001 2010_bridges_en1990 bisis of design some briefing

8/2/2019 001 2010_Bridges_EN1990 Bisis of Design Some Briefing

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Dissemination of information for training Vienna, 4-6 October 2010

EUROCODESBridges: Background and applications

1

EN1990 Basis of Design

Engineering Director, Parsons Brinckerhoff

Visiting Professor, University of Bath

Convenor, CEN/TC250 Horizontal Group - Bridges


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Dissemination of information for training Vienna, 4-6 October 2010 2

Agenda

Overview of EN1990

Verification of limit states and the combinations ofactions


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EN1990 Basis of Design: Contents

2 Requirements3 Principles of Limit State Design

as c ar a es5 Structural Analysis and Design Assisted

b Testin6 Verifications by the Partial Factor Method


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EN1990 Basis of Design Contents

Annex A2 Application for BridgesAnnex An Application for other structure types

nnex anagement o tructura e a tyfor Construction Works

Annex C Basis for Partial Factor Desi n andReliability Analysis

Annex D Design Assisted by Testing


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Role of EN1990

Provides principles and requirements for designers

,

drafters of the other Eurocode parts

ome o e requ remen s are very genera spec capproaches to satisfying them are often contained in other Eurocode

parts, e.g.


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EN1990: Section 1 - General

Scope [1.1]

Assumptions [1.3]

.

Symbols [1.6]


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Scope


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Scope (cont.)


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Some Important Assumptions


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EN1990: Section 2 - Requirements

Basic requirements [2.1]

Design working life [2.3]


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EN1990: Section 2 - Requirements


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EN1990: Section 3 Principles of limit state design

General [3.1]

Design situation [3.2]

.

Serviceability limit states [3.4] Limit state design [3.5]


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Key Concept 1


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Key Concept 1 Design Situations

Design situations are categorised as persistent, transient,accidental or seismic.

These categorisations draw together families of circumstances orconditions that the structure might experience during its life:

Persistent design situations refer to conditions of normal use. As such, fora highway bridge, they will include the passage of heavy vehicles since theability to carry heavy vehicles is a key functional requirement.

Transient design situations refer to circumstances when the structure isitself in some temporary configuration, such as during execution or repair.

structure is experiencing an extreme accidental event.

Seismic design situations concern conditions applicable to the structure


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Key Concept 2


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Key Concept 2 Reversible andIrreversible Serviceability Limit States

The Eurocodes differentiate between reversible and irreversibleserviceability limit states.

Irreversible serviceability limit states are of greater concern thanreversible serviceability limit states.

The acce table robabilit of an irreversible serviceabilit limit state beinexceeded is lower than that for a reversible serviceability limit state.

irreversible serviceability limit states than reversible serviceability limitstates.


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EN1990: Section 4 Basic variables

Actions and environmental influences [4.1]

Material and product properties [4.2] .


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EN1990: Section 4 Basic variables


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Representative values of variable actions

EN1990 established four representative values of a

Characteristic Value (Qk) [1.5.3.14]

0 k . . .

Frequent Value of a Variable Action (1Qk) [1.5.3.17]

Quasi-permanent Value of a Variable Action (2Qk) [1.5.3.18]

Key Concept 3


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Representative Values of a Variable Action

Instantaneous value of QCharacteristic value Qk

t2t1 t3

om nat on va ue o k

Frequent value 1Qk

Quasi-permanent value 2Qk

Time


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Key Concept 3 Representative values of variable actions

There are four different representative values of a Variable Action.

e c arac er s c va ue s a stat st ca y extreme va ue. t s t e ma n

representative value, and the value generally defined in EN1991.

The other representative values are called the combination value,frequent value and quasi-permanent value. They are determined by

multiplying the characteristic value by and respectively.

-,statistically extreme than the characteristic value, so and arealways less than 1.


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Material Properties


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EN1990: Section 5 Structural analysis anddesign assisted by testing


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EN1990: Section 6 Verification by the partial factor method

Key section will return to it further later

Design values [6.3] Actions materials eometric data effects of actions resistances

Ultimate limit states [6.4] ULSs to be verified, verification rules, combination rules

Serviceability limit states [6.5] Verification rules, combinations of actions


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Ultimate Limit States


EQU Equilibrium

STR Structural

FAT - Fatigue

UPL Uplift

HYD Hydraulic heave


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EQU Equilibrium

STR Structural

Key Concept 4

FAT - Fatigue

UPL Uplift

HYD Hydraulic heave


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EQU Equilibrium

STR Structural

Resistance

FAT - Fatigue

UPL Uplift

HYD Hydraulic heave


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EQU Equilibrium

STR Structural

Resistance

FAT - Fatigue

UPL Uplift

Stability

HYD Hydraulic heave


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EQU Equilibrium

STR Structural

Resistance

FAT - Fatigue

UPL Uplift

Stability

HYD Hydraulic heaveEN1997


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Key Concept 4 Six different Ultimate Limit States

The Eurocodes explicitly establish six different ultimate limit states.

wo o ese, an , are spec c o .

Two are concerned with resistances: STR when verifying structuralresistance and GEO when verifying the resistance of the ground.

FAT is concerned with fatigue.

