- Issue Time
This article will share specific methods for testing the mechanical properties of prestressed concrete strands for your reference.
The mechanical properties of prestressed concrete steel strands must be superior so that they can carry a larger load and will be more stable in the application. Then we can use the following three tests to test the mechanical properties of prestressed concrete steel strands.
Tensile test of steel strand for prestressed concrete
1. Force range
The force range test of the whole steel strand is carried out in accordance with the provisions of GB/T 228. If the sample breaks in the chuck and is within 2 times the nominal diameter of the steel strand from the jaws, the test is invalid if the performance requirements of this standard are not met. When calculating the tensile strength, take the reference cross-sectional area value of the steel strand.
2. Prescribe non-proportional extension force
The non-proportional extension force of the steel strand is the force when the non-proportional extension of the extensometer gauge length reaches 0.2% of the original gauge length. In order to facilitate the daily inspection of the supplier, the force can also be determined when the specified total extension reaches 1% of the original gauge length and the value meets the value specified in this standard.
Stress relaxation performance test of steel strand for prestressed concrete
1. The stress relaxation performance test of steel strands should be carried out in accordance with GB/T 10120.
2. During the test, the ambient temperature of the sample should be kept within 20℃±2℃.
3. The test gauge length is not less than 60 times the nominal diameter.
4. No heat treatment or cold working shall be carried out after sample preparation.
5. The initial load should be evenly applied within 3min to 5min, and the relaxation value should be recorded after the load is held for 1min.
6. Allow at least 100h of test data to calculate the relaxation rate value of 1000h.
Fatigue test of steel strand for prestressed concrete
1. The sample used in the fatigue test is the sample taken directly from the finished steel strand. The length of the sample should ensure that the distance between the two clamps is not less than 500mm.
2. In the whole process of the test, the static measurement error of the pulsating tensile stress to maintain constant stress should not be greater than ±1%.
3. The stress cycle frequency cannot exceed 120Hz.
4. All stresses are transmitted to the specimen along the axial direction, and there shall be no influence of jaws and notches, and there shall be a corresponding device that can limit any slippage of the specimen in the chuck.
5. The test is invalid when the sample is broken in the chuck and in the clamping area (2 times the nominal diameter of the steel strand) due to the influence of the notch or local overheating.
6. During the test, the temperature of the test piece shall not exceed 40℃, and the ambient temperature of the test room shall be 18℃~25℃.
Whether in the process of testing or application, we should strictly follow the standards to prevent the performance of the prestressed concrete steel strands from being affected.
As a professional manufacturer of prestressed concrete products, we have always been committed to providing customers with high-quality and safe products. We have an experienced manufacturing team and a strict quality inspection department to strictly control the quality of the production process. At the same time, we can also provide corresponding customized services according to customer needs. If you are interested in our prestressed concrete steel strands, please contact us immediately!