Advantages of prestressed steel strand with point contact of wires

An analytical study of complex stress-strain state of the steel twisted rope with point contact of wires is introduced. The rope under investigation is used as a prestressed reinforcement of concrete structures. Currently, the set of rules and regulations SP 52-102-2004 contains only two types of steel strands: K1400 and K1500, which are the ropes with line contact of wires. The length of the wires of outer layer in such ropes depends on the length of the wires of inner layer. And at the same time the wires of each new independent layer are longer than the wires of inner layer and, thus, the wires of outer layer are more deformable. Consequently, they are less loaded, since minimum stress occurs in the longest wires, and maximum stress occurs in the shortest wires because of the difference of deformation characteristics. The stress in the wires is always distributed unevenly. The length of the wires of outer layer does not depend on the length of the wires of inner layer in the ropes with point contact. That is, it is possible to choose the length of outer wires so that the difference of lengths (deformation characteristics) of wires of various layers will be minimal. In this regard, the difference of stress in wires of various layers will be minimal as well. Hence, the coefficient of the use of wires strength, which is the determining criterion for the optimization of prestressed steel strand structures, will increase.