I was working on a question where I had to find the maximum shear stress in a I-beam due to a shear force applied on it. Heres the question : An I girder 600 mm x 300 mm has flanges 25 mm thick and a web 13 mm thick. Find the maximum shear stress due to a shear force of 500 kN and compare this value with the common approximation. For this my lecturer used this equation : τ = F/Ib ∫ y1600/2 y dA and he took y1=0 Can someone please explain how to use this equation because I dont understand the integration part from ybarA to 600/2. I dont understand how he got the limits of the integration. Thanks!