Warming-up

1. How can you describe the form of the shell?

2. What are shells used for? Read the text and tell about the advantages of the shell.

Text 1.

SHELLS

The term shell is used to denote a spanning and space-enclosing element of domed or other vaultlike form, but with a thickness and order of magnitude less than was usual for these masonry and mass-concrete forms. Like the latter, a shell may be curved in two directions or in one only; but the two curvatures of the doubly curved form may be of opposite sense, like those of a saddle — a possibility almost restricted to the fan vault in masonry — and the singly curved form may be taken to include /> a/re/-shaped and folded or corrugated forms that span along the length of the barrel or the folds, and act as deep beams. To achieve the reduction in thickness, tensile strength must be provided in the shell itself, or at the level of support, or in both places, in accordance with the requirements of the surface geometry, the pattern of loading, and the type of support.

The shelf, together with the doubly curved tensile membrane or cable net, has so enlarged the formal vocabulary of architecture that it will continue to play an important role where economy is not the overriding consideration. The Saarinen/Amman and Whitney roof of the TWA Terminal Building at Kennedy Airport demonstrates its versatility at the limits of practicality; Jon Utzon's original impracticable proposal of sharply ridged ‘shells for the Sydney Opera House went beyond these limits and called for a different arched type of construction.

Vocabulary

magnitude— величина, размеры

to curve — гнуть

barrel — цилиндр, барабан, вал

to fold — складывать, сгибать

corrugated — гофрированный, рифленый

overriding — основной, первостепенный

ridged — остроконечный

/. Choose the right verb.