y other engineers, as well as being
advocated by the author. The only conditions under which the speaker
would permit of the design of a continuous series of beams as simple
members would be when they are entirely separated from each other over
the supports, as by the introduction of artificial joints produced by a
double thickness of sheet metal or building paper. Even under these
conditions, the speaker's experience with separately moulded members,
manufactured in a shop and subsequently erected, has shown that similar
top cracking may take place under certain circumstances, due to the
vertical pressures caused by the reactions at the supports. It is very
doubtful whether the action described by the author, as to the type of
failure which would probably take place with his method of design, would
be as described by him, but the beams would be likely to crack as
described above, in accordance with the speaker's experience, so that
the whole load supported by the beam would be carried by the reinforcing
rods which extend from the beam into the supports and are almost
invariably entirely horizontal at such points. The load would thus be
carried more nearly by the shearing strength of the steel than is
otherwise possible to develop that type of stress. In every instance the
latter is a dangerous element.

This effect of vertical abutment action on a reinforced beam was very
marked in the beam built of bricks and tested by the speaker, as
described in the discussion[J] of the paper by John S. Sewell, M. Am,
Soc. S. E., on "The Economical Design of Reinforced Concrete Floor
Systems for Fire-Resisting Structures." That experiment also went far
toward showing the efficacy of vertical stirrups.

The same discussion also contains a description of a pair of beams
tested for comparative purposes, in one of which adhesion between the
concrete and the main reinforcing rods was possible only on the upper
half of the exterior surfaces of the latter rods except for short
distances near the ends. Stirrups were used, however. The fact that the
beam, which was theoretically very deficient in adhesion, failed in
compression, while the similar beam without stirrups, but with the most
perfect adhesion, and anchorage obtainable through the use of large end
hooks, failed in bond, has led the speaker to believe that, in affording
adhesive resistance, the upper half of a bar is much more effective than
the lower half. This seems to be demonstr