The invention provides a prefabricated structural element including an elongate body (11) and at least one first tensioner (1) that is fastened in the elongate body in such a manner that it compresses the elongate body. The structural element includes at least one second tensioner (2) that is fastened to the elongate body at two distinct points by two fastener element so that it compresses the elongate body, at least one of the fastener element being removable so as to make it possible to relax the compression exerted on the elongate body by the second tensioner.

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 method of manufacturing a pre-stressed beam or panel and the resulting beam or panel are described. The method includes providing a timber-based component (1); providing a pre-stressing member (9) arranged along the timber-based component; applying a tensile force to the pre-stressing member (9); providing concrete anchors (11a, 11b) at locations that are spaced apart along the timber-based component (1); coupling the pre-stressing member (9) to the concrete anchors (11a, 11b); and releasing the tensile force on the pre-stressing member (9) to transfer a compressive force to the timber-based component (1) through the concrete anchors (11a, 11b) to form a pre-stressed beam or panel.

A method of manufacturing a pre-stressed beam or panel and the resulting beam or panel are described. The method includes providing a timber-based component (1); providing a pre-stressing member (9) arranged along the timber-based component; applying a tensile force to the pre-stressing member (9); providing concrete anchors (11a, 11b) at locations that are spaced apart along the timber-based component (1); coupling the pre-stressing member (9) to the concrete anchors (11a, 11b); and releasing the tensile force on the pre-stressing member (9) to transfer a compressive force to the timber-based component (1) through the concrete anchors (11a, 11b) to form a pre-stressed beam or panel.

The precast reinforced concrete construction elements with pre-stressing connectors provide beam-column connections which are post-tensioned through a combination of active and passive pre-stressing tendons. The active pre-stressing tendons improve the efficiency and effectiveness of the beam-column connections under service loads, as well as during application of external forces and stresses, such as during earthquakes. The passive pre-stressing tendons are lightly pre-stressed and only become effective during progressive collapse of the building. Specifically, the passive pre-stressing tendons become stressed only during downward movement of a joint due to the loss/damage of a column, thus providing resistance against further downward movement of the joint and thereby resisting the progressive collapse.

The precast reinforced concrete construction elements with pre-stressing connectors provide beam-column connections which are post-tensioned through a combination of active and passive pre-stressing tendons. The active pre-stressing tendons improve the efficiency and effectiveness of the beam-column connections under service loads, as well as during application of external forces and stresses, such as during earthquakes. The passive pre-stressing tendons are lightly pre-stressed and only become effective during progressive collapse of the building. Specifically, the passive pre-stressing tendons become stressed only during downward movement of a joint due to the loss/damage of a column, thus providing resistance against further downward movement of the joint and thereby resisting the progressive collapse.

This method is suitable for the strengthening of concrete or timber structures (1, 4) by applying prestressed Carbon FRP or Glass FRP lamella (8). Firstly, at least one groove (22) is cut into the concrete or timber structure (1, 4) along the direction in which the concrete or timber structure (1, 4) is to be strengthened. The grooves (22) are filled with epoxy resin (9) and a layer of epoxy resin (9) is put onto the entire section to be equipped with the CRFP or GFRP lamella (8). The lamella (8) will be prestressed and anchored at both ends. U-shaped brackets (24) are then being put over the two end sections of the CFRP or GFRP lamella (8) by inserting and submerging its both U-legs (27) into holes (26) filled with resin as well. These holding brackets (24) will then tightly press onto the CFRP or GFRP lamella (8) to prevent cracking or fracture of the concrete or timber and bending away of the extremities of the CFRP or GFRP lamella.

This method is suitable for the strengthening of concrete or timber structures (1, 4) by applying prestressed Carbon FRP or Glass FRP lamella (8). Firstly, at least one groove (22) is cut into the concrete or timber structure (1, 4) along the direction in which the concrete or timber structure (1, 4) is to be strengthened. The grooves (22) are filled with epoxy resin (9) and a layer of epoxy resin (9) is put onto the entire section to be equipped with the CRFP or GFRP lamella (8). The lamella (8) will be prestressed and anchored at both ends. U-shaped brackets (24) are then being put over the two end sections of the CFRP or GFRP lamella (8) by inserting and submerging its both U-legs (27) into holes (26) filled with resin as well. These holding brackets (24) will then tightly press onto the CFRP or GFRP lamella (8) to prevent cracking or fracture of the concrete or timber and bending away of the extremities of the CFRP or GFRP lamella.

There is provided a method of introducing prestress into a beam-column joint of PC construction to make it into a triaxially compressed state, in which the beam-column joint is made into a triaxial compression state and reasonable prestress is introduced into cross section areas of the ends of the members forming the beam-column joint. A tensile introducing force is generated by tensionally anchoring PC cables passed through the beam-column joint to introduce prestresses into the cross section areas of the ends of the members forming the beam-column joints in respective axial directions to make triaxial compression state, to satisfy the following conditions (1) and (2): (1) no tensile strength is generated, with respect to long term design load, in cross-section areas of the members forming the end of the beam and the end of the column, which ends are in contact with the beam-column joint; and (2) upon occurring of extremely large scale earthquake (very rarely occurred earthquake), in the beam-column joint, no generation of diagonal cracks is allowed to be generated but diagonal tensile stress intensity caused due to shear force inputted by seismic load is made less than allowable tensile stress intensity of concrete.

There is provided a method of introducing prestress into a beam-column joint of PC construction to make it into a triaxially compressed state, in which the beam-column joint is made into a triaxial compression state and reasonable prestress is introduced into cross section areas of the ends of the members forming the beam-column joint. A tensile introducing force is generated by tensionally anchoring PC cables passed through the beam-column joint to introduce prestresses into the cross section areas of the ends of the members forming the beam-column joints in respective axial directions to make triaxial compression state, to satisfy the following conditions (1) and (2): (1) no tensile strength is generated, with respect to long term design load, in cross-section areas of the members forming the end of the beam and the end of the column, which ends are in contact with the beam-column joint; and (2) upon occurring of extremely large scale earthquake (very rarely occurred earthquake), in the beam-column joint, no generation of diagonal cracks is allowed to be generated but diagonal tensile stress intensity caused due to shear force inputted by seismic load is made less than allowable tensile stress intensity of concrete.