Abstract:
In the design of plate girders, the best approach is to put the material as far from the
neutral axis as possible and keep the web area as small as possible. This approach
maximized the section’s efficiency for strength. As a result of this principle, Plate
girders used in bridges are usually deep beams with relatively thin webs and,
subsequently, web buckling becomes an important factor to consider during their
design. When the limit state of web buckling governs the design, transverse and
longitudinal stiffeners may be used to increase section strength. Therefore; an Optimum
location of longitudinal stiffeners in plate girders under high shear low moment near
support were investigated in this study.
This study explores simple span, plate girders with yield stresses of 240Mpa for flange
and 280MPa of web and investigates optimal horizontal single stiffener location.
Parametric studies are conducted for a range of slenderness ratio, aspect ratio and
relative location of longitudinal stiffener with the web using ABAQUS, and sections are
examined under where high shear-low moment conditions near supports. The girders
studied were divided into three groups. Each group is composed of seven girders.
A model for each combination of parameters is built, and seven cases are analyzed. In
the first group, the second group and the third group the percentage increased the value
of Pcr at 0.5D location of the longitudinal stiffener is 173%, 162%, and 128%
respectively of a plate girder without longitudinal stiffener. Recommendations are
proposed for the location of a longitudinal stiffener for this case, 0.5D. Therefore, in
high shear-low moment conditions, longitudinal stiffeners can be used to increase
girder strength to resist shear by placing it at the mid-depth of the web. The contribution
of a web longitudinal stiffener to increase the strength of the plate girder depends upon
the aspect ratio. For a plate girder aspect ratio value of (a/D) 1 and 2 units, the
contribution of longitudinal stiffener placed at the optimal location is 2.5 and 2 times
a plate girder without longitudinal stiffener respectively.
