Prestressed concrete deflects quite a lot in my experience.
Im a master mason and build onto prestressed concrete beams and they bounce like a rubber ball when heavy loads are put on or even men walking over them. they will deflect but usually when the wieght is put on and stays on.
thats beams at 225x150 at 2 metres deflects 10mm.


Quote Originally Posted by irving2008 View Post
FYI 83kN/m means a 1m lintel supported under the ends can support a distributed load of 8.3 tonnes without cracking and deflecting less than a prescribed amount as set out in tables issued by the BSI and used by structural engineers & building control. For this purpose its massive overkill and, as has been said, you can't drill into it as if you damage one of the prestressed steel rods you can release some serious forces and I wouldn't want to be in the vicinity when you do!