Similar to joining walls and floors you can join beams in Etabs on upload. Konstru joins frames (bemas and columns) by groups. Add elements you want to join into a group starting with KonstruJoin eg. "KonstruJoin Beams A" - once you check the join elements option in the Konstru dialog those frames will be joined into one single frame:
Konstru will build a frame across the input geometry using start and endpoint from maximum extends of all elements within the group. This means both elements don't have to be connected necessarily.
On Upload, when applying properties, Konstru goes by majority. So if 3 elements have section A and 2 section B, Konstru will apply section A to the overall joined element. When downloading Konstru applies properties of the single element to all 5 children the same.