Chris Hendy - Do you need any more documents than the Eurocodes
CH CH Chris Hendy
CH You do need the National Annex for each of the 58 parts; with that there’s one part that doesn’t have a National Annex, so there’re 57 National Annexes. So you do need those and obviously the National Annex is specific to the country that you’re working in. But the National Annexes are certainly intended to be, and generally are, very short documents. They can’t say, I don’t like this Eurocode rule and do something different. They can only put in information where the Eurocode has permitted it, so that tends to be typically partial factors, where there’s a choice. If the Eurocode gives you several alternative methods that can be used, then the National Annex, if permitted by the Eurocode, may limit you to one of those methods, or allow them all. And it can also make reference to what’s called NCCI – Non-Contradictory Complementary Information – which is not mandatory information, but it’s generally helpful information that helps the designer comply with the Eurocode principles. So National Annexes are essential, and then we get into all sorts of other material which you may or may not need, depending on your client. So if you work for the Highways Agency for example, then there are a series of Highways Agency BDs that still need to be used. But in difference to previous practice, the BDs can only address subjects that the Eurocodes do not. So in the past the BDs could say, use this British Standard, but please make a Highways Agency specific change to this area. We can’t do that now, because that would be a restriction of trade, as it’s not fair for somebody to come in from mainland Europe and have to pick up a different set of codes. This was the whole point of Eurocodes was to eliminate that. But the BDs do still give clients specific requirements that don’t conflict with the Eurocodes. So they might be high level requirements, such as we wish all of our bridges to be waterproofed and surfaced, but we can’t specifically change clauses.
There’s also a series of BSI PDs – published documents - and these are typically being referenced as NCCI. So in some situations they do complement things like the Highways Agency standards and give requirements for things which are not covered by the Eurocodes, but typically they’re giving recommendations for what the UK considers is a perfectly fair means of complying with the Eurocode principle. And they have a slightly higher status probably than other NCCI like textbooks or books, because they’ve been put together by British Standard Committees.
The final thing that you do need, again in design, are certain Euro norms, and these are documents which cover workmanship requirements and execution, and also they’re used to specify the actual products. And they’re both important. They’re mainly for the actual execution side, but the designer needs to take notice of them. Because in putting together drawings we need to specify materials to these Euro norms, because the Eurocode rules only work, they’re only safe, if you specify materials in accordance with the Euro norms that they’re assuming. And the same is true of the Execution Standards, so it’s no use using Eurocodes and then carrying out your workmanship to other standards, because again there are assumptions in terms of the tolerances that are used that are actually fundamental to some of the formulae and rules that are required in the code. And that’s one thing that is a challenge perhaps for non-European countries who wish to pick up the Eurocodes. Because some, not all of the economy that comes from the Eurocodes, is due to actually good workmanship practice, and so if you haven’t got that sort of control on the workmanship side, then it may be that some of the economies that the Eurocode rules give you cannot be realized in principle. But that’s not the case for all of the economy: some of it’s just because we have a better understanding of the way structures behave, and that’s been incorporated in the design rules.
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