Traditionally, shell structures of anything more than moderate span have been built of reinforced concretes, or reinforced cement pastes, with thicknesses varying from about a quarter to three-quarters of an inch (6mm to 19mm). However even with these thicknesses the dead weight of the shell forms a major part of the total design load. A much lighter material such as plastic suffers from its relatively high cost, with variations in dimension with temperature changes, and its lack of strength especially at joints. A logical alternative, which is not only lighter than a concrete shell but much cheaper to erect, is steel sheet. In this school gymnasium, just two types of standard curved corrugated steel panels are used to form the complete outer shell of a 100ft (30m) wide building, one panel being half the length of the other. There is an inner shell perforated for acoustic insulation, but otherwise of similar construction, with insulation provided between the two shells. All panels are simply bolted together, a 2in (50mm) spacer being used between the inner and outer shell. The end walls are glass, which determines contact with the outside.
All arch panels are galvanised steel just over 2ft (600mm) wide and curved to a 70ft (21.35m) radius along their length, with drilled holes around the perimeter to receive 9.5mm bolts for connection to the adjacent panels. There is a double row of holes for the joint connecting the panel to those above and below it. In the outer shell this joint is staggered with reference to those in the panels either side. In section the panels are 9 ¼ in (235mm) deep which gives them considerable effective bending strength. Between the outer and inner shell there is a 2in (50mm) thick sheet of fibreglass. This acts not only as thermal insulation, but, with the perforated holes on the inner sheet, as a sound one.
The shells are supported at ground level by concreting into a lightly reinforced edge beam resting on a shallow strip footing.
The curtain wall is supported off a light steel framework which also provides lateral stiffness at each end of the building. This framework is set in 2ft (600mm) from the end of the shells and bolted up against them using the modified standard panel bolting detail.
Notes:
dead weight собственный вес\масса
fibreglass n. стекловолокно
gymnasium n. гимнастический зал
perforated adj. перфорированный
with reference to относительно