Overview of Eurocodes

7/27/2019 Overview of Eurocodes

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Overview of Eurocodes

9 Introduction to EN 1990

as s o es gn limit state design

combination of actions



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Sco e of Eurocodes

-

-

EN 1991 - Actions on structures

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Sco e of Eurocodes

Remaining 8 codes are material-specific:

EN 1992 - Design of concrete structures

EN 1993 - Design of steel structures

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EN 1995 - Design of timber structures EN 1996 - Design of masonry structures

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EN 1998 - Design of structures for earthquakes

EN 1999 - Design of aluminium structures

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s a es a a s ruc ure s a e

designed adequately and you are required to

ruc ura res s ance

Serviceability Durability

Fire resistance

Robustness

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-

Subscript Definition Example

Ed Design value of an effect MEd Design bending moment

Rd Design resistance MRd Design resistance for bending

El Elastic ro ert W Elastic section modulus

Pl Plastic property Wpl Plastic section modulus

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Actions (F):

-

indirect actions - temperature changes, vibrations

both essentially produce same effect

Effects of action(E): on structural members and whole structure

for example bending moments, shear forces,

capacity of a structural element to resist bendingmoment, axial force, shear, etc.

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Permanent actions G : are those that essentiall

do not vary with time such as self-weight of

structure fixed e ui ment

Variable actions Q : leadin and non-leadin

actions, and those that can vary with time such

as imposed loads, wind loads and snow loads

Accidental actions (A): are usually of short

duration, but high magnitude such asexplosions, impacts

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Outlined in EN 1990 Basis of structural Desi n

Based on limit state design

Principal limit states

Ultimate limit state concerned with colla se

yielding; buckling; overturning

Serviceability limit state, concerned with function Deflection; vibration

Other limit states

Fire resistance Durabilit

robustness

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Limit states: s a es eyon w c e s ruc ure can no

longer meets its original design intention

Ultimate limit states:

similar forms of structural failure, for e.g.

,

states correspond to function, beyond which

for e.g. deflection, vibration

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Define relevant limit states

Determine appropriate combined actions {F}, e.g.

temperature changes

e erm ne es gn e ec s

bending moments deflections

Determine desi n resistance R

Ensure no limit state is exceeded {R > E}

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Characteristic values of actions

Representative value of action above which not more than a

small percentage of the action may exceed during the design

working life Design values

es gn va ues use o c ec m s a e con on

Design value of actionshe characteristic value of action multiplied by the

relevant partial factor for action

Design value of strength

The characteristic value of strength divided by the

re evan par a ac or or ma er a

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values for both actions material to account for

variabilit

The value of depends on:

e m s a e un er cons era on

The variable to which it is applied The context e.g. is an action beneficial in relation

to the considered effect

F for actions (loading)

M

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Action Partial factor

Ultimate limit

state

Permanent Action (G)

Unfavourable conditions G = 1.35

= .

Variable Action (Q)

Unfavourable conditions Q = 1.50F

avourable conditions Q = 0.0

Serviceability Permanent Action (G) G

= 0.0

Var a e Act on (Q) Q = 1.00

M

M0 1.00 (1.00) Cross-sectionsM

. .

M2 1.25 (1.10) fracture

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Fundamental combinations of actions may be determined

1.5 combination factor

from EN 1990 using Equation 6.10:

other variable actions

++

,,0,k,11,,, ikiiQQjkjG

QQG (6.10)=

. permanen ac ons .

variable actionscombination factor

Load factors 1.35 and 1.5 are a lied when actions are

unfavorable

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Identif leadin variable action Q ,

The leading variable action is the one that leads to the

most unfavourable effect (i.e. the critical combination)

To generate the various load combinations, eachvariable action should be considered in turn as the

.

