Eurocodes - Questions That Need Answering

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Eurocodes in Britain:the questions thatstill need answering

Alasdair N BealBSc, CEng, MICE, FIStructE

LLP Mmb at Thma LLP,L, UK

Proceedings of ICE

cvl e 163 Fbuay 2010Pa 2734 Pap 09-00016

In May 2008 BSI British Standardspublished the final two parts of the newsuite of ten structural Eurocodes andhas provided all of the required nationalannexes (Figure 1). The 58 Eurocodeparts supersede a total of 57 UK designstandards, such as BS 8110 (BSI, 1997b)for concrete and BS 5950 (BSI, 2000)

for steel, and BSI is due to withdrawthese in March 2010.

From 1 April, the withdrawn codesmay still be used but they will not beupdated and, according to a Europeanpublic procurement directive (EC,2004) enacted in England, Wales andNorthern Ireland by the Public Contracts

Regulations 2006 (HMG, 2006), whichcame into force on 31January 2006 public projects must be specified interms of Eurocodes. Civil and structuralengineers in the UK should thereforenow be in the final throes of a designoffice revolution, with new codes andsoftware being purchased and thousandsof engineers being retrained.

Work on Eurocodes started in 1975,when the European Commission decidedon an action programme in the fieldof construction under article 95 of theTreaty of Rome aimed at the elimina-

tion of technical obstacles to trade andharmonising technical specifications(BSI, 2002a, p.6). It took 17 years fora first draft of Eurocode 2 for concreteto appear, a further 12 years for this to

Figure 1. BSI British Standards completedpublication of all ten Eurocodes in May 2008 all required national annexes should now alsobe published


2/828 Proceedings oF THe insTiTUTion oF ciViL engineers ciViL ENGINEERING, 2010, 163, n. ce1 issn 0965 089 X

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be developed into the final version (BSI,2004a), and the UK national annex forthe general part (BSI, 2005b) was pub-lished in December 2005 a total of 30years.

However, in contrast to the lengthydrafting programme, the proposedchangeover timetable is remarkably short existing UK codes are to be withdrawnonly 16 months after publication of thekey national annex to Eurocode 1 part 1-4

on wind loads (BSI, 2008). A year beforethe changeover, 13 out of 58 UK nationalannexes had still not been published.

Until fairly recently, structural design-ers in the UK have largely ignoredEurocodes. However with the 1 April2010 deadline fast approaching, manynow realise that they may not be ableto do this for much longer. This paperreviews the issues involved and discussesthe choices they now face.

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At present, there is no requirement touse Eurocodes for private projects. Forpublic projects, the technical specifica-tion must be based on Eurocodes butdesigns based on other codes may stillbe accepted if these can be shown to betechnically equivalent. However this maywell change in future: a stated purposeof the Eurocodes is the elimination oftechnical obstacles to trade. There hasbeen little discussion of what this mightmean and its possible legal implicationsfor engineers and their work.

At present, UK building regula-tions and relevant codes of practice setminimum standards for structural designbut engineers are free to apply higherstandards if they wish, both in their owndesigns and in the performance speci-fications they prepare for contractor-designed parts of the work.

With Eurocodes available, is it stillpermissible for an engineer to specify dif-ferent requirements, such as specifyingthat piled foundations for a project mustcomply with soon-to-be withdrawn foun-dation standard BS 8004 (BSI, 1986)? Inthis situation, if a contractor submitted alow tender based on BS EN 1997-1 (BSI,2004d), the BSI version of Eurocode 7part 1 on geotechnical design, and thiswas rejected by the engineer, what would

happen if the contractor disputed thisdecision and went to court to try to forcethe engineer to accept its tender?

The engineer would explain to thecourt that he or she has a duty to theclient to ensure that the piled founda-tions are properly designed. BS8004 wasspecified because the engineer knewfrom experience that it ensures satisfac-tory pile designs, whereas he or she hasreservations about BS EN 1997-1, whichis complex, unfamiliar and untried.The engineers barrister would drawthe judges attention to recent case law

which confirms that an engineer has aprofessional duty to clients to check thatcontractor-designed items are satisfac-tory. The barrister would also drawattention to the note in BS EN 1997-1(p. i) which states, Compliance with aBritish Standard does not of itself conferimmunity from legal obligations.

