Grid waffle slab

 Definition
 Where this system can be used
 Features of the Grid Slab
 Decorative grid slabs in historical structures
 Types of Grid Slab
 Comparison: Long Span Structures
 Construction
 Construction Technique
 Formwork Required
 Reinforcements Details
 Modification in Grid Slab for Utility
 Services Provided in Grid Slab
 Benefits
 Iconic Landmarks using Grid Slabs

• A grid 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.

• 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.

• 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

• 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.

 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.

• 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.

 Can be used as both ceiling and floor slab.
 Used in the areas where less number of columns are provided, i.e. it is basically used in the areas
which has huge spans.
 Used for specialized projects that involve clean rooms, spaces requiring seclusion from
low frequency vibration or those needing low floor deflections.
 The concrete grid 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. Grid slab also holds a greater amount of load compared
with conventional concrete slabs.

 They are used on flat sites.
 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 thana
stiffened raft.
 They use 20% less steel than a stiffened raft.

Apsis in Nazaré, Portugal
Tomb of Galileo, Vatican City
Arch of Septimius Severus, Rome

Late 16th century coffered ceiling of
Santa Maria in Aracoeli, Rome
Coffering on the ceiling of the
Pantheon, Rome

Diagrid Orthogonal
3-way Grids For Triangular & Hexagonal Areas

3m-50 m 6m-60m 8m-75m
10m-70m 10m-90m 20m-1200m

 Grids are generally limited to the interior of
a slab, leaving one or two of the forms out
to create a solid fill around the supports.
 The solid fills provide the strength required
for shear transfer to the supports.
 The fills also reduce the compression
stresses at the soffit of the floor around the
supports, thus avoiding the necessity of
bottom reinforcement in this region.
 Picture illustrate typical grid constructions
using unbounded tendons.
 A light top mesh over the grid is generally
the only top reinforcement at the interior of
the floor panels.

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

 The formwork required for grid slabs are as
follows:
• Grid Pod
• Vertical support stand
• Horizontal support beams
• Connectors
• Wall connectors
• Clits
• Pods
• Metal/Steel bars
• Cube junctions
• Hole plates

Reinforcement detail at
junction of wall and grid
slab.
Reinforcement Detail at
Junction of Beam and
grid slab.

 Lens lights –to provide diffused
daylight through concrete roofs.
 Lens lights are used in a concrete roof
as roof lights to provide resistance to
fire, for reasons of security and to
reduce sound transmission.
 Square or round glass blocks or lenses
those are cast into reinforced concrete
ribs.
 The lens lights can be pre-cast and
bedded in place on site or in-situ cast in
a concrete roof.

 Spanish architects, Alarcon & Associates,
have modified the conventional grid 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 grid system
following services can be provided:
• Air-conditioning
• Plumbing
• Lighting
• Insulation Materials
• Wiring etc.

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.

Museum of the Park
Fortaleza, Brazil
Lodytel Communication Development
Centre, Spain

Thank you
Mr. VIKAS MEHTA
School of Mechanical and civil engineering
Shoolini University
Village Bajhol, Solan (H.P)
vikasmehta@shooliniuniversity.com
+91 9459268898

Grid waffle slab

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Grid waffle slab