Working Stress Method MCQ with answer and solution

Concept

Modular Ratio

Formula

m = 280 / (3 × σcbc)

Step-by-step solution

1. Identify the permissible compressive stress in flexural compression (σcbc). 2. Substitute the value of σcbc into the modular ratio formula: m = 280 / (3 \* σcbc).

Explanation

According to IS 456 (Working Stress Method), the modular ratio (m) is calculated using the formula m = 280 / (3 × σcbc), which partially takes into account long-term effects like creep in concrete under flexural compression.

Shortcut

Remember "280 over 3": Modular ratio m = 280 / (3 × σcbc). Associate the 3 with the 3 letters in "cbc".

Common mistake

Students often select option A (280 / σcbc) by forgetting the factor of 3 in the denominator, confusing the empirical formula for modular ratio with a direct ratio.