Post-Tensioning
The post-tensioning tendons are modeled as tendons and their anchor-set and friction losses are calculated before they enter the analysis model. The tendon is divided into a number a small linear segments and the horizontal curvature is included in the friction loss effect is requested. Tendon elongation is calculated for one-end and two-end jacking. For one-end jacking, the elongation is calculated as 80% of the theoretical elongation. For two-end jacking, it is assumed that the left end is jacked first. Post-tensioning tendons become part of the transformed section at final case. If the tendon type is specified as "Unknown", then the area of tendon is assumed to be such that the jacking force produces a stress of 0.75*fpu. The PT duct diameter for a tendon type of "Unknown" is set to 0.0.
| Setting | Description |
|---|---|
| Jacking | Initial jacking can be specified from the left, right, or both ends of the box girder. The jacking force is input or a percentage of the ultimate stress can be specified (typically between 70 to 80%) |
| Friction/Wobble Coefficients | Both the friction and wobble coefficients can be specified as user input. |
| Anchor Set | The anchor set is specified as user input. |
| Tendon Path | There are several options for the layout of the post-tensioning path (profile). The path can be either standard or general. Standard paths are based on the spans and extend through the full length of the bridge. The general paths are made of pieces that can be linear, parabolic, or double-curvature. The program performs no center of gravity adjustment of the post-tensioning tendon. |
| Relaxation | The program will compute the ultimate relaxation in the post-tensioning cable or the user can specify a value independently. |