Che materia stai cercando?

Eurocode - Basis of structural design Appunti scolastici Premium

EN 1990 establishes Principles and requirements for the safety, serviceability and durability of structures, describes the basis for their design and verification and gives guidelines for related aspects of structural reliability. EN 1990 is intended to be used in conjunction with EN 1991 to EN 1999 for the structural design of buildings and civil engineering works, including geotechnical... Vedi di più

Esame di Tecnica delle costruzioni docente Prof. F. D'assisi Ricciardelli

Anteprima

ESTRATTO DOCUMENTO

EN 1990:2002 (E)

EN 1997 Eurocode 7 : Geotechnical design

EN 1998 Eurocode 8 : Design of structures for earthquake resistance

EN 1999 Eurocode 9 : Design of aluminium structures

1.3 Assumptions

(1) Design which employs the Principles and Application Rules is deemed to meet the

requirements provided the assumptions given in EN 1990 to EN 1999 are satisfied (see

Section 2).

(2) The general assumptions of EN 1990 are :

BSI - the choice of the structural system and the design of the structure is made by appro-

© priately qualified and experienced personnel;

Copy, – execution is carried out by personnel having the appropriate skill and experience;

– adequate supervision and quality control is provided during execution of the work,

i.e. in design offices, factories, plants, and on site;

Uncontrolled – the construction materials and products are used as specified in EN 1990 or in

EN 1991 to EN 1999 or in the relevant execution standards, or reference material or

product specifications;

– the structure will be adequately maintained;

– the structure will be used in accordance with the design assumptions.

NOTE There may be cases when the above assumptions need to be supplemented.

12/07/2004, 1.4 Distinction between Principles and Application Rules

(1) Depending on the character of the individual clauses, distinction is made in EN 1990

between Principles and Application Rules.

PORTSMOUTH, (2) The Principles comprise :

– general statements and definitions for which there is no alternative, as well as ;

– requirements and analytical models for which no alternative is permitted unless spe-

cifically stated.

(3) The Principles are identified by the letter P following the paragraph number.

OF (4) The Application Rules are generally recognised rules which comply with the Princi-

copy:UNIVERSITY ples and satisfy their requirements.

(5) It is permissible to use alternative design rules different from the Application Rules

given in EN 1990 for works, provided that it is shown that the alternative rules accord

with the relevant Principles and are at least equivalent with regard to the structural

safety, serviceability and durability which would be expected when using the Eurocodes.

Licensed 10 EN 1990:2002 (E)

NOTE If an alternative design rule is substituted for an application rule, the resulting design cannot be

claimed to be wholly in accordance with EN 1990 although the design will remain in accordance with the

Principles of EN 1990. When EN 1990 is used in respect of a property listed in an Annex Z of a product

standard or an ETAG, the use of an alternative design rule may not be acceptable for CE marking.

(6) In EN 1990, the Application Rules are identified by a number in brackets e.g. as this

clause.

1.5 Terms and definitions

NOTE For the purposes of this European Standard, the terms and definitions are derived from ISO 2394,

ISO 3898, ISO 8930, ISO 8402.

1.5.1 Common terms used in EN 1990 to EN 1999

BSI 1.5.1.1

construction works

© everything that is constructed or results from construction operations

Copy, NOTE This definition accords with ISO 6707-1. The term covers both building and civil engineering works.

It refers to the complete construction works comprising structural, non-structural and geotechnical elements.

Uncontrolled 1.5.1.2

type of building or civil engineering works e.g.

type of construction works designating its intended purpose, dwelling house, re-

taining wall, industrial building, road bridge

1.5.1.3

12/07/2004, type of construction e.g.

indication of the principal structural material, reinforced concrete construction, steel

construction, timber construction, masonry construction, steel and concrete composite

construction

1.5.1.4

PORTSMOUTH, method of construction e.g.

manner in which the execution will be carried out, cast in place, prefabricated, can-

tilevered

1.5.1.5

construction material

OF e.g.

material used in construction work, concrete, steel, timber, masonry

copy:UNIVERSITY 1.5.1.6

structure

organised combination of connected parts designed to carry loads and provide adequate

rigidity

Licensed 11

EN 1990:2002 (E)

1.5.1.7

structural member e.g.

physically distinguishable part of a structure, a column, a beam, a slab, a foundation

pile

1.5.1.8

form of structure

arrangement of structural members

NOTE Forms of structure are, for example, frames, suspension bridges.

