Which type of prestressed concrete girder has the prestressing force applied after the concrete has cured?

• A. Post-tensioned Girder
• B. Pretensioned Girder
• C. Prestressed Girder
• D. Precast

Answer: (B)

In prestressed concrete, the timing of when the steel is stressed distinguishes the two main methods. Pretensioning bonds the steel to the formwork and tightens it before the concrete is poured; after the concrete hardens, the steel is released, transferring the prestress to the concrete. Post-tensioning, on the other hand, places ducts in the concrete and, once the concrete has gained strength, the tendons are threaded through those ducts, tensioned, and anchored at the ends to impose compression. Since the prestress is applied after the concrete has cured, this describes the post-tensioned approach. The terms prestressed or precast describe overall concepts or manufacturing methods, not the timing of prestress, so they don’t specify when the force is applied.