Page 19 - Reinforced concrete voided slabs subjected to gravity and seismic actions

19 Structural typology description§cap 1It was clear that the culturalferment linked to the spreadof reinforced concrete was be-coming prolific. In fact, ArturFerdinandovich Loleit develo-ped independently in Russia asimilar system of reinforced so-lid slab in two orthogonal direc-tions, on columns with capitals(mushroom type), and in 1907he used it in the construction ofthe “Bogorodsk Glukhovskoy”textile factory near Moscow.The modern understanding ofthe structural behaviour of slabsis expressed by the design ofPierluigi Nervi in numerous de-signs such as the Lanificio Gatti (figure 1.8), the Palazzo del Lavoro in Turin and the offices of UNESCO in Paris, expressions of the type of ribbed slab. The presence of torque with bending involves the rotation of the main directions along which loads are transferred, describing the trajectories drawn from the ribs of the design (Mainstone, 1975; Halpern et al. 2013, Zago, 1972).1.2.2. The need to lightenThe need to lighten was clearly a situation that arose not long after the demand to cover great spans. An excursus into the world of historical buildings is relevant at this point. Since Roman times, one of the first methods used to lighten the horizontal closures of large spans consisted of varying the material used. Vaults in opus caementicium were created with ribs in triangular shaped (semilateres cocti) or square (bessalis) bricks or domes were created whose first courses, in the lower part, were brick wall, while in the upper part, these were gradually replaced by courses in limestone blocks, with use at the top of lighter volcanic stone.The Pantheon (rebuilt in the configuration that we know, between 118 and 128 A.D.) was one of the first works in which a dome was erected whose structure was made with opus caementicium with caementae mixed with mortar that gradually becomes lighter the higher it goes: from the scales of bricks for the layer closer to the cylindrical drum, climbing there is concrete with chips of tuff, while in the upper part, near the oculus, concrete packed with traditional inert material is found, blended with ground volcanic pumice (figure 1.9a).The dome of the Pantheon, 43.4 m in diameter, was the prototype of the domes that were built in the following centuries throughout Europe and the Mediterranean.up © 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