Beam

Bar laid in a horizontal position upon two supports and carrying weights which cause deflection and stre . A load concentrated at the middle of a beam causes twice as much stre as the same load spread uniformly over it. At the middle of a beam horizontal tensile stre es occur on the lower side and compre ive stre es on the upper side. For a beam of rectangular section these are equal, and they may be computed from the formula, 3 W1 S= 2 b d29 in which W is the load at the middle of the beam, 1 its length, bits breadth, and dits depth. For example, a wooden beam 120 in. long, 2 in. wide, and 8 in. deep, loaded with 640 pounds at the middle, has there a stre S equal to 900 pounds per sq. in. A bar resting on more than two supports is called a continuous beam, and one projecting from a wall a cantilever beam. The theory of beams was first discu ed by Galileo in 1638. Beam. Pyrus Aria . Small tree of the Apple family, native of Europe.