Link points to Internet Archive / others. Not hosted by InfraLens. Details
IS 8745:1994 is the Indian Standard (BIS) for methods of presentation of data on physical and mechanical properties of timber. This standard provides guidelines for the uniform presentation of data on the physical and mechanical properties of timber. It specifies the list of properties, the necessary statistical calculations, and the standard format for reporting, ensuring consistency and comparability of data from different sources.
Methods of presentation of data on physical and mechanical properties of timber
Standard Practice for Establishing Clear Wood Strength Values
Covers procedures for deriving and presenting allowable design properties from tests on small clear specimens.
EN 384:2018CEN (European Committee for Standardization), Europe
HighCurrent
Structural timber — Determination of characteristic values of mechanical properties and density
Specifies methods to determine characteristic strength, stiffness, and density values from test data for design purposes.
AS/NZS 4063.2:2010Standards Australia/Standards New Zealand, Australia/New Zealand
HighCurrent
Characterisation of structural timber - Part 2: Determination of characteristic values
Provides methods for determining characteristic values for structural properties of timber from test data.
ISO 13061 (Series)ISO (International Organization for Standardization), International
LowCurrent
Physical and mechanical properties of wood — Test methods for small clear wood specimens
This series defines testing methods whose results are presented using IS 8745, but doesn't cover data presentation itself.
Key Differences
≠IS 8745 uses the 'Safe Working Stress' concept, an Allowable Stress Design (ASD) approach based on applying safety factors to average strength. Modern international standards like EN 384 use 'Characteristic Values' (typically a 5th percentile value), which are used in Limit State Design (LSD).
≠The Indian standard mandates a specific tabular format for presenting a comprehensive set of data (botanical, physical, mechanical). International equivalents like ASTM D2555 are more focused on the procedure for deriving design values rather than a fixed reporting format for all properties.
≠IS 8745 specifies data presentation for two conditions: 'green' and 'air-dry' (12% MC). While international standards also use these conditions, they often incorporate more complex and detailed procedures for adjusting properties across a range of moisture contents, particularly for deriving design values.
Key Similarities
≈Both IS 8745 and its international counterparts are concerned with the same core set of fundamental properties: density, static bending (MOR/MOE), compression (parallel/perpendicular), shear, and hardness.
≈All standards require reporting of key statistical information for each property, including the mean, standard deviation, and coefficient of variation, to quantify the timber's inherent variability.
≈IS 8745 relies on a separate testing standard (IS 2511). This mirrors the international approach, where data derivation standards (like ASTM D2555 or EN 384) rely on data generated from separate testing standards (like ASTM D143 or EN 408).
≈Moisture content is universally recognized as a critical variable. All standards require data to be presented or adjusted to a standard reference moisture content, commonly 12%, for the 'dry' condition.
Parameter Comparison
Parameter
IS Value
International
Source
Basis for Design Strength
Safe Working Stress (derived from average strength)
Characteristic Value (derived from 5th percentile)
EN 384
Standard Temperature for Testing/Conditioning
27 ± 2 °C (as per reference test standard IS 2511)
20 ± 3 °C (as per reference test standard ASTM D143)
ASTM D143
Reference Moisture Content for 'Dry' Timber
12% (referred to as 'Air-Dry')
12% (standard reference condition)
ASTM D2555
Hardness Test Tool Diameter
11.28 mm (as per IS 2511)
0.444 in (11.28 mm)
ASTM D143
Presentation Format
Mandatory tabular format (Table 1 and Table 2)
No mandated comprehensive report format; focuses on calculation output.
ASTM D2555
Static Bending Specimen Size
50 x 50 x 750 mm (as per IS 2511)
50 x 50 x 760 mm (2 x 2 x 30 in)
ASTM D143
⚠ Verify details from original standards before use
Key Values4
Quick Reference Values
Standard moisture content for reporting12 percent
Minimum number of observations for statistical validity5
Number of significant figures for Mean Value3
Number of significant figures for Standard Deviation2
Key Formulas
P12 = Pg [1 + α (12 - M)] — Adjustment of property to 12% moisture content
s = √[ (Σx² - (Σx)²/n) / (n-1) ] — Standard Deviation
Tables & Referenced Sections
Key Tables
Table 1 - Format for Presentation of Physical and Mechanical Properties of Timber
Key Clauses
Clause 4 - List of Properties to be Given
Clause 5 - Statistical Calculations
Clause 6 - Presentation of Data
Clause 7 - Adjustment of Strength Properties for Moisture Content