1.5.1.9

structural system

load-bearing members of a building or civil engineering works and the way in which

BSI these members function together

1.5.1.10

© structural model

Copy, idealisation of the structural system used for the purposes of analysis, design and verifi-

cation

Uncontrolled 1.5.1.11

execution

all activities carried out for the physical completion of the work including procurement,

the inspection and documentation thereof

NOTE The term covers work on site; it may also signify the fabrication of components off site and their

12/07/2004, subsequent erection on site.

1.5.2 Special terms relating to design in general

1.5.2.1

design criteria

quantitative formulations that describe for each limit state the conditions to be fulfilled

PORTSMOUTH, 1.5.2.2

design situations

sets of physical conditions representing the real conditions occurring during a certain

time interval for which the design will demonstrate that relevant limit states are not ex-

ceeded

OF

copy:UNIVERSITY 1.5.2.3

transient design situation

design situation that is relevant during a period much shorter than the design working

life of the structure and which has a high probability of occurrence e.g.

NOTE A transient design situation refers to temporary conditions of the structure, of use, or exposure,

during construction or repair.

Licensed 12 EN 1990:2002 (E)

1.5.2.4

persistent design situation

design situation that is relevant during a period of the same order as the design working

life of the structure

NOTE Generally it refers to conditions of normal use.

1.5.2.5

accidental design situation

design situation involving exceptional conditions of the structure or its exposure, in-

cluding fire, explosion, impact or local failure

1.5.2.6

fire design

BSI design of a structure to fulfil the required performance in case of fire

1.5.2.7

© seismic design situation

Copy, design situation involving exceptional conditions of the structure when subjected to a

seismic event

Uncontrolled 1.5.2.8

design working life

assumed period for which a structure or part of it is to be used for its intended purpose

with anticipated maintenance but without major repair being necessary

1.5.2.9

12/07/2004, hazard e.g.

for the purpose of EN 1990 to EN 1999, an unusual and severe event, an abnormal

action or environmental influence, insufficient strength or resistance, or excessive de-

viation from intended dimensions

1.5.2.10

PORTSMOUTH, load arrangement

identification of the position, magnitude and direction of a free action

1.5.2.11

load case

compatible load arrangements, sets of deformations and imperfections considered si-

OF multaneously with fixed variable actions and permanent actions for a particular verifi-

cation

copy:UNIVERSITY 1.5.2.12

limit states

states beyond which the structure no longer fulfils the relevant design criteria

1.5.2.13

ultimate limit states

states associated with collapse or with other similar forms of structural failure

Licensed 13

EN 1990:2002 (E)

NOTE They generally correspond to the maximum load-carrying resistance of a structure or structural mem-

ber.

1.5.2.14

serviceability limit states

states that correspond to conditions beyond which specified service requirements for a

structure or structural member are no longer met

1.5.2.14.1

irreversible serviceability limit states

serviceability limit states where some consequences of actions exceeding the specified

service requirements will remain when the actions are removed

1.5.2.14.2

BSI reversible serviceability limit states

serviceability limit states where no consequences of actions exceeding the specified

© service requirements will remain when the actions are removed

Copy, 1.5.2.14.3

serviceability criterion

Uncontrolled design criterion for a serviceability limit state

1.5.2.15

resistance

capacity of a member or component, or a cross-section of a member or component of a

e.g.

structure, to withstand actions without mechanical failure bending resistance, buck-

12/07/2004, ling resistance, tension resistance

1.5.2.16

strength

mechanical property of a material indicating its ability to resist actions, usually given in

units of stress

PORTSMOUTH, 1.5.2.17

reliability

ability of a structure or a structural member to fulfil the specified requirements, includ-

ing the design working life, for which it has been designed. Reliability is usually ex-

pressed in probabilistic terms

OF NOTE Reliability covers safety, serviceability and durability of a structure.

copy:UNIVERSITY 1.5.2.18

reliability differentiation

measures intended for the socio-economic optimisation of the resources to be used to

build construction works, taking into account all the expected consequences of failures

and the cost of the construction works

Licensed 14 EN 1990:2002 (E)

1.5.2.19

basic variable

part of a specified set of variables representing physical quantities which characterise

actions and environmental influences, geometrical quantities, and material properties

including soil properties

1.5.2.20

maintenance

set of activities performed during the working life of the structure in order to enable it to

fulfil the requirements for reliability

NOTE Activities to restore the structure after an accidental or seismic event are normally outside the

scope of maintenance.

1.5.2.21

BSI repair

activities performed to preserve or to restore the function of a structure that fall outside

© the definition of maintenance

Copy, 1.5.2.22

nominal value

Uncontrolled value fixed on non-statistical bases, for instance on acquired experience or on physical

conditions

1.5.3 Terms relating to actions

1.5.3.1

12/07/2004, action (F)

a) Set of forces (loads) applied to the structure (direct action);

b) Set of imposed deformations or accelerations caused for example, by temperature

changes, moisture variation, uneven settlement or earthquakes (indirect action).

