Increasing The Depth Of Beam. Where beams are required to be of greater depth than can be conveniently obtained by a single beam, two beams are laid edge to edge, and secured in various ways. Fig. 327 illustrates one method known as cogging, caulking or keying. A series of grooves, as a a, fig. 328 - which is a plan of the upper edge of the lower beam b b in fig. 327 - are cut in the edges of the beam, at equal distances, as shown, and keys or cogs c c driven into the grooves. These prevent all lateral or side movements of the two beams a a, b b upon one another; and the beams are secured and kept together vertically by the screw bolts d d. In place of these, straps, as e e, are sometimes employed. These are also sometimes used in place of bolts in scarfing of beams, already illustrated, and also at a a, fig. 329 (A). Other methods of increasing the depth of beams are illustrated in figs. 329, 330, 331. In figs. 329, 330, A is elevation and vertical sections, B plan. Fig. 331 is used in bridge work.

Fig. 327.

Fig, 328.

Fig. 329.

Fig. 330.

Fig. 331.