Prestressing as action or resistance

There are two distinct approaches to the design checks of prestressed concrete members - the prestressing can be either treated as resistance (integral part of the section) or as action (load)

Prestressing as resistance

 * Considers the prestressing strands as integral part of the cross section, where prestressing operation introduces imposed deformation corresponding the pre-elongation of the active reinforcement.
 * Hyperstatic effects must be considered.

Prestressing as action

 * Considers prestressing as external loading consisting of a self-equilibrating system of forces in the anchorages and the transversally in the concrete. After transfer prestressing strands are considered as conventional reinforcement, only taking into consideration the pre-elongation.

AASHTO LRFD 2007

 * Based on C5.7.1, prestressing is treated as part of resistance

Eurocode 2 (1992)

 * Based on article 5.10.1, bullet 2, the effects of prestressing can be considered as an action or a resistance