Question

M60 structural steel tube has a radius of gyration 20mm. The unbraced length up to which the tube can be used as a compression member is .........

• A. 3.6 m
• B. 5.0 m
• C. 6.0 m
• D. 7.2 m

Hint:

The unbraced length for a compression member can be calculated by multiplying the radius of gyration by the effective length factor. Ensure the units are consistent for accurate calculation.

Answer 1

The Correct Option is A

The unbraced length of a compression member is determined using the radius of gyration and the effective length factor. For structural steel members, the unbraced length \( L_{u} \) can be found using the formula: \[ L_u = k \cdot r \] where:
- \( k \) is the effective length factor (usually 1.0 for a simply supported compression member),
- \( r \) is the radius of gyration.
Given that the radius of gyration \( r = 20 \, \text{mm} = 0.02 \, \text{m} \), and for M60 steel the value of \( k \) is typically 1.8, the unbraced length \( L_u \) is: \[ L_u = 1.8 \cdot 0.02 = 3.6 \, \text{m} \] Thus, the unbraced length is 3.6 meters.