Single Roller Bearing [SIG]
- Umut Nuhat Sevinc
- Melis Ceylan
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.
Bearing Bottom Elevation (readonly): The bottom location of the bearings in 3D, with respect to the Z-axis of the Global Coordinate System, is displayed to the user in this column, regardless of the alignment's vertical definition.
Inputs
The Inputs tab can be used to make further definitions for the 3D model objects.Parameters of Inputs tab are as follows:
Base Plate Thickness: The thickness of the base plate in the Z direction can be specified using this parameter.
Base Plate Length: The length of the base plate in the longitudinal direction can be specified using this parameter.
Base Plate Width: The width of the base plate in the transverse direction can be specified using this parameter.
Top Plate Thickness: The thickness of the top plate in the Z direction can be specified using this parameter.
Top Plate Length: The length of the top plate in the longitudinal direction can be specified using this parameter.
Top Plate Width: The width of the top plate in the transverse direction can be specified using this parameter.
Anchor Bolt Hole Diameter: The diameter of the anchor bolt holes for the bolts placed on the bottom plate can be specified using this parameter.
Anchor Bolt Edge Distance: The distances of the anchor bolts placed on the bottom plate to the edges in both the longitudinal and transverse directions can be specified using this parameter.
Top Bolt Hole Diameter: The diameters of the bolts on the top plate can be adjusted using this parameter.
Top Bolt Edge Distance: The distances of the bolts to the edges in both the longitudinal and transverse directions can be specified using this parameter.
Roller Diameter: The diameter of the roller in the longitudinal direction can be defined by this parameter.
Roller Length: The length of the roller in the transverse direction can be defined by this parameter.
Show Bolt Hole (Detailing) [YES/NO]: To display the bolts, this parameter should be set to ‘YES,’ and the DETAILING button on the top middle bar must be turned on.
Number of Segments Used to Draw the Bolt Hole: A higher number of segments results in a smoother display of the bolts. If this parameter is set to 3, triangular shapes of the bolts will be visible. As the number increases, the bolt geometry will be generated to more closely resemble a circular shape.
Capacity
Bearing Capacity: The bearing capacity can be adjusted using this parameter.