar to the IS code's philosophy.
AS 1720.1-2010Standards Australia, Australia
MediumCurrent
Timber structures, Part 1: Design methods
Includes a section on structural testing (proof and prototype) as a method for design verification, but is not a dedicated test method standard.
EN 1995-1-1:2004CEN (European Committee for Standardization), Europe
MediumCurrent
Eurocode 5: Design of timber structures - Part 1-1: General - Common rules and rules for buildings
Annex A outlines principles for testing to determine structural properties, a more general approach than a specific prototype test method.
Key Differences
≠IS 4924 is exclusively for nail-jointed trusses, whereas modern international standards like ANSI/TPI 1 are primarily focused on trusses assembled with punched metal plate connectors.
≠The Indian Standard mandates a 24-hour sustained load test at full design load to assess creep and long-term performance, a significantly longer duration than the short-term (e.g., 10-60 minutes) tests specified in standards like ANSI/TPI 1.
≠The ultimate load factor in IS 4924 is specified as 1.0 Dead Load + 2.25 Live Load, which differs from the factor of 2.0 times the Total Design Load (Dead + Live) required by ANSI/TPI 1.
≠IS 4924 specifies a minimum deflection recovery of 80% within 24 hours after unloading, while ANSI/TPI 1 requires a 90% recovery after a one-hour test, reflecting different criteria for joint elasticity.
Key Similarities
≈All standards are based on the fundamental concept of testing a full-scale prototype truss to verify design calculations and manufacturing quality.
≈The test setup consistently involves applying loads vertically to the top chord at panel points, simulating the load path from roofing materials and external forces (like snow or wind).
≈Measurement of vertical deflection at mid-span and other critical locations is a common requirement to ensure the truss meets serviceability limits and does not sag excessively.
≈A common procedure is to apply a small preload (e.g., 10-20% of design load) and then remove it before the official test starts, in order to settle the truss and the testing apparatus.
≈The test protocol in all cases includes loading the truss incrementally until failure to determine its ultimate strength and failure mode.
Parameter Comparison
Parameter
IS Value
International
Source
Sustained Load Test Duration
24 hours at full design load.
10 minutes at total design load for deflection check.
ANSI/TPI 1-2014
Ultimate Load Capacity Requirement
Must sustain ≥ (1.0 DL + 2.25 LL).
Must sustain ≥ 2.0 × (DL + LL) for 5 minutes.
ANSI/TPI 1-2014
Maximum Deflection Limit (at design load)
Span / 240 (measured after 24 hours).
Typically Span / 240 for total load (measured over short term).
ANSI/TPI 1-2014
Deflection Recovery after Unloading
At least 80% recovery within 24 hours.
At least 90% recovery after 1 hour load test.
ANSI/TPI 1-2014
Number of Trusses for Prototype Test
One truss.
Two trusses tested as a pair.
BS 5268-3:1998 (Withdrawn)
Rate of Loading
Applied in not less than 8 equal increments.
Applied at a uniform rate to reach target load in a specified time.
ANSI/TPI 1-2014
Pre-loading
Apply (DL + 10% LL), hold for 5 minutes, then release.
An initial load cycle to Total Design Load (TDL) is applied and removed.
ANSI/TPI 1-2014
⚠ Verify details from original standards before use
Key Values3
Quick Reference Values
Deflection measurement accuracy0.01 mm
Moisture content reading accuracy1 percent
Typical load incrementFractional increments of the design load (e.g., 20% to 25%)
Tables & Referenced Sections
Key Tables
No tables data
Key Clauses
Clause 3 - Test Specimen
Clause 4 - Apparatus and Testing Arrangement
Clause 5 - Procedure for Loading
Clause 6 - Recording of Deflection and Observation of Failure