الفهرس 
Behavior of open box girder bridgesOnly 14 pages are availabe for public view
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Abstract
Composite steel box girder bridges represent the optimum
system in many cases for short and middle span bridges.
However, during construction, the open box steel girder is
erected first and the concrete deck is added later. The open box
section is relatively flexible in torsion. It has small stiffness
against torsion compared with the stiffness of the closed box
section after casting the concrete deck. A critical design stage
for steel girder occurs during the construction phase, where its
deformations and the corresponding stresses mcrease than
safety values.
Three dimensional finite element models are proposed and
solved by program ANSYS-8. 0 to study the behavior of straight
simple and continuous open box girder bridges consisting of
steel girders with rectangular or trapezoidal cross section and
two top flanges, during girder erection and bridge construction.
The proposed finite element model has been verified by
comparing its results, with the results of other models that have
been investigated.
A parametric study was carried to study the behavior of simple
and continuous span open steel box girders for two main cases,
without bracing and with different bracing systems due to
torsional moment (concentrated and distributed) and vertical
loads (symmetrical and asymmetrical).
It was found that the classical method, which is used in the
torsion analysis, is not recommended to determine the rotation
angle of girder cross section about its axis in cases of girders
with cross sections having shear center in direction and other
cross section points in another direction, such as open box
section. New equations are derived to determine the accurate
values of the rotation angle for the top and bottom flanges for
open box cross sections. The form of the classical method