What is a Waffle slabs?

What is a Waffle slabs

Waffle slabs are a reinforced concrete footing and slab system constructed on the ground. They consist of a perimeter footing (edge beam) and a series of narrow internal beams (strip footings) at one-meter nominal centers running each way. The whole footing and slab system is constructed on top of the ground.

Advantages:

• Savings on weight and materials


• Long Spans


• Attractive soffit appearance if exposed


• Economical when reusable formwork pans used


• Vertical penetrations between ribs are easy.

Disadvantages:

• Depth of slab between the ribs may control the fire rating


• Requires special or proprietary formwork


• Greater floor-to-floor height


• Large vertical penetrations are more difficult to handle.

Where is this system used?

1. 1. 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 the areas which have huge spans.
   
   
   2. 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.
   
   
   3. 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.
   
   
   4. This form of construction is used in airports, parking garages, commercial and industrial buildings, bridges, residences and other structures requiring extra stability.
   
   
   5. 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.

Design & Production of the Waffle Slab:

1. Production:
   
   
   
   • Waffle slabs can be cast by placing the pods on the 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.
2. 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.

Reinforcements of Waffle Slab

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