Stress Distribution in and Equivalent Width of Flanges of Wide, Thin-Wall Steel Beams Page: 3 of 27
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NACA Technical Note Ne. 784
of the flange at a given cross section. With the develop-
ment of Light-weight constructions of different kinds t-here
is, however, at present a definite trend toward the use o
I-, T-, and other sections of considerable width and rather
small thickness. Structural members of such kind are
widespread in ship and. airplane building and, with the
development of the spot-welding technique, are becoming
increasingly important for small-scale structures such as
rosidonce buildings. In connection with this development,
investigations have been undertaken to ascertain whether
in such cases the bending stresses still may be assumed to
be uniformly distributed over the- width of the flange.
(See references 1, 2, and 3.) It was found that in wide
beams the stress distribution considerably deviates from
uniformity and that for a rational design of such beans
this.nonuniformity must be taken into account. All those
investigations which treat the behavior of the beam as a
whole are concerned with special cases. Moreover, very
complex mathematical expressions are arrived at which, for
numerical evaluation, require an amount of algebraic com-
putation prohibitive in design practice. In addition, the
stress distribution in-the flanges is treated as a problem
in plane stress without analyzing the limitations arising
from this approach.
The present work, in which a different method was
used, undertakes to investigate the stress distribution
in the flanges of I-, T-, U-, and box-shape beams and to
present the numerical results in the form of tables and
curves for direct use in practical design work. In order
to achieve this purpose, two stops are necessary: (1) The
state of stress in the flanges is analyzed for diffcront
loading conditions and as a result curves are presented
from which the equivalent width for practically all possi-
ble beam dimensions can be read directly; and (2) an in-
vestigation is carried out to ascertain the limits within
which this analysis, based on plane stress, is sufficiently
exact; as a, result, simple formulas are given for the lim-
iting dimensions of beams to which the foregoing analysis
applies. In addition, it seemed desirable to proviio pos-
s-fbilitios for experimental verification of this analysis.
For this purpose, a further curve is computed, which gives
the ratio of the magnitudes of the stresses at the center
of the flange to that at the edges for I-beams. These
ratios can be checked experimentally by strain measurements.
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Winter, George. Stress Distribution in and Equivalent Width of Flanges of Wide, Thin-Wall Steel Beams, report, November 1940; (digital.library.unt.edu/ark:/67531/metadc56464/m1/3/: accessed December 11, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.