Shear Stress Distribution

What am I seeing?

• Transverse shear stress follows τ = VQ/(Ib): it peaks at the neutral axis and vanishes at free edges.
• In an I-section the web carries almost all the shear; the profile jumps where the width changes.
• For a rectangle the peak is exactly 1.5 times the average V/A, and 4/3 for a solid circle.
• Q is the first moment of the area above the level you are checking, taken about the neutral axis.