What is a 'Flat Plate' in structural terminology?

In structural terminology, a 'Flat Plate' refers to a two-way slab that is supported directly on a column grid without the use of beams. This means that the load from the slab is transferred directly to the columns, allowing for a more simplified construction method and greater flexibility in terms of the layout of the space above.

Flat plates are useful in situations where architectural aesthetics are important since the absence of beams creates a clean ceiling line. Additionally, this design can lead to potential savings in material and labor costs. The direct support from columns allows for more efficient load distribution.

In contrast, a one-way slab supported by two beams focuses on load transfer in a single direction, limiting its flexibility. A two-way slab with beams involves beams running between columns, adding complexity and reducing the height available for the slab. The option describing a slab made of lightweight materials does not specifically refer to the structural design but rather to the materials used, which is not the defining characteristic of a flat plate.