Using different levels of bolt pretension in a single connection is not permitted in the Steel Joints add-on, as it can lead to uneven load distribution among the bolts. As a result, each bolt type should be evaluated in separate checks. Otherwise, the connection may be susceptible to a "zipper effect", similar to issues seen in joints that are both bolted and welded.
If both pretensioned and snug-tightened bolts are present in the connection, it is recommended to first analyze the joint considering only the pretensioned bolts (Model A). If the connection fails, a second analysis can be performed with all bolts treated as snug-tightened (Model B). In this case, any displacement due to slip between the connected parts must be accounted for.
