A rod detensioning unit including a gripping unit removal device that engages a gripping unit on a rod, a chair frame configured to engage a rod, a rod tensioning unit that applies tension to an external portion of the rod to remove load from the gripping unit, a load cell unit that measures a tension level applied to the rod by the tensioning unit, a plate gripping unit that engages the rod and secures the chair frame, rod tensioning unit, load cell and plate gripping unit to the rod, a drive unit that engages the gripping unit removal device, and an extension unit affixed to the external portion of the rod when the original external rod length is too short to accommodate the de-tensioning unit.

The present invention relates to a system for monitoring tension forces of tendons in post-tensioning that accurately measures the tension forces of the tendons and/or controls the tension forces introduced into the tendons through a main server, thereby allowing the tension forces to be applied uniformly to the tendons.

According to the present invention, there is provided the system for monitoring tension forces of tendons disposed inside a concrete structure in post-tensioning, the system including: a hydraulic jack coupled to one tendon at one end of the concrete structure to apply the tension force to the tendon by means of the forward movement of a piston; a hydraulic pump connected to the hydraulic jack by means of a hydraulic pressure supply pipe to supply a hydraulic pressure to the hydraulic jack; a digital elongation length measurement sensor disposed on the hydraulic jack to measure the elongation length of the piston; a measurement unit having a data logger adapted to receive and store the elongation length data measured by the digital elongation length measurement sensor and to send the elongation length data to a main server; a digital pressure measurement sensor disposed on the hydraulic pressure supply pipe of the hydraulic pump; and a control module adapted to receive the elongation length data from the data logger or the main server, calculate the tension force, compensate for the coefficient of elasticity of the tendon according to the ratio of the real-time elongation length data to the pressure data, and compensate for the tension force calculated.

A method for producing a three-dimensional construction material component preferably having at least one curved surface. A plurality of spacers are arranged in a formwork. A textile reinforcement is supported on the spacers, such that the textile reinforcement has a defined position within a formwork interior of the formwork. A tensile force is applied via a tensioning device to the textile reinforcement in at least one tension direction. Construction material is introduced into the formwork interior and surrounds the textile reinforcement. The construction material is then hardened, wherein the tensile force is maintained during the hardening. During this process, the spacers are integrated into the construction material component. The tensioning device has at least one clamping unit for clamping an end portion of the textile reinforcement between two clamping surfaces. The clamping surfaces are provided on clamping insert bodies, which are of a plastic material of a defined hardness.

A method of de-tensioning a rod by attaching a gripping unit removal device to a gripping unit and rod, positioning a chair frame over the gripping unit, positioning a rod tensioning unit along the rod with one end of the rod tensioning unit being in contact with the chair frame, applying a first force to the rod tensioning unit, positioning a bearing plate on the rod in contact with the rod tensioning unit, positioning a load cell in contact with the rod on the rod tensioning unit, securing a drive unit to the chair frame such that a portion of the drive unit is in contact with the rod, applying a second pressure to the rod tensioning unit, actuating the drive unit, and releasing the second pressure on the rod tensioning unit.

A system for monitoring tension forces of tendons disposed inside a concrete structure in post-tensioning includes a hydraulic jack coupled to one tendon at one end of the concrete structure to apply the tension force to the tendon by means of the forward movement of a piston; a hydraulic pump connected to the hydraulic jack by means of a hydraulic pressure supply pipe to supply a hydraulic pressure to the hydraulic jack; a digital elongation length measurement sensor disposed on the hydraulic jack to measure the elongation length of the piston; a measurement unit having a data logger adapted to receive and store the elongation length data measured by the digital elongation length measurement sensor and to send the elongation length data to a main server; a digital pressure measurement sensor disposed on the hydraulic pressure supply pipe of the hydraulic pump; and a control module adapted to receive the elongation length data from the data logger or the main server, calculate the tension force, compensate for the coefficient of elasticity of the tendon according to the ratio of the real-time elongation length data to the pressure data, and compensate for the tension force calculated.

An improved method and apparatus for evaluating post-tensioning tendons, where the apparatus uses a positioning head placed directly into the pocket and against the anchor without making contact with the wedges as the apparatus seats on the tendon. From this position the apparatus evaluates the tendon by marking, measuring the tendon, and/or determining its location with increased reliability and precision.

A rod detensioning unit including a gripping unit removal device that engages a gripping unit on a rod, a chair frame configured to engage a rod, a rod tensioning unit that applies tension to an external portion of the rod to remove load from the gripping unit, a load cell unit that measures a tension level applied to the rod by the tensioning unit, a plate gripping unit that engages the rod and secures the chair frame, rod tensioning unit, load cell and plate gripping unit to the rod, a drive unit that engages the gripping unit removal device, and an extension unit affixed to the external portion of the rod when the original external rod length is too short to accommodate the de-tensioning unit.

A rod detensioning unit including a gripping unit removal device that engages a gripping unit on a rod, a chair frame configured to engage a rod, a rod tensioning unit that applies tension to an external portion of the rod to remove load from the gripping unit, a load cell unit that measures a tension level applied to the rod by the tensioning unit, a plate gripping unit that engages the rod and secures the chair frame, rod tensioning unit, load cell and plate gripping unit to the rod, a drive unit that engages the gripping unit removal device, and an extension unit affixed to the external portion of the rod when the original external rod length is too short to accommodate the de-tensioning unit.

In some embodiments, the disclosure is directed to a cable tensioning unit. In some embodiments, the cable tensioning unit includes a hydraulic jack mounting on a unit housing. In some embodiments, the unit housing includes a control panel with one or more actuators configured to control one or more pulling functions. In some embodiments, the cable tensioning unit includes a controller and a controller interface that enables a user to set interlocks and/or enter pull information. In some embodiments, pull information includes one or more of bed number, bed length, strand size, strand number, target initial tension, target final tension, target final elongation, date, time, actual initial tension, and/or actual final tension. In some embodiments, the controller is configured to automatically save data during one or more transient operations. In some embodiments, the controller is configured to display if pull information is within a tolerance during a pull operation.

A pre-stressed cast concrete structure comprises embedded fibrous reinforcing tendons in tension. The fibrous reinforcing tendons each comprises a plurality of continuous non-metallic fibers extending substantially the entire length of the tendon. A system for pre-stressing a cast concrete structure includes a mold for containing concrete, fibrous reinforcing tendons, chuck assemblies associated with the reinforcing tendons and a tensioning mechanism. When cured, the concrete rigidly surrounds the reinforcing tendons such that the reinforcing tendons are maintained in tension. The chuck assemblies have a plurality of jaws that contact the reinforcing tendons in a manner to resist damage to the fibers.