I assume that you mean by flat slab : a beamless slab with a two-way load path.

The two main constraints for using flat slabs in high rise building is Punching Shear near the columns and Long Term Deformation (creep)

Assembly requires extraordinary measurement control and precision. Small errors in lower floor alignment develop into tolerances far out of specification for floors over 10 stories. Best insurance for proper control is a well-experienced Construction Surveyor and the use of precise optical plumments and zenith telescopes. The use of proper surveying instruments is critical to reliable assembly.

Concrete slabs have advantages in strength, stiffness, air-sound insulation, fire resistance and adjustability on site. The stiffness and weight, however, are two disadvantages in earthquake areas. Stiffness causes increased load on columns, while the large mass is disadvatageous in general. Concrete floor designs should consider the fitting of pipes and ducts of the occupied floor above that floor instead of under the floor in the space of the lower area, which commonly is own by another occupant.

To avoid a lot of constraints in flat slab in high rise concrete buildings specially large volume amount of concrete needed in one flat slab first thing to do is calibrate the weighing scale of the batching plant,review and evaluate the quality test of material needed then give +-5mm tolerances on alignment deviation.

I assume that you mean by flat slab : a beamless slab with a two-way load path.

The two main constraints for using flat slabs in high rise building is Punching Shear near the columns and Long Term Deformation (creep)

Yes, Dr. Baekeland.

I was refering to beamless slabs with two-way load transfer.

I was looking for any special precautions that need to be taken at the planning stage.

Thank you for the comments

I agree with Sjoerd. You need to be very precise evaluating horizontal actions, wind and earthquake, and any hole for facilities needs to be previewed...... I disagree about sound and insulation, though.

There is a problem in transferring moment from columns and shear walls to the flat slabs and ensuring the required ductility.

Flat slabs create large horizontal diaphragm action as compared to vertical diaphragm action which is far less owing to absence of beams. For this reason, flat slabs are not treated as lateral thrust resistant structures. Therefore regions which possess/experience lateral thrust potential e.g. earthquake, wind, explosion, etc. should not opt for these structures.

flat slab system is weak in lateral direction when compared to two way slab system. Precautions should be taken in designing such sytem in areas with high earthquak activities.

At Cristina. Concrete being a high density material has excellent sound transmission characteristics. Contact sound travels fast and far through structures that make contact with the concrete which includes both concrete and steel framing. To avoid this, suspended (contact insulated) ceilings and floating floors are necessary. Especially in stacked apartment buildings with conctete flooring this is a large problem. Some building exploitants oblige the inhabitants to have thick carpets all over their floors.

At Soejd. I missunderstood you! Sorry. I was meaning excatly the same. Noise transmission is a great problem with concrete floor slabs. And any insulation to prevent it, though effective, is quite expensive in residential buildings........ And needs to be carefully executed, besides. Thanks for tour comment!

The weight.

Gabriele Sir,

Kindly elevorate the span and thickness perameters for the said salb.

With Regards,

Raj Kumar

The constraints for using flat slabs in high rise concrete building were adequately answered by m/s. Pieter, Jamilur , Ishwar et al.

It is further to note that the modelling of the structure for 3-D analysis shall pose serious problem in connectivity , as the high stiffness elements of columns shall have connectivity with members( plate elements) having very less stiffness, thus causing confinement zones highly vulnerable for failures during intensified stresses caused by lateral force activity.

It is also observed to increase dead loads due to higher thickness of plate elements as required to control deflection, thus compounding the problem of connectivity.

Structural designers usually prefered flat slab in high rise building as this types of building have different arch. plans in each floors. so usually we must pay attention in designing the shear wall.

Las losas planas en edificios de gran altura no son soluciones viables por cuanto los claros (luz) versus el espesor no son suficientes para absolver las solicitaciones por corte. Se debe optar por una solución vigas - losa.

Since RC flat slabs are thicker over its whole length/width than beam based structures their total mass will be greater. This has an increasing effect on the earthquake forces and should be avoided. For earthquake resistant design keep the mass low, columns stronger than beams/floors and floor constructions flexible; three aspects that are difficult to realize with flat RCC slabs

Flat slabs have the advantage that they are easier to construct, and mostly cheaper to construct due to the simple form-work that is used. Howerver, hat is a generalization because in many cases permanent form-work can be economical also. Have a look at the cost comparison of different formwork systems for Flat Slabs, compared to other slab construction types on may page.

Here is the flat slab cost comparison study mentioned above

Article Construction cost performance of structural frames in Australia

Deflections at middle strips.