1.5.3.2

PORTSMOUTH, effect of action (E)

effect of actions (or action effect) on structural members, (e.g. internal force, moment,

stress, strain) or on the whole structure (e.g. deflection, rotation)

1.5.3.3

permanent action (G)

action that is likely to act throughout a given reference period and for which the varia-

OF tion in magnitude with time is negligible, or for which the variation is always in the

copy:UNIVERSITY same direction (monotonic) until the action attains a certain limit value

1.5.3.4

variable action (Q)

action for which the variation in magnitude with time is neither negligible nor mono-

tonic

Licensed 15

EN 1990:2002 (E)

1.5.3.5

accidental action (A)

action, usually of short duration but of significant magnitude, that is unlikely to occur on

a given structure during the design working life

NOTE 1 An accidental action can be expected in many cases to cause severe consequences unless appropri-

ate measures are taken.

NOTE 2 Impact, snow, wind and seismic actions may be variable or accidental actions, depending on the

available information on statistical distributions.

1.5.3.6

seismic action (A )

E

action that arises due to earthquake ground motions

BSI 1.5.3.7

geotechnical action

© action transmitted to the structure by the ground, fill or groundwater

Copy, 1.5.3.8

fixed action

Uncontrolled action that has a fixed distribution and position over the structure or structural member

such that the magnitude and direction of the action are determined unambiguously for

the whole structure or structural member if this magnitude and direction are determined

at one point on the structure or structural member

1.5.3.9

free action

12/07/2004, action that may have various spatial distributions over the structure

1.5.3.10

single action

action that can be assumed to be statistically independent in time and space of any other

action acting on the structure

PORTSMOUTH, 1.5.3.11

static action

action that does not cause significant acceleration of the structure or structural members

1.5.3.12

OF dynamic action

action that causes significant acceleration of the structure or structural members

copy:UNIVERSITY 1.5.3.13

quasi-static action

dynamic action represented by an equivalent static action in a static model

1.5.3.14

characteristic value of an action (F )

k

principal representative value of an action

Licensed 16 EN 1990:2002 (E)

NOTE In so far as a characteristic value can be fixed on statistical bases, it is chosen so as to correspond to a

prescribed probability of not being exceeded on the unfavourable side during a "reference period" taking into

account the design working life of the structure and the duration of the design situation.

1.5.3.15

reference period

chosen period of time that is used as a basis for assessing statistically variable actions,

and possibly for accidental actions

1.5.3.16

combination value of a variable action ( )

Q

0 k

value chosen - in so far as it can be fixed on statistical bases - so that the probability that

the effects caused by the combination will be exceeded is approximately the same as by

the characteristic value of an individual action. It may be expressed as a determined part

BSI 1

of the characteristic value by using a factor 0

© 1.5.3.17

Copy, frequent value of a variable action ( )

Q

1 k

value determined - in so far as it can be fixed on statistical bases - so that either the total

time, within the reference period, during which it is exceeded is only a small given part

Uncontrolled of the reference period, or the frequency of it being exceeded is limited to a given value.

It may be expressed as a determined part of the characteristic value by using a factor

1

1

1.5.3.18

quasi-permanent value of a variable action ( )

Q

2 k

12/07/2004, value determined so that the total period of time for which it will be exceeded is a large

fraction of the reference period. It may be expressed as a determined part of the charac-

teristic value by using a factor 1

2

1.5.3.19

accompanying value of a variable action ( )

Q

k

PORTSMOUTH, value of a variable action that accompanies the leading action in a combination

NOTE The accompanying value of a variable action may be the combination value, the frequent value or

the quasi-permanent value.

1.5.3.20

representative value of an action (F )

OF rep

value used for the verification of a limit state. A representative value may be the char-

copy:UNIVERSITY acteristic value (F ) or an accompanying value (F )

k k

1.5.3.21

design value of an action (F )

d

value obtained by multiplying the representative value by the partial factor f

NOTE The product of the representative value multiplied by the partial factor may also

F Sd f

be designated as the design value of the action (See 6.3.2).

