Automatic Debonding and Critical Point
An automatic debonding (shielding) pattern is generated by clicking the Auto Debond button on the Debonding Pattern. The program will generate the debonding pattern according to the following algorithm. Precast/Prestressed Girder shields strand groups in lengths that are multiples of the debonding length increment (defined on the Materials tab) in an attempt to bring the following stresses within the allowable:
- To develop the ultimate capacity in the strand at midspan, a distance equal to the strand development length (or a multiple thereof, as specified by the user) must remain unshielded.
- Since all shielding must stop at a distance at least equal to the strand development length from midspan, stresses at release will not be effected by shielding in a region that extends from midspan to a point located at a distance equal to the transfer length, measured from the end of shielding. This point is called the critical point, since it is the point closest to the beam end, and therefore, where the self-weight is the smallest, which is not affected by shielding.