Pre-stressed rounded beams are made of concrete. These beams are usually hollow with large base diameter and smaller top diameter.
PC Wire and PC Bar are used in beams in order to make up tensile weakness of the concrete, in a manner that they act as skeleton of these beams.
Taking into account several advantages of pre-stressed concrete beam (compact) including higher strength in high pressure and tension during landslides, earthquakes or storms, they are very durable in comparison with other beams and they a lighter weight, higher strength against changes in weather (including moisture, heat, frost, acid rain, etc.) and their installation and operation is very easy. So, these beams are very popular to be used in power transmission lines, current transmission cables, closed-circuit cameras, etc.