Under what circumstances can a prestressed steel strand be stretched in a section

When the length of the unbonded prestressed tendon exceeds 30m, it is advisable to take tension at both ends; When the length of the rib exceeds 60m, it is advisable to take sectional tensioning and anchoring. Note: When there is a reliable design basis and engineering experience, the length of the unbonded prestressed tendon can be exempted from this limitation.

In the actual construction, it is recommended that you take less than 25 meters, single-sided tensioning; At 25-50 meters, both ends are stretched; Sectional tensioning when greater than 50 meters.

The prestressed steel strand is mainly made of cold-drawn high-carbon steel.

It is made with trace amounts of phosphide and lubricant residues on the surface.

Particularly high strength (e.g. 2300 MPa) requires the addition of alloying elements such as chromium, and galvanized high-strength products can increase the silicon content.

Partial carbon steel.

The surface of the prestressed steel strand made has coating materials, such as zinc, zinc-aluminum alloy, epoxy resin.

grease and high-density polyethylene.

sheaths, etc. Stainless steel can also be used to make prestressed steel strands, using high-strength duplex stainless steel.

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When can you stretch it in sections?

The prestressed steel strands are 1225 1960 MPa with higher strength, 1960 3135 MPa lead finger and 3135 MPa with high strength. According to the following basis, the ultimate strength of the steel strand is calculated: the tensile force of the steel strand prestressed tension construction design controls the tensile force, which refers to the tensile force of the steel strand in front of the anchor clamp after the prestressed tension is completed.

Therefore, in the calculation of the theoretical elongation of the prestressed tension of the steel strand, the distance between the anchor points at the two ends of the steel strand should be used as the calculated length of the steel strand, but the trembling key control tension of the steel strand is controlled at the jack tool anchor when the prestressed tension is made.

Prestressed steel strands.

It is a stranded steel cable composed of or 19 high-strength steel wires, and is made of stress relief. In most post-tension prestressing and pre-tensioning prestressing projects, smooth steel strand is the most widely used prestressed steel.

The main characteristics of the prestressed steel strand are high strength and good relaxation performance, and it is more upright than the ear. To prolong durability, the wire can have metallic or non-metallic plating or coating, such as galvanized and epoxy coating.

Wait. In order to increase the grip with the concrete, the surface can have tremors or nicks.

Prestressed steel strands include ordinary prestressed steel strands, galvanized prestressed steel strands, and unbonded prestressed steel strands.

Ordinary prestressed steel strands are not coated with lead anticorrosive grease or paraffin mountain reeds and wrapped with HDPE, which eliminates stress and has good toughness and strength, and is used in concrete structures.

Galvanized prestressed steel strands are also available in galvanized or galvanized aluminum alloy steel wires.

The unbonded prestressed steel strand is made of prestressed steel strand coated with HDPE after being coated with anticorrosive grease or paraffin.

Summary. Hello, glad to answer for you! The prestressed steel strand tension prestressed tension is to add tension in advance in the component, so that the applied prestressed tension member bears the compressive stress, and then makes it produce a certain deformation to cope with the load on the structure itself, including the load of the component's own weight, wind load, snow load, load action, etc.

Generally, steel strands, jacks, anchor plates, and clips are used for tensioning.

Hello, I'm glad to answer for you! The prestressed steel strand tension prestressed tension is to add tension in advance in the component, so that the applied prestressed tension member bears the compressive stress, and then makes its production zone produce a certain deformation, and the dust liquid reed should cope with the load on the structure itself, including the load of the weight of the component itself, wind load, snow load, load action, etc. Generally, steel strands, jacks, anchor plates, and clips are used for tensioning.

Before the external load of the engineering structural components, the pretensile stress of the steel strand in the tension module is applied to improve the bending ability and stiffness of the components, delay the occurrence of the lie joints, and increase the durability of the components. For the mechanical structure, the meaning is to make it stress in advance, and its advantage is that it can improve the rigidity of the structure itself, reduce vibration and deformation, and this can significantly improve the strength of the tension module and make the original anti-xing stronger. When the tensioning beam needs to be stretched many times due to the insufficient stroke of the jack tensioning piston, it should be tensioned gradingly, and after the temporary anchoring of the intermediate levels, the jack should be reinstalled, and the meter should be read and the elongation value should be measured again before continuing to be stretched, so as to avoid the cumulative error of elongation measurement.

Tension length value control: the tension force is the main method, and the elongation value is checked. The elongation of the jack piston is measured L1 when the initial stress is measured, and the elongation of the jack piston L2 is measured when the tension reaches 20% SCON, and the difference between the two is the actual estimated elongation of the steel hunger bundle.

The tension of the 100% SCON is then measured by the elongation of the jack piston L3, L3 L1 and the difference between the two dry ones is the actual tensile length of the steel bundle. The sum of the actual tensile length and the actual estimated elongation, compared with the theoretical elongation, the error shall not exceed +6% and -6%, otherwise the machine should be stopped to check the reason, and the tension can be adjusted before it can be tensioned, and it shall be processed if necessary.