A self-stressing shape memory alloy (SMA)/fiber reinforced polymer (FRP) composite patch is disclosed that can be used to repair cracked steel members or other civil infrastructures. Prestressed carbon FRP (CFRP) patches have emerged as a promising alternative to traditional methods of repair. However, prestressing these patches typically requires heavy and complex fixtures, which is impractical in many applications. This disclosure describes a new approach in which the prestressing force is applied by restraining the shape memory effect of nickel titanium niobium alloy (NiTiNb) SMA wires. The wires are subsequently embedded in an FRP overlay patch. This method overcomes the practical challenges associated with conventional prestressing.

A system for post tensioning a concrete member is disclosed. The system may include an anchor body, and a strand, the strand inserted through the anchor body. The strand may have a strand end and an outer diameter. The system may also include a pocket cap, the pocket cap positioned around the strand. The pocket cap may have a cylindrical interior wall, the cylindrical interior wall having a pocket cap diameter corresponding to the outer diameter of the strand.

A pocket former includes a pocket former body and a keyway former. The pocket former is adapted to form a void in a concrete member allowing access to the stressing end of a post-tensioning tendon. The keyway former is adapted to form a keyway in the concrete to allow grout to be more securely retained in the void.

A pocket former includes a pocket former body and a keyway former. The pocket former is adapted to form a void in a concrete member allowing access to the stressing end of a post-tensioning tendon. The keyway former is adapted to form a keyway in the concrete to allow grout to be more securely retained in the void.

A system for post tensioning a concrete member is disclosed. The system may include an anchor body, and a strand, the strand inserted through the anchor body. The strand may have a strand end and an outer diameter. The system may also include a pocket cap, the pocket cap positioned around the strand. The pocket cap may have a cylindrical interior wall, the cylindrical interior wall having a pocket cap diameter corresponding to the outer diameter of the strand.

An anchor assembly for a post-tensioning tendon may include a compact anchor and wedge. The compact anchor may include a wedge extension having a frustoconical inner surface. The frustoconical inner surface may have a diameter of 0.95 inches or less. The compact wedge may have a length of 1.1 inches or less. The compact anchor and compact wedge may be formed from steel having no added lead. The compact anchor and wedge may be formed by cold heading.

A concrete product comprising an adaptive prestressing system includes a concrete body and a composite wire embedded within the concrete body at a predetermined location. The composite wire comprises anchored end portions, each of which comprises a bonded wire segment constrained within the concrete body to resist axial motion, and an activable central portion between the end portions. The activable central portion comprises a shape memory alloy (SMA) wire segment and is axially movable within the concrete body. When heated at or above an austenite transformation temperature, the SMA wire segment contracts and the activable central portion exerts a tensile force on the end portions, thereby applying a compressive prestress within the concrete body at the predetermined location.