WELCOME

A PRESENTATION

ON

FLAT PLATE FLOORING SYSTEM

PRESENTED BY,

ASWATHI.T

FLAT PLATE FLOORING SYSTEM

• A flat plate floor system is a two-way concrete slab supported directly on columns with reinforcement in two orthogonal directions.

• Used in hostels, multi family residential buildings and hospitals.

FLAT SLAB FLOORING SYSTEM

• The flat slabs are plates which are stiffened near the column supports by means of drop panels and/or column capitals which are generally concealed under drop ceilings.

• Compared to flat plate system the flat slab system is suitable for higher loads and longer spans.

THE DESIGN OF FLAT SLAB STRUCTURE

• Framing system 1) Three continuous span in each direction or have an over hang at least

one-forth times adjacent span length in case of any two continuous spans.

2) Typical panel must be rectangular.3) The spans must be similar in length.• Engineering analysis Flat plate/slab may be analyzed and designed by any method as long

as the satisfy the strength , stiffness and stability requirements of the IS 456:2000 or ACI-318 codes.

• Reinforcement design and detailing. Maximum forces from the analysis shall be used in the design of

reinforcement . Reinforcement required for flexure by using minimum slab thickness .

GENERAL CONSIDERATION FOR USE OF FLAT PLATE FLOOR

SYSTEM

• Architectural layout should be planned to fully enhance the main area where high flat ceiling with neatly arranged concrete columns are required in the design.

• Spacing of column• Long term deflection of the flat plate.• Early planning of routing for M&E services opening for

void and location of staircase.

SEISMIC DESIGN OF FLAT PLATE/SLAB

• Flat plate/slab structure in area of low seismicity(Zone1&2) can be designed as permitted by code to resist both vertical and lateral loads.

• For areas of high seismicity(Zone3,4&5) code does not permit flat slab construction to resist earthquake lateral load, hence lateral load resisting system has to be designed separately in addition to flat plate/slab gravity system.

• When flat slab is used in combination with shear walls for lateral load resistance the column can be designed for only 25% of the design force.

POST TENTIONED FLAT PLATE/SLAB

• Post tensioned flat plate slab are common variations of the conventional plate structure where most of the reinforcement is placed by post tensioned strands of very high strength steel.

• The structural advantage of post tensioning over conventional RCC is that the slab is neatly crack free at full service load.

• The lack of cracking lead to a water tight structure.• The disadvantage in using post tensioned system in

commercial building in India is its lack of flexibility to create openings when the slab is completed with post tensioning.

COMPARISON BETWEEN FLAT PLATE FLOOR SYSTEM AND

TRADITIONAL BEAM SYSTEM

• Longer span length achieved The economical span of a flat plate can be extended by pre-stressing to

approximately D*30,D*37&D*40. Where as for the traditional reinforced concrete beam and slab floor has an economical span D*15,D*20.

• Flat soffit ie flat ceiling. The main & unique feature of the system is that provides a way for the

architect to achieve the concept of high and completely flat ceiling with no beam protrusion.

• Saving in shuttering cost. In traditional beam column slab system the need of shuttering area is more

& cost of form work is also more.

• Saving in construction time. As form work& stagging time is reduced the over all construction time also get

reduced in flat plate slab system.• Pre stressing. Pre stressing is not possible in traditional beam column system where as post

tensioned flat plate are a common variation of the conventional structure where most of the reinforcement is placed by post tensioned strands of very high strength steel.

• Building height. Traditional beam column slab system produces building or structure higher than flat

plate slab system.• Service In traditional beam column slab system the penetrations through beam for large

ducts difficult to handle.

ADVANTAGES OF FLAT PLATE FLOORING

• Simple formwork and suitable for direct fix or sprayed ceiling.

• No beams- simplifying under floor services.• Minimum structural depth and reduced floor

to floor height.

DRAW BACK OF FLAT PLATE FLOOR SYSTEM

• Deflection control Relatively thin slab of the structure make it susceptible

to excessive deflection and floor vibrations.• Punching shear at columns. It is not very efficient at resisting shear forces at

critical locations namely columns. If the slab is found inadequate to resist punching shear certain measure can be introduced to strengthen these locations.

• Future core drilling.

PROJECT APPLICATION

• The flat plate/slab are economical since they have no beams and hence can reduce the floor height by (10-15)%.

• The Mass-3 project has been completed successfully and is ready for occupation and the RPS project is currently under construction in India.

PROJECT MASS-3

• The project is located in Bangalore(Zone-2), framing system would resist both lateral &vertical loads.

• The design criteria are based on IS 456:2000, IS 1893 part1&IS 875 part3.

• The building is trapezoid in plan with an approximate dimension of 90m length 30m width&15m height.

• The structure consist of basement car parking floor+ 4upper floors+ terrace.

At 80 stories the Aqua building in Chicago topped out in early March. Using flat-plate floor construction, they were able to complete concrete construction well ahead of a structural steel building being built nearby.

CASE STUDY

140 WEST 42nd STREET, OFFICE BUILDING, NEWYORK• 140 West street is the first post tensioned concrete office

building with 24 story.• Requirement mean that the new tower’s floor to floor height

would have to match the Bush Tower is floor to floor’s height of 13’-9”

• The lateral force resisting system efficiently incorporated the 12” flat plate flat plate with 16”thick concrete sheer wall which completely encases the fire stair from the ground floor.

• The vertical structural elements also minimize the rentable floor space and economical drift control of the structure for occupant comfort.

CONCLUSION

• The flat plate slab system often provide the most economical solution for high rise residential of commercial construction.

• The system’s low floor height result in over all reduction of building height which further result lesser dead load leading to lower foundation cost.

• The flat plate/slab construction is developing technology in India.

• The flat plate/slab can be designed& built either by conventional RCC or post tensioning.

• The Indian codes in combination with other standards like the ACI,BS or Euro code to design and analyze flat slab/ plates.

THANK YOU