Methods and systems for monitoring stress in a tendon during concrete tensioning using a jack
A process for monitoring stress applied to a tendon by a hydraulic jack during tensioning of concrete is described. The process includes measuring an amount of hydraulic fluid that flows through the hydraulic jack during tensioning of the tendon. The measured amount of hydraulic fluid is corelated with an amount of stress applied per unit of hydraulic fluid to determine a total amount of stress employed on the tendon. The process can also include measuring the distance of travel of the hydraulic piston. The measured travel can then be used to calculated the distance the tendon has been pulled (i.e., the elongation), as well as the stress applied to the tendon.
1 . A process for monitoring stress applied to a tendon by a hydraulic jack during tensioning of concrete, comprising:
measuring, using at least one sensor, a distance of travel of a piston on a hydraulic jack during tensioning of concrete wherein the at least one sensor is mounted on the hydraulic jack proximate the piston and configured to measure a linear movement of the piston;
transmitting, wirelessly, the output of the at least one sensor to a pump unit that is located external to the hydraulic jack;
calculating, by one or more processors located on the pump unit, a total amount of stress employed on the tendon from the measured distance; and
displaying, at the hydraulic pump unit, the total amount of stress;
wherein the at least one sensor comprises a linear potentiometer, a linear magnetic Hall sensor, a magnetostrictive linear position sensor, a Linear Variable Differential Transformer (LVDT) sensor, a Linear Variable Inductance Transducer (LVIT) sensor, a Hall effect technology sensor, or an optical probe with optoelectronic sensor technology.
2 . The process of claim 1 , that further comprises measuring and displaying one or more operating parameters of the hydraulic pump, the one or more operating parameters comprising temperature and flow of hydraulic fluid.
3 . The process of claim 1 , wherein the hydraulic jack comprises a frameless lightweight hydraulic jack, a twin cylinder jack, or a single cylinder jack.
4 . The process of claim 1 , wherein the tendon is monostrand or multistrand.
5 . The process of claim 1 , further comprising: transmitting, wirelessly, the total amount of stress and the operating parameters to an external device that is separate and apart from the hydraulic jack and the pump unit.