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.
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