Post+and+Lintel

Post-and-lintel, in construction, is a system in which two upright members, the posts, hold up a third member, the lintel, laid horizontally across their top surfaces.
=== The lintel must bear loads that rest on it as well as its own load without deforming or breaking. Brick or stone, weak in tensile strength (inelastic and brittle), can provide only a short lintel; steel can be used for long lintels. Masonry lintels, depending on the cohesiveness of mortar, are especially weak; therefore, in masonry construction, lintels of monolithic (single slab) stone, wood, and stronger materials are used. === === The posts must support the lintel and its loads without crushing or buckling. Post material must be especially strong in compression. Stone has this property and is more versatile in its use as a post than as a lintel. Under heavy loads, stone is superior to wood but not to iron, steel, or reinforced concrete. Masonry posts, including those of brick, may be highly efficient, because loads compress the joints and add to their cohesiveness. ===