Location
Girders: Choose the two girders that are connected by the diaphragm.
Skew Angle: A positive skew value rotates the cross frame in a clockwise direction, while a negative skew value rotates it in a counterclockwise direction. It is important to remember that the cross frames are positioned at the specified station along a line perpendicular to the PGL, which is then rotated according to the entered skew value.
Station[Start/End]: Enter the station along the PGL. When dealing with curved girder bridges, collecting distance along the girder length can lead to different inputs for the right and left girder that are connected by cross frames, causing ambiguity. Therefore, collecting the station along the PGL is a more reliable solution to avoid such issues. Furthermore, since cross frames are typically continuous in the transverse direction, entering the same station for all cross frames ensures that their locations are consistent between each girder.
The same principle can be applied for skewed cross frames. If the user enters the same station and skew values for the cross frames between Girder 1-2, Girder 2-3, and Girder 3-4, it ensures continuity between the cross frames. It should also be noted that the cross frames are positioned along a line perpendicular to the PGL, which is rotated according to the entered skew value.
Inaccurate finite element models and disconnected nodes/elements in the cross frame can occur if the entered station values are not >= the girder start station or <= the girder end station. This can cause stability issues in the finite element model. To ensure correct station input, users should select the start/end options from the station input. This approach is especially recommended for cross frames located at the beginning or end of girders.
Diaphragm Loc. [Interior/ Left Exterior/ Right Exterior]: Concrete diaphragms can be defined as either Interior or Exterior. If the exterior option is chosen, additional width from the center of the web can be defined.
Section
Trans. Distance from Edge of Bottom Flange:
Additional Width from Center Of Web: If the diaphragm location is defined with options other than ‘Interior,’ this parameter can be defined; otherwise, it will be marked as not applicable (N/A). Depending on the girders chosen for the location definitions of concrete diaphragms, this parameter can be used to assign additional length to the exterior sides of the girders, based on the directions (left or right) specified for the Diaphragm Loc. parameter.
Diaphragm Depth: The depth of the concrete diaphragms can be adjusted by this parameter. It will affect the depth in the longitudinal direction, as shown below.
Material: The material definition for the concrete diaphragm can be made using this parameter. Materials can either be imported or assigned from previously defined ones.
Offsets
Top Vertical Offset from Top of Deck: For visual representation of top vertical offset from top of deck, refer to the figure below.
Bottom Vertical Offset from Bottom of Girder: For visual representation of bottom vertical offset from bottom of girder, refer to the figure below.
FEA Settings
FE Model[Two Beam+Shell/Single Beam]: If the 'Two Beam + Shell' option is selected, the top and bottom flanges will be modeled as beam elements, while the remaining portion will be modeled as a shell element.In the absence of this option, a complete section will be defined as a single beam and connected to both bottom and top flange nodes using rigid elements, based on the user's selected preferences.
If you choose two beam and shell elements, the rigid definitions below become not applicable (N/A).
Rigid Section Top: A diaphragm can be linked to the top flange node using a rigid beam element. Please designate a section for this purpose.
Disable Bottom Rigid Line [NO/YES]: Choose "Yes" if you prefer not to generate a rigid beam element between the diaphragm and the bottom flange node.
Rigid Section Bot: A diaphragm can be linked to the bottom flange node using a rigid beam element. Please designate a section for this purpose.
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