The shear lag effect in beam flanges are disregarded when the outstand of the beam flange is less than or equal to

Explanation:

IS 800(Page number 53)

The shear lag effects in flanges may be disregarded provided:

a) For outstand elements (supported along one edge), b_O ≤ L_O/20;

and b) For internal elements (supported along two edges), b_i ≤ L_O/ 10.

where L_O = length between points of zero moment (inflection) in the span, b_O = width of the flange with outstand, and b_i = width of the flange as an internal element..

Additional InformationShear Lag  

Shear lag is a structural effect where not all parts of a cross-section effectively resist stress, especially in tension or bending. This leads to non-uniform stress distribution, typically in wide flanges or tension plates.

• It occurs because stresses don’t distribute instantly across the entire section.

• Areas far from the point of load application (e.g., edges of wide flanges) respond with a delay.

• Shear lag is accounted for by reducing effective width or using effective area in calculations.

• Helps prevent overestimation of capacity, especially in critical structures.