The fourth, fifth, and sixth items bring out the fact that undoubtedly
there has been some confusion in the minds of designers and authors on
the subject of shear in the steel. The author is wholly justified in
criticising the use of the shearing stress in the steel ever being
brought into play in reinforced concrete. Referring to the report of the
Special Committee on Concrete and Reinforced Concrete, on this point, it
seems as if it might have made the intention of the Committee somewhat
clearer had the word, tensile, been inserted in connection with the
stress in the shear reinforcing rods. In considering a beam of
reinforced concrete in which the shearing stresses are really diagonal,
there is compression in one case and tension in another; and, assuming
that the metal must be inserted to resist the tensile portion of this
stress, it is not essential that it should necessarily be wholly
parallel to the tensile stress. Vertical tensile members can prevent the
cracking of the beam by diagonal tension, just as in a Howe truss all
the tensile stresses due to shear are taken in a vertical direction,
while the compressive stresses are carried in the diagonal direction by
the wooden struts. The author seems to overlook the fact, however, that
the reinforced concrete beam differs from the Howe truss in that the
concrete forms a multiple system of diagonal compression members. It is
not necessary that a stirrup at one point should carry all the vertical
tension, as this vertical tension is distributed by the concrete. There
is no doubt about the necessity of providing a suitable anchorage for
the vertical stirrups, and such is definitely required in the
recommendations of the Special Committee.

The cracks which the author refers to as being necessary before the
reinforcing material is brought into action, are just as likely to occur
in the case of the bent-up rods with anchors at the end, advocated by
him. While his method may be a safe one, there is also no question that
a suitable arrangement of vertical reinforcement may be all that is
necessary to make substantial construction.

With reference to the seventh point, namely, methods of calculating
moments, it might be said that it is not generally considered good
practice to reduce the positive moments at the center of a span to the
amount allowable in a beam fully fixed at the end, and if provision is
made for a negative moment over supports sufficient to develop the