ly lacking in practical foundation.
Even the assumption of reinforcing value to the longitudinal steel rods
is not at all borne out in tests. Designers add enormously to the
calculated strength of concrete columns when they insert some
longitudinal rods. It appears to be the rule that real columns are
weakened by the very means which these designers invest with reinforcing
properties. Whether or not it is the rule, the mere fact that many tests
have shown these so-called reinforced concrete columns to be weaker than
similar plain concrete columns is amply sufficient to condemn the
practice of assuming strength which may not exist. Of all parts of a
building, the columns are the most vital. The failure of one column
will, in all probability, carry with it many others stronger than
itself, whereas a weak and failing slab or beam does not put an extra
load and shock on the neighboring parts of a structure.

In Bulletin No. 10 of the University of Illinois Experiment Station,[C]
a plain concrete column, 9 by 9 in. by 12 ft., stood an ultimate
crushing load of 2,004 lb. per sq. in. Column 2, identical in size, and
having four 5/8-in. rods embedded in the concrete, stood 1,557 lb. per
sq. in. So much for longitudinal rods without hoops. This is not an
isolated case, but appears to be the rule; and yet, in reading the
literature on the subject, one would be led to believe that longitudinal
steel rods in a plain concrete column add greatly to the strength of the
column.

A paper, by Mr. M.O. Withey, before the American Society for Testing
Materials, in 1909, gave the results of some tests on concrete-steel and
plain concrete columns. (The term, concrete-steel, is used because this
particular combination is not "reinforced" concrete.) One group of
columns, namely, _W1_ to _W3_, 10-1/2 in. in diameter, 102 in. long, and
circular in shape, stood an average ultimate load of 2,600 lb. per sq.
in. These columns were of plain concrete. Another group, namely, _E1_ to
_E3_, were octagonal in shape, with a short diameter (12 in.), their
length being 120 in. These columns contained nine longitudinal rods, 5/8
in. in diameter, and 1/4-in. steel rings every foot. They stood an
ultimate load averaging 2,438 lb. per sq. in. This is less than the
column with no steel and with practically the same ratio of slenderness.

In some tests on columns made by the Department of Buildings, of
Minneapolis, Minn.[D], Test _A_ was a 9 by 9-in. column, 9