However, the contractor would arguethat a valid design to BS EN 1997-1should be acceptable for any project inthe EU. Its barrister would argue thatarticle 95 of the Treaty of Rome out-

laws technical barriers to trade, so it isagainst the law for an engineer to rejecta valid BS EN 1997-1 design. No doubtthis conundrum could generate manyinteresting (and lucrative) hours of legaldiscussion, but for engineers there is aworry they are being placed in a positionwhere they may be damned if they do

and damned if they dont.Note that the question is not just about

whether it is legal for an engineer to basea specification on withdrawn UK codes it is also about whether it is legal toinclude any requirements which exceedEurocode standards. If engineers areallowed to do this, it is difficult to seehow Eurocodes can fulfil their objectiveof removing barriers to trade yet ifengineers are not allowed to do this, how

can they fulfil their professional duty totheir clients?Intriguingly, any move to make

Eurocodes mandatory for public projectscould also be open to legal challenge. Ifpublic works contracts are restricted toa select coterie of engineers who havemastered Eurocodes, this would be a fargreater technical barrier to trade thanUK codes of practice have ever been and thus arguably incompatible with theTreaty of Rome.

Ki e

Most of the 58 parts of the Eurocodeshave a separate UK national annex. Acode such as BS EN 1992-1-1 (com-mon rules for concrete structures) (BSI,2004a) is not a freestanding document the general design rules and load factorsare in BS EN 1990 (basis of structuraldesign) (BSI, 2002a), some further detailsof design rules are in BS EN 1991-1-1(densities, self-weight and imposed loads)(BSI, 2002b) and if the structure needsto be fire resisting, BS EN 1992-1-2

(fire design of concrete structures) (BSI,2004b) is also required. For steel designthere are separate parts of Eurocode 3 forgeneral design, connections, tension com-ponents and plated elements.

However the kit code problem doesnot stop there. When a new Eurocodepart and national annex arrive from

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3/829issn 0965 089 X Proceedings oF THe insTiTUTion oF ciViL engineers ciViL ENGINEERING, 2010, 163, n. ce1

eUrocodes in BriTAin: THe qUesTionsTHAT sTiLL need AnsWering

BSI they are not assembled in a readyto use form. Not only do they arrive inloose-leaf form, with no binding, but theEurocode and its UK national annex arenot supplied as a combined consolidatedtext they come as separate documents.

To use a Eurocode, an engineer mustfirst read what it says, then read whatthe national annex says, then workout what the result of combining themwould be, then memorise this (because

it is not written down anywhere) andthen remember what it was that he orshe was trying to design. Eurocodes andnational annexes have been published inthis form as a matter of deliberate policy,for transparency and ease of comparisonbetween national versions. However, forpractising engineers it only adds to thedifficulty of using these complex newcodes. To design even the simplest struc-ture to be compliant with a Eurocode, anengineer needs to have no less than fourdocuments open: the design Eurocode,the basis Eurocode (BS EN 1990 (BSI,

2002a)) and the national annexes forboth of them.

In theory, the partial factor system,load factors and load combination rulesare all specified in BS EN 1990, charac-teristic loads are in the various parts ofEurocode 1 and design rules and materi-al factors for particular structural materi-als are in Eurocodes 26 and 9. Howeverthis rule is sometimes broken.

BS EN 1990 states that the combina-tion value of a load is

0times the char-acteristic load. However, BS EN 1991-1-1

(2002b) clause 3.3.2 contradicts this,stating that if the characteristic floor loadincludes an area reduction, 0 should notbe applied.

BS EN 1990 clause 6.5.3 states thatthe frequent value of imposed load(typically 50% of characteristic) shouldbe used for reversible serviceabilitylimit states and the quasi-permanentvalue (typically 30% of characteristic)should be used for long-term deflec-tion. However, this is contradicted in BSEN 1995-1-1 (timber buildings) (BSI,2004c), which states (clause 2.2.3(2))

that when calculating timber beamdeflection the full characteristic loadshould be used. BS EN 1993-1 (generalrules for steel buildings) national annex2.23 (BSI, 2006) also contradicts BS EN

1990, stating that steel beam deflectioncalculations should be based on the fullcharacteristic load, not the frequent orquasi-permanent loads.