Licensed 17

EN 1990:2002 (E)

1.5.3.22

combination of actions

set of design values used for the verification of the structural reliability for a limit state

under the simultaneous influence of different actions

1.5.4 Terms relating to material and product properties

1.5.4.1

characteristic value (X or )

R

k k

value of a material or product property having a prescribed probability of not being at-

tained in a hypothetical unlimited test series. This value generally corresponds to a

specified fractile of the assumed statistical distribution of the particular property of the

material or product. A nominal value is used as the characteristic value in some circum-

BSI stances

© 1.5.4.2

Copy, design value of a material or product property (X or )

R

d d

value obtained by dividing the characteristic value by a partial factor or , or, in

m M

special circumstances, by direct determination

Uncontrolled 1.5.4.3

nominal value of a material or product property (X or )

R

nom nom

value normally used as a characteristic value and established from an appropriate docu-

ment such as a European Standard or Prestandard

1.5.5 Terms relating to geometrical data

12/07/2004, 1.5.5.1

characteristic value of a geometrical property (a )

k

value usually corresponding to the dimensions specified in the design. Where relevant,

values of geometrical quantities may correspond to some prescribed fractiles of the sta-

tistical distribution

PORTSMOUTH, 1.5.5.2

design value of a geometrical property (a )

d

generally a nominal value. Where relevant, values of geometrical quantities may corre-

spond to some prescribed fractile of the statistical distribution

OF NOTE The design value of a geometrical property is generally equal to the characteristic value. However,

it may be treated differently in cases where the limit state under consideration is very sensitive to the value

copy:UNIVERSITY of the geometrical property, for example when considering the effect of geometrical imperfections on

buckling. In such cases, the design value will normally be established as a value specified directly, for

example in an appropriate European Standard or Prestandard. Alternatively, it can be established from a

statistical basis, with a value corresponding to a more appropriate fractile (e.g. a rarer value) than applies

to the characteristic value.

Licensed 18 EN 1990:2002 (E)

1.5.6 Terms relating to structural analysis

NOTE The definitions contained in the clause may not necessarily relate to terms used in EN 1990, but

are included here to ensure a harmonisation of terms relating to structural analysis for EN 1991 to

EN 1999.

1.5.6.1

structural analysis

procedure or algorithm for determination of action effects in every point of a structure

NOTE A structural analysis may have to be performed at three levels using different models : global

analysis, member analysis, local analysis.

1.5.6.2

global analysis

BSI determination, in a structure, of a consistent set of either internal forces and moments, or

stresses, that are in equilibrium with a particular defined set of actions on the structure,

© and depend on geometrical, structural and material properties

Copy, 1.5.6.3

first order linear-elastic analysis without redistribution

Uncontrolled elastic structural analysis based on linear stress/strain or moment/curvature laws and

performed on the initial geometry

1.5.6.4

first order linear-elastic analysis with redistribution

linear elastic analysis in which the internal moments and forces are modified for structural

design, consistently with the given external actions and without more explicit calculation

12/07/2004, of the rotation capacity

1.5.6.5

second order linear-elastic analysis

elastic structural analysis, using linear stress/strain laws, applied to the geometry of the

deformed structure

PORTSMOUTH, 1.5.6.6

first order non-linear analysis

structural analysis, performed on the initial geometry, that takes account of the non-linear

deformation properties of materials

OF NOTE First order non-linear analysis is either elastic with appropriate assumptions, or elastic-perfectly

plastic (see 1.5.6.8 and 1.5.6.9), or elasto-plastic (see 1.5.6.10) or rigid-plastic (see 1.5.6.11).

copy:UNIVERSITY 1.5.6.7

second order non-linear analysis

structural analysis, performed on the geometry of the deformed structure, that takes

account of the non-linear deformation properties of materials

NOTE Second order non-linear analysis is either elastic-perfectly plastic or elasto-plastic.

Licensed 19

EN 1990:2002 (E)

1.5.6.8

first order elastic-perfectly plastic analysis

structural analysis based on moment/curvature relationships consisting of a linear elastic

part followed by a plastic part without hardening, performed on the initial geometry of the

structure

1.5.6.9

second order elastic-perfectly plastic analysis

structural analysis based on moment/curvature relationships consisting of a linear elastic

part followed by a plastic part without hardening, performed on the geometry of the

displaced (or deformed) structure

1.5.6.10

elasto-plastic analysis (first or second order)

BSI structural analysis that uses stress-strain or moment/curvature relationships consisting of a

linear elastic part followed by a plastic part with or without hardening

©

Copy, NOTE In general, it is performed on the initial structural geometry, but it may also be applied to the

geometry of the displaced (or deformed) structure.

1.5.6.11

Uncontrolled rigid plastic analysis

analysis, performed on the initial geometry of the structure, that uses limit analysis

theorems for direct assessment of the ultimate loading .

NOTE The moment/curvature law is assumed without elastic deformation and without hardening

12/07/2004, 1.6 Symbols

For the purposes of this European Standard, the following symbols apply.

