Support Displacement 2

Your talking about gap elements and no, STAAD does not have them. I suppose you could do a poor man's gap element by not supporting the node in question and checking it's displacement. If it is larger than the physical gap you have, make it a support and give it an enforced displacement equal to your gap.

If you have lot's of loads and/or load combinations you can see where this could get pretty hairy if for some cases the gap closed and some cases it doesn't. That would require separate runs for closed and not closed cases.

I'm not sure what you mean by "How can I model it without imposing a load on the member?" The enforced support case by itself would impose a load on the attached members. However, you would only use the enforced displacement if the beam would have deflected that far anyway. And it has to be combined with your applied loads.

You know what, maybe you better get a program that has gap elements. I know SAP 2000 does.

I totally agree with you regarding SAP 2000. STAAD is not what it used to be.

Thanks

If I understand your problem correctly, I think that you may want to check out the STAAD online manual "5.32.8 Support Joint Displacement Specification". There are 2 ways of using this command, a displacement mode and a load mode.