The definitions made in this section affect the 3D model and, accordingly, the 2D model. The finite element model will be visible when fixity values are defined. The definitions related with 3D model of the object can be specified by using the tab ‘Inputs’.
Articulation
Insertion Point: Used for specifying the bearing location and can be selected by using the three dots and the options ‘Pick...’ and ‘Select...’.
Tx[Fixed/Free/Stiffness]:When the bearing rotation is 0 degrees, Tx represents the stiffness in the longitudinal direction. It is typical for a continuous girder to have at least one fixed bearing (or to use a real stiffness value) in the Tx direction.
Ty[Fixed/Free/Stiffness]: Ty represents the stiffness in the transverse direction when the bearing rotation is 0 degrees.
Tz[Fixed/Free/Stiffness]: Tz represents the stiffness in the vertical direction. It is common to use a high stiffness value, such as 1000 kip/in, or to fix the bearing.
Rx[Fixed/Free/Stiffness]: To address stability concerns, a small Rx stiffness can be used in the torsional direction (Rx) under certain conditions. If the constructed girders are not connected with bracings to other girders at any stage, it can result in stability issues. Therefore, a small Rx stiffness is recommended to overcome this problem.
Ry[Fixed/Free/Stiffness]: Typically, bearings are free to rotate in the Ry direction.
Rz[Fixed/Free/Stiffness]: Typically, bearings are free to rotate in the Rz direction.
Bearing Rotation: Curved decks can be guided either radially from a fixed point or tangentially to the radius of curvature. When the deck is guided radially, precise geometry is crucial for the bearings that are farthest from the fixed point. For structures with a constant curvature, it is recommended to align the bearings tangentially to effectively guide the deck around the curve as it expands and contracts.
Transfer Forces to Substructure [Yes/No]: If the user chooses to connect the superstructure to the substructure, a two-node spring is required between the pier cap and the girder, which can be generated by selecting “YES”. Conversely, if there is no substructure or if the abutments are being considered (currently, abutments in OpenBrIM have the "Generate FEM" option set to “NO”), the correct setting for the "Transfer Forces to Substructure" parameter is“NO” and one node springs are needed.
Inputs
The Inputs tab can be used to make further definitions for the 3D model objects.The parameters of Inputs tab are as follows:
Bottom Plate Thickness:
Bottom Plate Length:
Bottom Plate Width:
Top Plate Thickness:
Top Plate Length:
Top Plate Width:
Bottom Anchor Bolt Hole Diameter:
Bottom Anchor Bolt Edge Distance:
Top Bolt Hole Diameter:
Top Bolt Edge Distance:
Angle of Curvature at Top:
Angle of Curvature at Bottom:
Sliding Plate Length:
Plate Radius of Curvature:
Thickness of Sliding Plate at Top:
Thickness of Sliding Plate at Bottom:
Show Bolt Hole (Detailing) [YES/NO]:
Number of Segments Used to Draw the Bolt Hole:
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