Flat slab is a reinforced concrete slab supported directly by concrete columns without the use of beams. Flat slab is defined as one sided or two-sided support system with sheer load of the slab being concentrated on the supporting columns and a square slab called ‘drop panels’.
Drop panels play a significant role here as they augment the overall capacity and sturdiness of the flooring system beneath the vertical loads thereby boosting cost effectiveness of the construction. Usually the height of drop panels is about two times the height of slab.
- Procedure related to design
- Presence or absence of holes
- Significance of deflections
- Previous layout application experience
- Types of Flat Slab Construction
- Advantages of Flat Slabs
- Types of Flat Slab Design
- Benefits of Using Flat Slab Construction Method
Types of Flat Slab ConstructionFollowing are the types of flab slab construction:
- Simple flat slab
- Flat slab with drop panels
- Flat slab with column heads
- Flat slab with both drop panels and column heads
Uses of Column Heads
- It increase shear strength of slab
- It reduce the moment in the slab by reducing the clear or effective span
Uses of Drop Panels
- It increase shear strength of slab
- It increase negative moment capacity of slab
- It stiffen the slab and hence reduce deflection
Advantages of Flat SlabsIt is recognized that Flat Slabs without drop panels can be built at a very fast pace as the framework of structure is simplified and diminished. Also, speedy turn-around can be achieved using an arrangement using early striking and flying systems. Flat slab construction can deeply reduce floor-to –floor height especially in the absence of false ceiling as flat slab construction does act as limiting factor on the placement of horizontal services and partitions. This can prove gainful in case of lower building height, decreased cladding expense and pre-fabricated services. In case the client plans changes in the interior and wants to use the accommodation to suit the need, flat slab construction is the perfect choice as it offers that flexibility to the owner. This flexibility is possible due to the use of square lattice and absence of beam that makes channelling of services and allocation of partitions difficult.
Thickness of flat slabThickness of flat slab is another very attractive benefit because thin slab provides the advantage of increased floor to ceiling height and lower cladding cost for the owner. However, there is profound lower limit to thickness of slab because extra reinforcements are needed to tackle design issues. Besides this, added margin must be provided to facilitate architectural alterations at later stages.
Types of Flat Slab DesignMultitudes of process and methods are involved in designing flat slabs and evaluating these slabs in flexures. Some of these methods are as following:
- The empirical method
- The sub-frame method
- The yield line method
- Finite –element analysis
Benefits of Using Flat Slab Construction Method
- Flexibility in room layout
- Saving in building height
- Shorter construction time
- Ease of installation of M&E services
- Use of prefabricated welded mesh
- Buildable score
Flexibility in Room LayoutFlat slabs allows Architect to introduce partition walls anywhere required, this allows owner to change the size of room layout. Use of flat slab allows choice of omitting false ceiling and finish soffit of slab with skim coating.
Saving in Building Height
- Lower storey height will reduce building weight due to lower partitions and cladding to façade
- Approximately saves 10% in vertical members
- Reduced foundation load