Page 13 - Reinforced concrete voided slabs subjected to gravity and seismic actions

1. Structural typology description1.1. Voided slabs: general classificationIn the contemporary Architecture and Engineering context what is evident is the impor- tance that the slab floor has taken in the world of construction, thanks to the peculiarity of being a horizontal element with excellent structural performance, able to adapt to highly irregular and statically demanding support schemes (figure 1.1, figure 1.2).The latest development of the use of slabs is motivated by a combination of design and constructional advantages. The possibility of creating flat intrados floors is, from a con- structive point of view, a significant simplification of formwork, allowing more rapid and economic processes, also thanks to formwork with high technological performance. Architecturally the flat intrados simplifies the passage of systems and offers better aes- thetics. Again in the architectural field, the structural possibility of providing irregular supports is ensured by the multi-directional load transfer mechanism of the slabs. The smaller thickness of slabs compared to solutions with extrados beams results in particu- larly advantageous volume savings in tall buildings.The essence of the behaviour of a slab with respect to a beam consists of the deve- lopment of a combined action of bending, torsion and shear within a flat element. This means that, while in a beam the transfer of loads occurs in the plane of the floor with straight trajectory along the axis of the beam, in a slab such transfer takes place along orthogonal paths curved by development of torsion (figure 1.3).Voided slab floors represent an evolution of the system that combines reduction of the weight and the quantity of material used with the structural performance of this type. This is accomplished by creating voids, laid out in a regular grid, within the thickness of the slab (figure 1.4). For example, in the case of use of U-Boot Beton® voids as sta- tionary formworks, the cross sections of voided slabs can be viewed as a set of two thin slabs on the extrados and intrados and as orthogonal bands of connection between the two slabs. The resistant mechanism due bending and torsion typical of slabs, both solid and voided, develops through forces of compression and tension acting in the concrete slabs and in the extrados and intrados reinforcement. The entire concrete cross-section transfers transversal shear to the plane.13up © 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