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.
The values that appear in these columns as soon as an insertion point is chosen are calculated based on the 3D geometry of the model. These values can be changed or kept as default. The calculations for these values can be displayed if the section related to ‘Elastomeric Bearing Stiffness’ under the category ‘Reports’ is defined.
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.
Elastomeric Pad
The Elastomeric Pad of the bearing can also be further modeled by defining the parameters below:
Geometry Type:
Bearing pad dimension perpendicular to bridge span:
Bearing pad dimension parallel to bridge span:
Bearing pad diameter:
Number of internal elastomer layers:
Thickness of internal elastomer layer:
Thickness of iexterior elastomer layer:
Steel plate thickness:
Side cover of pad:
Elastomer Shear Modulus 'G':
Elastomer Bulk Modulus 'K':
‘Kc’ Compression Stiffness (readonly):
‘Ks’ Shear Stiffness (readonly):
Plate Inputs-Visual
Plate of the bearing can also be further modeled by defining the parameters below:
Top plate thickness:
Top plate length:
Top plate width:
Base plate thickness:
Base plate length:
Base plate width:
Top bolt hole diameter:
Top bolt hole diameter:
Top bolt edge distance:
Anchor bolt hole diameter:
Anchor bolt edge distance:
Show Bolt Hole (Detailing) [YES/NO]:
Number of Segments Used to Draw the Bolt Hole:
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