Castellated beams are created by cutting two standard beams or girders along their webs at a predetermined position, the high points of the webs are then welded together to form the castellated section, they are useful for their high strength to weight ratio resulting in a lighter section capable of greater spans. Castellated beams are also selected for their flexibility of shape and aesthetic qualities.
Like –I- sections, castellated beams are not resistant to high lateral loads or torsion, and they do not lend themselves to fixed end, moment resisting connections, or to high concentrated loads. Where these conditions apply, it may be necessary to ‘plug’ the castellated opening with an infill plate, or alternatively reinforce the opening with a flat plate ‘flange’.
They can be however, quite aesthetically pleasing, and are often employed by architects for long span and relatively lightly loaded applications. The castellation’s also provide access for pipes, electrical conduits, and other services that may be required.
Like Castellated Beams, Cellular beams are fabricated from 2 parts of the same section except the castellation’s are circular instead of hexagonal. The Cellular beam is more flexible than the traditional hexagonal castellated beam in that the beam depth may vary to match the exact structural and architectural requirements and is not dependent on the proportions of the original beam depth
There are guidelines for proportioning Cellular beams with regards to the cellular opening sizes relative to the section size which are indicated in the table:
Another reason for the current popularity of Cellular beams is that they may be shaped or bent into an arc before welding of the 2 halves.