Steel Core Aluminum Stranded Wire Prestressing Terminology

Prestressing is a technical means to counteract the stresses encountered during the service of the structure, improve the structural load bearing capacity, and apply a reverse stress to the structure before the structure is serviced. Typical application examples include prefabricated PC bridges, PC slabs, sleepers, poles, PCCP pipes, curtain walls with cables, prestressed steel beams, nuclear containment, rock and soil anchoring, etc. Chinese traditional wooden hoops are actually one The application of a kind of prestressing technology. Here PC is the meaning of prestressed concrete, and the non-prestressed concrete is abbreviated as RC.

When the material maintains tensile stress for a long period of time, the phenomenon that the stress gradually decreases slowly is stress relaxation. The ratio of this loss to the initial stress is the stress relaxation rate. This feature can be improved by special processing to achieve a lower relaxation rate, which is the basic meaning of the low relaxation concept.

For prestressed steel strands, the standard stress relaxation test conditions are 20 degrees, the initial stress is 70% of the nominal maximum force (60% and 80% are rarely used), and the low relaxation level is 1000 hours. The stress relaxation rate is not more than 2.5%. This indicator of normal relaxation is 8%, and in fact the long-term relaxation difference is larger than this.