The beams and bars are holding the weight of the upper floors and there is tremendous weight on the beams and bars. The weight is acting on the downward direction according to laws of gravitation.
This tremendous gravitational force is working on the person working under the beam or bar. Because of this the person feels uneasy, work is not done properly and it leads to failure in work.
If beam is on top of your bed and part of the body which comes exactly under the beam is affected and there are innumerable example of diseases pertaining to those parts.
In reality the main entrance of the building should not be taken under the beam.
The students should not study under the beam.
If the main entrance door is not proper place a pyramid yantra in the centre of the door, above the frame and each side of the frame.