NOTE The notation used is based on ISO 3898:1987

PORTSMOUTH, Latin upper case letters

A Accidental action

A Design value of an accidental action

d

A A A

Design value of seismic action

Ed Ed I Ek

A Characteristic value of seismic action

Ek

OF C Nominal value, or a function of certain design properties of materials

d

E Effect of actions

copy:UNIVERSITY E Design value of effect of actions

d

E Design value of effect of destabilising actions

d,dst

E Design value of effect of stabilising actions

d,stb

F Action

F Design value of an action

d

F Characteristic value of an action

k

F Representative value of an action

rep

G Permanent action

Licensed 20 EN 1990:2002 (E)

Design value of a permanent action

G

d Lower design value of a permanent action

G

d,inf Upper design value of a permanent action

G

d,sup Characteristic value of a permanent action

G

k Characteristic value of permanent action

G j

k,j Upper/lower characteristic value of permanent action j

G /

kj,sup

G

kj,inf Relevant representative value of a prestressing action (see EN 1992

P to EN 1996 and EN 1998 to EN 1999)

Design value of a prestressing action

P

d Characteristic value of a prestressing action

P

k Mean value of a prestressing action

P

m Variable action

Q Design value of a variable action

Q

d

BSI Characteristic value of a single variable action

Q

k Characteristic value of the leading variable action 1

Q

k,1

© Characteristic value of the accompanying variable action i

Q

k,I

Copy, Resistance

R Design value of the resistance

R

d Characteristic value of the resistance

R

k

Uncontrolled Material property

X Design value of a material property

X

d Characteristic value of a material property

X

k

Latin lower case letters

Design values of geometrical data

a d

12/07/2004, Characteristic values of geometrical data

a k Nominal value of geometrical data

a nom Horizontal displacement of a structure or structural member

u Vertical deflection of a structural member

w

Greek upper case letters

PORTSMOUTH, Change made to nominal geometrical data for particular design pur-

a poses, assessment of effects of imperfections

e.g.

Greek lower case letters

OF Partial factor (safety or serviceability)

Partial factor for actions, which takes account of the possibility of

copy:UNIVERSITY f unfavourable deviations of the action values from the representative

values

Partial factor for actions, also accounting for model uncertainties and

F dimensional variations

Partial factor for permanent actions, which takes account of the pos-

g sibility of unfavourable deviations of the action values from the rep-

resentative values

Partial factor for permanent actions, also accounting for model un-

Licensed G 21

EN 1990:2002 (E) certainties and dimensional variations

Partial factor for permanent action j

G,j

Partial factor for permanent action j in calculating upper/lower de-

/

Gj,sup

sign values

Gj,inf

Importance factor (see EN 1998)

Partial factor for a material property

m

Partial factor for a material property, also accounting for model un-

M certainties and dimensional variations

Partial factor for prestressing actions (see EN 1992 to EN 1996 and

P EN 1998 to EN 1999)

Partial factor for variable actions, which takes account of the possi-

q bility of unfavourable deviations of the action values from the repre-

sentative values

Partial factor for variable actions, also accounting for model uncer-

Q

BSI tainties and dimensional variations

Partial factor for variable action i

Q,i

© Partial factor associated with the uncertainty of the resistance model

Rd

Copy, Partial factor associated with the uncertainty of the action and/or

Sd action effect model

Conversion factor

Uncontrolled Reduction factor

Factor for combination value of a variable action

0

Factor for frequent value of a variable action

1

Factor for quasi-permanent value of a variable action

2

12/07/2004,

PORTSMOUTH,

OF

copy:UNIVERSITY

Licensed 22 EN 1990:2002 (E)

Section 2 Requirements

2.1 Basic requirements

(1)P A structure shall be designed and executed in such a way that it will, during its in-

tended life, with appropriate degrees of reliability and in an economical way

– sustain all actions and influences likely to occur during execution and use, and

– remain fit for the use for which it is required.

(2)P A structure shall be designed to have adequate :

– structural resistance,

serviceability, and

– durability.

BSI (3)P In the case of fire, the structural resistance shall be adequate for the required period

© of time.

Copy, NOTE See also EN 1991-1-2

Uncontrolled (4)P A structure shall be designed and executed in such a way that it will not be dam-

aged by events such as :

– explosion,

– impact, and

– the consequences of human errors,

to an extent disproportionate to the original cause.

12/07/2004, NOTE 1 The events to be taken into account are those agreed for an individual project with the client and

the relevant authority.

NOTE 2 Further information is given in EN 1991-1-7.

