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4.2.1.1.4 Analysis

Analyses are carried out using idealizations of both the geometry and the behaviour of the structure. The idealization selected shall be appropriate to the problem being considered.

No guidance is given in EC2 on the selection of analysis models for flat slabs, or on the division of panels into middle and column strips and the distribution of analysis moments between these strips. This is left to the assessment of individual engineers. The requirements set down in BS 8110 for the above points are taken as a means of complying with EC2 Clause 2.5.1.1P(3).

EC2 allows analysis of beams and slabs as continuous over pinned supports. 2.5.3.3(3) It then permits a reduction in the support moment given by 2.5.3.3(4)

Sd Sd.sup sup

The analysis in this example includes framing into columns. Thus the reduction AM„„ is not taken.

Consider two frames from Figure 4.14 as typical:

Analysis results for the frames described above are given in Figure 4.15. The results for each frame are practically identical as the analysis for Grid B has an increased loaded width (5.2 m), since this is the first internal support for frames in the orthogonal direction.

Member stiffnesses have been based on a plain concrete section in this analysis. Column moments and reactions are given in Table 4.1.

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