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PC Strand diameter and strength charts guide engineers in selecting the right prestressed concrete strand for projects like bridges and buildings. These charts detail sizes, tensile strengths, and weights per ASTM A416 standards. Understanding them ensures optimal performance and compliance.
PC Strand is a twisted bundle of seven high-strength steel wires, designed for prestressing concrete to handle tension loads effectively. Diameters range from 9.5mm to 18mm, with grades like 1725 MPa (Grade 250) for standard uses and 1860 MPa (Grade 270) for high-demand applications. Strength refers to minimum breaking load, calculated from nominal steel area and tensile grade.
Charts list nominal diameter, area, weight, and loads, helping match strand to span length and load requirements.
Most projects use 12.7mm, 15.2mm, or 15.7mm strands due to balance of strength and handling ease. Smaller 9.53mm suits lighter slabs; larger 17.8mm handles heavy bridges. Grades indicate MPa: 1770 for general, 1860 for demanding spans.
Tolerances are tight—e.g., +0.65/-0.15mm for Grade 270—to ensure uniform performance.
ASTM A416 defines uncoated seven-wire low-relaxation strand specs. Below is a key excerpt for Grade 1860 (270 ksi) and Grade 1725 (250 ksi).
Strand No. | Diameter mm (in.) | Area mm² (in²) | Weight kg/1000m (lb/1000ft) | Min Breaking Load kN (lbf) Grade 1860 | Min 1% Extension Load kN (lbf) |
9 | 9.53 (0.375) | 54.8 (0.085) | 432 (290) | 102.3 (23,000) | 92.1 (20,700) |
11 | 11.11 (0.438) | 74.2 (0.115) | 582 (390) | 137.9 (31,000) | 124.1 (27,900) |
13 | 12.70 (0.500) | 98.7 (0.153) | 775 (520) | 183.7 (41,300) | 165.3 (37,170) |
13a | 13.20 (0.520) | 107.7 (0.167) | 844 (568) | 200.2 (45,000) | 180.1 (40,500) |
15 | 15.24 (0.600) | 140.0 (0.217) | 1102 (740) | 260.7 (58,600) | 234.6 (52,740) |
18 | 17.78 (0.700) | 189.7 (0.294) | 1487 (1000) | 353.2 (79,400) | 318.0 (71,500) |
For Grade 1725, loads are lower: e.g., 12.7mm at 160.1 kN.
BS 5896 offers European equivalents, with super 7-wire for higher strengths.
Nominal Dia. mm | Area mm² | Weight kg/1000m | Tensile Strength MPa | Breaking Load kN (Super) |
9.6 | 55 | 432 | 1860 | 102 |
11.3 | 75 | 590 | 1860 | 139 |
12.9 | 100 | 785 | 1860 | 186 |
15.7 | 150 | 1180 | 1770 | 265 |
Relaxation max: 2.5% at 70% load after 1000h.
Slabs/Parking: 9.53-12.7mm, Grade 1725; lighter weight reduces handling costs.
Bridges: 15.2-15.7mm, Grade 1860; higher breaking load for spans >30m.
Flyovers: 12.7-17.8mm; epoxy-coated for corrosion in traffic exposure.
High-Rise: 15.24mm; elongation ≥3.5% ensures ductility.
Calculate needs: Breaking load = Area × Grade. For 15.7mm (150mm²) at 1860MPa: ~279kN.
Tensile strength is ultimate load before break; yield at 1% extension is 90% of that for low-relaxation. Elongation ≥3.5% over 610mm gage prevents brittle failure. Modulus ~195 GPa aids deflection predictions.
Coatings like epoxy add protection without altering core strength.
Manufacturers test per A370/A981: breaking, yield, relaxation. One test per 18-ton lot; rejects if below spec. Center wire > outer by 0.076-0.114mm ensures uniformity.
Larger 21.8mm strands emerge for mega-bridges; ultra-high 2100MPa grades for extreme loads. Low-relaxation (≤2.5%) dominates over normal (≤3.5%).
TJ Wasungen provides ASTM-compliant PC Strands in all diameters/grades, with charts and custom packs. Contact via WhatsApp +86-13622011252 or sales@tjwasungen.com.
