Wire ropes & strand · Size & tolerance table

Seven-wire prestressing strand sizes (ASTM A416, Grade 270)

Standard: ASTM A416/A416M

Uncoated seven-wire strand is six helical wires laid around a slightly larger straight centre wire. Grade 270 (1860 MPa) low-relaxation strand is the usual grade for post-tensioned slabs, bridges and pretensioned precast work. The minimum breaking strength is the nominal steel area times 1860 MPa.

British practice orders strand to BS 5896 (for example 12.9 mm and 15.7 mm "super" strand); the European prEN 10138 series has not been published as an EN.

Grade 270 (1860 MPa), low relaxation

Nominal diameter in	Nominal diameter mm	Steel area mm²	Mass kg/m	Min. breaking strength kN	Min. breaking strength lbf
3/8	9.53	54.84	0.432	102.3	23,000
7/16	11.11	74.19	0.582	137.9	31,000
1/2	12.70	98.71	0.775	183.7	41,300
0.6	15.24	140.00	1.102	260.7	58,600

Notes

The mass is the steel area at 7,850 kg/m³; the minimum yield (load at 1% extension) of low-relaxation strand is 90% of the minimum breaking strength.
Strand is supplied in reelless coils of about 3–4 t; check the relaxation class and the coil weight on the order.