Custom Bracing [CSB]
- Melis Ceylan
Bracing
Girders: Choose the two girders that are connected by the cross frame.
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.
Section: Assign a section for the bracing, which can be imported from the AISC database by the users.
Offset from Edge of Web: The offset in the transverse direction from both ends can be specified using this parameter. This parameter's definition will affect both the 3D model and FEM.
Offset from Top of Web: The offset in the Z-axis direction. The definition of this parameter will affect both the 3D model and FEM.
Type[Truss/Beam]: The finite element representation is in the form of a truss or beam.
Orientation Angle[0/90/180/270]: Specify an angle for the bracing to rotate around its longitudinal axis.
FEA
Axial Rigidity Coefficient: This parameter specifies the axial rigidity coefficient of the bracing.
Geometry
Chord - Vert. Distance of WP from Top of Girder: The vertical distance of the bracing from the top of the girder can be specified using this parameter.
Chord - Horz. Distance of WP from Center of Web: The horizontal distance of the bracing from the center of the web can be specified using this parameter.