Title: Feasibility Study for High-Strength Spun Concrete Pylon Prestressed with Carbon Fiber Reinforced Plastic for Transmitting Voltages at 110 kV Level
Author(s): G.P. Terrasi, U. Meier, and B. Burkhardt
Publication: Symposium Paper
Appears on pages(s): 467-480
Keywords: carbon; casting; durability; high-strength concrete; pretensioning
The aim of this project is the production of a 28 m high CFRP-prestressed spun concrete pylon as a support for electric lines at the 110 kV voltage level (Duralight concept). It is intended to use this pylon as a support mast in a section of the 110 kV line of the Nordostschweizerische Kraftewerke (NOK, Power Company of North East Switzerland) Beznau-Baden. The fundamental advantage of this new design is the low weight in combination with an optimum corrosion resistance. The high corrosion resistance of the CFRP prestressing and shear reinforcement allows minimization of the concrete cover so that a cross-sectional wall thickness in the region of only 4 cm (1.6 inches) can be obtained. This is at present about 10 cm (4 inches) if steel reinforcement is used. The low weight of the CFRP reinforcement (the density of CFRP is only 1.6 g/cm3, which is a fifth of the density of steel) and its high tensile strength (CFRP pretensioning rods have a tensile strength of 3000 MPa, which is twice that of a prestressing steel) are also noteworthy. These two factors permit a weight reduction on the reinforcement side of 90% compared with conventional pre-stressed concrete construction. On the matrix side, high-strength spun concrete of strength class B110 is used. Owing to its high strength, it helps to achieve the stated minimization of the cross-sectional dimensions. The envisaged pylon weight of 4730 kg means a 45% weight reduction compared with the traditional steel reinforced spun concrete pylon. The transport and installation costs are thus lower and the expected life without maintenance is 50 years. This paper describes the technical fundamentals studied in a four year research program at the Swiss Federal Laboratories for Materials Testing and Research EMPA for designing and manufacturing this prototype pylon. The presented pilot project results from a close co-operation of the spun concrete element production plant SACAC with EMPA and the power company NOK.