(5)P Potential damage shall be avoided or limited by appropriate choice of one or more

of the following :

PORTSMOUTH, – avoiding, eliminating or reducing the hazards to which the structure can be subjected;

– selecting a structural form which has low sensitivity to the hazards considered ;

– selecting a structural form and design that can survive adequately the accidental re-

moval of an individual member or a limited part of the structure, or the occurrence of

acceptable localised damage ;

– avoiding as far as possible structural systems that can collapse without warning ;

OF – tying the structural members together.

copy:UNIVERSITY (6) The basic requirements should be met :

– by the choice of suitable materials,

– by appropriate design and detailing, and

– by specifying control procedures for design, production, execution, and use

relevant to the particular project.

Licensed 23

EN 1990:2002 (E)

(7) The provisions of Section 2 should be interpreted on the basis that due skill and care

appropriate to the circumstances is exercised in the design, based on such knowledge

and good practice as is generally available at the time that the design of the structure is

carried out.

2.2 Reliability management

(1)P The reliability required for structures within the scope of EN 1990 shall be

achieved:

a) by design in accordance with EN 1990 to EN 1999 and

b) by

– appropriate execution and

– quality management measures.

BSI NOTE See 2.2(5) and Annex B

© inter alia

(2) Different levels of reliability may be adopted :

Copy, – for structural resistance ;

– for serviceability.

Uncontrolled (3) The choice of the levels of reliability for a particular structure should take account of

the relevant factors, including :

– the possible cause and /or mode of attaining a limit state ;

– the possible consequences of failure in terms of risk to life, injury, potential eco-

nomical losses ;

– public aversion to failure ;

– the expense and procedures necessary to reduce the risk of failure.

12/07/2004, (4) The levels of reliability that apply to a particular structure may be specified in one or

both of the following ways :

– by the classification of the structure as a whole ;

– by the classification of its components.

PORTSMOUTH, NOTE See also Annex B

(5) The levels of reliability relating to structural resistance and serviceability can be

achieved by suitable combinations of :

a) preventative and protective measures (e.g. implementation of safety barriers, active

and passive protective measures against fire, protection against risks of corrosion such

OF as painting or cathodic protection) ;

copy:UNIVERSITY b) measures relating to design calculations :

– representative values of actions ;

– the choice of partial factors ;

c) measures relating to quality management ;

Licensed 24 EN 1990:2002 (E)

d) measures aimed to reduce errors in design and execution of the structure, and gross

human errors ;

e) other measures relating to the following other design matters :

– the basic requirements ;

– the degree of robustness (structural integrity) ;

– durability, including the choice of the design working life ;

– the extent and quality of preliminary investigations of soils and possible environ-

mental influences ;

– the accuracy of the mechanical models used ;

– the detailing ; e.g.

f) efficient execution, in accordance with execution standards referred to in

EN 1991 to EN 1999.

BSI g) adequate inspection and maintenance according to procedures specified in the project

© documentation.

Copy, (6) The measures to prevent potential causes of failure and/or reduce their consequences

may, in appropriate circumstances, be interchanged to a limited extent provided that the

Uncontrolled required reliability levels are maintained.

2.3 Design working life

(1) The design working life should be specified.

NOTE Indicative categories are given in Table 2.1. The values given in Table 2.1 may also be used for

12/07/2004, determining time-dependent performance (e.g. fatigue-related calculations). See also Annex A.

Table 2.1 - Indicative design working life

Design working Indicative design Examples

life category working life

(years)

PORTSMOUTH, (1)

1 10 Temporary structures

2 10 to 25 Replaceable structural parts, e.g. gantry girders,

bearings

3 15 to 30 Agricultural and similar structures

4 50 Building structures and other common structures

5 100 Monumental building structures, bridges, and other

civil engineering structures

OF (1) Structures or parts of structures that can be dismantled with a view to being re-used should

not be considered as temporary.

copy:UNIVERSITY 2.4 Durability

(1)P The structure shall be designed such that deterioration over its design working life

does not impair the performance of the structure below that intended, having due regard

to its environment and the anticipated level of maintenance.

Licensed 25

EN 1990:2002 (E)

(2) In order to achieve an adequately durable structure, the following should be taken

into account :

– the intended or foreseeable use of the structure ;

– the required design criteria ;

– the expected environmental conditions ;

– the composition, properties and performance of the materials and products ;

– the properties of the soil ;

– the choice of the structural system ;

– the shape of members and the structural detailing ;

– the quality of workmanship, and the level of control ;

– the particular protective measures ;

– the intended maintenance during the design working life.

NOTE The relevant EN 1992 to EN 1999 specify appropriate measures to reduce deterioration.

BSI (3)P The environmental conditions shall be identified at the design stage so that their

significance can be assessed in relation to durability and adequate provisions can be

© made for protection of the materials used in the structure.

