ABSTRACT
Beams are the main horizontal load carrying members in skeletal structures. They are, by definition, relatively small prismatic sections of large flexural and shear capacity. In a precast concrete structure they must at some point in time support the self-weight of the floor slabs alone and should therefore be capable of resisting all of the possible load combinations that precast construction brings - for example, torsion will be present if, in the temporary construction stage, the floor units are all positioned on one side of the beam. This must be allowed for both in the design of the beam and at the end connections to the column. Internal beams are usually symmetrically loaded, that is floor slabs are on both sides of the beam, and therefore the beam is symmetrical in cross-section. Internal beams may be designed compositely, with the floor slab acting as a compression flange.
