Abstract

This contribution describes selected architectural projects realized by using thin-walled structural elements made of high performance concrete (HPC) prestressed by carbon fibre reinforced plastic (CFRP) and gives information about design and experimental validation work. A first full scale structural element made from HPC prestressed with pultruded CFRP tendons was produced, tested and installed in the years 2000-2001 by the Swiss prefabrication element plant SACAC Schleuderbetonwerk AG in the form of a thin-walled overhead power line pylon. This 27 metres high tubular pylon for the transmission of high voltages was produced by centrifugal casting technique with a concrete wall-thickness of merely 48 mm. It was therefore 40% lighter than a conventional steel-reinforced concrete pylon used for the same purpose. The transport and erection costs were reduced which, with an expected maintenance free service life of 50 years, should result in lower life-cycle costs than those of tubular steel or steel lattice pylons which need a new coat of corrosion protection paint after approximately 20 years. In 2002, this technology that was originally developed in close collaboration with the Swiss Federal Laboratories for Materials Testing and Research Empa, was further optimized by SACAC to produce durable and lightweight CFRP prestressed concrete lighting columns. A series of the first type of column from this product line (with length 9.2 m) was subject to a very detailed experimental study with static, dynamic and durability tests at the University of Cambridge. Since then SACAC sold more than 1’000 CFRP prestressed columns. In 2005-2006 this novel technique was implemented in the structural and architectural field with the realisation of two greater building façades in Zurich Switzerland using totally 3’000 m1 filigree CFRP prestressed self compacting concrete profiles. One key feature in order to increase the cost effectiveness of this technique is the increase of the prestressing level of the CFRP tendons. Two approaches are followed in the frame of a current research project: The increase of the anchorage performance of the clamping devices used for pretensioning the HPC as well as the optimization of relevant material properties (transverse compressive strength and interlaminar shear strength of the pultruded CFRP tendons). First results are summarized.