Semi rigid connections and their influence on steel column behaviour.

A review of
the development of
the analysis of
frames with semi-rigid end restraint
is given,
including
the treatment of
frame stability and effective
lengths.
The available experimental data
relating to the moment
versus
in-plane
rotational behaviour of practical beam-
to-column connections, as used
in steel
frames, has
also been
reviewed. This data is found to be a non-
linear function of connection deformation. Methods of
mathematically modelling connection data have been
reviewed and an
improved
representation based on the
use of cubic B-spline curve
fitting techniques is
proposed.
An analytical procedure has been developed to
investigate the influence of realistic end restraint on
the strength and
behaviour of
"real" steel columns. A
FORTRAN finite element computer program, which
includes
the effects of
initial out-of-straightness, spread of
yield and
internal
residual stresses
is outlined. This
is based on an
incremental approach, with Newton Raphson
equilibrium
iterations, to follow the load-deflection
behaviour up to the maximum
load level. The validity
of
the procedure
is verified by
comparison with
available experimental data for an end restrained
column
test.
A parametric study was carried out
to assess
the
behaviour of columns with semi-rigid end restraint. The important pararReters relating to the connection,
the column section and
the geometrical
imperfections
were studied. It was
found that an
increase in
connection
stiffness produces a corresponding reduction
in column
deflections and an
increase in maximum
load capacity,
except
in those cases where
the column
is so stocky
that
it
can attain
its full squash
load.
Effective length factors calculated
from these
results
indicate the column design economies
th at would
be possible
if the actual end restraint conditions were
properly accounted
for.