The most significant example of con-tradiction in Eurocodes is BS EN 1991-1-4 (wind loads), where the UK nationalannex (BSI, 2008) includes the following(p. 34):

Advisory note regarding BS EN

1991-1-4, 7.2.3 to 7.2.6Calibrationof BS EN 1991-1-4 against BS 6399-2has shown that there are differences inthe values of pressure coefficients andin some cases the EN values are sig-nificantly different to those currentlyused in the UK. National choice is notallowed for the external pressure coef-ficients. It is therefore recommendedthat the external pressure coefficientsin BS 6399-2 continue to be used tomaintain the current levels of safetyand economy of construction.

It is not clear how UK engineers aresupposed to design to BS EN 1991-1-4after BS 6399-2 (BSI, 1997a) is with-drawn in March 2010.

Therefore, although in theory BS EN1990 (and its national annex) definesall load factors and load combinationrules, in practice this is not the case.The engineer must also check Eurocode1 (actions) and the design Eurocodesin case any of these overrule it and saysomething different.

For busy engineers, Eurocodes are

impractical to use in their present formand unless great care is taken errors arelikely.

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Each Eurocode includes a long list ofunfamiliar abbreviations and a systemof Greek symbols and complex suffixeswhich will be inconvenient for both handand computer calculations. Many engi-neers will also find the language ratherstrange in English versions of Eurocodes,with obscure words such as orography

and words borrowed from French suchas normative and consistence.

There are clauses such as BS EN 1990clause 2.1(1)P, where the words are famil-iar but their meaning may not be.

A structure shall be designed andexecuted in such a way that it will,during its intended life, with appro-priate degrees of reliability and in aneconomical way sustain all actions andinfluences likely to occur during execu-tion and use.

At first sight, clause 1.3 (2) is alsorather troubling:

The general assumptions of EN1990 are: ... execution is carried out bypersonnel having the appropriate skilland experience.

These peculiar clauses use recognisableEnglish words, yet they make no sense ifthe words have their normal meanings.Structures are not usually executed, theydo not sustain influences and what areactions...likely to occur during executionand use?

To decode the clauses, engineers needto understand the sometimes subtle

linguistic traps of Eurocode English.Familiar English words are given newand unfamiliar meanings and then usedin place of the words that would havenormally been used. Thus instead of anappendix, a Eurocode has an annex,instead of resisting forces, the structuresustains them and instead of buildingsbeing constructed, they are executed.

The most surprising aspect is thatEurocodes also attempt to create a newtechnical language for engineering. Allover the world, English-language engi-

neering textbooks and codes have beenwritten for over a century in standardtechnical English, using the familiarterms stress, strain, load, compres-sion, tension, force, moment, shear,torsion and imposed deformation.However, Eurocodes set out to replacethis with a new language based on theword action, which is given a newmeaning of load or imposed deforma-tion. In this new language, loads becomedirect actions, imposed deformations areindirect actions and axial forces, shearforces and moments become action

effects, which may be transverse, tan-gentialand so on. Dead load becomesa permanent direct action and imposedloads are variable direct actions.

Earlier drafts of the Eurocodes



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attempted to describe everything interms of this new language, producingsome very obscure passages. Fortunatelyin the final versions this has been moder-ated and there are welcome reappear-ances of words such as load and shear.Unfortunately, instead of being fullyrewritten in a consistent language, theEurocodes now have a confused mixtureof action terminology and standardtechnical English. For example, BS EN

1990 clause 1.5.2.11 states,

Load Case: load arrangements, setsof deformations and imperfectionsconsidered simultaneously with fixedvariable actions and permanent actionsfor a particular verification.

This mixed-up language creates scopefor misunderstanding, for example BSEN 1991-1-1 (BSI, 2002b) clause 3.3.1(2)P states,

In design situations when imposed

loads act simultaneously with othervariable actions (e.g. actions inducedby wind, snow, cranes or machinery),the total imposed loads considered inthe load case shall be considered as asingle action.

