17.8mm 2230 Mpa PC Strand

Introduction to low-relaxation Prestressed Steel strand with a diameter of 17.80mm and a strength of 2230MPa

I. Product definition and structure

Prestressed steel strand is a spiral steel bar made of multiple high-strength steel wires. It improves the crack resistance and bearing capacity of concrete structures by applying prestress. The diameter of 17.80mm refers to the diameter of the circumscribed circle of the steel strand, which belongs to a large-size model; the strength of 2230MPa means that its tensile strength reaches the ultra-high strength level (the strength of ordinary steel strand is usually 1720-1860MPa); low relaxation means that the stress loss caused by stress relaxation of the steel strand under stress is significantly lower than that of ordinary steel strand (for example, the stress loss in 1000 hours is ≤2.5%, while the loss rate of ordinary steel strand is about 8%-10%).

II. Materials and production process

Material composition:

Steel wire material: high carbon steel (such as 82B steel) with a carbon content of about 0.8%, supplemented with alloy elements such as manganese and silicon to improve strength and toughness.

Structural form: Commonly 7-wire twist (1 center steel wire + 6 outer steel wires), the twist pitch is 12-16 times the diameter to ensure structural stability.

Production process:

Wire rod pretreatment → cold drawing → twisting → stress relaxation treatment (eliminating internal stress by constant temperature heating) → surface anti-corrosion treatment (such as galvanizing, epoxy coating optional).

III. Mechanical properties and characteristics

Parameter type Specific indicators

Tensile strength ≥2230MPa, far exceeding ordinary construction steel (such as HRB400 steel bar tensile strength of about 400MPa).

Yield strength (0.2% condition) ≥2000MPa, the elastic section of the stress-strain curve is long, suitable for structures under high stress.

Relaxation performance At 20℃, when the initial stress is 70% of the nominal strength, the stress loss in 1000 hours is ≤2.5%, reducing the stress attenuation of the later structure.

Elongation: Elongation after fracture ≥ 3.5%, ensuring that the material has a certain plastic deformation capacity when subjected to stress to avoid brittle failure.

Fatigue resistance: No fracture after 2 million cycles of load (stress amplitude 195MPa), suitable for dynamic load environments (such as bridges).

IV. Scope of use and engineering applications

(I) Construction engineering field

Large-span prestressed concrete structure:

Application scenarios: Stadium dome, airport terminal, industrial plant large-span beam, plate structure (such as roof beam with span > 30 meters).

Advantages: By applying prestress to offset the tensile stress generated by the load, reduce concrete cracks and improve structural durability.

High-rise building slabs and walls:

Unbonded prestressed slabs used in super high-rise buildings (such as transfer layers with thickness > 300mm) reduce self-weight while improving crack resistance.

(II) Bridge Engineering Field

Prestressed concrete bridges:

Inner/outer prestressed tendons of simply supported beams, continuous beams, and T-beams, especially suitable for bridges with a span of 50-150 meters (such as highway viaducts).

Cable-stayed and suspension bridges:

Cables of cable-stayed bridges (need to be matched with high-strength anchors), main cable strands of suspension bridges (17.8mm diameter steel strands can be used as single strands, and multiple strands are combined to form the main cable).

(III) Geotechnical Engineering and Infrastructure

Slope and foundation pit support:

High-strength anchor cables (such as anchor cables made of 17.8mm diameter steel strands, with an anchoring force of up to 500-1000kN) are used for deep foundation pit support and highway slope reinforcement.

Tunnel and mining engineering:

Prestressed anchor rods of tunnel linings and high-stress anchoring of mine tunnels to resist surrounding rock deformation.

Water conservancy projects: Prestressed reinforcement of dam bodies and aqueduct support structures to withstand water pressure and temperature deformation stress.

(IV) Special engineering fields

Nuclear power plants and pressure vessels: The annular prestressed tendons of nuclear power plant containment must meet high safety and low relaxation requirements to prevent radioactive leakage.

Marine engineering: Prestressed reinforcement of offshore wind power foundation piles and anchoring systems of offshore platforms (with anti-corrosion coatings to resist seawater erosion).

V. Product advantages and selection considerations

Advantages: high bearing capacity (breaking force of a single 17.8mm steel strand is about 350kN), long-term stress stability (low relaxation), and convenient construction (can be transported on a reel, suitable for large-tonnage tensioning equipment).

Notes:

Anchors (such as M17.8 clip anchors) and tensioning equipment (jack tonnage ≥ 400kN) of corresponding specifications must be matched;

Galvanized or epoxy-coated steel strands must be used in open air or corrosive environments to extend service life;

The tensioning stress must be controlled during construction (usually 60%-75% of the strength standard value) to avoid over-tensioning and causing fracture.

 

This specification of steel strand is mainly used in large-scale projects with extremely high requirements for bearing capacity and durability due to its ultra-high strength and low relaxation characteristics. It is one of the core materials in modern prestressed technology.17.8mm 2230 Mpa PC Strand .