Which of the following phenomena occurs due to shear strains modifying bending stresses in the flange and causes the sections to warp?

Explanation:

• Shear lag is a phenomenon that occurs in flanged sections like I-beams and box girders when shear strains modify the distribution of bending stresses.

• It results in non-uniform stress distribution across the flange, causing the edges of the flange to carry less stress than the central region.

• This uneven distribution of stress leads to warping of the section, which is a characteristic effect of shear lag.

 Additional Information

• Local buckling: This is related to instability in thin-walled sections under compressive loads, not shear strain modification.

• Web crippling: This is localized failure in the web of the beam due to high compressive loads, independent of shear lag.

• Torsional instability: This is the twisting failure of sections under torque, not related to shear strain modifications in flanges.