Part 1: Architect’s Guide 1 - 13 4 BASIS OF GOOD DESIGN: THE STRUCTURE 4.1 The load-bearing system In multi-storey structures, load-bearing and load distribution functions are ensured by installing a main frame consisting of beams and columns. 4.1.1 Load-bearing framework Optimisation of the number of load points is a question which is always raised at the design stage and the response must take into account the building use. As far as layout of space is concerned, columns are always considered obstacles that must be limited as much as possible. Traditional framework structures use spans of the order of 4,50 to 6 m for residential buildings. Large spans of between 12 and 18 m for offices and 15 to 16 m for car parks can free up a lot of space. 15 m 15 m 5 × 6 m Figure 4.1 Example of grid for columns and beams The number of load-bearing points also depends on the type of foundation in respect of soil conditions. When the soil is poor, it is advisable to limit the foundation points and consequently reduce the number of columns. A steel frame has the benefit of reducing the overall weight of the building and therefore reducing the size of the foundations. 4.1.2 Columns The main purpose of the columns is to transfer the vertical loads to the foundations. However a part of the horizontal actions (wind action) is also transferred through the columns. In multi-storey buildings, the columns are heavily compressed and they are designed for buckling.
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