Section stiffness could be reduced or manipulated using the SectionManager under Properties tab.From Main Menu select
Properties > Section Manager > Stiffness…To model a section as cracked and to arbitrarily reduce its load carrying capacity, its stiffness could be reduced, by applying Stiffness reduction factors.
Select the section whose capacity has to be modified from the ‘Section Manager’ window and input the appropriate reduction factors.
As boxed out in the image above, suitable modification factor could be applied for changing the cross sectional area,
shear area, torsion moment of inertia or weight for any section at desired location and in desired direction.
For example, say to reduce the stiffness of the section on cracking, the moment of inertia about local y direction could be reduced by a factor.
This factor could be assigned to particular boundary groups as well in case construction stage or boundary change assignment needs to be performed.
The scale factors for I and J end are kept same by default. However, these can be different in case of a tapered section.