Prestressed steel includes: prestressed reinforcement, prestressed steel tendon and prestressed steel strand.
In order to improve the bearing capacity of concrete, the concrete is subjected to a certain compressive stress in advance by applying prestress to the reinforcement. The reinforcement that is used to apply pressure but bears tension itself is called prestressed reinforcement.
Prestressing tendons are usually composed of single or bundled steel wires, strands or bars. In the production of pretensioning method, in order to bond with concrete reliably, half of them are deformed steel bars, nicked steel wires or steel strands; In post tensioning production, smooth steel bars, smooth steel wires or steel strands are used, and they are divided into unbonded prestressed reinforcement and bonded prestressed reinforcement.
1. Prestressed thick reinforcement Prestressed steel bars are made by pre tensioning or post tensioning the steel bars before the use of structural members.
2. Prestressed tendons The steel wire bundle is composed of parallel steel wires into a neat set of steel wires, that is, steel wire bundles.
3. Prestressed steel strand Prestressed steel strand is a stranded steel cable composed of 2, 3, 7 or 19 high-strength steel wires, and is suitable for prestressed concrete or similar purposes after stress relief treatment (stabilization treatment). According to the surface morphology, it can be divided into smooth steel strand, nicked steel strand, die drawn steel strand, epoxy resin coated steel strand, etc.
(1) Wire/piece: refers to a steel wire with a single diameter of 5.0mm
(2) Strand: refers to a strand composed of several steel wires.
(3) Tendon: the number of steel strand strands seen in the section of prestressed member, and each strand is equipped with two sets of anchors.
(4) Bundle length: the length of one tensioning, that is, the length of steel strand between anchorages at both ends. If a connector is used for the tendon, the connector shall be regarded as an anchorage, that is, the tendon length is the length of the tendon between the anchorage and the connector or between the connector and the connector.
(5) XX holes: refer to the number of holes of the anchorage used, and holes of the anchorage model refer to the anchorage unit.
(6) XX bundles per ton: refers to the number of bundles converted from each ton of steel strand within the standard tensioning length, which is the basic data for the calculation of steel strand quantities.
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