Does this mean that the complex loadcombination rules of BS EN 1990 shouldbe ignored and instead all loads shouldsimply be added up and considered asone loading?

Clause 3.3.2(1) adds to the confusion

by stating,

on roofs, imposed loads and snowloads or wind actions should not beapplied together simultaneously.

Given that snow loads and wind loadsare imposed loads, what does it mean?

According to BS EN 1991-1-1, clause6.1(1),

Imposed loads on buildings arethose arising from occupancy.

If that is the case, what happens toall the other types of imposed load? Isclause 3.3.1 (2)P based on the idea thatthey are now other variable actions?However BS EN 1991-3 (BSI, 2003a)

clause 1.1(1), says that crane loads areimposed loads and BS EN 1992-1 (BSI,2004a) table 10.1 defines snow load asa type of imposed loading. Also, whenEurocode 7 (BSI, 2004d) clause 2.4.2refers to dead and imposed loads fromstructures, it clearly means all imposedloads, not just those in BS EN 1991-1-1.Maybe snow loads, crane loads and windloads are still imposed loads after all.

The clauses are all saying something

important about load combinations, buttheir meaning is likely to remain unclearuntil they are translated into clear stand-ard technical English.

,n

Limit-state codes and partial factorshave been around for many years inconcrete, steel and masonry design, sosome believe that changing to Eurocodesshould not be too difficult for these:

For structural engineers, the

changes required to existing practiceare relatively minor. As Chris Hendy,head of bridge design and technol-ogy at Atkins, has said, the impact ofStructural Eurocodes can be summedup as Same principles, different rules(Bond, 2007).

UK codes have a variety of factors fordifferent load types and the values ofthese vary depending on the load combi-nation being considered. In most situa-tions Eurocodes adopt a two sizes fit all

approach to basic ultimate-load factors:= 135 for all permanent loads andimposed deformations, and = 15 for allvariable loads and imposed deformations.However, in addition to the factors,there are also three sets of load-reductionfactors to apply:

0,

1and

2. Imposed

loads may be factored by 0

in ultimate-load combinations and by 0, 1 and 2in serviceability calculations. There isthen another factor, , which is some-times applied to dead loads.

In traditional codes, a structure is firstdesigned for combination 1 (dead load +

imposed load) and then it is checked forcombination 2 (dead load + imposed load+ wind load) with increased permissiblestresses (permissible stress design) orreduced load factors (limit-state design).

Eurocode load combinations work ina different way: combination 1 no longerexists. Instead there is a series of loadcombinations, each of which includes allrelevant loads and imposed deformationsbut applies different combinations of par-tial factors to them. In the BS EN 1990simplified approach (equation 6.10), loadcombinations take the form

Design load =(DL + PID) + (leading VL or VID)

+ sum of (0(other VLs)) + sum of(

0(other VIDs))

where DL is load; PID is permanentimposed deformations; VL is variableload; VID is variable imposed deforma-tion; is the partial load factor (135 onpermanent loads, 15 on variable loads);and

0is the combination factor applied

to imposed loads and deformations (typi-cally 07 for floor and roof loads (exceptstorage), 05 for wind and snow loadsand 06 for thermal movement).

Eurocode load combinations involveconsidering each imposed load in turnas a leading variable action, while otherimposed loads and deformations areapplied as reduced accompanying vari-able actions. All the different possiblepermutations of factors must then beconsidered to find which has the worsteffect. Thermal movement and differen-tial settlement must be included in everyload combination see BS EN 1990clause 6.3.4.1(6) and BS EN 1991-1-53(2)P (BSI, 2003b). Where dead load

variability is significant, maximum andminimum values must also be calculated see BS EN 1990 clause 4.1.2(2)P).

BS EN 1990 (BSI, 2002a) also allowsan alternative approach where the designload is the worse of equations 6.10a and6.10b These are

Design load =(DL+PID) + sum of

0(VLs) +sum of

0(VIDs)

and

Design load =(DL+PID) + (leading VL or PID)+ sum of

0(other VLs) + sum of

0VID




where = 0925 in the UK.For those who enjoy calculations and

working with numbers, there is certainlyfun to be had. However, before equation6.10 can be applied the engineer mustidentify which variable actions can beconsidered as being separate actions inthe calculation and which cannot, so asto apply the factors correctly. This alsoaffects safety and economy, because ifthe total imposed load can be divided

into separate actions, this reduces thedesign load and the structures safetyfactor. The more the loading on thestructure can be divided up into sepa-rate actions, the lower the safety factorbecomes.

