According to IS:800 (1962 era) guidance, what value is commonly adopted for the coefficient of linear thermal expansion of steel per degree Celsius (per unit length)?

Introduction / Context:
Thermal expansion influences stresses in restrained members, joint detailing, and expansion joint spacing. A standard coefficient allows consistent temperature-effect calculations in steel structures.

Given Data / Assumptions:

• Structural steel within normal service temperatures.
• Linear coefficient assumed constant over the range for design purposes.

Concept / Approach:
The coefficient of linear thermal expansion, often denoted alpha, gives the change in length per unit length per degree Celsius. For structural steels, a typical value used in legacy Indian standards and many textbooks is about 12 × 10^-6 per °C, written as 0.000012 per °C per unit length.

Step-by-Step Solution:

Verification / Alternative check:
Compare with common international references (≈ 11–13 × 10^-6 per °C); 12 × 10^-6 per °C sits within the typical range.

Why Other Options Are Wrong:
Values like 0.000008 or 0.000016 are outside typical structural steel design assumptions in many codes and would misestimate movements.

Common Pitfalls:
Mixing per °C with per °F; ignoring temperature gradients via composite action; neglecting restraint leading to unintended thermal stresses.

Final Answer:
0.000012