Beam:
A beam is a horizontal linear element that goes across, or spans, an opening. A beam is supported at both ends by walls or columns.
Beams are such essential structural components that you can find them in almost every building, from small houses to huge skyscrapers and bridges, although you can't always see them because they're often covered up by the finish material on interior and exterior walls. When beams are used with columns as the main support for a building, the structure is referred to as post and beam. (In this terminology, "post" means an undecorated column used for support, not decoration.) Stonehenge (top left slide), one of the oldest human constructions known, was made using post and beam construction.
The weight of the load presses down along the entire length of a beam, causing it to bend. In a rigid material, this bend is so slight that you can't see it, but if you imagine a flexible beam, you can see that it would bend the most in the middle. If you exaggerate this bend, you'll see that the lower side gets stretched (is "in tension") and the upper side gets shorter (is compressed). (Slide, not shown here.) A beam, then, has to be strong in both tension and compression to handle these two kinds of forces. Wood, steel, and reinforced concrete, all of which are strong in both tension and compression, are the usual choices for beams.
A lintel is a beam used to span the opening in a wall left for a window or a doorway. The lintel supports the wall that goes above the opening. Here's an old wall in Venice (bottom left slide). Can you find three lintels, two of wood and one of stone? (Hint: The bricks have filled in what was originally a window.)
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AIE is a program of the AIA Philadelphia Chapter
Structure in Architecture and the AIE Web site: Copyright 1999 Foundation for Architecture
AIE is a program of the AIA Philadelphia Chapter
Structure in Architecture and the AIE Web site: Copyright 1999 Foundation for Architecture