What design philosophy does IS 8147:1976 follow?

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.

IS 8147

: 1976

Code of Practice for the use of Aluminium Alloys in Structures

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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

Quick Reference Values

Modulus of Elasticity, E0.7 x 10^5 N/mm²

Poisson's Ratio, v0.33

Modulus of Rigidity, G0.26 x 10^5 N/mm²

Coefficient of Linear Thermal Expansion23 x 10^-6 per °C

Unit Mass of Aluminium2700 kg/m³

Factor of Safety on Ultimate Stress (Tension)1.95

Key Formulas

Pc = 125 - 0.75 * (l/r) — Permissible compressive stress for Alloy H20-WP (6351S-T6) for l/r < 67

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 It has been superseded by IS 8147:2023, which adopts the Limit State Method (LSM), making the design philosophy consistent with modern steel (IS 800) and concrete (IS 456) codes.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.