neering department
of a college, for some ideas for the students to work up for theses, and
suggested that they test beams of this sort. He was met by the
astounding and fatuous reply that such would not be reinforced concrete
beams. They would certainly be concrete beams, and just as certainly be
reinforced.

Bulletin 29 of the University of Illinois Experiment Station contains a
record of tests of reinforced concrete beams of this sort. They failed
by the crushing of the concrete or by failure in the steel rods, and
nearly all the cracks were in the middle third of the beams, whereas
beams rich in shear rods cracked principally in the end thirds, that is,
in the neighborhood of the shear rods. The former failures are ideal,
and are easier to provide against. A crack in a beam near the middle of
the span is of little consequence, whereas one near the support is a
menace to safety.

The seventh point of common practice to which attention is called, is
the manner in which bending moments in so-called continuous beams are
juggled to reduce them to what the designer would like to have them.
This has come to be almost a matter of taste, and is done with as much
precision or reason as geologists guess at the age of a fossil in
millions of years.

If a line of continuous beams be loaded uniformly, the maximum moments
are negative and are over the supports. Who ever heard of a line of
beams in which the reinforcement over the supports was double that at
mid-spans? The end support of such a line of beams cannot be said to be
fixed, but is simply supported, hence the end beam would have a negative
bending moment over next to the last support equal to that of a simple
span. Who ever heard of a beam being reinforced for this? The common
practice is to make a reduction in the bending moment, at the middle of
the span, to about that of a line of continuous beams, regardless of the
fact that they may not be continuous or even contiguous, and in spite of
the fact that the loading of only one gives quite different results, and
may give results approaching those of a simple beam.

If the beams be designed as simple beams--taking the clear distance
between supports as the span and not the centers of bearings or the
centers of supports--and if a reasonable top reinforcement be used over
these supports to prevent cracks, every requirement of good engineering
is met. Under extreme conditions such construction might be heavily
stressed