Bidirectional lightened slabs are reinforced concrete slabs in which the excess parts of concrete are eliminated, producing voids that reduce the amount of concrete and reduce its own weight.
While concrete has been used for thousands of years, the use of reinforced concrete is generally attributed to Joseph-Louis Lambot") in 1848. Joseph Monier, a French gardener, patented a design for reinforced garden tubs in 1868, and later patented reinforced concrete beams, railway posts, and road guardrails.
The main drawback in concrete constructions, in the case of horizontal slabs, is their high weight, which limits the span span. For this reason, important developments in reinforced concrete have focused on improving this handicap, either to reduce weight or to improve its tensile and flexural behavior.
One of the earliest examples still in use is the Pantheon in Rome, built AD 125. Although it is not reinforced concrete, arks were used to reduce weight.
Bidirectional slabs
Contenido
Las losas bidireccionales van dirigidas a la reducción el peso propio. Varios métodos se han introducido en las últimas décadas, pero con un éxito muy limitado, debido a los problemas principales con capacidad a cortante, punzonamiento y la resistencia al fuego.
En la segunda mitad del siglo , se hicieron varios intentos para crear losas bidireccionales con cavidades huecas para reducir el peso. Mayoría de los intentos han consistido en la colocación de bloques de materiales menos pesados tales como el poliestireno expandido entre el fondo y la capa de compresión, o de cubetas de polipropileno para la formación de forjados reticulares.
Una de estas variantes son los forjados reticulares, que han ido ganando aceptación en el mercado. En un inicio estuvo limitado su uso debido a reducidas resistencias a cortante y punzonamiento local, lo que ha de combatirse con macizados de hormigón armado en los apoyos.
Composition
The geometry of bidirectional slabs and in particular of a waffle slab is characterized by orthohedral castings of a certain size, placed in a precise modular grid. Waffle slabs are reinforced concrete slabs, heterogeneous in terms of section, reinforced in two perpendicular directions and lightened.
Ribbed slab
Introduction
Bidirectional lightened slabs are reinforced concrete slabs in which the excess parts of concrete are eliminated, producing voids that reduce the amount of concrete and reduce its own weight.
While concrete has been used for thousands of years, the use of reinforced concrete is generally attributed to Joseph-Louis Lambot") in 1848. Joseph Monier, a French gardener, patented a design for reinforced garden tubs in 1868, and later patented reinforced concrete beams, railway posts, and road guardrails.
The main drawback in concrete constructions, in the case of horizontal slabs, is their high weight, which limits the span span. For this reason, important developments in reinforced concrete have focused on improving this handicap, either to reduce weight or to improve its tensile and flexural behavior.
One of the earliest examples still in use is the Pantheon in Rome, built AD 125. Although it is not reinforced concrete, arks were used to reduce weight.
Bidirectional slabs
Contenido
Las losas bidireccionales van dirigidas a la reducción el peso propio. Varios métodos se han introducido en las últimas décadas, pero con un éxito muy limitado, debido a los problemas principales con capacidad a cortante, punzonamiento y la resistencia al fuego.
En la segunda mitad del siglo , se hicieron varios intentos para crear losas bidireccionales con cavidades huecas para reducir el peso. Mayoría de los intentos han consistido en la colocación de bloques de materiales menos pesados tales como el poliestireno expandido entre el fondo y la capa de compresión, o de cubetas de polipropileno para la formación de forjados reticulares.
Una de estas variantes son los forjados reticulares, que han ido ganando aceptación en el mercado. En un inicio estuvo limitado su uso debido a reducidas resistencias a cortante y punzonamiento local, lo que ha de combatirse con macizados de hormigón armado en los apoyos.
Composition
These structures admit bending that can be decomposed according to the assembly directions, forming with the supports a spatial matrix with great capacity to collect vertical actions and with sufficient capacity for horizontal ones.
Waffle slabs do not have hanging beams, forming part of the so-called flat slabs, these being the most used in construction.
The fundamental parameters that define the characteristics of the waffle slab are:
The geometry of the Holedeck system is made up of a series of molds or trays, generally square in size, and which are regularly arranged in a matrix, leaving interstitial spaces between the molds in which the reinforcement is housed to later pour the concrete.
The Holedeck construction system achieves slabs with ribs with different heights and with slab cells and grids of different dimensions. In order to achieve slabs with different heights of ribs, Holedeck uses longitudinal growth pieces, together with a central piece to which they are connected, being able to achieve a reduction in the height of ribs longitudinally and transversely, these pieces being recoverable once the mold supports are removed.
In addition, Holedeck pieces are recoverable, allowing the forging to be adapted to the structural characteristics or needs. To achieve forgings with grids of different dimensions without discarding the molds or trays used until now, two pieces are specifically used:
Theory
In principle, two-way lightened slabs act as solid slabs. Consequently, its design is similar to these but with less self-weight due to the reduced amount of concrete. Research carried out by universities in Germany, Holland and Denmark based on the Eurocodes concludes that bidirectional lightweight slabs act in the same way as a solid slab.
While a bidirectional lightened slab, such as the BubbleDeck system") or the U-boot Beton® system") (D.Coronelli, L. Martinelli, F. Foti (2016), "Reinforced concrete voided slabs to gravity and seismic actions", Dario Flaccovio Editore), must be calculated as a solid slab, certain ribbed slab systems, such as the Holedeck system, consisting of a grid of beams orthogonal, they must be calculated as beams.
The Holedeck system also has gaps in the ribs, which makes the resulting structure lighter, more versatile and sustainable, in addition to allowing installations to pass through its interior.
The technology of bidirectional lightweight slabs has been incorporated into international regulations such as the Eurocodes and several national codes such as the CUR of the Netherlands.
