Detensioning system and a method for detensioning a structural element or a tensioning element

A detensioning method for detensioning a portion of a structural element or a tensioning element, comprising the following steps:

• a) removing of sheath and/or grout covering the portion of the structural element or the tensioning element in case such sheath and/or grout is present, thereby exposing a core element of the structural element or the tensioning element;
• b) placing first and second clamping devices on the exposed core element, wherein the first and second clamping devices are positioned between the portion of the structural element or the tensioning element to be detensioned, wherein each clamping device of the first and second clamping devices has an internal surface profile is configured to form an elongated, annular cavity surrounding the structural element or the tensioning element to be detensioned, comprising an empty space configured to introduce one or more inner elements within the elongated, annular cavity, wherein the elongated, annular cavity comprises a gradually declining diameter along a longitudinal axis of the elongated, annular cavity shaped by at least one peak and one groove of the internal surface profile;
• c) joining the first and second clamping devices with at least two stressbars;
• d) activating stressbar hydraulic cylinders which are mounted either directly to the first and second clamping devices, respectively, or mounted on a respective stressing chair which in turn is bearing against a corresponding one of the first and second clamping devices in order to transfer a load from the structural element or the tensioning element to the at least two stressbars, wherein the stressbar hydraulic cylinders are actuated until reaching approximately the same or slightly below an original load carried by the structural element or the tensioning element;
• e) retaining the load transferred to the at least two stressbars joining the first and second clamping devices;
• f) cutting the exposed core element of the portion of the structural element or the tensioning element to be detensioned while holding the load and strain of the structural element or the tensioning element;
• g) relaxing the stressbar hydraulic cylinders until the portion of the structural element or the tensioning element is completely detensioned.