Your article on composites (NCE 28 March/4 April) was interesting. However, I would like to correct the caption to one of the photographs.
The design of the connections for the frame constructed from pultruded FRP sections was indeed carried out by CETEC, but the overall concept, analysis and design was carried out by Halcrow. The photograph shows the trial erection of the structure in the UK before it was shipped overseas.
The FRP structure was to support a secondary structure containing magnetic coils in a very precise configuration to extremely tight tolerances in all three axes. The frame in its final location sits within a masonry and timber structure.
The challenge for all the structures was to ensure a complete absence of ferrous metals or indeed, significant amounts of electric conducting materials where eddy currents could have been induced.
The connections within the frame, of course, also had to be non-ferrous - a challenge successfully met by CETEC.
Andrew Scarth (F), ScarthAC@halcrow. com