Consider a beam which supports anoffice and shop on one side and a roofand car park on the other (Figure 2). Arethese four separate variable actions, orare they all parts of one variable action(the imposed floor load)? The totalcharacteristic imposed load on beam A= 4 3(25 + 15 + 4 + 25) = 126 kN. If

all of the imposed loads are consideredas parts of one variable action, then thefactored load for design = 15 126= 189 kN. However if the four differ-ent imposed loads are considered to beseparate variable actions, then the designfactored load = 15 4 3((07 25) +(07 15) + 4 + (07 25)) = 1539 kN.If the beam was designed to BS EN1993-1-1 (BSI, 2005a), with M = 10,then applying first interpretation wouldgive it a safety factor against failure of15 but the second interpretation would

reduce the safety factor to 122.BS EN 1990 gives no rules to definewhich imposed loadings (or parts ofimposed loadings) can be considered asseparate actions in equations 6.10, 6.10aand 6.10b. This is fundamental to theoperation of the equations and these inturn are fundamental to all Eurocodedesign, yet BS EN 1990 leaves the ques-tion unanswered. Perhaps the answer isin clause 3.3.1(2)P in BS EN 1991-1-1but, as previously discussed, the currentwording of this clause makes its meaningunclear.

The Eurocode safety factor systemappears to have several anomalies.

n Design safety factors should includean allowance for the effects of cor-

rosion, minor damage, other dete-rioration, or other unanticipatedinfluences which may affect thestructure. However, in Eurocodes,

F

only covers analysis uncertainties andunfavourable load deviations (BS EN1990 clause 6.3.1 and 6.3.2) and

M

only covers geometrical deviationsand possible deviations from charac-

teristic strength (BS EN 1990 clause6.3.4). Logically, corrosion and soon should be covered by M but, inBS EN 1993-1

M= 10, so it seemsthis has not been done. It thereforeappears that the safety factors inEurocodes do not include any allow-ance for the effects of corrosion orminor damage on a structure.

n A low partial safety factor (F

= 135)is applied to all permanent loads anda high factor (F = 15) is applied toall variable loads. This seems inap-propriate as some permanent loads

(e.g. earth pressure or weight ofscreeds and finishes) are highly vari-able, whereas there are variable loads(e.g. weight of water in a tank) whichcan be calculated to within 1%.

n Eurocode design rules appear toaim for constant failure probability,regardless of circumstances and con-sequences of failure. This producessome unusual results: the safety factoron a 1:50 years, 3 s wind gust is high-er than the safety factor on permanentearth pressure and, because of theload combination rules, a structure

subjected to only dead load and windload (e.g. a signpost) is given a highersafety factor than a structure whichalso carries imposed floor loads (e.g. ahouse or public building).

None of these seems to make muchsense from an engineering point of view.Engineers would thus be well advised tobe cautious in any situation where theyfind Eurocodes appear to justify signifi-cantly more economical designs thanpast practice.

As noted earlier, it is also necessary

to apply load factors in serviceabilitycalculations:

0,

1, or

2. With so many

different factors to be applied, great careneeds to be taken to avoid mistakes, par-ticularly as some design Eurocodes and

4 m

Car park 2.5 kN/m2 Roof 1.5 kN/m2

Office 2.5 kN/m2Retail 4 kN/m2

Beam A

4 m

6m

6m

Figure 2. The central beam will need to be 23%stronger if the four different types of loadingare considered as a single variable load ratherthan four separate ones but Eurocodes areunclear on this

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national annexes contain clauses whichsometimes amend or contradict the BSEN 1990 rules.

Also, if reduction factors are applied toloads for serviceability calculations, thenlimits on deflection and so on may needto be reduced correspondingly to avoidtrouble.

