Method of de-tensioning a rod

A method of detensioning a rod, the method comprising:

• removably attaching a gripping unit removal device on a gripping unit where the gripping unit engages the rod;
• positioning a chair frame on the rod over a periphery of the gripping unit;
• positioning a rod tensioning unit on the rod with a first end of the rod tensioning unit being in contact with a surface of 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;
• releasing the second pressure on the rod tensioning unit.