Funicular Shell Roof

The design of funicular shell is derived from design of arches and vault structures which transfer loads predominantly through compression. Therefore, it is more economical to construct funicular shells using masonry, which uses lesser quantity of cement per unit volume as compared to reinforced concrete.

The starting point for the structural design of funicular shell roof is the design of the given roofing area into smaller units contained by a network of beams, like in a coffer slab. Each of these smaller spans can be constructed as a funicular shell.             

Normally, the optimal span of a funicular shell is not more than 3 metres which can be efficiently supported by a network of beams. The ratio of the rise at the centre to the span of the funicular shell roof is 1:6. The corresponding rise varies from 30 to 50 cm. Although the shell can be designed for much greater spans of upto 15 metres. But a practical consideration is the rise of shell to make it feasible to construct a flat roof or an intermediate floor.