adding bolts

The beam element has no geometry to attach the bolt element to.  The bolt element needs a circular edge which will have rigid element connection to the rigid link (which represents the bolt) attaching to the other part.

Model your 'beam' as a solid and it should work fine.  CAUTION: heed the warning and ignore stress w/in a diameter of the bolt connection.  (You could hand-calculate those.)

Arif, you need to right click on the beam body and select 'Treat as solid'.

See below:

Do it for all beams. Then you can create your bolt connector.