to transfer the tension in diagonal
planes, and failure results. For a beam loaded with a single load, _W_,
the failure would probably be in a diagonal line near the point of
application, while in a uniformly loaded beam, it would probably occur
in a diagonal line near the support, where the shear is greatest.

It is evident that the introduction of vertical stirrups, as at _b_, or
the more rational inclined stirrups, as at _c_, influences the action of
the shearing forces as indicated, the intensity of stress at the point
of connection of the stirrups being high. It is advisable to space the
stirrups moderately close, in order to reduce this intensity to
reasonable limits. If the assumption is made that the diagonal
compression in the concrete acts in a plane inclined at 45 deg., then the
tension in the vertical stirrups will be the vertical shear times the
horizontal spacing of the stirrups divided by the distance, center to
center, of the top and bottom flanges of the beam. If the stirrups are
inclined at 45 deg., the stress in them would be 0.7 the stress in vertical
stirrups with the same spacing. Bending up bottom rods sharply, in order
to dispense with suspenders, is bad practice; the writer has observed
diagonal cracks in the beams of a well-known building in New York City,
which are due to this cause.

[Illustration: FIG. 4.]

In several structures which the writer has recently designed, he has
been able to dispense with stirrups, and, at the same time, effect a
saving in concrete, by bending some of the bottom reinforcing rods and
placing a bar between them and those which remain horizontal. A typical
detail is shown in Fig. 4. The bend occurs at a point where the vertical
component of the stress in the bent bars equals the vertical shear, and
sufficient bearing is provided by the short cross-bar. The bars which
remain horizontal throughout the beam, are deflected at the center of
the beam in order to obtain the maximum effective depth. There being no
shear at the center, the bars are spaced as closely as possible, and
still provide sufficient room for the concrete to flow to the soffit of
the beam. Two or more adjacent beams are readily made continuous by
extending the bars bent up from each span, a distance along the top
flanges. By this system of construction one avoids stopping a bar where
the live load unit stress in adjoining bars is high, as their continual
lengthening and shortening under stress woul