I am trying to model members with varying cross section. How can I do that ?
Case 1 If the sections are tapered wide flanges or tubes ( circular/square/other polygonal shapes), you can model the beam/column as a single member and assign a Tapered I or Tapered Tube property. Go to the General > Property page and choose either of these two options shown below
Case 2 In case of other types of cross section, you can split the beam/column into multiple segments and assign the General Section property to each segment ( also marked in the above picture ). For General Sections, you need to calculate the property for each segment and assign these properties appropriately.
The above solution would also apply for modeling beams with openings.
While modeling beams with openings, if the sections in which holes are to be cut, are standard sections, one may use segments as mentioned above but instead of specifying the properties through the General option, one can assign the standard section from the database to all segments. Subsequently one may apply the Property Reduction Factors ( available within Spec ) to the segments where the openings exist.