g from the front wall to the
horizontal slab, and anchored into each in such a manner as would be
adopted were these slabs suspended on the rods, is the only rational and
the only efficient design possible. This design is illustrated at _b_ in
Fig. 2.

[Illustration: FIG. 2.]

The fourth point concerns shear in steel rods embedded in concrete. For
decades, specifications for steel bridges have gravely given a unit
shear to be allowed on bridge pins, and every bridge engineer knows or
ought to know that, if a bridge pin is properly proportioned for bending
and bearing, there is no possibility of its being weak from shear. The
centers of bearings cannot be brought close enough together to reduce
the size of the pin to where its shear need be considered, because of
the width required for bearing on the parts. Concrete is about
one-thirtieth as strong as steel in bearing. There is, therefore,
somewhat less than one-thirtieth of a reason for specifying any shear on
steel rods embedded in concrete.

The gravity of the situation is not so much the serious manner in which
this unit of shear in steel is written in specifications and building
codes for reinforced concrete work (it does not mean anything in
specifications for steelwork, because it is ignored), but it is apparent
when designers soberly use these absurd units, and proportion shear rods
accordingly.

Many designers actually proportion shear rods for shear, shear in the
steel at units of 10,000 or 12,000 lb. per sq. in.; and the blame for
this dangerous practice can be laid directly to the literature on
reinforced concrete. Shear rods are given as standard features in the
design of reinforced concrete beams. In the Joint Report of the
Committee of the various engineering societies, a method for
proportioning shear members is given. The stress, or shear per shear
member, is the longitudinal shear which would occur in the space from
member to member. No hint is given as to whether these bars are in shear
or tension; in fact, either would be absurd and impossible without
greatly overstressing some other part. This is just a sample of the
state of the literature on this important subject. Shear bars will be
taken up more fully in subsequent paragraphs.

The fifth point concerns vertical stirrups in a beam. These stirrups are
conspicuous features in the designs of reinforcing concrete beams.
Explanations of how they act are conspicuous in the literature on
reinforce