Andrew Bond 2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

Transcription

1 Andrew Bond

2 Survey procedure Some unexpected results NDPs for slope stability NDPs for shallow foundations NDPs for deep foundations Accidental design situations Conclusions

3 Results of the NDP Survey 2009/10

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6 Manfred Fross (Austria) Carsten Sorensen (Denmark) Lea Tuberik (Estonia) Tim Länsivaara (Finland) Roger Frank (France) Bernd Schuppener (Germany) Michael Kavvadas (Greece) Robert Szepesházi (Hungary) Trevor Orr (Ireland) Liudvikas Furmonavicius (Lithuania) Giuseppe Scarpelli (Italy) Adriaan van Seters (Netherlands) Fritz Nowacki/Roald Sægrov (Norway) Marek Świeca/Agnieszka Gawryluk (Poland) Iacint Manoliu (Romania) Rui Correia (Portugal) Lovisa Moritz (Sweden) Brian Simpson (UK)

7 Results of the NDP Survey 2009/10

8 Consequence Description of Examples Minimum β K FI or reliability consequence values class For human life Economic, social, or environmental CC1/RC1 Low Small or negligible Agricultural (e.g. storage) buildings, greenhouses CC2/RC2 Medium Considerable Residential and office buildings CC3/RC3 High Very great Grandstands, public buildings (e.g. concert hall) 1 year 50 years May- Decoding the Structural Eurocodes Geocentrix Ltd. All rights reserved 8

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10 Single verification using Eq from EN 1990: γ G + γ Q + γ ψ Q Gj, kj, Q,1 k,1 Qi, 0, i ki, j 1 i > 1 or, less favourable of Eq. 6.10(a) and (b): γ G + γ ψ Q + γ ψ Q Gj, kj, Q,1 0,1 k,1 Qi, 0, i ki, j 1 i > 1 ξγ G + γ Q + γ ψ Q j Gj, kj, Q,1 k,1 Qi, 0, i ki, j 1 i> 1 where the circled terms reduce the effect of the corresponding action

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12 Results of the NDP Survey 2009/10

13 Design Approaches allowed DA1 DA2 DA3 EST FRA AUT, DNK, FRA, IRL IRL FIN, DEU, GRC, ITA LTU PRT UK (6) ITA (3) HUN, IRL, NLD, NOR, POL, ROM, SVK, SWE (14)

14 γ ϕ and γ for slopes γ c EN Sweden Greece Persistent Transient Accidental High risk (RC3/CC3) Medium (RC2/CC2) Low (RC1/CC1) Germany Portugal Denmark Netherlands not decided γ ϕ γ c γ c combined ULS+SLS check γ c Austria

15 γ cu and γ qu for slopes EN Sweden Greece Germany Portugal Denmark Netherlands combined ULS+SLS check not decided Persistent Transient Accidental High risk (RC3/CC3) Medium (RC2/CC2) Low (RC1/CC1) Austria Poland Italy γ cu γ qu

16 Results of the NDP Survey 2009/10

17 Design Approaches allowed DA1 DA2 DA3 IRL ITA LTU PRT ROM UK (6) AUT, EST, FIN, DNK, FRA, DEU, GRC, FRA, HUN, IRL, ITA, IRL, POL, SVK NLD, (11) NOR, SWE (6)

18 In Design Approach 1, check two combinations of: { γ, γ, } { γ, γ, } E F X a R F X a F rep k M d F rep k M d In Design Approach 2, check one combination: {,, } {,, } γ E F X a R F X a In Design Approach 3, check one combination: γ F rep k d rep k d R {,, } {,, } E γ F X γ a R γ F X γ a γ F rep k M d F rep k M d R One measure of required reliability is: γ γ γ G cu Rv

19 γ G x γ cu x γ for spread foundations Rv EN Portugal? DA1 DAs 2 & 3 Italy Netherlands Estonia Slovakia Austria Germany DA1 DA2 Persistent Transient Accidental Finland Hungary 6.10(b) 610(b) 6.10(b) 6.10(a) 6.10(a) Denmark 6.10(b) 6.10(a) Sweden SC1 SC3

20 Design Approaches allowed DA1 DA2 DA3 IRL ITA LTU PRT ROM UK (6) AUT, EST, FIN, AUT*, FRA, DEU, GRC, DNK, HUN, IRL, ITA, FRA, POL, SVK IRL, (11) NLD, NOR, SWE (7) *for numerical analysis

21 Results of the NDP Survey 2009/10

22 Design Approaches allowed DA1 DA2 DA3 IRL ITA LTU PRT ROM UK (6) AUT, EST, FIN, DNK, FRA, DEU, GRC, FRA, HUN, IRL, ITA, IRL, POL, SVK, SWE NLD, (12) NOR, SWE (6)

23 Correlation factor ξ 1 Correlation factor ξ Correlation facto ors Correlation facto ors Number of tests Number of tests EN Denmark Germany Netherlands Romania UK EN Denmark Germany Netherlands Romania UK

24 Correlation factor ξ Correlation facto ors EN Estonia Finland Ireland Italy Netherlands Norway Romania UK Number of tests

25 γ b, γs, γtand γ st for piles (Set R2) EN Hungary Estonia Italy Sweden Finland Denmark Austria Bored Driven Base Shaft Tension = 2.88 with provisional model factor

26 Design Approaches allowed DA1 DA2 DA3 IRL ITA LTU PRT ROM UK (6) AUT, EST, FIN, DNK, FRA, DEU, GRC, FRA, HUN, IRL, ITA, IRL, POL, SVK NLD, (11) NOR, SWE (6)

27 Results of the NDP Survey 2009/10

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29 Results of the NDP Survey 2009/10

30 Enormous variation in values of NDPs Does this prevent further harmonization of national practice? Why have countries felt the need to change so many NDPs from their recommended d values? Did we get the recommended values wrong? Several countries have refined their NDPs Different values used for different levels of risk (e.g. CC, RC, safety class, amount of pile testing) Should Eurocode 7 provide better coverage of this idea? What other ideas from different countries NAs should be promoted to the EN? Complexity is growing (which h is NOT desirable) How can we simplify to make the important ideas accessible to practicing engineers?

31 Variation of partial factors with: Design situation (Persistent > Transient > Accidental) Risk (RC3/CC3 > RC2/CC2 > RC1/CC1) Less onerous combination of actions: Explicit consideration of equations 6.10(a) and (b) from EN 1990 Partial factors for use in accidental design situations: Factors on actions = 1.0? Factors on material properties/resistance > 1.0 Correlation factors for pile design Why have these factors been increased by such a large amount? Do we need different factors for different ground tests? Partial ata factors actosfor combined edss SLS+ULS Scheck Combine Design Approaches into one simpler scheme

32 Previous NDP survey ( 09/10) Questions unanswered Questions unasked Ambiguities NAs not finalised 10 countries did not answer New NDP survey (2010/11) Existing answers already included NSBs will be asked to correct the mistakes and fill in the gaps