LIMIT STATE OF COLLAPSE IN SHEAR - - The shear stress develops in beam due to longitudinal- transverse displacement. Shear stress distributions (a) Ultimate stage - doubly reinforced concrete singly reinforced beam (b) Elastic stage - shear in RC beam resisted by following sections - 1. Dowel action of main steel 2. Aggregate interlocking 3. Uncracked sections Critical section for shear - (a) When supports are in Compression - - In this case , critical section occurs at 'd' distance from face of support. Supports in compression (b) When supports are in tension then critical section occurs at face of support. supports are in tension Nominal shear stress - τ = V u / bd - If depth is varrying - τ = ( V u +,- M/d • tanβ ) / bd τ = Nominal shear stress , Vu = Shear force, b= width , d = dept