Composite columns part 1
To introduce composite columns, to describe their behaviour, and to explain the design method for axially loaded composite columns.
The different types of composite columns are introduced and their advantages summarised. Methods of fabrication are described together with the typical connection details used at column/beam junctions. The simplified design method for an axially loaded column, given in Eurocode 4 , which involves the use of buckling curves, is explained and the restrictions to its application outlined. Rules are also given to ensure local buckling does not cause premature failure. The influence of the long-term behaviour of the concrete, i.e. creep and shrinkage, is also considered.
In the 1960s, intensive research work commenced on the assessment of the resistance of columns in which a steel cross-section acts together with surrounding concrete. These columns could not be designed at that time by the rules for steelwork or by those for concrete structures. The result of this research work was described in various publications and led, in 1979, to design recommendations for composite columns .
These recommendations, together with further research work, have been used in Eurocode 4 , which deals with composite construction in buildings.
Eurocode 4 defines the general requirements for the design of composite columns. However, if all the geometrical and physical non-linearities of the different materials are observed, it is only possible to meet the code requirements using numerical methods of analysis. Eurocode 4, however, also gives a simplified method which is the subject of this lecture.Read more