...
How
...
are
...
suspension
...
bridges
...
and
...
cable
...
forces
...
modeled
...
and
...
analyzed?
...
Answer:
...
Suspension
...
bridges
...
may
...
be
...
...
and
...
analyzed
...
in
...
...
through
...
either
...
of
...
the
...
following
...
methods:
...
...
...
- ,
...
- which
...
- simulates
...
- the
...
- construction
...
- sequence.
...
- Direct
...
- solution
...
- of
...
- the
...
- deformed
...
- equilibrium
...
- configuration
...
- under
...
- dead
...
- load.
...
Once
...
bridge
...
stiffness
...
under
...
dead
...
load
...
is
...
obtained,
...
additional
...
analyses
...
(
...
...
,
...
wind,
...
seismic,
...
etc.)
...
may
...
be
...
performed
...
using
...
the
...
stiffness
...
at
...
the
...
end
...
of
...
the
...
dead
...
load
...
case.
...
Detailed staged-construction
...
analysis
...
To
...
perform
...
the
...
staged-construction
...
analysis
...
of
...
a
...
suspension
...
bridge,
...
create
...
a
...
staged-construction
...
...
...
which
...
reflects
...
the
...
erection
...
sequence
...
from
...
foundation
...
construction
...
through
...
pylon,
...
main-cable,
...
suspender,
...
and
...
deck
...
assembly.
...
Solve for deformed equilibrium configuration
When deformed configuration is derived through input parameters (main cable sag, main cable span, deck profile, etc.),
...
the
...
corresponding
...
force
...
values
...
may
...
be
...
obtained
...
using
...
...
.
...
Analysis
...
may
...
begin
...
with
...
coordinates
...
which
...
specify
...
the
...
final
...
deflected
...
shape.
...
The
...
cable
...
load
...
which
...
corresponds
...
to
...
the
...
final
...
deformed
...
configuration
...
should
...
be
...
specified
...
in
...
the
...
Cable
...
Geometry
...
menu.
...
After
...
analysis,
...
...
coordinates
...
should
...
be
...
modified
...
through
...
Analyze
...
>
...
Modify
...
Undeformed
...
Geometry
...
such
...
that
...
deflected
...
shape
...
at
...
the
...
end
...
of
...
staged
...
construction
...
matches
...
the
...
geometry
...
initially
...
specified.
...
Several
...
iterations
...
may
...
be
...
necessary
...
for
...
convergence
...
to
...
the
...
desired
...
shape.
...
See Also
References
- Ren, W., Blandford, G., Harik, I. (2004, March/April). Roebling Suspension Bridge. I: Finite-Element Model and Free Vibration Response, Journal of Bridge Engineering, Volume 9, Issue 2, 110.