How does posttensioned steel strengthen a concrete gravity dam?

In the context of dam engineering, posttensioned steel is used to strengthen concrete gravity dams by resisting the overturning forces caused by the pressure of retained water.

The process involves installing a series of vertical steel rods near the upstream face of the dam. These rods are stressed using jacks and are securely anchored into the underlying rock foundation. By applying this tension, the system creates a compressive force that helps stabilize the structure, allowing for a more slender cross-section than would be possible with a conventional gravity dam relying solely on its own weight.12

Beyond initial construction, this technique is also used to raise the crest level of existing gravity dams, which provides an economical way to increase the storage capacity of a reservoir.12