The shear stress in a symmetrical ‘I’ section of a beam is maximum at 

Explanation

Shear stress at any point in a cross-section is given by the following formula:

\({\rm{f}} = \frac{{{\rm{VQ}}}}{{{\rm{Ib}}}}\)

Where,

f = shear stress

Q = First moment of area about the neutral axis of the area above the point where we want to calculate the shear stress

Q = A × y

V is Shear force

y is the centroid of the area above the point where we want to calculate the shear stress measured from the neutral axis.

A = Cross-sectional area above the point where we want to calculate the shear stress

I = moment of inertia about the neutral axis

b= width of the section where shear stress is to be calculated.

Shear stress is zero at extreme fibres 

For a symmetric ‘I’ section, the intensity of shear stress is maximum at the centroid of the section which is neutral axis as shown in the figure.