Bearing Fixity Change [SPIG]

During construction, bearing fixities may need to change stage-by-stage. This workflow item overrides the original bearing fixity starting at the selected stage and continuing through subsequent stages.

Superstructure Connection Change

Stage: Construction stage at which the new fixity definitions take effect. All subsequent stages use the new values.

Insertion Points: Insertion Points identifying the bearings whose fixity is being changed.

Tx [Fixed/Free/Stiffness]: Longitudinal translational fixity at zero bearing rotation. For a continuous girder at least one bearing is typically fixed or given a real stiffness in Tx.

Ty [Fixed/Free/Stiffness]: Transverse translational fixity.

Tz [Fixed/Free/Stiffness]: Vertical translational fixity. Commonly Fixed or a high stiffness such as 1000 kip/in.

Rx [Fixed/Free/Stiffness]: Torsional rotational fixity. A small Rx stiffness may be added to prevent stability issues when girders are unbraced at early stages.

Ry [Fixed/Free/Stiffness]: Rotational fixity about the transverse axis — typically Free.

Rz [Fixed/Free/Stiffness]: Rotational fixity about the vertical axis — typically Free.