EQU is principally concerned with ultimate limit states involving a loss ofoverall equilibrium. However, it has an important relationship with thesingle source principle (see Key Concept 5)

Different artial factors on actions and eotechnical material

properties are used for different ultimate limit states


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Single Source Principle

EN 1990, Annex A2:

Key Concept 5


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Single Source Principle

Key Concept 5

NOTE 3 The characteristic values of all permanent actions from oneG,sup unfavourable and G,inf if the total resulting action effect is favourable. Forexample, all actions originating from the self weight of the structure may

materials are involved. See however A2.3.1(2)


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Balanced Cantilever


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C S S


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Key Concept 5 Single Source Principle

Application of the single source principle allows a single partial factor tobe applied to the whole of an action arising from a single source.

The value of the partial factor used depends on whether the resultingaction effect is favourable or unfavourable.

verifications.

EQU addresses cases when minor variations in the magnitude orspatial distribution of a permanent action from a single source issignificant.

EN1990 A A2 A li ti f b id


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EN1990: Annex A2 Application for bridges

Another key section for bridge design

Combinations of action [A2.2]General, rules for different brid e t es, values of factors

Ultimate limit states [A2.3]

, ,

Serviceability limit states [A2.4]

Design values, deformation, vibrations

EN1990 A A2 A li ti f b id


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EN1990 Annex A2 Application for bridges


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Partial factors on actions


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ULS Partial Factors Set A - Bridges


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ULS Partial Factors Set A - Bridges



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ULS Partial Factors Set B - Bridges


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ULS Partial Factors Set B Bridges

Design situations cases where


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geotechnical actions or resistance present

ULS Partial Factors Set C - Bridges


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ULS Partial Factors Set C Bridges

Illustration of STR and EQU:


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Verification of launched structure

G,sup Gk,sup

STR Verification : Moment over central support

Single source principle can be applied

EN1990 Set B Partial Factors used

Illustration of STR and EQU:V ifi i f l h d


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Verification of launched structure

G,sup Gk,supG,inf Gk,inf

EQU Verification

Single source principle not applied

EN1990 Set A Partial Factors used

Agenda


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g

Overview of EN1990

Verification of limit states and the combinations ofactions

Key Concept 6

Verification (ULS)


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Verification (ULS)


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ULS Verification(Persistent and Transient Design Situation)


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(Persistent and Transient Design Situation)

Ed

Rd



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Ed

Rd

.



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( g )

Ed

Rd

Ed = E { j1G,jGk,j+pP +Q,1Qk,1+i>1Q,i 0,i Qk,i }

.



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( g )




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( g )

effect




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effect


Effect of



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effectPermanentactions


Effect of



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Effect of

Combinedwith



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Effect of Prestress

Combinedwith



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variableaction


Effect of Prestress

Combinedwith



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variableaction


Effect of Prestress Accompanying

actionsCombinedwith

BS EN 1990 verification (ULS, STR)


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ActionsXk

mEd


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Dissemination of information for training Vienna 4 6 October 2010 70

ULS Verification Equ 6.10a and b(Persistent or Transient Design Situation)


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As an alternative to 6.10, less favourable of thefollowing two expressions applies:

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Combination factor applied to leading




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Dissemination of information for training Vienna, 4 6 October 2010 72


Combination factor applied to leading

Reduction factor applied topermanent actions


factors for highway bridges


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g


ULS Verification (Accidental Design Situation)


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Ed = E { j1Gk,j+ P + Ad+ (1,1 or 2,1) Qk,1

+ , ,


Serviceability Limit States


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Based on criteria concerning e orma ons a ec ng appearance, com or or unc on ng o

structure

structure

Dama e adversel affectin a earance durabilit or function


SLS Verification Combinations of Actions


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Characteristic Combination

Normally used for irreversible limit states

Ed = E { j1Gk,j+ P + Qk,1+i>10,i Qk,i }


Example from EN1992-1-1


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Frequent Combination

Normally used for reversible limit states

Ed = E { j1Gk,j+ P +1,1 Qk,1+i>12,i Qk,i }




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Quasi-Permanent Combination

Normally used for long term effects

Ed = E { j1Gk,j+ P +i12,i Qk,i }


Example from EN1992-1-1


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Combinations of Actions Treatment of variable actions


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Leading Accompanying

(1) (1)

Combinationalso includes

ULS Persistent and Transient DesignSituations Q 1.0 Q 0

ULS Accidental Design Situation 1.0 1(2) 1.0 2or 2

Ad

(SLS) Characteristic Combination 1.0 1.0 1.0 0

(SLS) Frequent combination 1.0 1 1.0 2

Notes:

(SLS) Quasi permanent Combination(also used for long term effects)

1.0 2 1.0 2

(1) Values of Q are obtained from tables A2.4(A) (C) of EN 1990.

(2) Expression 6.11 allows the use of either or 1 or2(3) Guidance on which combination should be used for specific verifications is given in the relevant Parts ofEN 1992 to EN 1999 for SLS, and is dependent upon the design situation at ULS.


Key Concept 6 Five Combinations of Actions


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EN1990 establishes five different combinations of actions.

limit states. They have different statistical likelihoods of

occurring.

The quasi-permanent combination is also used when analysinglong-term effects.

whether partial factors are applied; which representative values ofvariable actions are used; and, whether there is an accidental

.

The different combinations of actions are used in conjunction withthe Eurocode material arts. The Eurocode art enerall statesexplicitly which combination is to be used in each SLS verification.


Six key concepts - summary


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Design situations

evers e an rrevers e serv cea ty m t states

Representative values of variable actions

Six ultimate limit states

Five combinations of actions

001 2010_bridges_en1990 bisis of design some briefing

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