The transformed-section method will be used to compute the centroid location and the moment of inertia of the composite shape about its centroid.
The flexure formula will be used to compute two values for the maximum bending moment:
• the moment that produces the allowable stress in the wood, and
• the moment that produces the allowable stress in the steel.
The lesser of these two values will control the design.
Once the controlling moment is determined, the maximum allowable uniformly distributed load on the 12-ft span can be computed.