Primary Beam & Secondary Beam

If you make the secondary beam connection too strong the primary beam will be destroyed.     

• The primary beam behaves as a fixed beam becaause the rebars go deep inside the column which gives enough anchorage and can resist negative bending moments at the ends easily.

• If anchorage bars cannot be provided then the ends wouldnt beableto resist negative the negative moment

  

  • this happens in the case of the secondary beam as there is no space ot provide anchorage bars deep inside the primary beam

  • the secondary beam needs to act as a purely supporting beam allowing it to bend

  • This is to not cause torsion to the primary beams (allows moment release), as primary beams should only be subjected to shear force.