Concept design – frames
There are various types of reinforced suspended concrete floors that may be used in buildings, ranging from flat slabs, through one- and two-way slabs, to ribbed and waffle slabs. A wide range of factors will govern the selection of an appropriate option. A spreadsheet, Concept.xls, has been developed by the Concrete Centre to aid the selection process.
The spreadsheet is intended for time and cost comparisons and gives initial member sizing, quantities of formwork, reinforcement and concrete – all useful information when making a choice of frame. The optimised solution takes full account of the interaction between frame, cladding and foundation costs as well as frame construction time. Spans up to 12 m (16 m for wide beams) are catered for.
The designer inputs information such as the number of bays, spans and loads. Cost and time data, and many of the basic assumptions, can be changed. The programme compares conceptual designs for different forms of floor and then ranks them in order of total or construction cost. The designer can then proceed with detailed design of the chosen option in the normal way.
A free trial download of Concept.xls is available from The Concrete Centre
Flat slabs often prove to be the most economic choice. Further information on the design of slabs may be found in Concrete Society Technical Report 64, Guide to the design and construction of reinforced concrete flat slabs and in Technical Report 43, Post-tensioned concrete floors: design handbook. In addition, Economic concrete frame elements to Eurocode 2 is a pre-scheme handbook to the rapid sizing and selection of reinforced concrete frame elements, which replaces the earlier Economic concrete frame elements published in 1997 in which design was in accordance with BS 8110.