Method for static load anchorage test of prestressed anchors in Guizhou

The static load anchorage test is to test the mechanical properties of the anchor parts, test their reliability and applicability in the anchoring process, and permanent anchoring performance. The prestressed anchors can evenly transmit the force to the prestressed concrete components and steel There should be no large deformation or lateral or diagonal fractures in the components. The anchors should also have the ability to be reused many times, and all of these must be tested through static load tests to check whether they are qualified or not. Test method
When everything is ready, you can do this test. The steel strand is provided by us. When the design grade of the steel strand and the anchorage submitted for inspection are the same, we will conduct the test according to the test method. The number of holes in the anchor, the length of the meter should be cut. When taking the steel strand, pay attention to the fact that the steel strand must not have any damage or butt welding joints. Only such steel strand can be used. Then observe the room temperature and humidity. Whether it meets the temperature and humidity requirements of the test. If there are no special requirements for the temperature, it is ℃. When the temperature and humidity meet the requirements, you can start the test. First, you should make the hardness according to the specifications. When the hardness meets the requirements, you can do the static load test. .
Preparation before the test
First check whether each line and the cables of the upper and lower computers are connected correctly and securely. After checking that everything is connected, first turn on the switch of the computer and the intelligent digital display collector, and then enter the software. Double-click the software icon and enter the user name and password to enter the software interface. Click the new test icon on the toolbar. A dialog box will appear. Select the test type as tensile test, select the test as static load anchorage test, and the execution standard as anchorage for prestressed tendons, and then Enter the group number of this test to confirm, and then enter the test parameter interface. In the test parameter interface, first enter the sample parameters and test parameters. In the test parameters, enter the number of prestressed steel rods as the root and the nominal section of the single specimen. area, actual average ultimate tensile strength, etc. After inputting, press the Enter key, then uncover the mesh cover of the steel strand root and insert it into both ends of the testing machine, and then run the jack on one side of the tensioning end repeatedly to remove the air. If Any oil leakage must be tightened promptly, the load generated when extending the jack must be cleared, and each sensor channel must be cleared before clamping the specimen. Then arrange the steel strands into a parallel state, install anchor rings at both ends, and install transition pads at the tension ends. The anchors are also installed so that each steel strand is tensile in parallel. At this time, test the elasticity of the machine. The compressed dial indicator is installed in place so that it just touches and clears to zero. Then use a small jack to add initial stress to the prestressed tendons at the tension end. When the initial stress reaches the standard value of the tensile strength of the steel strands, the initial stresses of the three steel strands must be consistent and uniform. At this time, the steel strands have been tightened. Use a tape measure to measure the distance between the clamping points of the anchors at both ends, then enter it into the test parameter force length column and press Enter.
At this time, use a vernier caliper to measure D. D is to take several representative prestressed steel strands and measure the relative displacement between them and the anchors. In order to obtain several representative parts of the anchor, the anchor measures the relative displacement between them. Take good notes.
Run the test
At this time, click Run to switch to the main curve interface, manually control the oil delivery valve to refuel, and apply the test load. The steps are: according to the standard value of tensile strength of prestressed steel, ,,, graded and constant speed After loading, the loading speed should be about / or so, and then the holding load should be slowly loaded at a speed lower than / or so until complete failure, so that the load reaches the maximum value. The standard tensile strength of a steel strand is =. When it is added, start measuring and record it. Observe that the number recorded should be smaller than the number but proportionally smaller. If D is not proportional, it means that the steel strand should be checked to see if it loses anchorage and slips. If it is not proportional, check whether the relevant parts (anchor ring, anchor plate, etc.) have plastic deformation. By analogy, when the load is applied, D should remain stable during the load holding period. Measure D twice during half the time of holding the load. If it continues to increase and cannot be stable, it indicates that the reliable anchoring ability has been lost. During the test, the changes in the curve should be observed at all times in order to master the test details. Record the starting and ending time of holding the load. At this time, record the dial indicator reading of the elastic deformation of the pedestal and remove it.
After the load holding time is over, load slowly at a speed less than // to complete failure. When the specimen reaches the maximum tensile force, the ultimate tensile force and the total strain of the free length of the prestressed tendon shall be recorded. When the specimen breaks, turn off the oil pump immediately, record the jack and displacement, and record the maximum pulling force. The failure mode of the prestressed tendon anchor assembly should be the fracture of the prestressed steel (multiple roots break at the same time), and the deformation of the anchor parts should not be excessive or broken. The clips of clip-type anchors are not allowed to crack or break when the prestressed tendon stress reaches. Micro cracks and longitudinal breaks are allowed after meeting the qualification standards, and transverse, oblique breaks and fragmentation are not allowed. It is normal for the clip to be damaged or broken due to the impact of violent breakage of multiple or entire bundles of prestressed tendons. When the tensile force of the prestressed tendon reaches the ultimate breaking point, the anchor plate and its tapered anchor hole are not allowed to undergo excessive plastic deformation, and the residual deformation in the center of the anchor plate should not show obvious deflection
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Address: North of Pengdu Township, Binhu New District, Hengshui, Hebei Province Tamura