Other variable actions reduced by a combination factor

Accounts for probability of simultaneous occurrence of

multiple variable loads

Imposed load = 0.7

Wind load = 0.6 (SS NA = 0.5)

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the load combinations about EC 3Gk= Dead load (permanent action);

Qk= imposed load;

Wk= wind load

Dead load & imposed load 1.35Gk+ 1.5Qk

. k . k

Dead load, imposed and

wind load1.35Gk+ 1.50Wk+ 1.05Qkor

1.35G + 1.50 + 0.75W

*1.05 = 0.7 1.50Leading variable action 0.75 = 0.5 1.50

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- -

EN 1991-1 contains the following sub-parts: EN 1991-1-1: Densities, self-weight, imposed

loads

EN 1991-1-2: Fire

- - : now oa s

EN 1991-1-4: Wind actions

EN 1991-1-5: Thermal actions

- - : ct ons ur ng execut on

EN 1991-1-7: Accidental actions Im act and

explosions)

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Overview of EN 1993 Eurocode 3

Eurocode 3 EC3 contains 6 arts:

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EN 1993-2: Bridges

EN 1993-3: Towers, masts & chimneys

- ,

EN 1993-5: Piling

EN 1993-6: Crane supporting structures

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- -

Eurocode 3 Part 1 has 12 sub-parts:

EN 1993-1-1: General rules

- - : re EN 1993-1-3: Cold-formed thin gauge

EN 1993-1-4: Stainless steel

EN 1993-1- : P ate e ements

EN 1993-1-6: Shells

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- -

EN 1993-1-7: Plates transversely loaded

EN 1993-1-8: Joints

EN 1993-1-9: Fatigue

EN 1993-1-10: Fracture toughness

- -

EN 1993-1-12: High strength steels

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Ever Eurocode will contain a National Annex

The National Standard implementing Eurocode

(e.g. SS EN 1993-1-1: 2010) must comprise thefull, unaltered text of that Eurocode, including all

Annexes.

e a ona nnex may on y nc u e n orma on

on those parameters within clauses that have

. .

EN 1993-1-1: 2010)

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-

Minor axis z-z

Longitudinal axis of element x-x

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Major axis y-yMinor axis z-z

Longitudinal axis of element x-x

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Material Properties Nominal values of yield strengthfyand ultimate tensile

strengthfu for hot-rolled structural steel can be taken froma e 3.1 o EC3-1-1

Table 3.1 of EC3-1-1 (part)

Standardand steel

Nominal thickness of the element (mm)

T40mm 40mm 80mm

fy(N/mm2) fu (N/mm

2) fy(N/mm2) fu (N/mm

2)

-

S235 235 360 215 360

S275 275 430 255 410

S335 335 510 335 470

S450 440 550 410 550

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Material Properties

The National Annex may give the choice for the value of

and which could be obtained from either the Product

Standards (EN 10025 for hot-rolled sections) or by using

Table 3.1.

The National Annex of Singapore (NA to SS EN 1993-1-1)choose the earlier. The nominal values of thefyandfu for

structura stee s ou e t ose o ta ne rom t e

product standards.

n ngapore, non- ma er a s are a owe o e use .

Further information on the values offyandfu for steel

-

given in BC1: 2012a.a BC1: 2012 Design Guide on Use of Alternative Structural Steel to BS5950 and

Eurocode 3, Building and Construction Authority, Singapore

(ISBN: 978-981-05-9754-2)

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Material Properties

Values of yield strength for the most common grades of- -

S335) form Table 3.1, the product standard EN 10025-2

Thickness EC 32

EN 10025

2

BS 5950

2

EC 3

2

EN 10025

2

BS 5950

2

y y y y y y

S275 S275 S275 S335 S335 S335

40 275 265 265 355 345 345

63 255 255 255 335 335 335

80 255 245 245 335 325 325

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es gn va ues o ma er a coe c en s o e use n

EN 1993-1:

Modulus of elasticityE = 210 000 N/mm2

Shear modulus:

G = E/2(1 +

) = 81 000 N/mm2

Poissons ratio:

= 0.3

Coefficient of thermal expansion:

a= 12 10-6/

(for temperatures below 100 )

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Documents

Overview of Eurocodes