ft. 6 in.
long, with ten longitudinal, round rods, 1/2 in. in diameter, and
1-1/2-in. by 3/16-in. circular bands (having two 1/2-in. rivets in the
splice), spaced 4 in. apart, the circles being 7 in. in diameter. It
carried an ultimate load of 130,000 lb., which is much less than half
"the compressive resistance of a hooped member," worked out according to
the authoritative quotation before given. Another similar column stood a
little more than half that "compressive resistance." Five of the
seventeen tests on the concrete-steel columns, made at Minneapolis,
stood less than the plain concrete columns. So much for the longitudinal
rods, and for hoops which are not close enough to stiffen the rods; and
yet, in reading the literature on the subject, any one would be led to
believe that longitudinal rods and hoops add enormously to the strength
of a concrete column.

The sixteenth indictment against common practice is in reference to flat
slabs supported on four sides. Grashof's formula for flat plates has no
application to reinforced concrete slabs, because it is derived for a
material strong in all directions and equally stressed. The strength of
concrete in tension is almost nil, at least, it should be so considered.
Poisson's ratio, so prominent in Grashof's formula, has no meaning
whatever in steel reinforcement for a slab, because each rod must take
tension only; and instead of a material equally stressed in all
directions, there are generally sets of independent rods in only two
directions. In a solution of the problem given by a high English
authority, the slab is assumed to have a bending moment of equal
intensity along its diagonal. It is quite absurd to assume an intensity
of bending clear into the corner of a slab, and on the very support
equal to that at its center. A method published by the writer some years
ago has not been challenged. By this method strips are taken across the
slab and the moment in them is found, considering the limitations of the
several strips in deflection imposed by those running at right angles
therewith. This method shows (as tests demonstrate) that when the slab
is oblong, reinforcement in the long direction rapidly diminishes in
usefulness. When the ratio is 1:1-1/2, reinforcement in the long
direction is needless, since that in the short direction is required to
take its full amount. In this way French and other regulations give
false results, and fail to work out.

If the writer