What Is a PC Strand?
PC strands are tensioning materials that apply tension to pre-stressed concrete (PC).
There are three types of tensioning materials: PC strands, which are high-strength steel with a diameter of 8 mm or less; PC Bars, which are high-strength steel with a diameter of 10 mm or more; and PC strands, which are multiple steel wires that are stranded together. PC strands are characterized by the fact that multiple steel wires are strung together.
Other features include high tensile strength, high elongation at break, low relaxation value, and good straightness and workability.
Applications of PC Strands
PC strands are used in a wide range of applications, including road and railroad bridges, sleepers, tanks, construction, and ground anchors.
PC strands increase the resistance of pre-stressed concrete to tension, bending, and torsion. The number of strands to be matched increases the tensile strength, which is why they are often used for reinforcing members of buildings and architectural structures. PC strands that are 5 to 6 times stronger than the material for which drag is to be strengthened are selected for use.
Types of PC Strands
PC strands are classified according to the number and strength of the steel wires to be stranded. The nominal name, standard size diameter, nominal cross-sectional area, mass per unit, test stress to 0.2% permanent elongation, maximum test force, elongation, relaxation value, and strength level are specified in each standard.
PC strands are available in 2-strand, 3-strand, 7-strand, and 19-strand types, with 7-strand types classified as Class A and Class B. Basically, the higher the number of strands, the higher the strength. Basically, the greater the number of strands, the higher the strength. The more the number of pieces, the higher the strength, and the more the area of division and the mass of the pieces tends to increase. Some PC strands are also categorized into normal-strength PC strands and high-strength PC strands, even if the number of strands is the same.
For example, the maximum test force for the same 7 PC strands of 15.2mm is 240kN or more for normal strength, while the maximum test force for high strength PC strands is 317kN or more, or about 1.32 times higher. There is also a difference in tensile strength standards between Class A and Class B. The tensile strength of Class B is about 100 N/mm2 higher than that of Class A.