In case of plastic design, the calculated maximum shear capacity of a beam as per IS : 800 shall be (where, Aw = effective cross-sectional area resisting shear, fy = yield stress of the steel) A. 0.55 Aw fy B. 0.65 Aw fy C. 0.75 Aw fy D. 0.85 Aw fy

The correct answer is: D. 0.85 Aw fy

The maximum shear capacity of a beam as per IS : 800 is given by the following equation:

$V_{max} = 0.85Awfy$

where:

• $V_{max}$ is the maximum shear capacity of the beam
• $Aw$ is the effective cross-sectional area resisting shear
• $fy$ is the yield stress of the steel

The value of 0.85 is a factor of safety that is used to account for the uncertainty in the material properties and the loading conditions.

The other options are incorrect because they do not take into account the factor of safety.