ABSTRACT
L-shaped edge beams support non-symmetrical floor loads. The part of the beam supporting the floor is called the “boot”, and the main web is the “upstand”. The design of beams is based on ordinary reinforced or prestressed concrete principles for specified loads and support conditions. A predetermined set of standardised beam sections is selected by a manufacturer according to the requirements of most building structures. Flexural and shear reinforcements are computed for the optimum reinforcement quantities appropriate to each size of the beam. The effects of the relative shrinkage of the precast beam to the in situ concrete must also be considered in deflection calculations, particularly in the case of plank floors where the volume of wet concrete is large. In many cases due to the high degree of prestress in beams and the large spans over which they operate, designed shear reinforcement is often quite small and the nominal area suffices.
