Testing method for friction loss and anchorage loss of post-tensioned prestressed concrete structures

Abstract

The invention discloses a method for detecting the friction loss and anchoring loss of a post-tensioned pre-stressing concrete structure. The method can detect two pre-stress loss indexes such as the friction loss and anchoring loss required by the specification, and can also measure the friction loss of a pre-stress tendon in both a one-end tensioning construction process and a two-end tensioning construction process. The method disclosed by the invention is higher in detection precision and stability, and all the defects of stress loss detection of the conventional sensor method can be overcome; and meanwhile, whole pre-stress construction processes can be effectively detected and monitored. The method can be widely applied to high-intensity materials for pre-stressing, such as non-bonded pre-stressed tendons, retard-bonded pre-stressed tendons, steel bars, steel ropes and carbon fiber bars, so as to detect the friction loss and anchoring loss of the post-tensioned pre-stressing concrete structure of each pre-stressed tendon during pre-stress tensioning construction.

Description

technical field [0001] The invention belongs to the field of construction detection and monitoring during prestressed tensioning construction of post-tensioned prestressed concrete structures in construction engineering, and in particular relates to a detection method for friction loss and anchorage loss of post-tensioned prestressed concrete structures. Background technique [0002] When the post-tensioned prestressed concrete structure is tensioned on site, the prestress loss mainly includes friction loss and anchorage loss. Friction loss refers to the sum of the friction loss at the anchor port at the tension end and the friction loss between the prestress tendon and the tunnel wall when the prestressed tendon is stretched; the anchor loss refers to the deformation and Prestress loss caused by shrinkage of prestressed tendons. At present, the sensor method of installing sensors under the anchorage or before and after the anchorage is often used to detect the friction los...

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Problems solved by technology

[0003] Using the method of embedding sensors under the anchor or installing sensors before and after the anchorage to detect the loss of prestress often has the following problems: 1. The sensor method to detect the friction loss of prestress can only be used for prestressed tunnels that are stretched at both ends, and is not applicable Because of the prestressed channel stretched at one end, it is impossible to measure the prestressed friction loss at one end. This is because the sensor method detects the prestressed friction loss. During tensioning construction, a sensor needs to be installed under the anchorage at both ends of the channel. Since the fixed end of one end of tension is poured into the concrete, the sensor cannot be installed during tension, and a sensor can only be installed under the anchorage of the tension end, so that the friction loss value cannot be measured when one end is tensioned; 2. Sensor If the centering is not good or uneven eccentricity is pressed, it is easy to cause the sensor to display inaccurately. If the sensor is found to be inaccurate during the tension test, it needs to be reinstalled, which is labor-intensive and time-consuming; 3. Repeated tensioning is required when testing the channel friction 3 times, this will easily cause the steel strand at the tool anchor to break; 4. After testing the anchorage loss, the anchorage needs to be withdrawn to take out the sensor, which brings inconvenience to the construction, and if the sensor is not taken out, the cost is high; 5. Some construction sites have poor conditions, especially when the dark anchor is designed, the installation of the sensor is very inconvenient, which often causes the installation to be out of position

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