How do I reduce the moment of inertia in a concrete beam for the effects of cracking?
Select the beam(s), and then go to the Assign > Frame/Line > Frame Property Modifiers command. On the Analysis Property Modification Factors form, you may specify a multiplication factor equal to or greater than zero for any of the section properties – 0 meaning this quantity will have zero value, and 1 meaning this quantity will have full value. 1 is the default setting. For example, if you wanted to reduce the major moment of inertia of the frame by 50% for cracking, you would simply type .5 in Moment of inertia M3 axis field. In addition, the Frame Property Modifiers can also be specified using Define > Frame Sections using the ‘Set Modifiers’ button.
