Navigate to Superstructure > Boundary Conditions > Bearing Fixity in the tree view.
Bearing Fixity navigation
Step 2: Select Insertion Points
Click the first cell in the Insertion Point column and use the Pick button to select insertion points that define the bearing locations.
Pick Insertion Points
Step 3: Define Fixity Values
Set the translational (Tx, Ty, Tz) and rotational (Rx, Ry, Rz) fixity values for each bearing:
Parameter
Description
Tx
Axial direction - Only IP1 and IP2 have assigned values (axial forces accommodated at these supports)
Ty, Tz
Transverse and vertical directions - Remain constant for all bearings
Rx
Torsional stability - Set to 10 for all supports to maintain stability during construction
Ry, Rz
Rotational constraints - Set as needed
Fixity Values 1
Fixity Values 2
Fixity Values 3
Quick Tip: Rx Parameter for Torsional Stability
Setting a non-zero Rx value is necessary to address torsional stability when constructing a beam without transverse components like diaphragms or decks. In this example, all supports are assigned Rx = 10.
Step 4: Configure Force Transfer
Set Transfer Force to Substructure to Yes for all bearing locations.
Transfer Force
Quick Tip: Transfer Force to Substructure
Setting
Behavior
Yes
Creates a two-node spring between pier cap and girder (use when substructure is modeled)
No
Creates a one-node spring at the bottom of the girder (use for abutment locations without substructure model)
Verification
The completed bearing fixity configuration is shown below.