Copy, (4) The degree of any deterioration may be estimated on the basis of calculations, ex-

perimental investigation, experience from earlier constructions, or a combination of

Uncontrolled these considerations.

2.5 Quality management

(1) In order to provide a structure that corresponds to the requirements and to the as-

sumptions made in the design, appropriate quality management measures should be in

12/07/2004, place. These measures comprise :

– definition of the reliability requirements,

– organisational measures and

– controls at the stages of design, execution, use and maintenance.

NOTE EN ISO 9001:2000 is an acceptable basis for quality management measures, where relevant.

PORTSMOUTH,

OF

copy:UNIVERSITY

Licensed 26 EN 1990:2002 (E)

Section 3 Principles of limit states design

3.1 General

(1)P A distinction shall be made between ultimate limit states and serviceability limit

states.

NOTE In some cases, additional verifications may be needed, for example to ensure traffic safety.

(2) Verification of one of the two categories of limit states may be omitted provided that

sufficient information is available to prove that it is satisfied by the other.

(3)P Limit states shall be related to design situations, see 3.2.

BSI (4) Design situations should be classified as persistent, transient or accidental, see 3.2.

©

Copy, (5) Verification of limit states that are concerned with time dependent effects (e.g. fatigue)

should be related to the design working life of the construction.

Uncontrolled NOTE Most time dependent effects are cumulative.

3.2 Design situations

(1)P The relevant design situations shall be selected taking into account the circum-

stances under which the structure is required to fulfil its function.

12/07/2004, (2)P Design situations shall be classified as follows :

– persistent design situations, which refer to the conditions of normal use ;

– transient design situations, which refer to temporary conditions applicable to the

e.g.

structure, during execution or repair ;

– accidental design situations, which refer to exceptional conditions applicable to the

e.g.

structure or to its exposure, to fire, explosion, impact or the consequences of lo-

PORTSMOUTH, calised failure ;

– seismic design situations, which refer to conditions applicable to the structure when

subjected to seismic events.

NOTE Information on specific design situations within each of these classes is given in EN 1991 to

EN 1999.

OF (3)P The selected design situations shall be sufficiently severe and varied so as to en-

copy:UNIVERSITY compass all conditions that can reasonably be foreseen to occur during the execution

and use of the structure.

Licensed 27

EN 1990:2002 (E)

3.3 Ultimate limit states

(1)P The limit states that concern :

– the safety of people, and/or

– the safety of the structure

shall be classified as ultimate limit states.

(2) In some circumstances, the limit states that concern the protection of the contents

should be classified as ultimate limit states.

NOTE The circumstances are those agreed for a particular project with the client and the relevant author-

ity.

(3) States prior to structural collapse, which, for simplicity, are considered in place of

the collapse itself, may be treated as ultimate limit states.

BSI (4)P The following ultimate limit states shall be verified where they are relevant :

© – loss of equilibrium of the structure or any part of it, considered as a rigid body ;

Copy, – failure by excessive deformation, transformation of the structure or any part of it into

a mechanism, rupture, loss of stability of the structure or any part of it, including

supports and foundations ;

Uncontrolled – failure caused by fatigue or other time-dependent effects.

NOTE Different sets of partial factors are associated with the various ultimate limit states, see 6.4.1.

Failure due to excessive deformation is structural failure due to mechanical instability.

3.4 Serviceability limit states

12/07/2004, (1)P The limit states that concern :

– the functioning of the structure or structural members under normal use ;

– the comfort of people ;

– the appearance of the construction works,

shall be classified as serviceability limit states.

PORTSMOUTH, NOTE 1 In the context of serviceability, the term “appearance” is concerned with such criteria as high de-

flection and extensive cracking, rather than aesthetics.

NOTE 2 Usually the serviceability requirements are agreed for each individual project.

(2)P A distinction shall be made between reversible and irreversible serviceability limit

states.

OF

copy:UNIVERSITY (3) The verification of serviceability limit states should be based on criteria concerning

the following aspects :

a) deformations that affect

– the appearance,

– the comfort of users, or

– the functioning of the structure (including the functioning of machines or serv-

ices),

or that cause damage to finishes or non-structural members ;

Licensed 28 EN 1990:2002 (E)

b) vibrations

– that cause discomfort to people, or

– that limit the functional effectiveness of the structure ;

c) damage that is likely to adversely affect

– the appearance,

– the durability, or

– the functioning of the structure.

NOTE Additional provisions related to serviceability criteria are given in the relevant EN 1992 to EN 1999.

3.5 Limit state design

BSI (1)P Design for limit states shall be based on the use of structural and load models for

relevant limit states.

