Prestressing steel strands are used for prestressing structures.

A prestressing steel strand is made from a number of wires twisted together in the same direction and with the same lay length. The strand is then subjected to a finishing thermo-mechanical treatment. If the strand is additionally drawn through a die or rollers, it is referred to as compacted. The strands are then wound into coils.

Prestressing steel strands can also be factory-fitted with a corrosion protection system consisting of a grease and an HDPE sheathing in a downstream manufacturing process. This variant is known as a monostrand.

Regulatory framework

DIBt grants national technical approvals (abZ) for prestressing steel strands. Approvals are currently only granted for prestressing steel strands consisting of seven cold-drawn smooth individual wires. The strands can also be compacted.

Please also refer to the applicable design and execution rules, cf., in particular, MVV TB, Part A 1.

With regard to the design and execution of structural works, please note that DIN EN 1992-1-1:2011-01 in conjunction with DIN EN 1992-1-1/NA:2013-04 does not contain conclusive technical rules for the use of prestressing steel strands as a tendon for internal bonded and unbonded post-tensioning. In cases which are relevant from a regulatory point of view, a construction technique permit (aBG) is generally required. DIBt grants general construction technique permits upon request.

The use of prestressing steel strand for pre-tensioning of precast elements (direct bonding) at the factory is permitted for nominal diameters of up to 12.5 mm.