Page 15 - Reinforced concrete voided slabs subjected to gravity and seismic actions

15 Structural typology description§cap 1Figure 1.3. Synthetic comparison of the response of beams, slabs and the isostatic lines of principal stressesFigure 1.4. Configuration of a voided slab floor: formwork and casting; digital modelSlabs created in this manner offer considerable savings of concrete and reinforcing steel due to the relevant reduction in the self weight of the floor compared to what would be in the case of a solid slab of equal thickness. For this reason voided slabs represent an effec- tive compromise between stiffness and lightness and are particularly suitable for medium- large spans. In fact, thanks to the voids within the slab it is possible to achieve greater use- ful heights while however keeping the weight far below what a solid slab of equal effective depth would have thereby penalising minimally the stiffness of the structure. This weight reduction of horizontal structures, feasible with the use of voided slabs, is also very bene- ficial in seismic design due to the consequent considerable reduction of mass of the floors. The design of voided slabs corresponds to that of slabs. It is possible to achieve different configurations, depending on the geometry of the solid parts where the voided slabs are not used, creating solid areas near the columns or solid bands to connect the columns (figure 1.5). In both cases the intrados and extrados surfaces remain flat.The greater the number of ribs within a slab field, the better the equivalence with the solid slab. One design criterion requires a minimum of 6-8 ribs in each direction for each slab field (Park and Gamble, 2000).The use of voided or solid slabs in construction is now a well established practice in Europe and in the rest of the world, supported in the technical literature by extendedup © 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