Fire behavior
Since bidirectional lightened slabs (e.g. with spheres) act like a solid slab, fire resistance is only a matter of compression layer thickness. Fire resistance depends on the temperature in the bars and therefore on heat transmission. Since the areas where the reinforcement is concentrated is solid, the fire resistance varies based on the proposed concrete cover.
The Holedeck system complies with the CTE-DBSI regulations, approved Eurocode 2, of European regulations. Its behavior is similar to that of a conventional bidirectional slab with removable coffers. Holedeck offers variations in the width of the ribs, type of window and compression layer to achieve fire-resistant coatings of up to 120 minutes (according to European regulations) without the need for extra protection.[1].
Acoustic
Holedeck complies with the CTE DB-HR acoustic regulations regarding reverberation and acoustic insulation without the need for false ceilings. Acoustic insulation is favored by reinforced concrete whose weight favors the application of the law of masses. With Holedeck, the reverberation time is reduced to 1/5 compared to a flat concrete slab due to the porosity of the material and especially due to the spongy shape of the resulting slab.[1].
Characteristics
The Holedeck system complies with the following principles:.
Advantages
As a consequence of the Holedeck system technology, the use of Holedeck qualifies for LEED and BREEAM certification.[3].
Less consumption of concrete and steel with equal thickness. Decrease in slab thicknesses. Possibility of increasing the number of floors of the building with the same total height (Towers) and increasing the volume of the building (buildability). Quick and easy to implement.
Span light up to 20 meters. No beams between pillars. Reduction in the number of pillars. Can be used in conjunction with prefabs. No handling or lifting equipment required. Possibility of unidirectional structures through implements.
Good behavior against earthquakes due to its lower seismic mass. Less dimensional limitations of the elements.
The geometry of bidirectional slabs and in particular of a waffle slab is characterized by orthohedral castings of a certain size, placed in a precise modular grid. Waffle slabs are reinforced concrete slabs, heterogeneous in terms of section, reinforced in two perpendicular directions and lightened.
These structures admit bending that can be decomposed according to the assembly directions, forming with the supports a spatial matrix with great capacity to collect vertical actions and with sufficient capacity for horizontal ones.
Waffle slabs do not have hanging beams, forming part of the so-called flat slabs, these being the most used in construction.
The fundamental parameters that define the characteristics of the waffle slab are:
The geometry of the Holedeck system is made up of a series of molds or trays, generally square in size, and which are regularly arranged in a matrix, leaving interstitial spaces between the molds in which the reinforcement is housed to later pour the concrete.
The Holedeck construction system achieves slabs with ribs with different heights and with slab cells and grids of different dimensions. In order to achieve slabs with different heights of ribs, Holedeck uses longitudinal growth pieces, together with a central piece to which they are connected, being able to achieve a reduction in the height of ribs longitudinally and transversely, these pieces being recoverable once the mold supports are removed.
In addition, Holedeck pieces are recoverable, allowing the forging to be adapted to the structural characteristics or needs. To achieve forgings with grids of different dimensions without discarding the molds or trays used until now, two pieces are specifically used:
Theory
In principle, two-way lightened slabs act as solid slabs. Consequently, its design is similar to these but with less self-weight due to the reduced amount of concrete. Research carried out by universities in Germany, Holland and Denmark based on the Eurocodes concludes that bidirectional lightweight slabs act in the same way as a solid slab.
While a bidirectional lightened slab, such as the BubbleDeck system") or the U-boot Beton® system") (D.Coronelli, L. Martinelli, F. Foti (2016), "Reinforced concrete voided slabs to gravity and seismic actions", Dario Flaccovio Editore), must be calculated as a solid slab, certain ribbed slab systems, such as the Holedeck system, consisting of a grid of beams orthogonal, they must be calculated as beams.
The Holedeck system also has gaps in the ribs, which makes the resulting structure lighter, more versatile and sustainable, in addition to allowing installations to pass through its interior.
The technology of bidirectional lightweight slabs has been incorporated into international regulations such as the Eurocodes and several national codes such as the CUR of the Netherlands.
Fire behavior
Since bidirectional lightened slabs (e.g. with spheres) act like a solid slab, fire resistance is only a matter of compression layer thickness. Fire resistance depends on the temperature in the bars and therefore on heat transmission. Since the areas where the reinforcement is concentrated is solid, the fire resistance varies based on the proposed concrete cover.
The Holedeck system complies with the CTE-DBSI regulations, approved Eurocode 2, of European regulations. Its behavior is similar to that of a conventional bidirectional slab with removable coffers. Holedeck offers variations in the width of the ribs, type of window and compression layer to achieve fire-resistant coatings of up to 120 minutes (according to European regulations) without the need for extra protection.[1].
Acoustic
Holedeck complies with the CTE DB-HR acoustic regulations regarding reverberation and acoustic insulation without the need for false ceilings. Acoustic insulation is favored by reinforced concrete whose weight favors the application of the law of masses. With Holedeck, the reverberation time is reduced to 1/5 compared to a flat concrete slab due to the porosity of the material and especially due to the spongy shape of the resulting slab.[1].
Characteristics
The Holedeck system complies with the following principles:.
Advantages
As a consequence of the Holedeck system technology, the use of Holedeck qualifies for LEED and BREEAM certification.[3].
Less consumption of concrete and steel with equal thickness. Decrease in slab thicknesses. Possibility of increasing the number of floors of the building with the same total height (Towers) and increasing the volume of the building (buildability). Quick and easy to implement.
Span light up to 20 meters. No beams between pillars. Reduction in the number of pillars. Can be used in conjunction with prefabs. No handling or lifting equipment required. Possibility of unidirectional structures through implements.
Good behavior against earthquakes due to its lower seismic mass. Less dimensional limitations of the elements.