Discussion on Tensile Test Method of Prestressed Concrete Steel Strand

Discussion on Tensile Test Method of Prestressed Concrete Steel Strand

Summary

This article takes the prestressed concrete steel wire mechanical properties test method as the main research content and key of the test equipment and discusses the tensile test method of the prestressed steel wire.

 the prestressed concrete steel wire mechanical properties test method

In order to meet the structural safety requirements, the mechanical properties of the steel strands are an important aspect. This paper takes the prestressed concrete steel wire mechanical performance test method as the main research content and key of the test equipment discusses the tension and yield load, ultimate load, and other issues, and provides a good reference value for engineers engaged in related work.

Prestressed construction technology is also used in the construction of railways, highways, bridges, and buildings in my country. In order to ensure the quality of prestressed engineering materials, the prestressed concrete steel wire must be inspected strictly in accordance with the GB/t5224-2003 standard test.

The uncertainty evaluation and analysis of the tensile strength test results of prestressed concrete steel strands provide a basis for improving the detection level and also provide a reference basis for the uncertainty of the test results.

Calculation of elongation of prestressed concrete strand
 
Prestressed concrete strand construction is divided into two types, namely the pre-tensioning method, and the post-tensioning method. Since the average stress in different linear intervals is very different, it is necessary to calculate the elongation value after each calculation.

Tensile prestressed concrete construction, in order to ensure the quality of construction, in addition to the use of pressure control and elongation, this article also requires the difference between the actual elongation value and the theoretical elongation value to be controlled within plus or minus 6%, so in the prestress, the calculation of the beam tension extension is very important. Based on relevant data and own construction experience, this article puts forward some opinions on the calculation and measurement of tensile stress elongation.

Use round clamps

The biggest feature of the circular clamp is that the lower jaw is round. When it holds the steel strand, the lower jaw on any cross-section of the figure is surrounded by a circle, which can ensure the lower jaw 6. The outer steel wire and the steel strand are engraved at the same time. Use a circular clamp after the tensile test specimen: the lower jaws on the 6 outer steel strands are basically continuous and uniform in length, depth, and load points are completely synchronized.

Add metal pieces to the V-shaped fixture

The length of the pliers of the testing machine is 225mm, and the aluminum plate of 1.2x20x250mm is used, covered with a layer of 30 layers of emery, and bent into an arc. The trial will wrap the test machine between the chin with two pieces of clamp steel chain. The required clamping length is as complete as possible, so as to prevent sliding and avoid damage to the steel chain by the clamp incision, just because of friction, some roughness, the middle sample Broken, all seven wires are broken, showing ductile fracture.

Pay attention to the adhesive tape of silicon carbide. At the end of the blank aluminum tape of about 20 mm, in order to prevent the tracking of the hydraulic jaws, stress concentration is generated at the end and the steel strand is broken at the root of the tooth.

Determination of maximum tension

Because the steel wire has a special appearance shape and strong notch sensitivity, the determination of the maximum tension is often affected by some objective factors, so special attention should be paid to Whether the specimen clamping device is reasonable; whether the specimen causes scratches; whether It is necessary to conduct experiments; proper loading speed is an important guarantee for experiments.

After the specimen fails, the maximum tensile strength cannot meet the standard value, and the reason for the fracture of the broken wire is analyzed. If the fracture is significantly thinner, the data is correct. If the specimen grabs or bites due to the unreasonable clamping device and clamping device, stress concentration occurs, resulting in scratches on the pre-broken specimen, it should not be judged as an evaluation based on the test The data should be sampled and tested.

This article provides two methods to make the steel strand evenly gain strength on the external steel wire and improve the accuracy of the test results. As an expert who has studied prestressed concrete steel strands for many years, CHUNPENG can give you some professional guiding opinions to a certain extent.

CHUNPENG is a professional manufacturer of prestressed concrete products. We have many years of experience and a strict quality inspection system. We uphold a responsible attitude towards users and take full control of all aspects of product manufacturing and export. At the same time, we will also provide a one-stop-shopping service according to the diverse needs of users. If you want to buy our prestressed concrete strands, please contact us immediately!