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229 lines
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229 lines
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"# Hollow core slabs"
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"Hollow core slabs are prefabricated floor elements. The hollow plates are prestressed and arrive on site fully\n",
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"prefabricated. The hollow cores save a considerable amount of weight compared to the massive slab floor.\n",
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"The savings can be as much as 50%. This means that also the main bearing structure and foundation can be made\n",
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"considerably lighter. \n",
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"\n",
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"The floor concept is based on the following principles:\n",
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"- No voids.\n",
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"- No concentrated loads.\n",
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"- Free supports (no clamped supports)\n",
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"- Standard fire resistance\n",
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"- Deflection under variable load of max. 0,003 L\n",
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"\n",
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"```{figure} Images/HollowCore1.jpg``` \n",
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"```{figure} Images/HollowCore2.jpg``` \n",
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"\n",
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"```{note}\n",
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"www.vbi.nl\n",
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"www.dycore.nl\n",
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"```\n",
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"\n",
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"```{note} Sources\n",
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"Handbook VBI floors\n",
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"Product information VBI\n",
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"Product information Dycore\n",
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"```\n",
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"\n",
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"## Aplications\n",
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"\n",
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"In contrast to what one may expect hollow core slabs also offer opportunities for free formed floor plans. The use of hollow core slabs is not restricted to the rectangular floor\n",
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"plans used in offices and flats. Both round shaps as chamfered egdes are possible. It is important to realize that the plates can be cut under an angle.\n",
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"\n",
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"```{figure} Images/HollowCoreApplication1.jpg``` \n",
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"```{figure} Images/HollowCoreApplication2.jpg``` \n",
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"```{figure} Images/HollowCoreApplication3.jpg``` \n",
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"```{figure} Images/HollowCoreApplication4.jpg``` \n",
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"```{figure} Images/HollowCoreApplication5.jpg``` \n",
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"```{figure} Images/HollowCoreApplication6.jpg``` \n",
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"\n",
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"## Execution aspects\n",
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"\n",
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"Small voids can be directly applied in prefabrication. The floor slabs can also be ordered with cast in light sockets and electricity ducts. When using hollow core slabs it must\n",
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"be noted that the prestress causes a precamber of the unloaded plate. This is mainly an issue with larger spans. \n",
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" \n",
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"Rules of thumb for this precamber are:\n",
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"- 1/1000 L with light prestress\n",
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"- 3/1000 L with heavy prestress\n",
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" \n",
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"Depending on the stiffness of the floor slab, the bearing and the levelness of the bearing the slabs can be supported in different ways:\n",
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"- directly on the underlying structure\n",
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"- in mortar\n",
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"- on fabric\n",
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"- on elastomeric strips\n",
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" \n",
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"For variable loads to 3 kN/m2 and spans up to 6,5 m all support variants are possible. In other cases the elastomeric strips are recommended.\n",
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"The common bearing length is 100 mm in residential buildings, and 150 mm in non residential buildings.\n",
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" \n",
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"To activate diaphragm action of the floors there are several option. In order of increasing load:\n",
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"- Mortar filled joints with added reinforcement.\n",
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"- Coupling of the plates to each other and the structure by means of extra reinforcement.\n",
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"- Application of a structural topping with a tensile tie coupled to the structure.\n",
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"- A combination of the aformentioned provisions with a cast-in peripheral beam which contains the tensile tie.\n",
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" \n",
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"The horizontal loads from the floor are transmitted by concrete ‘studs’ to the stabilizing elements of the building.\n",
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"\n",
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"```{figure} Images/ExecutionAspects1.jpg``` \n",
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"```{figure} Images/ExecutionAspects2.jpg``` \n",
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"\n",
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"## Product specifications VBI isolation slabfloor A200\n",
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"\n",
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"| Property | Value |\n",
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"|-------------------------------|-------------------------------|\n",
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"| Weight including joint mortar | 303 kg/m² |\n",
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"| Fire resistance | 60 - 90 minutes |\n",
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"| Maximum slab length | |\n",
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"| - non-residential buildings | 10.00 m |\n",
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"| - floor residential buildings | 7.60 m |\n",
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"| - roof residential buildings | 9.00 m |\n",
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"| Filler slabs width | |\n",
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"| - residential | 300 + n x 100 mm (AL200) |\n",
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"| - non-residential | 300 + n x 150 mm |\n",
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"| Joint mortar | 7.3 l/m |\n",
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"| Strength class | C45/55 |\n",
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"| Cross section | 144623 mm² |\n",
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"| Center of gravity | 99.3 mm |\n",
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"| Moment of inertia | 680.0 E+06 mm⁴ |\n",
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"| Use of recycled concrete granule | 20% on request |\n",
