# Bearing Fixity
This section defines the translational and rotational fixities at each bearing location, controlling how forces transfer between the superstructure and substructure.
{% hint style="info" %}
**Navigation:** Superstructure > Boundary Conditions > Bearing Fixity
{% endhint %}
## Steps
### Step 1: Navigate to Bearing Fixity
Navigate to **Superstructure > Boundary Conditions > Bearing Fixity** in the tree view.
### Step 2: Select Insertion Points
Click the first cell in the **Insertion Point** column, then click **Pick** to graphically select the insertion points that define boundary conditions.
### Step 3: Define Fixities
For each bearing location, set the fixities or stiffness values in the Tx, Ty, Tz, Rx, Ry, and Rz directions based on the bearing type.
{% hint style="info" %}
To determine Tx and Ty stiffness values, compute them based on your bearing pad stiffness. This example uses a value of **10**.
{% endhint %}
### Step 4: Set Transfer Force to Substructure
Set **Transfer Force to Substructure** to **Yes** for all bearing locations where substructure is modeled.
{% hint style="warning" %}
* **Yes**: Creates a two-node spring between the 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 modeled substructure)
{% endhint %}
Quick Tip: Degree of Freedom Reference
Nodes are assigned degrees of freedom (DOFs) based on the local coordinate system at each insertion point, which varies along the support line and alignment.
**Tx/Ty/Tz/Rx/Ry/Rz fixities:**
-20221022-132407.png?api=v2)
**Bearing Rotation** rotates the support clockwise in the XY plane:
**Transfer Force to Substructure** FE behavior:
Quick Tip: Torsional Stability
Setting **Rx = 0** requires constructing the diaphragm with girders to maintain torsional stability. To overcome stability issues when the girder is constructed without transverse elements (diaphragm or deck), a nonzero Rx value is necessary.
## Verification
{% hint style="success" %}
After completing these steps, your bearing fixity configuration should match the view shown below.
{% endhint %}
### Video Walkthrough