Geehni eign

It is worth remembering that everystructure has foundations and Eurocode7 part 1 for geotechnical design (BSI,2004d) is the most radical and differentof all Eurocodes. It proposes a completechange from past practice, with anew, complex system of partial factorsreplacing the traditional global safetyfactors of geotechnical design. Accordingto Bond (2007),

When I last counted, there were 112partial factors to choose from in EN1997-1, with a further 34 converted

from characteristic values to designvalues by the application of specificfactors.

BS EN 1997-1 changes almosteverything that is said about geotechnicaldesign in existing soil mechanics booksand codes of practice, yet if engineers areto design structures to Eurocodes, theywill have to master it.

d n

In the UK and most other English-speaking countries . denotes a decimalpoint and , separates thousands. OtherEuropean countries have the oppositeconvention: they use , as a decimalpoint and . to separate thousands. It is along-standing difference, rather like driv-ing on different sides of the road, and itis dealt with in the same way: when inFrance, British people drive on the right,and when in the UK French people driveon the left. It is not ideal but as long aseveryone sticks to the rules of the coun-try they are in, everything works and

nobody gets hurt.For some reason, the English editions

of Eurocodes have adopted continentaldecimal notation, using , as the decimalpoint. Presumably this was done for

convenience during drafting but it isnot clear why it has been retained inthe published final editions. Was itan oversight, or is the intention thatcontinental decimal notation shouldbe used for Eurocode designs in theUK? The Eurocodes do not actually saywhat is intended. UK national annexesonly add to the confusion: the nationalannexes for BS EN 1990 and Eurocodes1, 2, 5 and 6 use continental notation but

the national annexes for Eurocodes 3, 4and 7 use UK notation.Is the UK construction industry sup-

posed to change its decimal notation aspart of the Eurocode changeover or not?If so, this would need careful planning but if this is not the intention, then thisalso needs to be made clear. In engineer-ing, as in driving, there is no middleway: confusing the meanings of 1,234and 1.234 could have disasterous con-sequences.

The government has not announcedany plans for the UK to change to conti-

nental decimal notation, so presumablyif engineers are to adopt it for Eurocodecalculations they will be doing this ontheir own. It is not realistic to ask engi-neers to do this if everyone else in thecountry is continuing to use standardUK notation and schoolchildren are stillbeing taught that . is a decimal pointand , means thousands. It would alsorequire office computers to recognise ,as a thousands marker in financial cal-culations but as a decimal point in engi-neering calculations.

BS EN 1993 introduces anotherchange which with potential safety impli-cations: the major and minor axes, whichhave always been xx and yy in UKsteel section tables, are relabelled as yyand zz. The potential for errors createdby this change is obvious, yet there hasbeen little discussion about whether itis necessary and no serious planning ofhow the changeover is to be organised.

Some may see these as relatively trivialmatters that engineers will just haveto get used to. However, anyone withknowledge of engineering failures knows

that the dangers of introducing evenapparently trivial changes to standardconventions and notation without care-ful thought and planning should not beunderestimated.

Figure 3. The Eurocodes Expert website funded bythe Institution of Civil Engineers provides detailsof Eurocode training courses, publications andweb resources plus FAQs and news

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BS EN 1990 clause 1.3 (2) states

The general assumptions of EN1990 are ... adequate supervision andquality control is provided duringexecution of the work, i.e.in designoffices, factories, plants, and on site

In the UK today there is rarely a clerk

of works or resident engineer or archi-tect on site checking the contractorswork; when architects and engineers areappointed on design only contracts,they usually do not check the contrac-tors work at all. Work on site is usuallycarried out by subcontractors, oftenwith minimal supervision and checkingof their work by the main contractorprovided it is completed on time for theagreed price. Does this constitute ade-quate supervision and quality control asassumed by BS EN 1990? If it does not,then Eurocodes may require changes on

construction sites as well as in designoffices.

sppr n rining

A considerable amount of workhas gone into textbooks, guides andmanuals for Eurocodes. In addition, theInstitution of Civil Engineers and theInstitution of Structural Engineers havecreated the Eurocodes Expert website atwww.eurocodes.co.uk to help engineersdeal with the proposed changeover

(Figure 3). This gives access to basicinformation about the availability ofEurocodes and related publications,training courses and software. It alsoincludes a list of frequently askedquestions.

