SIST EN 1998-5:2005

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Eurocode 8: Design of structures for earthquake resistance Part 5: Foundations, retaining structures and geotechnical aspectsEurocode 8: Calcul des structures pour leur résistance aux séismes Partie 5: Fondations, ouvrages de soutenement et aspects géotechniquesEurocode 8: Auslegung von Bauwerken gegen Erdbeben - Teil 5: Gründungen, Stützbauwerke und geotechnische AspekteTa slovenski standard je istoveten z:EN 1998-5:2004SIST EN 1998-5:2005en91.120.25YLEUDFLMDPLSeismic and vibration protection91.010.30Technical aspectsICS:SIST ENV 1998-5:1995+D1:19951DGRPHãþDSLOVENSKI
STANDARDSIST EN 1998-5:200501-maj-2005

EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 1998-5
November 2004 ICS 91.120.25 Supersedes ENV 1998-5:1994 English version
Eurocode 8: Design of structures for earthquake resistance Part 5: Foundations, retaining structures and geotechnical aspects
Eurocode 8: Calcul des structures pour leur résistance aux séismes Partie 5: Fondations, ouvrages de soutènement et aspects géotechniques
Eurocode 8: Auslegung von Bauwerken gegen Erdbeben Teil 5: Gründungen, Stützbauwerke und geotechnische Aspekte This European Standard was approved by CEN on 16 April 2004.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
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B-1050 Brussels © 2004 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 1998-5:2004: E

1 Agreement between the Commission of the European Communities and the European Committee for Standardisation (CEN)concerning the work on EUROCODES for the design of building and civil engineering works (BC/CEN/03/89).

2 According to Art. 3.3 of the CPD, the essential requirements (ERs) shall be given concrete form in interpretative documents for thecreation of the necessary links between the essential requirements and the mandates for harmonised ENs and ETAGs/ETAs.3 According to Art. 12 of the CPD the interpretative documents shall :a) give concrete form to the essential requirements by harmonising the terminology and the technical bases and indicating classesor levels for each requirement where necessary ;b) indicate methods of correlating these classes or levels of requirement with the technical specifications, e.g. methods ofcalculation and of proof, technical rules for project design, etc. ;c) serve as a reference for the establishment of harmonised standards and guidelines for European technical approvals.The Eurocodes, de facto, play a similar role in the field of the ER 1 and a part of ER 2.

country specific data (geographical, climatic, etc.), e.g. snow map,– the procedure to be used where alternative procedures are given in the Eurocode.It may also contain– decisions on the application of informative annexes,– references to non-contradictory complementary information to assist the user toapply the Eurocode.Links between Eurocodes and harmonised technical specifications (ENs and ETAs)for productsThere is a need for consistency between the harmonised technical specifications forconstruction products and the technical rules for works4. Furthermore, all theinformation accompanying the CE Marking of the construction products which refer toEurocodes shall clearly mention which Nationally Determined Parameters have beentaken into account.Additional information specific to EN 1998-5The scope of Eurocode 8 is defined in EN 1998-1:2004, 1.1.1 and the scope of this Partof Eurocode 8 is defined in 1.1. Additional Parts of Eurocode 8 are listed in EN 1998-1:2004, 1.1.3.
4 see Art.3.3 and Art.12 of the CPD, as well as
4.2, 4.3.1, 4.3.2 and 5.2 of ID 1.

In theabsence of such tests, and for the purpose of preliminary design, it may be estimatedthrough empirical correlations.4.1.3.4 Safety verification for the pseudo-static method(1)PFor saturated soils in areas where α⋅S > 0,15, consideration shall be given topossible strength degradation and increases in pore pressure due to cyclic loadingsubject to the limitations stated in 4.1.3.3 (8).(2)For quiescent slides where the chances of reactivation by earthquakes are higher,large strain values of the ground strength parameters should be used. In cohesionlessmaterials susceptible to cyclic pore-pressure increase within the limits of 4.1.3.3, thelatter may be accounted for by decreasing the resisting frictional force through anappropriate pore pressure coefficient proportional to the maximum increment of porepressure. Such an increment may be estimated as indicated in 4.1.3.3 (9).(3)No reduction of the shear strength need be applied for strongly dilatantcohesionless soils, such as dense sands.(4)PThe safety verification of the ground slope shall be executed according to theprinciples of EN 1997-1:2004.4.1.4 Potentially liquefiable soils(1)PA decrease in the shear strength and/or stiffness caused by the increase in porewater pressures in saturated cohesionless materials during earthquake ground motion,such as to give rise to significant permanent deformations or even to a condition ofnear-zero effective stress in the soil, shall be hereinafter referred to as liquefaction.(2)PAn evaluation of the liquefaction susceptibility shall be made when thefoundation soils include extended layers or thick lenses of loose sand, with or withoutsilt/clay fines, beneath the water table level, and when the water table level is close tothe ground surface. This evaluation shall be performed for the free-field site conditions(ground surface elevation, water table elevation) prevailing during the lifetime of thestructure.

ratio of impact energy
to theoretical free-fall energy of 0,6. For depths ofless than 3 m, the measured NSPT values should be reduced by 25%.(5)Normalisation with respect to overburden effects may be performed bymultiplying the measured NSPT value by the factor (100/σ′vo)1/2, where σ′vo (kPa) is theeffective overburden pressure acting at the depth where the SPT measurement has beenmade, and at the time of its execution. The normalisation factor (100/σ′vo)1/2 should betaken as being not smaller than 0,5 and not greater than 2.(6)Energy normalisation requires multiplying the blowcount value obtained in (5)of this subclause by the factor ER/60, where ER is one hundred times the energy ratiospecific to the testing equipment.(7)For buildings on shallow foundations, evaluation of the liquefactionsusceptibility may be omitted when the saturated sandy soils are found at depths greaterthan 15 m from ground surface.(8) The liquefaction hazard may be neglected when α⋅S < 0,15 and at least one ofthe following conditions is fulfilled:- the sands have a clay content greater than 20% with plasticity index PI > 10;- the sands have a silt content greater than 35% and, at the same time, the SPTblowcount value normalised for overburden effects and for the energy ratioN1(60) > 20;- the sands are clean, with the SPT blowcount value normalised for overburdeneffects and for the energy ratio N1(60) > 30.(9)PIf the liquefaction hazard may not be neglected, it shall as a minimum beevaluated by well-established methods of geotechnical engineering, based on fieldcorrelations between in situ measurements and the critical cyclic shear stresses knownto have caused liquefaction during past earthquakes.(10)Empirical liquefaction charts illustrating the field correlation approach underlevel ground conditions applied to different types of in situ measurements are given inAnnex B. In this approach, the seismic shear stress τe, may be estimated from thesimplified expressionτe = 0,65 α ⋅S⋅σvo(4.4)where σvo is the total overburden pressure and the other variables are as in expressions(4.1) to (4.3). This expression may not be applied for depths larger than 20 m.(11)PIf the field correlation approach is used, a soil shall be considered susceptible toliquefaction under level ground conditions whenever the earthquake-induced shear
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