Disclosed invention comprises innovations in the fabrication process and the associated design methodology for producing refined prestressed concrete elements/components. The innovations disclosed are fabrication using multiple stages, the use of ultra high strength materials for only critical subcomponents, utilizing thinner sections made of ultra high strength materials, and a unique method of inducing and controlling camber. The embodiments of this invention enable the accelerated construction of concrete structures that are both durable and cost effective. This disclosure demonstrates the significant improvements to the prior art in the areas of durability, constructability, and cost reduction for prestressed concrete components. The embodiments presented in this disclosure are for bridge superstructure applications.

A pre-stressed concrete box culvert includes a three-sided culvert top section having a pre-stressed top slab, a first sidewall and a second sidewall. The first and the second sidewalls extend orthogonally from opposite ends of the pre-stressed top slab, and the first and the second sidewalls each include a free end that has at least one male or female connector. The pre-stressed concrete box culvert includes a three-sided culvert bottom section having a pre-stressed bottom slab and a third sidewall and a fourth sidewall. The third and the fourth sidewalls extend orthogonally from opposite ends of the pre-stressed bottom slab, and the third and the fourth sidewalls each include a free end that has at least one male or female connector to mate with the at least one corresponding male or female connector arranged at one of the respective free ends of the first and the second sidewalls.

The method according to the invention for producing a prestressed concrete workpiece is characterized in that the prestress is created by a heat treatment, wherein the concrete and the reinforcement therefor are selected in such a way that, when cooling the concrete workpiece from an elevated temperature, the heat expansion coefficient of the concrete is less than that of the reinforcement, and in that, during cooling, the concrete and the reinforcement adhere sufficiently strongly to one another if, during cooling, the concrete is hydrated at least to such an extent in order to be able to expand the reinforcement on account of the different heat expansion coefficients, and in that the concrete, together with the reinforcement, is brought to the elevated temperature in such a way that and is hydrated during cooling at least to such an extent that it is prestressed by the reinforcement after cooling.

A process for molding prestressed slender and corrugated surface concrete bars to be used subsequently in casting concrete pieces or structures includes, placing them conveniently inside said pieces or structures, in order to also prestress said pieces or structures by gripping and relieving the tensions contained in said bar from the middle section of its longitudinal length.

A pre-stressed concrete box culvert includes a three-sided culvert top section having a pre-stressed top slab, a first sidewall and a second sidewall. The first and the second sidewalls extend orthogonally from opposite ends of the pre-stressed top slab, and the first and the second sidewalls each include a free end that has at least one male or female connector. The pre-stressed concrete box culvert includes a three-sided culvert bottom section having a pre-stressed bottom slab and a third sidewall and a fourth sidewall. The third and the fourth sidewalls extend orthogonally from opposite ends of the pre-stressed bottom slab, and the third and the fourth sidewalls each include a free end that has at least one male or female connector to mate with the at least one corresponding male or female connector arranged at one of the respective free ends of the first and the second sidewalls.

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 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.

In a method for producing a plurality of concrete cast elements of prestressed concrete, in particular for producing of railway sleepers, in a long bed which is a multiple of the length of a concrete cast element, in which separating elements are installed in the long bed to define the length of each of the concrete cast elements to be casted, a first and a second separating element for defining the length of a concrete cast element together with a tensioning device with tensioning elements for tensioning the concrete cast element between the two separating elements are mounted in the long bed, whereupon the concrete cast element is cast between the two separating elements and is at least partially hardened in the long bed.

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 pocketformer includes a pocketformer body having a tapered exterior surface. The exterior surface has at least one portion along a length thereof of substantially constant diameter. The pocketformer body has a feature for engaging an anchor base in a concrete structure prior to pouring concrete and a grout ring having a substantially constant inner diameter substantially equal in diameter to the at least one portion. The grout ring has an exterior surface shaped to cause retention of the grout ring in set concrete.