What does the isolation sleeve of prestressed steel bar refer to

Prestressed reinforcement.

The isolation sleeve refers to a bellows or a layer of plastic skin coated with anticorrosive oil.

The prestressed tendons and the isolation sleeve should be worn into place together after the reinforcement skeleton is completed. Once in place, it is strictly forbidden to use arc welding.

Cut or weld the beam reinforcement and formwork. The inner end of the isolation sleeve should be plugged tightly.

The tensile force is applied to the steel bar first, and then the concrete is poured, and the steel bar is loosened when the strength reaches the requirements, so that the steel bar is retracted, and the tensile force of the normal use load is offset (pre-tensioning method).

The post-tensioning method is to pour the concrete to reserve holes, add tensile steel bars after forming, and then anchor them at both ends of the component with instruments.

It refers to the bellows or a layer of plastic skin smeared with anti-corrosion oil, this thing, you have to distinguish between bonded and unbonded anchor cables, unbonded ones are needed, and bonded ones are not needed.

The first thing to do is to distinguish whether you are playing first or later.

The people above are very good!

There is no isolation sleeve, and the concrete is poured directly.

You're talking about bellows. There is no first.

Yes. When the tendon is stretched, the end is stressed too much, so in order to reduce the force at the end, an isolation sleeve is used. The pre-tensioning method often needs to set up failure sections at both ends of the beam plate, and the failure sections need to be separated from the concrete with an isolation sleeve, which can prevent excessive tensile stress at the upper edge of the end.

Isolation sleeves and post-tensioned pipes are not the same thing at all. The isolation sleeve of the prestressed steel bar refers to the bellows or a layer of plastic skin coated with anticorrosive oil.

Isolation sleeve settings:

The isolation sleeve is generally arranged at the end of the beam body, not all the prestressed tendons are set, and not the entire prestressed tendon is accidentally leaked to the isolation sleeve. Moreover, the general filial piety is to jump off one or two prestressed tendons, and there will be tremors, and a prestressed tendon is set up with an end isolation sleeve. The aim is to prevent all tendons from putting pressure on the ends.

It is equivalent to the compression surface of the dispersed precast beam.

Not all tendons are provided with isolation sleeves, and not all tendons are wrapped in isolation sleeves. And generally one or two prestressed tendons are jumped, and there is a prestressed tendon to set the end isolation sleeve. The aim is to prevent all tendons from putting pressure on the ends.

It is equivalent to the compression surface of the dispersed precast beam.

For the pre-tensioned prestressed reinforced concrete components with or without skeleton, they are divided into two types: ordinary skeleton and no ordinary reinforcement skeleton.

There is no ordinary steel skeleton pre-tensioning prestressed reinforced concrete member, and it can be tensioned directly according to the parameters of double control or single control (this depends on the design requirements).

There is an ordinary steel bar skeleton prestressed steel reinforced concrete member by the first tensioning method, and the ordinary steel bar skeleton that crosses with the prestressed steel bar should be installed first, and then the prestressed steel bar is passed through in the skeleton, and the isolation sleeve is worn before tensioning, which is to reduce the influence of the ordinary steel bar skeleton on the tensile control parameters, and this casing is a small section of casing placed at the intersection of the prestressed steel bar and the ordinary steel bar skeleton, not a long pipe (the long pipe is the process of the post-tensioning method).

When tensioning to double the control stress, install those ordinary steel bars and formwork and embedded parts that do not cross with the prestress.

1.Doesn't the fifth point clearly say that the steel bar should be tensioned first, and then the ordinary steel bar, formwork, and embedded parts should be installed? Why is the second point requiring the installation of the steel skeleton first?

If the ordinary steel skeleton that crosses with the prestress is not installed first, it will be illegally installed after tensioning.

2.What is the purpose of the pre-tensioning method that requires isolation sleeve protection? What are the requirements that need to be protected like this, and wouldn't it be better to pour it together with concrete?

The installation of the isolation sleeve is to reduce the influence of the ordinary reinforcement skeleton on the tension control parameters. This casing does not affect the combination of prestressed steel bars and concrete.

The casing is connected with the concrete by isolating the reinforcement, which is determined by the mechanical characteristics of the simply supported beam, and the reinforcement with the casing only bears the bending moment in the middle of the proximity to the span, so there is no need to anchor at the end like other reinforcements.

The textbook is written incorrectly, this sad broken book. Ignore him and you'll get it.