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Flat Grid / Waffle Slab


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Flat Grid Slab / Waffle Slab Information

Published in: Engineering

Flat Grid / Waffle Slab

  1. 1. FLAT GRID OR WAFFLE SYSTEM Sinhagad College of Architecture This Presentation is compiled by: Akshay Gawade Mihir Yadav Shanan Jaiswal
  2. 2. What is Flat Grid Slab / Waffle Slab System ?  Definition : • A waffle slab is a type of building material that has two-directional reinforcement on the outside of the material, giving it the shape of the pockets on a waffle. • This type of reinforcement is common on concrete, wood and metal construction. A waffle slab gives a substance significantly more structural stability without using a lot of additional material. • This makes a waffle slab perfect for large flat areas like foundations or floors.  Appearance : • The top of a waffle slab is generally smooth, like a traditional building surface, but the underside has a shape reminiscent of a waffle. • Straight lines run the entire width and length of the slab, generally raised several inches from the surface. • These ridges form the namesake square pockets of the entire length and width of the slab
  3. 3. Where this system is used ? • Waffle slab can be used as both ceiling and floor slab. They are used in the areas where less number of columns are provided, i.e. it is basically used in th areas which has huge spans. • Waffle slab is not used in typical construction projects. They are used for specialized projects that involve clean rooms, spaces requiring seclusion from low frequency vibration or those needing low floor deflections. • The concrete waffle slab is often used for industrial and commercial buildings while wood and metal waffle slabs are used in many other construction sites. • This form of construction is used in airports, parking garages, commercial and industrial buildings, bridges, residences and other structures requiring extra stability. • The main purpose of employing this technology is for its strong foundation characteristics of crack and sagging resistance. Waffle slab also holds a greater amount of load compared with conventional concrete slabs.
  4. 4. Features of the Waffle Slab The features of the Waffle slab are as follows : • They are used on flat sites • They are wholly above ground • No beam excavation is required • No controlled or rolled fill is used • Cardboard slab panel/void formers are used • Slab panels are on 1 metre grids (approximately) • Trench mesh or individual bars can be used • Slab thickness is 85 - 100 mm • Internal beams are 110 – 200 mm wide • There is minimal concrete volume • No beam down drag from clay (above ground slab) occurs • Shrinkage of slab is lower than stiffened rafts and footing slabs • They use 30% less concrete than a stiffened raft • They use 20% less steel than a stiffened raft.
  5. 5. Design & Production of the Waffle Slab  Production : • Waffle slabs can be casted by placing he pods on he formwork itself or they can be available pre-casted. • Concrete waffle slabs can be purchased and shipped to the construction site as prefabricated or precast sections, or they can be poured on-site. • If prefabricated products are not in the budget, consider purchasing casts for the concrete waffle slabs. • The pre-casted pods are then placed directly on the site and then provided with reinforcement and filled with concrete.  Design : • There are three basic designs for concrete slabs that improve the strength-to- weight ratio. For each design, the top surface is flat while the underside is modulated with either a corrugated, ribbed or waffle design. • Corrugated slabs are created when concrete is poured into a wavy metal form. This shape prevents the slab from sagging. • Ribbed slabs add strength in one direction, while the concrete waffle slab design adds strength in perpendicular directions. Concrete slabs can be reinforced with rebar for additional strength.
  6. 6. Services Provided in Waffle Slab Spanish architects, Alarcon & Associates, have modified the conventional waffle slab to fill it with holes so that services can be run within the depth of the slab, reducing the floor to floor height and getting some of that extra cost back. This new system they invented is called the Holedeck Due to the holes in the waffle system following services can be provided: • Air-conditioning • Plumbing • Lighting • Insulation Materials • Wiring,etc.
  7. 7. Managing Services  Electricity and Telecomunication : • Wiring installations can flow in pipes embedded in the floor, or inside a registrable tile system . • They can also circulate through the suspended ceiling, being fully accessible by just lifting it.  Maintainance and Cleaning: • It is registrable, and performing plenum ventilation, easy cleaning of the ducts without requiring demolition or specific equipment is possible. • In addition, , immediate access to installations, enables repairs and reconfigurations withot requiring the interruption of the normal activity of the building.
  8. 8. Formwork Required The formwork required for waffle slabs are as follows: • Vertical support stand • Horizontal support beams • Connectors Different Types of Pods • Wall connectors • Clits • Pods • Metal/Steel bars • Cube junctions • Hole plates
  9. 9. Waffle Pods Providers (India)  The main element required to provide waffle slab is “Waffle Pod”.  There are many Waffle pod producers all over India, and some of their names are as follows:- • Supreme Fibre Glass Pvt. Ltd. (Mumbai) • Envo plast (Kolkata) • Teknik Kalip (Mumbai,Banglore) • Utracon (Gujarat) • Geo plast (Chennai) • Maruti Plastics (Mumbai)
  10. 10. Types of slab  Index : 1. Floor 2. Mortar 3. Wire-tray 4. Radiant Floor ducts 5. Insulation/Ducts Seat 6. Installations Tray 7. Holedeck slab 8. Reinforcement 9. AC Ducts  Index : 1. AC Ducts 2. Holedeck slab 3. Installation tray 4. Reinforcement 5. Installation drop tower 6. Air impeller Square Pod System Triangular Pod System
  11. 11. Reinforcements of Waffle Slab
  12. 12. Reinforcements Details Reinforcement Detail at Junction of Sloping Slab and Waffle slab. Reinforcement Detail at Junction of Wall and Waffle slab. Reinforcement Detail at Junction of Beam and Waffle slab.
  13. 13. Example of the Slab Reflected Ceiling View of the slab Plan of tendon placement layout 3d view of the Ceiling 3d view of tendon placement Load deflection in the provided waffle slab
  14. 14. Construction Technique 1. Arranging the Framework 2. Fixing the Connectors 3. Fixing the Framework 4. Providing a horizontal connector 5. Placing the Pods 6. Fixing pods to the connectors 7. Removing framework 8. Removing connectors 9. Removing pods 10. Providing stacking
  15. 15. Construction Procedure for Floor Slab
  16. 16. Construction Procedure for Ceiling Slab
  17. 17. Advantages & Dis-advantages  Advantages : • Waffle slabs are able to carry heavier loads and span longer distances than flat slabs as these systems are light in weight. • Suitable for spans of 7m – 16m ; longer spans may be possible with posttensioning. • It is also economical as the amount of concrete and steel is reduced as compared to flush slabs. Saving 15% concrete and 10% steel as compared to traditional T beams. • These systems are light in weight and hence considerable saving is ensured in the framework as light framework is required. • Coffered underside is usually left exposed for visual appearance.  Dis-advantages : • Construction requires strict supervision and skilled labour. • The casting forms or moulds required for pre- cast units are very costly and hence only economical when large scale production of similar units are desired. • Headroom is reduced , hence increased storey height. • Due to waffle ceiling , it creates problem in lighting facilities and hanging pipes or ducts.
  18. 18. Iconic Landmarks using Waffle Slabs Lodytel Communication Development Centre, Spain It was the first building to use the Holedeck pods for waffle sytem. Chattrapati Shivaji Terminal,India It is recognized for its innovative column design which also consists waffle design. Metropol Parasol,Italy It is the world’s largest wooden structure which is made up of waffle system.
  19. 19. THANK YOU!