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"\n",
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"```{figure} Images/VBI1.jpg``` \n",
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"```{figure} Images/VBI2.jpg``` \n",
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"\n",
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"### Spans\n",
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" \n",
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"```{figure} Images/HollowCoreSpans.jpg```\n",
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"\n",
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"### Connections (All types of hollow core slabs)\n",
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"\n",
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"The bearing length ‘a’ should, when a SBR centering strip is used, fulfill the following conditions:\n",
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"$a = 40 + 0,004 L (floors)$\n",
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"$a = 30 + 0,004 L (roofs)$\n",
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"$L = span in mm.$\n",
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"$a = a_r + a_o$\n",
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"$a_o = see figure$\n",
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"$a_r = distance from edge of supporting member to edge of bearing, for a_r, a value no larger than 25 mm can be used. Preferably it is exactly 25 mm.$\n",
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"\n",
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"SBR centering strips centering strips have different functions, depending on their application:\n",
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"- centering the load;\n",
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"- prevent the slabs from shifting;\n",
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"- preventing or limit clamping moments.\n",
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"\n",
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"Centering strips are used in different situations:\n",
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"- when the floor is clamped;\n",
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"- for bearings on concrete and masonry;\n",
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"- for bearings on a steel substructure where the load needs to be centered.\n",
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"\n",
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"```{figure} Images/HollowCoreConnections.jpg```\n",
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"\n",
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"## Product specifications VBI isolation slabfloor A320\n",
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"\n",
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"| Property | Value |\n",
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"|-------------------------------|---------------------------------|\n",
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"| Weight including joint mortar | 443 kg/m² |\n",
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"| Fire resistance | 90 - 120 minutes |\n",
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"| Maximum slab length | 14.70 m |\n",
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"| Filler slabs width | 300 + n x 150 mm |\n",
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"| Joint mortar | 11.9 l/m |\n",
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"| Strength class | C45/55 |\n",
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"| Cross section | 209918 mm² |\n",
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"| Center of gravity | 153.8 mm |\n",
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"| Moment of inertia | 2568.1 E+06 mm⁴ |\n",
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"| Top surface | Normal or rough |\n",
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"| Use of recycled concrete granule | 20% on request |\n",
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"\n",
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"```{figure} Images/VBI3.jpg``` \n",
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"```{figure} Images/VBI4.jpg```\n",
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"\n",
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"### Spans\n",
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"\n",
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"```{figure} Images/HollowCoreSpans2.jpg```\n",
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"\n",
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"### Connections (All types of hollow core slabs)\n",
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"\n",
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"```{figure} Images/HollowCoreConnections2.jpg```\n",
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"\n",
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"Support on cavity wall\n",
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"\n",
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"```{figure} Images/HollowCoreConnections3.jpg```\n",
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"\n",
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"For walls separating two houses the hollow cores near voids are filled with mortar, mineral wool of polymer foam.\n",
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"\n",
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"```{figure} Images/HollowCoreConnections4.jpg```\n",
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"\n",
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"Bearing on console\n",
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"\n",
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"## Product specifications Dycore hollow core slabs\n",
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"\n",
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"| Property | Value |\n",
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"|-------------------|---------------------|\n",
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"| Fire resistance | 60 - 90 minutes |\n",
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"| Density | 2400 kg/m³ |\n",
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"| Prestressing Steel| FeP 1860 | \n",
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"\n",
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"\n",
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"| Type | Height [mm] | Weight [kN/m²] | Joints [l/m] | Cross Section [mm²] | Filler slabs min. Width [mm] | Max. Length [m] |\n",
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"|------|-------------|-----------------|--------------|----------------------|------------------|------------------|\n",
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"| W | 150 | 2.4 | 4.4 | 0.11 | 297 | 6 | 5.0 |\n",
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"| N | 200 | 2.7 | 5.7 | 0.13 | 643 | 9 | 7.2 |\n",
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"| U | 200 | 3.1 | 5.7 | 0.15 | 666 | 9 | 7.2 |\n",
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"| T | 255 | 3.7 | 7.2 | 0.17 | 1364 | 12 | 9.3 |\n",
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"| H | 320 | 4.3 | 8.7 | 0.20 | 2517 | 15 | 11.5 |\n",
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"| K | 400 | 5.0 | 10.9 | 0.23 | 4625 | 18 | 14.4 |\n",
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"\n",
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"```{figure} Images/ProductSpecificationsDycore.jpg```\n",
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"\n",
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"### Spans\n",
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"\n",
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"```{figure} Images/Dycorespans.jpg```\n",
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"\n",
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"```{note}\n",
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"The graph indicates the maximum distributed load (excluding self weight) for different spans for slabs on two supports\n",
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"```\n",
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" \n",
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"### Connections (All types of hollow core slabs)\n",
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"\n",
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"```{figure} Images/Integrated_Beams.jpg```"
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