Shear lag in R.C Beams

[Ahmed A. Alamin]

Hello engineers i came across the concept of effective width in R.C beams, i found that the concept behind it is to account for shear lag and concequently the unevem stress distribution though i could not fully grasp how exactly this happens. Could anyone explain this more to me?

 

[r13]

Are you talking about effective width for T beam?

 

[HTURKAK]

Consider T beams having large flange width.The bending compressive stress is not uniform over its width and has the maximum value near the web and reduces to minimum at midpoints between the webs .The reason is the shear lag effect ,that is the shearing deformation of the flange relieves some compression stress at away from the web.

The following snap is from the book : Reinforced Concrete Mechanics and Design (James K. Wight)