Page 17 - Reinforced concrete voided slabs subjected to gravity and seismic actions

1.2.1. The originsThe origins of the slab system can be traced, in Europe, to work of Robert Maillart, while, with regard to the United Sta- tes, reference can be made to the studies by Claude Allen Porter Turner (Gasparini, 2002; Zago, 1972).In 1908 Maillart focused hisstudies and experiments on thepossibility of creating reinfor-ced concrete floors withoutusing beams. At that time, rein-forced concrete buildings werebeing constructed according to the design methods outlined by François Hennebique (1842-1921), namely with frames with columns and primary beams, on which rested the secondary beams and then the slabs.Maillart completely eliminated the beams, supporting the floors directly on the columns, which formed the widened capital in order to improve the shear and bending response, characterised by stress peaks at the supports.Maillart began to test this construction system in 1908 with several models scaled 1:1. He patented the result in January 1909 and used it for the first time in 1910 in the Giesshübel warehouse construction in Zurich (figure 1.6).The system proved to be a success as the elimination of beams, in addition to an ae- sthetic appeal, was accompanied by operating advantages at the executive phase (the need to create formworks for the beams was avoided) and offered greater headroom. Given the particular shape of the capitals, this type of solid slab floor was soon known as mushroom floor.However, Maillart was not the only one to have this idea. Completely independently in the United States, as early as 1905, Turner was carrying out experiments with “mushro- om columns”.The mushroom floor system designed by Turner was reinforced along four axes: the longitudinal and transversal ones and the two diagonal ones (figure 1.7). He used it for the first time in 1906 for the construction of a five-storey building: the Johnson Bovey Building in Minneapolis (now demolished). In 1906 he used it again for the Marshall Building in Milwaukee, Wisconsin. This building still exists today and was designa- ted Engineering Landmark by ASCE in 2002. Turner filed for a patent for his design on June 11th 1907 and the patent was issued on September 12th 1911 U.S. patent no. 1,003,384). Both Maillart, and Turner later successfully used their systems for the con- struction of several reinforced concrete slabs in bridge decks.17 Structural typology description§cap 1up © Dalifoform Group © Daliform Grouup © Daliform Group © Daliform Group © Dalifoform Group © Daliform Group © Daliform Group © Daliform Grouup © Daliform Group © Daliform Group © Daliform Group © Daliform Group © Dalifoform Group © Daliform Group © Daliform Group © Daliform Group © Daliform Group © Daliform Grouup © Daliform Group © Daliform Group © Daliform Group © Daliform Group © Daliform Group © Daliform Group © Dalifoform Group © Daliform Group © Daliform Group © Daliform Group © Daliform Group © Daliform Group © Daliform Group © Daliform Grouup © Daliform Group © Daliform Group © Daliform Group © Daliform Group © Daliform Group © Daliform Group © Daliform Group © Dalifo form Group © Daliform Group © Daliform Group © Daliform Group © Daliform Group © Daliform Group © Daliform Group © Daliform Grou© Daliform Group © Daliform Group © Daliform Group © Daliform Group © Daliform Group © Daliform Group © Daliform Group © Dalifo iform Group © Daliform Group © Daliform Group © Daliform Group © Daliform Group © Daliform Group © Daliform Grouup © Daliform Group © Daliform Group © Daliform Group © Daliform Group © Daliform Group © Dalifo form Group © Daliform Group © Daliform Group © Daliform Group © Daliform Grouup © Daliform Group © Daliform Group © Daliform Group © Dalifoform Group © Daliform Group © Daliform Grouup © Daliform Group © Dalif form Grou