The allowable shear stress in the web of mild steel beams decreases with (where ‘h’ is height and ‘t’ is thickness) A. Decrease in h/t ratio B. Increase in h/t ratio C. Decrease in thickness D. Increase in height

The correct answer is: A. Decrease in h/t ratio.

The allowable shear stress in the web of mild steel beams decreases with a decrease in the h/t ratio. This is because the web is subjected to shear stresses, which are proportional to the h/t ratio. As the h/t ratio decreases, the shear stresses increase, and the allowable shear stress decreases.

The h/t ratio is the ratio of the height of the beam to the thickness of the web. The h/t ratio is a measure of the slenderness of the beam. A slender beam is a beam that is long and thin. A slender beam is more likely to buckle than a short, thick beam.

The allowable shear stress is the maximum shear stress that a beam can withstand without buckling. The allowable shear stress is a function of the h/t ratio. The allowable shear stress decreases as the h/t ratio increases.

The following are the explanations for each option:

• Option A: Decrease in h/t ratio. This is the correct answer. The allowable shear stress in the web of mild steel beams decreases with a decrease in the h/t ratio.
• Option B: Increase in h/t ratio. This is the incorrect answer. The allowable shear stress in the web of mild steel beams decreases with a decrease in the h/t ratio.
• Option C: Decrease in thickness. This is the incorrect answer. The allowable shear stress in the web of mild steel beams is not affected by the thickness of the web.
• Option D: Increase in height. This is the incorrect answer. The allowable shear stress in the web of mild steel beams is not affected by the height of the beam.