Principal stresses in a tee beam

At D, which is located 2.96 in. below the neutral axis, the bending stress is:


σx=-MyI=--25 kip-ft-2.96 in.12 in./ft70.55 in.4                 =-12.59 ksi                 =    12.59 ksi (compression)

The normal stresses produced by a bending moment is computed from the flexure formula:

σx=-MyI

where y= distance measured from neutral surface, M= bending moment, and I= moment of inertia about the centroidal axis.