loading might be relatively greater.

The writer once had an experience which sustains this point. On peeling
off the forms from a beam reinforced according to the method indicated,
it was found that, because of the crowding together of the bars in the
bottom, coupled with a little too stiff a mixture, the beam had hardly
any concrete on the underside to grip the steel in the portion between
the points of bending up, or for about the middle half of the member;
consequently, it was decided to test this beam. The actual working load
was first applied and no deflection, cracking, or slippage of the bars
was apparent; but, as the loading was continued, deflection set in and
increased rapidly for small increments of loading, a number of fine
cracks opened up near the mid-section, which extended to the neutral
plane, and the steel slipped just enough, when drawn taut, to destroy
what bond there was originally, owing to the contact of the concrete
above. At three times the live load, or 450 lb. per sq. ft., the
deflection apparently reached a maximum, being about 5/16 in. for a
clear distance, between the supports, of 20 ft.; and, as the load was
increased to 600 lb. per sq. ft., there was no appreciable increase
either in deflection or cracking; whereupon, the owner being satisfied,
the loading was discontinued. The load was reduced in amount to three
times the working load (450 lb.) and left on over night; the next
morning, there being no detectable change, the beam was declared to be
sound. When the load was removed the beam recovered all but about 1/8
in. of its deflection, and then repairs were made by attaching light
expanded metal to the exposed bars and plastering up to form. Although
nearly three years have elapsed, there have been no unfavorable
indications, and the owner, no doubt, has eased his mind entirely in
regard to the matter. This truly remarkable showing can only be
explained by the catenary action of the main steel, and some truss
action by the steel which was horizontal, in conjunction with the
U-bars, of which there were plenty. As before noted, the clear span
was 20 ft., the width of the bay, 8 ft., and the size under the slab
(which was 5 in. thick) 8 by 18 in. The reinforcement consisted of three
1-1/8-in. round medium-steel bars, with 3/8-in. U-bars placed the
effective depth of the member apart and closer toward the supports, the
first two or three being 6 in. apart, the next two or three, 9 in., th