Restraining Moments Tab
To review or modify the restraining moments, click the Restraining Moments to display the appropriate screen as shown. There are three methods available to calculated restraining moments: Full Continuity, Manual Restraining Moment, and Calculated Restraining Moment. Note that the NCHRP Method is not available in this version of Precast/Prestressed Girder. Select the method you want to use and input the required information in the text boxes.
- Manual Restraining Moments
Left Pier - User-specified positive moment at left pier.
Right Pier - User-specified positive moment at right pier.
- Calculated Restraining Moment
Age at which continuity is established. Number of days elapsed between the casting of the beams and the casting of the slab/diaphragm.
- Continuity Factor
The restraint moments at the left and right pier are calculated as the sum of the moments due to prestress creep, dead load creep, and shrinkage. They are calculated assuming the exterior supports as pinned and the interior supports as fixed. That is, fixed end moments are not adjusted for moment distribution, as specified in PCA Method. This is the approximation used in Precast/Prestressed Girder; however, you may want to consider the moment redistribution and input the continuity factors for the left and right pier.
- Restraining Moments
All restraining moments are calculated using the method described in Ref. 7, PCA Method. They are caused by long-term creep and shrinkage deformation. When the beams are restrained against rotation at the diaphragm, restraining moments are induced.