N°227. 1995. Non-linear Analysis of Beams and Frames - Discussion of a parametric research.

The present report is a contribution of the authors to the work of the Working Party "Non-linear Analysis" of CEB Commission 1 "Safety and Performance Concepts". Initially the document had been conceived as a Supporting Document to the corresponding chapters of Eurocode 2; successively the scope was enlarged to take into account further proposals put forward on the subject and to assess the consequences of new rules expressed in some National Application Documents of Eurocode 2. 

In the first chapters of the report the field of application and limits of validity of the procedures of non-linear analysis envisaged in Eurocode 2 are thoroughly discussed. Special attention is also devoted to the reliability aspects and a simplified numerical approach is described and controlled. Later, several hundreds of numerical analyses of beams and frames are presented taking as basic variables not only the geometrical and mechanica! parameters, but also the concept of detailing assumed for dimensioning. The calculations concern as well the ultimate as the serviceability conditions and the correlation between the ultimate response and the stress levels in service is systematically considered. In this respect proposals are made to help the designer who is obliged to be content with the use of simplified procedures. For this purpose the classica! concept consisting in limiting the "ratio of redistribution" with a formula similar to equation 2. 17 of Eurocode 2 is applied both for dimensioning and verification, and its use is extended to the whole set of methods: redistribution, plastic and, as preliminary guidance, non-linear. 

Special chapters consider the problems of dimensioning and that of imposed deformations. For the first aspect the old method proposed by Baker is compared with a new approach based on the ideas expressed above. For imposed deformations- settlements of

supports and thermal effects- the influence of the loading level for which the intervention takes place is analysed. The influence of some geometrical parameters and of the amplitude of the imposed deformations are also considered. 

This Bulletin is to be seen as a document the contents of which, even if based on a very extended parametric research, is still the expression of the author's views. It has also to be taken into account that the maintenance ofEurocodes is a topic still under discussion. 

The authors would wish that the members of the Task Group will consider the collection of data presented in this report, and mainly those pointed out in the Overview presented in Chapter 9, and will contribute to the discussion of their proposals.