Despite the amount of work thathas gone into publications and websitesto help engineers with Eurocodes, thescale of the retraining challenge posedby the proposed changeover is daunting.In 2004, a study for the Institution ofStructural Engineers (IStructE, 2004)estimated the cost for an office of 16

engineers as 255 000, or an averageof 16 000 per engineer. However thisassumed that the 16 engineers couldmanage with only one set of Eurocodesbetween them and that three man-days

on courses and 12 man-days of individ-ual study would be sufficient to retraineach engineer. Bearing in mind thatin this time they would have to masterBS EN 1990 (basis); Eurocode 2 part1-1 (densities, self-weight and imposedloads), part 1-4 (wind loading) and part1-5 (thermal effects); Eurocode 2 (con-crete); Eurocode 3 (steel); Eurocode 5(timber); Eurocode 6 (masonry); andEurocode 7 (geotechnical); all of them

unfamiliar and some radically differentfrom existing codes, this estimate looksdecidedly optimistic.

If it is assumed that an office of 16engineers would need several sets ofEurocodes and if we allow a rathermore cautious estimate of 15 days oncourses plus 15 days of individual studyfor each engineer to learn to use thenew codes, plus increased costs since2004, the cost could easily be doublethe previous estimate say 30 000 perengineer. Retraining (say) 5000 UK civiland structural engineers in time for the

planned 1 April 2010 changeover couldcost 150 million and require trainersto provide 75 000 man-days of training,or 3000 days of seminars with an aver-age class-size of 25. In October 2009there were just 58 institutional trainingcourses listed on the Eurocodes Expertwebsite.

In practical terms, UK consultingengineers may struggle to find the staffand the money to cover the trainingrequired for the Eurocode changeover.Furthermore, Britains construction train-

ing industry is unlikely to find sufficientresources to retrain all of the countrysengineers before 1 April 2010.

It is a similar problem for local author-ity building control departments: the gov-ernment has given them no extra moneyto retrain their staff yet, unless this isdone, it is difficult to see how they cancheck Eurocode calculations submitted.

Ipeenin pin

Some UK engineers may be temptedto continue to use withdrawn UK codes

of practice and hope for the best. Thiswould be a decision based on simpleeconomics: without substantial govern-ment assistance (which is not on offer)they may not be able to afford to do

anything else. They would also know thatwithdrawn codes will still be acceptedunder the Building Regulations for manyyears to come and that, even if a projectis specified as design to Eurocodes, theycould probably get away with a designbased on withdrawn codes without any-one noticing.

For engineers who wish to try to useEurocodes, there are two choices: eitheruse the codes directly or use Eurocode

manuals published by the Institution ofStructural Engineers and others (Figure4). Though they may have some limita-tions, a lot of work has gone into thesemanuals, they are written in English,they combine Eurocode and nationalannex requirements in one documentand they simplify and clarify some of therequirements.

However, designing to a Eurocodemanual is not the same as designing toEurocodes. If a contractors design doesnot comply with the Eurocode manual,it may still comply with the Eurocodes,

but the engineer can only check this byreferring to the Eurocodes themselves.Therefore, the manuals only offer a partialsolution. Eurocode manual design is eas-ier than Eurocode design and it should

Figure 4. The Institution of Structural Engineershas published a series of Eurocode designmanuals which can be used directly for designwork far easier than using the codes directly



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produce results which comply with thecode but so (by and large) will designsprepared to withdrawn UK codes. It isthus difficult to see many situations wheretraining staff to design using Eurocodemanuals would offer a commercial benefitto a consulting engineer.

cnin

Although the proposed changeover

to Eurocodes on 1 April 2010 is nowimminent, there are still important ques-tions about the project which need to beanswered.

n Can the idea of using Eurocodes toremove technical barriers to trade bereconciled with an engineers profes-sional responsibility to their clients?

n Is it realistic to expect busy practis-ing engineers to use Eurocodes intheir present form, without any pub-lished consolidated texts that com-bine Eurocodes with their national

annexes?n Why are English Eurocodes not writ-

ten in standard technical English?n How can the BS EN 1990 system of

partial factors and load combinationsbe used if the code does not definewhich imposed loads are to be con-sidered as separate variable actionsand which are not?

