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IS 8147:1976 is the Indian Standard (BIS) for the use of aluminium alloys in structures. This code of practice provides guidelines for the structural use of aluminium alloys based on the Working Stress Method (WSM). It covers material specifications, general design requirements, design of members under various loads (tension, compression, bending), and provisions for connections, fabrication, and erection.
Code of Practice for the use of Aluminium Alloys in Structures
Overview
Status
Current
Usage level
Specialized
Domain
Structural Engineering — Structural Engineering and Structural Sections
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! This 1976 version uses the Working Stress Method (WSM). It has been superseded by IS 8147:2023, which adopts the Limit State Method (LSM), making the design philosophy consistent with modern steel (IS 800) and concrete (IS 456) codes.
! Aluminium's Modulus of Elasticity is approximately one-third that of steel, resulting in larger deflections. Serviceability and deflection checks are critical.
! The mechanical properties of aluminium are highly dependent on the alloy and its temper condition (e.g., 6061-T6). Careful selection based on Table 1 is essential.
Provides both Allowable Stress Design (ASD) and LRFD rules, with its ASD part being a modern evolution of the principles in IS 8147.
BS EN 1999-1-1:2007CEN (European Committee for Standardization), Europe
MediumCurrent
Eurocode 9: Design of aluminium structures - Part 1-1: General structural rules
Covers the same domain but uses a different design philosophy (Limit State Design) with partial safety factors.
AS/NZS 1664.2:1997Standards Australia / Standards New Zealand
HighCurrent
Aluminium structures - Part 2: Allowable stress design
Directly provides a framework for Allowable Stress Design, which is conceptually identical to the Working Stress method of IS 8147.
BS 8118-1:1991BSI (British Standards Institution), United Kingdom
MediumWithdrawn
Structural use of aluminium - Part 1: Code of practice for design
A predecessor to the Eurocode, it represents the shift from working stress to limit state design in British practice.
Key Differences
≠IS 8147 uses the Working Stress Design (WSD) method, where a single factor of safety is applied to the ultimate material strength to get a 'permissible stress'. Modern codes like EN 1999 use Limit State Design (LSD), which applies separate partial safety factors to loads and material resistances.
≠The Indian standard references older IS alloy designations (e.g., HE30-WP). International standards use the 4-digit system (e.g., 6061-T6), which is now globally prevalent and offers more detailed temper specifications.
≠Rules for stability and buckling in IS 8147 are simpler and based on empirical formulae from the era. Modern codes like AA ADM and EN 1999 provide much more extensive and refined analysis for local, distortional, and flexural-torsional buckling, especially for thin-walled sections.
≠IS 8147 provides a single set of permissible stresses for a given alloy and condition. Modern codes provide different resistance calculations for various failure modes (e.g., yielding, rupture, buckling) and use complex interaction formulae, offering a more nuanced design.
Key Similarities
≈All standards are fundamentally based on the principles of structural mechanics to ensure equilibrium, stability, and strength under load.
≈All codes recognize the significant strength reduction in the Heat-Affected Zone (HAZ) of welded heat-treatable aluminium alloys and mandate specific design considerations to account for it.
≈The fundamental physical properties of aluminium, such as the Modulus of Elasticity (E), Shear Modulus (G), and Coefficient of Thermal Expansion, are consistent across all standards for similar alloys.
≈The scope of all standards includes providing design guidance for standard structural components like tension and compression members, beams, and their connections (bolted, riveted, and welded).
Parameter Comparison
Parameter
IS Value
International
Source
Design Methodology
Working Stress Design (Permissible Stress)
Limit State Design (LSD/LRFD) and Allowable Stress Design (ASD)
EN 1999-1-1 / AA ADM 2020
Factor of Safety on Ultimate Strength (Tension)
1.95 (for rivets, bolts) to 2.1 (for parent material)
1.95 (for building structures)
AA ADM 2020 (ASD)
Permissible Axial Tensile Stress on Net Area (Alloy 6061-T6 / HE30-WP)
11.8 kgf/mm² (115.7 MPa)
146.0 MPa, calculated as Min(F_tu/1.95, F_ty/1.65)
AA ADM 2020 (ASD)
Partial Safety Factor for Material Resistance (γM)
Not used; embedded in the single overall Factor of Safety.
The code is based on the Working Stress Method (WSM) of design (Clause 3.2).
What is the value for Modulus of Elasticity (E) of aluminium used in this code?+
A value of 0.7 x 10^5 N/mm² (or 70 GPa) is specified for design purposes (Clause 3.3.1).
What is the factor of safety for a member in pure tension?+
The permissible axial tensile stress is determined by applying a factor of safety of 1.95 to the specified minimum ultimate tensile stress of the alloy (Clause 4.2.1).
Does the code cover welded connections?+
Yes, Section 5.4 provides guidelines for the design of welded connections, including permissible stresses for butt and fillet welds.