I Girder Bent
The properties of the I Girder Bent can be specified using the parameters listed below. For a visual representation of each, refer to the figure below.
Location: Choose a support line to indicate the position of the bent cap.
Length: Length of the bent cap.
Top Elevation Offset from Alignment: Specify the distance from the midpoint of the bent cap at the top to the PGL location, where 0 indicates that the midpoint of the pier cap is at the PGL location vertically. Generally, a value equivalent to the sum of the deck thickness, girder depth, bearing depth, and haunch depth is employed.
Longitudinal Offset: If you intend to adjust the centerline of the bent cap in the longitudinal direction, use this offset value. For end bents, a value of typically half the section width can be helpful, as support lines are typically not defined at the centerline for end bents.
Transverse Offset: When 0 is entered, the midpoint of the bent cap (equal to half of the cap length) will be positioned at the PGL location. If a negative value is used, the bent cap will be offset in the left direction when looking up-station from the alignment, and if a positive value is used, it will be offset in the right direction when looking up-station from the alignment.
The positive direction of the Y-axis will be to the left when looking upstream along the PGL. However, based on the requests of engineers who have been using OpenBrIM for their bridge projects, positive transverse offset values will indicate the right-hand side when looking upstream along the PGL. This distinction should be taken into account when defining the location of bridge elements using transverse offset values (where positive transverse offset indicates the right side), as well as when making definitions related to FEM and loading (where positive Fy indicates the left side along the PGL).
Top Flange Width: The width of the top flange can be specified by defining this parameter.
Top Flange Thickness: The thickness of the top flange can be specified by defining this parameter.
Web Depth: The depth of the web (vertical portion of the I-girder) can be specified using this parameter.
Web Thickness: The thickness of the web can be specified by defining this parameter.
Bottom Flange Width: The width of the bottom flange can be specified using this parameter.
Bottom Flange Thickness: The thickness of the bottom flange can be specified by defining this parameter.
Top Flange Material: Assign a material to the top flange. Materials can be selected from previously defined options or imported as needed.
Web Material: Assign a material to the web. Materials can be selected from previously defined options or imported as needed.
Bottom Flange Material: Assign a material to the bottom flange. Materials can be selected from previously defined options or imported as needed.
FEM
Rigid Section: To connect the pier cap finite element to the bearing, the user needs to specify the properties of the rigid section. When bearings are longitudinally offset from the support line, rigid elements are automatically generated to link those bearings to the pier cap.
Mesh Size: The maximum distance between nodes in the elements local X-direction is specified using the mesh size.
Number of Result Extraction Stations: The result extraction station settings are solely for viewing FEA composite results in either the spreadsheet or FEA view, and do not impact standard finite element analysis results like member end forces, node displacement, and node reactions.
Flange FEM[Beam/Shell]: The finite model of the I-girder bent can be generated using both beam elements and shell elements, which can be specified by this parameter.
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