Beams are the main horizontal load-bearing elements of frame buildings and of structures such as bridges. They are primarily designed to carry bending and shear, sometimes in conjunction with limited torsion (twisting load).
They may be cast in situ or be precast. In most cases the cross-sections are rectangular although Tee sections are used to increase the structural efficiency. Other shapes may be used, for example projecting lintels to support brickwork or secondary members.