The differences in the use of Eurocode 7 in the various countries cannot be simply represented by the differences in the partial factors.
The implementation of Eurocodes in Italy is still a long lasting process, with a large impact on the professional engineering community, struggling to change their design strategy based on the global safety factors into the new performance based design with the use of partial factors. The change is not only a new design code to be considered but it is a full change enforced on to professional engineers by law both for public an private construction works.
Eurocode 7 itself is now available in the Italian language together with the other parent Codes and the National Annexes only recently approved by the Consiglio Superiore dei Lavori Pubblici. Still some administrative difficulties have to be overcome to consider Eurocodes effectively applicable for design in Italy. However, it is possible to assume that Eurocodes in general and EC7 in particular are fully operative in Italy as their content is substantially included in the National Code for Constructions (that is the NTC 2008), which is compulsory since 2009.
The most important consequence for such a revolution is that a common language is now established between all the different specialists involved in a design, and this is particularly evident for structural and geotechnical engineers, very rarely collaborating efficiently in the past for a design process. In Italy, to avoid such collaboration, a particular attitude by the structural engineers has been developed to let any occurring geotechnical problem to be solved by their geology consultant rather then developing some autonomous geotechnical skills or involving a proper geotechnical consultant in the most difficult cases. The need of a more deep understanding of the structure performance for a sound geotechnical design tend towards a removal of such bad practice.
Italian engineers have acquired some experience in the use of the Eurocode design philosophy and the many discussions on practical applications of Eurocode 7 which have occurred in public conferences, professional teaching courses and in writing and approving the NTC 2008, have given us a strong feeling on the various possibilities of using the code, and many interesting critical points have now emerged for the responsible people to think about.
Limiting to EC7:
- should we reduce the number of possible design approaches ? possibly, only one for any geotechnical structure could be sufficient, as calibration of the partial factors has been carried out in Italy to minimise differences between the different DA’s;
- in EC7 and in our NTC there isn’t any special consideration for design concerning existing constructions, that is for the majority of construction works in Italy with a strong impact on economy; should we look for short cuts and simplifications of the code to render the approval of small impact designs, less heavy and less expensive, without affecting real safety margins?
- in EC7 and in NTC, correlation factors are used to derive characteristic from measured resistances in pile or anchor testing; such correlation factors depend on the number of testing. This computation philosophy appears inappropriate for the highly non homogeneous Italian typical geological conditions, where increasing the number of tests does not ensure a proportional improvement of knowledge of the site specific geotechnical behaviour; shouldn’t we transfer such incentives valuating our knowledge of the site geotechnical model ?
But above all, we always have to develop our geotechnical designs in Italy to face important seismic actions. The traditional separation between competences of geotechnical and structural engineers deeply embedded within Eurocode committee philosophy, ended in a geotechnical chapter dispersed in the EC8 for seismic design that seems not fully integrating with EC7.
It will be very easy here to show how inappropriate could be the design of an anchored sheet pile wall not considering as unique, the static and the seismic conditions.
But we leave this discussion for the future.