Shell Roofs ~ these can be defined as a structural curved skin
covering a given plan shape and area where the forces in the shell
or membrane are compressive and in the restraining edge beams
are tensile. The usual materials employed in shell roof construction
are in-situ reinforced concrete and timber. Concrete shell roofs are
constructed over formwork which in itself is very often a shell roof
making this format expensive since the principle of use and reuse of
formwork can not normally be applied. The main factors of shell
roofs are:-
- The entire roof is primarily a structural element.
- Basic strength of any particular shell is inherent in its
geometrical shape and form. - Comparatively less material is required for shell roofs than
other forms of roof construction.
Domes ~ these are double curvature shells which can be
rotationally formed by any curved geometrical plane figure rotating
about a central vertical axis. Translation domes are formed by a
curved line moving over another curved line whereas pendentive
domes are formed by inscribing within the base circle a regular
polygon and vertical planes through the true hemispherical dome.
Shell Roof Construction