THE FEDERATION of Piling Specialists has strongly criticised the latest draft of Eurocode 7: Geotechnical design - Part 1: General rules, calling it a 'poor quality'document.
It is 'too much like an academic textbook and full of lengthy tracts of text with few explanatory diagrams.Some of the elaborate formulation adjustments have lost touch with reality, 'it said.
FPS claimed that if EC7 or a similar code became a European standard, it would 'inhibit the development of better geo-technical methods for at least a decade, just at a time when serious advances in foundation engineering are becoming possible' It added: 'There needs to be explicit provision for the development and application of new, well proven and established methods.'
'It [EC7] is aimed at providing compatibility with the European structural codes rather than being a workable and practical code for geotechnical design. There are inconsistencies between the different sections of the code, reflecting the Committee (camel) approach, ' the FPS told Ground Engineering.
Members' comments were presented at the British Standards Institution B526 committee meeting on 30 March and again at the TC250 CEN committee meeting in Madrid on 5 and 6 April.
'The outcome of the meeting was yet another modification in the 20 year history of this document that has effectively removed any real possibility of it becoming a common standard throughout Europe, ' the FPS said.
'Member countries will individually set many of the parameters used in the partial factoring system.Design will not be the same in England, France, Germany and elsewhere throughout Europe, 'it added.
FPS members' main technical criticism of the code is that deformation is not treated with any degree of recognition and can never be controlled solely by factoring loads.
'There is apparently no logical basis for the selection or derivation of the partial factors, apart from simulating numbers to replicate the old 'lump'factor methods as nearly as possible.
'The logic of some proposed 'calibration factors'such as those related to dynamic pile driving formulae and in reference to the number of piles tested on a particular site, defies all statistical justification. In simple truth a return to a lump factor of safety approach in combination with a realistic treatment of deformation would offer a better way forward.'
While it may be argued that the EC7 base code is a more academic document, FPS felt that because work is carried out under design and construct rules, a more balanced committee was required.
'It is apparent the code has been drawn up with a serious absence of practitioners on the committee. The rapid development of the TC288 'execution codes' carries the strong message that when real experts come together, as has been arranged through the aegis of the European Federation of Foundation Contractors, working codes can be developed rapidly.'
The question, FPS said, was: 'why has it not been possible to reach agreement on this new code after 20 years of endless committee meeting? A credible answer is that perhaps because its concept is wrong and it can never work'