Brussels Cinquantenaire Park halls: a structural revolution or evolution?

To celebrate 50 years of independence, King Leopold II of Belgium conceived a jubilee park in 1880, which was later used for national and international exhibitions. The large-span exhibition hall that was built in 1888 on the site is still in use at present – after having experienced several architectural and functional mutations over time – and reflects a successful design. The structure consists of a series of three-bay wrought-iron portal frames and is part of the evolution of an emblematic type of building in world fairs, which is the galerie des machines typology (machinery hall). This paper reveals how and to what extent the Brussels exhibition hall came into structural development towards a three-hinged arch by situating it within the built machinery halls (Paris 1867, Paris 1878, Paris 1889, Chicago 1893) and other famous arched structures. By relating breakthroughs in engineering (enlarging the span length, dealing with the arch thrust, support condition, etc.), the relevance and the innovative character of the Brussels Cinquantenaire halls is discussed.