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Continued...
The cone is fabricated from 8mm thick panels of phosphor bronze
welded together to give a seamless finish. Phosphor bronze has a high
coefficient of thermal expansion. With the dark patinated surface finish, the
cone changes temperature quickly under the heat of the sun, and expands as the
temperature rises. The Phosphor bronze shell covers a soundproof steel and
concrete construction. A flexible support system was required to support the
shell off the steel and concrete structure whilst allowing expansion and
contraction of the bronze shell without any noticeable distortion.
A range of temperature cases were considered to act on the cone
including maximum and minimum temperatures for winter and summer conditions, and
also where the cone begins to heat up under the sun. For this last case the
differential of temperature over the cone surface was calculated and analysed
using the Finite Element model. With uneven temperature loadings, different
areas of the cone will expand at different rates, which could cause greater
movement of the expanding sections of the shell.
Underneath the bronze surface rubber-tipped ribs run the full
length of the structure, attached to the steel and concrete cone underneath. The
individual panels rested on these ribs during construction, helping position the
panels correctly during the difficult welding processes. As the cone geometry
made it impossible to introduce supports during construction that could be
removed afterwards, these rubber ribs had to be considered as semi permanent, to
degrade over time, and the design of the cone had to consider both the final
condition, without the ribs, and the temporary case where the ribs were present. |
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