Deployable, folding and retractable space grids
A recent development in space grid structures has been the use of deployable, folding and retractable systems.
Examples of these are the folding grids of Emilio Perez Piñero, Félix Escrig etc., the deployable roof of the Venezuela Pavilion at Expo'92 Seville, the "Pantadome" erection process of Mamoru Kawaguchi and retractable roofs such as the Toronto Skydome and the Fukuoka Dome in Japan.
Emilio Pérez Piñero experimented with folding grids in the 1960s but due to his untimely death in 1972 his work was not fully developed.
In recent years this has been remedied by several researchers including Félix Escrig at the Seville School of Architecture and examples of folding grids are now being constructed. Santiago Calatrava's doctoral thesis was on folding structures and his study of these structures has manifested itself in several of his works (although not as space grids).
The roof structure of the Venezuela Pavilion at Expo'92, Seville was fabricated in Venezuela, folded into a packages of maximum dimension 18.8 m x 3.0 m x 2.8 m, transported to Seville and then unfolded and erected in less than one day.
A series of planar trusses were joined alternately with hinges at their top and bottom chord to form a "concertina" which when unfolded was stabilised by the introduction of horizontal bars between the adjacent hinge lines. This formed a square-on-square offset space grid which was clad by panels fixed to the inner nodes. After the Expo the structure was taken down re-folded and transported back to Venezuela for re-use.
The "Pantadome" erection system was developed by Japanese engineer Mamoru Kawaguchi to minimise erection costs and improve site safety in the construction of large space grids.
Temporary hinged mechanisms are formed in the space grid roofs to enable them to be assembled at low level with limited cranage. Once assembled they are jacked up into their final position. During this process considerable changes in the roof profile take place and these are stabilised by the introduction of additional members into the foldable structure. This process, first used in 1984 for the World Memorial Hall, Kobe has also been used for The Singapore Indoor Stadium; Sant Jordi Sports Palace, Barcelona; Namihaya Dome, Kadoma; Sun Dome, Sabae and most recently the Town Hall in Nara. Most of these are structures of complex geometry.
