【国外标准】 Standard Specification for Steel Strand, Seven-Wire, Uncoated, Compacted for Prestressed Concrete

This specification covers seven-wire, uncoated, compacted, stress-relieved steel strand for prestressed concrete. The chemical requirements, mechanical requirements, and dimensions and permissible variations are presented. The mechanical requirement includes breaking strength, load at 1% extension and elongation. Different test method shall be performed on the strand that includes dimension test, breaking strength test, load at 1% extension test, elongation test and workmanship.1.1 This specification covers two types and three grades of compacted, seven-wire, uncoated strand for use in prestressed concrete construction. The two types of strand are low-relaxation and stress-relieved (normal-relaxation). The three grades are 245 [1700], 260 [1800] and 270 [1860].1.2 This specification is applicable for orders in either inch-pound units (as Specification A779) or in SI units (as Specification A779M).1.3 The values stated in either inch-pound or SI units are to be regarded as standard. Within the text, the SI units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the specification.