n Is it necessary to introduce load fac-tors for serviceability calculations aswell as for strength calculations?

n Are UK engineers to change to conti-

nental decimal notation for Eurocodecalculations and, if so, how are thepractical problems and safety risksassociated with this to be overcome?There are similar safety implicationswith the proposed change to axislabels for steel members.

n Where are consulting engineers tofind the resources to fund retrain-ing of their staff for Eurocodes andwhere can the training industry findthe resources to train the number ofengineers involved?

n Unless the government injects sub-

stantial resources into local author-ity building control departmentsfor retraining, how are Eurocodedesigns to be checked under build-ing regulations?

These questions are unlikely to worry anti-Eurocode engineers or those who are likelyto retire in the near future. However, for

those who would like to see the UK suc-cessfully change to using Eurocodes, theyneed answering and soon.

wh y hink?If y ike en n hi pper, pee ei p 200 r he eir [email protected].

If y ike rie pper f 2000 3500 r yr n experiene in hi r ny ree re f

ivi engineering, he eir i e hppy prvie ny hep r vie y nee.

Referencesbn a (2007) when n irreiie fre ee n ive je. Geodrilling International, apri, p. 22.

bsI (briih snr Iniin) (1986) bs 8004:1986: ce f prie fr fnin. bsI, lnn.

bsI (1997) bs 6399-2:1997: ling fr iing. Pr 2: e f prie fr in . bsI, lnn.

bsI (1997) bs 8110-1:1997: srr e f nree. ce f prie fr eign n nrin. bsI,lnn.

bsI (2000) bs 5950-1:2000: srr e f eerk in iing. ce f prie fr eign. Re nee ein. bsI, lnn.

bsI (2002) bs EN 1990:2002: Ere: i f eign. bsI, lnn.bsI (2002) bs EN 1991-1-1:2002: Ere 1: in n rre. Gener in eniie, ef-

eigh, ipe fr iing. bsI, lnn.

bsI (2003) bs EN 1991-1-3:2003: Ere 1: in n rre. Gener in n . bsI,lnn.

bsI (2003) bs EN 1991-1-5:2003: Ere 1: in n rre. Gener in her in.bsI, lnn.

bsI (2004) bs EN 1992-1-1:2004: Ere 2: eign f nree rre. Gener re n re friing. bsI, lnn.

bsI (2004) bs EN 1992-1-2:2004: Ere 2: eign f nree rre. Gener re rrfire eign. bsI, lnn.

bsI (2004) bs EN 1995-1-1:2004: Ere 5. deign f ier rre. Gener. cn re nre fr iing. bsI, lnn.

bsI (2004) bs EN 1997-1:2004: Ere 7: geehni eign. Gener re. bsI, lnn.

bsI (2005) bs EN 1993-1-1:2005: Ere 3. deign f ee rre. Gener re n re fr i-ing. bsI, lnn.

bsI (2005) Na bs EN 1992-1-1:2004:2005: uK Nin nnex Ere 2: eign f nreerre. Gener re n re fr iing. bsI, lnn.

bsI (2006) Na bs EN 1993-1:2005:2006: uK Nin annex Ere 3. deign f ee rre.Gener re. bsI, lnn.

bsI (2008) Na bs EN 1991-1-4:2005:2008: uK Nin nnex Ere 1: in n rre.Gener in in in. bsI, lnn.

Ec (Erpen cniy) (2004) direive 2004/18/Ec f he Erpen Prien n f he cni f31 mrh 2004 n he rinin f prere fr he r f pi rk nr, pi p-py nr n pi ervie nr. Official Journal of the European Communities, L134/114.

HmG (Her mjey Gvernen) (2006) Pi cnr Regin 2006. the sinery offie,lnn, sry Inren 2006 N. 5.

IsrE (Iniin f srr Engineer) (2004)National strategy for implementation of the structuralEurocodes: design guidance. the Iniin f srr Engineer, lnn, p. 13.

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patmt f ta, hw aeu t b hku bul ulat?

Eurocodes - Questions That Need Answering

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