The RM Bridge Recalculation Window at the Extended Settings in the Special Settings has one set that allows the user to create additional definitions for the Shear Lag of the specified elements: Use Shear Lag Defs for Stiffness reduct. - Use Shear lag Definitions for Stiffness reductions.

   

There are two possibilities for setting the program calculations about the element's shear lag:

• If unchecked, the program Defaults uses shear lag definitions only to calculate the stresses due to bending. These shear Lag areas are ignored for bending moments of inertia, reducing the CS values.
• If checked or toggled, the shear lag definitions are used to reduce the element stiffness, the normal force, and bending, as well as to calculate the stresses in the stress points only for bending.

More technical information is available at the link below, which refers to the specific FAQ document about Shear Lag.

https://bentleysystems.service-now.com/community?id=kb_article_view&sysparm_article=KB0112484