Built-up Columns MCQ with answer and solution

Concept

Battens give less shear stiffness than lacing, so a battened column is weaker. Its effective length (slenderness ratio) is increased by 10%.

Formula

KL_battened = 1.1 × KL

Step-by-step solution

1. A battened column is a built-up column with main members joined by battens (plates). 2. Battens resist shear less well than lacing, so shear deformation is more. 3. This lowers the buckling strength of the column. 4. To allow for this, IS 800 increases the effective length (or effective slenderness ratio) by 10%. 5. So the answer is option (B).

Explanation

Battens connect the column parts less rigidly than lacing. So the column bends more and can buckle at a lower load. To be safe, the code increases the effective length by 10%.

Why the other options are wrong

(A) and (C) are wrong because decreasing the length would overestimate strength and be unsafe. (D) 20% is not the code value; the code uses a 10% increase.

Shortcut

Laced column: increase by 5%. Battened column: increase by 10%.

Common mistake

Mixing up the lacing value (5%) and the batten value (10%), or thinking the length should be reduced.