Introducing Eurocode 7 - Eurocode 7 & New Design Challenges · Introducing Eurocode 7 Belidor...
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Introducing Eurocode 7 Georgios Katsigiannis University College of London & Arup Early Career Members Event 22 nd September 2014
Transcript of Introducing Eurocode 7 - Eurocode 7 & New Design Challenges · Introducing Eurocode 7 Belidor...
Introducing Eurocode 7
Georgios Katsigiannis University College of London & Arup
Early Career Members Event
22nd September 2014
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Contents
EC7 Background & History
Terminology
Contents of EC7 Part 1 & 2
Limit States
Design Approaches
EC7 Evolution & Review
Background Terminology Contents Limit States Design Approaches EC7 Evolution 2
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Introducing Eurocode 7
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EC7 Background 3
Introducing Eurocode 7
Belidor (1729) and Coulomb (1773) were the first to propose
the use of factor of safety for stability problems. Traditionally, in
geotechnical engineering design a global factor of safety has
been used to ensure safety and account for all the
uncertainties involved
According to Terzaghi (1943) the
geotechnical problems can be
distinguished between stability and
elasticity problems
Brinch Hansen in 1956 suggested for ULS the application of
different partial factors to the loads and soil strength
properties. This was widely accepted and had big influence in
geotechnical engineering practice in Europe
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Background Terminology Contents Limit States Design Approaches EC7 Evolution
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EC7 Background 4
Introducing Eurocode 7
The Commission of the European Community
aiming to harmonize the technical standards
among the European countries took the initiative to
introduce the first generation of the standards
Harmonization of the civil engineering
standards would
provide a common language between the
European engineers
enhance the competitiveness of the European
companies in the world market
facilitate the exchange of engineering services
and products
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EC7 Background 5
Introducing Eurocode 7
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Eurocode 7 consists of two parts :
EN 1997-1 Geotechnical design - Part 1: General rules (CEN, 2004)
EN 1997-2 Geotechnical design - Part 2: Ground investigation and testing
(CEN, 2007)
The Structural
Eurocodes are design
codes for buildings and
civil engineering works
Set of 10 standards,
divided into 58 parts
Based on the Limit
State Design approach
and employ partial
factors R. Frank, Brussels, 18-20 February 2008,
Dissemination of Information workshop
Background Terminology Contents Limit States Design Approaches EC7 Evolution
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EC7 History 6
1) 1974-1981 Initiation Stage
2) 1981-1987 Model Code Stage
3) 1988-1990 Conversion to
Eurocode
4) 1990-1994 ENV Stage
5) 1994-1998 ENV Trial Stage
6) 1998-2004 EN Stage
7) 2005-2010 Implementation
Stage
In 1990, the task of drafting
design codes was transferred to
the CEN, European Committee
for Standardization
CEN is composed of the
National Standard Bodies of a
number of European countries
Introducing Eurocode 7
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Background Terminology Contents Limit States Design Approaches EC7 Evolution
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EC7 History 7
CEN/TC 250 (Technical Committee
250) is in charge of the Structural
Eurocodes
TC250/SC7 is in charge of Eurocode 7 on Geotechnical Design
Introducing Eurocode 7
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EC7 History 8
In 1993, SC7 adopted the
ENV 1997-1 pre-standard:
‘Geotechnical design - Part 1:
General Rules’ (CEN, 1994)
Conversion of ENV 1997-1 into EN performed from 1997 to 2003
Cases A, B and C became EQU and SRT/GEO Limit States
Introduced alternative ways of verifying STR/GEO via 3 Design
Approaches
Introduced additional Limit States UPL and HYD
Introducing Eurocode 7
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Background Terminology Contents Limit States Design Approaches EC7 Evolution
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EC7 History 9
The formal positive vote was obtained in early 2004
CEN finally published Eurocode 7 – Part 1 (EN 1997-1) in
November 2004 (CEN, 2004)
Each National Standard Body had to write its National Annex
to EC 7-1 within two years after publication by CEN (2 year
calibration period)
After the calibration period and some further 3 year coexistence
period…
…EN1997-1 became mandatory in all EU Member States in
2010!
