ANS:B -

When longitudinally spanning stairs are casted along with their landings, the maximum bending moment per meter width is taken as: wL^2/12​ Where:

• w = Uniformly distributed load on the stair tread and landing (including self-weight), usually expressed in force per unit length (e.g., kN/m, kgf/m, or lbs/ft).
• L = Length of the span (length of the stair tread and landing in the direction of the span).

This formula represents the maximum bending moment per unit width of the stair tread and landing. It is derived from the bending moment equation for a simply supported beam subjected to a uniformly distributed load. Understanding and calculating the maximum bending moment is crucial for designing and reinforcing the structural elements of stairs to ensure they can safely support the applied loads without experiencing excessive deflection or failure.