Trade Journals for the Concrete Industry

Floor designs with span widths up to approximately 7 m are nowadays generally produced using flat floor structures with an in-situ concrete construction method. Flat floors have replaced beam-supported floors, which had for many years been employed in this field of application. The great advantage of flat floors is to be found in their smooth underside, which, in comparison with earlier times, makes it possible to install pipelines for technical building services with no conflict of purposes. Whereas, by dint of a skilful arrangement of main and secondary beams, floors supported by beams have the least consumption in terms of materials, material consumption with flat floors rises particularly with increasing span width. In times of resource-efficient construction methods and stipulations as regards cutting down CO2 emissions, more thought must be given to optimising material consumption. This affects large span width floor structures to a greater extent as they have to possess an appropriate structural thickness in order to ensure required bending and shear resistances. Floor designs with a solid cross section can then be eliminated due to their heavy material consumption. When these marginal conditions are taken into consideration, the current rationale for creating flat floors of medium and large-sized span widths with an in-situ concrete construction method is no longer justified.