Introducing Eurocode 7
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Eurocode Terminology 10
Introducing Eurocode 7
The concepts of Actions and Resistances are described in detail
in the EN 1990-Basis of Design
An action is defined as: ‘(a) Set of forces (loads) applied to the
structure (direct actions); (b) Set of imposed deformations or
accelerations caused, for example, by temperature changes,
moisture variation, uneven settlement or earthquakes (indirect
actions)’
A geotechnical action is defined as an ‘action transmitted to the
structure by the ground, fill, standing water or ground-water’
A resistance is defined as the ‘capacity of a member or
component . . . to withstand actions without mechanical failure’
An action effect is defined as a function of the actions, the
material properties and the geometry
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Characteristic & Design Values 11
Introducing Eurocode 7
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P The characteristic value of a geotechnical parameter shall be
selected as a cautious estimate of the value affecting the
occurrence of the limit state
If statistical methods are used, the characteristic value should be
derived such that the calculated probability of a worse value
governing the occurrence of the limit state under consideration is
not greater than 5%
Design value of a geotechnical parameter: Xd=Xk/γM
Background Terminology Contents Limit States Design Approaches EC7 Evolution
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Geotechnical properties 12
Introducing Eurocode 7
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R. Frank, Brussels, 18-20 February
2008, Dissemination of Information
workshop
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Contents of EN1997-1 13
Introducing Eurocode 7
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Section 1 General
Section 2 Basis of geotechnical
design
Section 3 Geotechnical data
Section 4 Supervision of
construction, monitoring and
maintenance
Section 5 Fill, dewatering, ground
improvement and reinforcement
Background Terminology Contents Limit States Design Approaches EC7 Evolution
EN 1997-1 Geotechnical design
Part 1: General rules (CEN, 2004)
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Contents of EN1997-1 14
Introducing Eurocode 7
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EN 1997-1 Geotechnical design
Part 1: General rules (CEN, 2004)
Section 6 Spread foundations
Section 7 Pile foundations
Section 8 Anchorages
Section 9 Retaining structures
Section 10 Hydraulic failure
Section 11 Site stability
Section 12 Embankments
Informative annexes on active & passive earth pressures, bearing
capacity and settlement of foundations
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Contents of EN1997-2 15
Introducing Eurocode 7
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EN 1997-2 Geotechnical design
Part 2: Ground investigation and testing (CEN, 2007)
Section 1 General
Section 2 Planning and reporting of
ground investigations
Section 3 Drilling, sampling and
groundwater measurements
Section 4 Field tests in soils and rocks
Section 5 Laboratory tests on soils and
rocks
Section 6 Ground investigation report
+Informative annexes
Background Terminology Contents Limit States Design Approaches EC7 Evolution
Serviceability Limit States (SLSs) are concerned with the comfort
of the users and the functioning and the appearance of the structure
(EN 1990 §3.4(1) P)
Limit State Design 16
Introducing Eurocode 7
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Limit State Design 17
Serviceability limit states (SLSs) “correspond to conditions beyond
which specified service requirements for a structure or structural
member are no longer met”
Bond & Harris (2008)
Verification of serviceability is expressed
by the following inequality
Ed=design effects of actions (e.g.
displacement, distortion)
Cd=limited design value of the effects of
actions
Introducing Eurocode 7
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Background Terminology Contents Limit States Design Approaches EC7 Evolution
Ultimate Limit States generally are associated with collapse. They
relate to the safety of people and the structure (EN 1990 §3.3(1) P)
Serious failures involving danger or severe economic loss
Limit State Design 18
Introducing Eurocode 7
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Limit State Design 19
GEO «failure or excessive
deformation of the ground, in which
the strength of soil or rock is
significant in providing resistance»
STR «Internal failure or excessive
deformation of the structure or
structural elements… in which the
strength of structural material is
significant in providing resistance»
Ultimate limit states (ULSs) are “associated with collapse, or with
other similar forms of structural failure”
Bond & Harris (2008)
Introducing Eurocode 7
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Limit State Design 20
Introducing Eurocode 7
Verification of strength is
expressed by the following inequality
Ed= design effects of actions
Rd= design corresponding resistance
Applies to GEO/STR Limit States
Bond & Harris (2008)
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Limit State Design 21
EQU «loss of equilibrium of the structure
or the ground, considered as a rigid body,
in which the strengths of structural
materials and the ground are insignificant
in providing resistance»
UPL «loss of equilibrium of the structure
or the ground, due to uplift by water
pressure (buoyancy) or other vertical
actions»
HYD relates to hydraulic heave and
internal erosion conditions
Ultimate limit states (ULSs) are “associated with collapse, or with other
similar forms of structural failure”
Bond & Harris (2008)
Introducing Eurocode 7
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Background Terminology Contents Limit States Design Approaches EC7 Evolution
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Limit State Design 22
Introducing Eurocode 7
Verification of stability is expressed
by the following inequality
Ed,dst= destabilising effect of actions
Ed,st= stabilising effect of actions
Rd= additional design resistance
Applies to EQU and UPL Limit States
Bond & Harris (2008)
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Limit State Design 23
Introducing Eurocode 7
Verification of HYD Limit State is expressed by the following
inequality
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Design Approaches 24
LFA MFA
Bond & Harris (2008)
Introducing Eurocode 7
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Eurocode 7 Evolution & Review
At the 26th meeting of TC250/SC7 a decision
was made to establish a number of Evolution
Groups (EGs) to look at the technical issues
that require improved coverage in a future
revision of Eurocode 7.
12 EC7 Evolution Groups
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http://www.eurocode7.com/sc7/
evolutiongroups
Structural Eurocodes Systematic Review
The process of reviewing the Eurocodes
has started. From April to September
Eurocodes are ‘out for comment’
This is our opportunity to influence the
Eurocode 'Evolution' process
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Background Terminology Contents Limit States Design Approaches EC7 Evolution
Introducing Eurocode 7
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THANK YOU
FOR YOUR ATTENTION