©

Copy, (2)P It shall be verified that no limit state is exceeded when relevant design values for

– actions,

– material properties, or

Uncontrolled – product properties, and

– geometrical data

are used in these models.

(3)P The verifications shall be carried out for all relevant design situations and load

cases.

12/07/2004, (4) The requirements of 3.5(1)P should be achieved by the partial factor method, described

in section 6.

(5) As an alternative, a design directly based on probabilistic methods may be used.

NOTE 1 The relevant authority can give specific conditions for use.

PORTSMOUTH, NOTE 2 For a basis of probabilistic methods, see Annex C.

(6)P The selected design situations shall be considered and critical load cases identified.

(7) For a particular verification load cases should be selected, identifying compatible load

arrangements, sets of deformations and imperfections that should be considered

OF simultaneously with fixed variable actions and permanent actions.

copy:UNIVERSITY (8)P Possible deviations from the assumed directions or positions of actions shall be taken

into account.

(9) Structural and load models can be either physical models or mathematical models.

Licensed 29

EN 1990:2002 (E)

Section 4 Basic variables

4.1 Actions and environmental influences

4.1.1 Classification of actions

(1)P Actions shall be classified by their variation in time as follows :

(G),

– permanent actions e.g. self-weight of structures, fixed equipment and road sur-

facing, and indirect actions caused by shrinkage and uneven settlements ;

(Q),

– variable actions e.g. imposed loads on building floors, beams and roofs, wind

actions or snow loads ;

(A),

– accidental actions e.g. explosions, or impact from vehicles.

BSI NOTE Indirect actions caused by imposed deformations can be either permanent or variable.

(2) Certain actions, such as seismic actions and snow loads, may be considered as either

© accidental and/or variable actions, depending on the site location, see EN 1991 and

Copy, EN 1998.

(3) Actions caused by water may be considered as permanent and/or variable actions

Uncontrolled depending on the variation of their magnitude with time.

(4)P Actions shall also be classified

– by their origin, as direct or indirect,

– by their spatial variation, as fixed or free, or

– by their nature and/or the structural response, as static or dynamic.

12/07/2004, (5) An action should be described by a model, its magnitude being represented in the

most common cases by one scalar which may have several representative values.

NOTE For some actions and some verifications, a more complex representation of the magnitudes of

some actions may be necessary.

PORTSMOUTH, 4.1.2 Characteristic values of actions

F

(1)P The characteristic value of an action is its main representative value and shall be

k

specified :

– as a mean value, an upper or lower value, or a nominal value (which does not refer to

a known statistical distribution) (see EN 1991) ;

OF – in the project documentation, provided that consistency is achieved with methods

copy:UNIVERSITY given in EN 1991.

(2)P The characteristic value of a permanent action shall be assessed as follows :

G G

– if the variability of can be considered as small, one single value may be used ;

k

G

– if the variability of cannot be considered as small, two values shall be used : an

G G

upper value and a lower value .

k,sup k,inf

Licensed 30 EN 1990:2002 (E)

G G

(3) The variability of may be neglected if does not vary significantly during the

G

design working life of the structure and its coefficient of variation is small. should

k

then be taken equal to the mean value.

NOTE This coefficient of variation can be in the range of 0,05 to 0,10 depending on the type of structure.

G

(4) In cases when the structure is very sensitive to variations in (e.g. some types of

prestressed concrete structures), two values should be used even if the coefficient of

G G

variation is small. Then is the 5% fractile and is the 95% fractile of the sta-

k,inf k,sup

G,

tistical distribution for which may be assumed to be Gaussian.

(5) The self-weight of the structure may be represented by a single characteristic value

and be calculated on the basis of the nominal dimensions and mean unit masses, see EN

1991-1-1.

BSI NOTE For the settlement of foundations, see EN 1997.

© (6) Prestressing (P) should be classified as a permanent action caused by either con-

Copy, trolled forces and/or controlled deformations imposed on a structure. These types of

prestress should be distinguished from each other as relevant (e.g. prestress by tendons,

prestress by imposed deformation at supports).

Uncontrolled P

NOTE The characteristic values of prestress, at a given time t, may be an upper value (t) and a lower

k,sup

P P

value (t). For ultimate limit states, a mean value (t) can be used. Detailed information is given in

k,inf m

EN 1992 to EN 1996 and EN 1999.

(7)P For variable actions, the characteristic value (Q ) shall correspond to either :

k

– an upper value with an intended probability of not being exceeded or a lower value

12/07/2004, with an intended probability of being achieved, during some specific reference pe-

riod;

– a nominal value, which may be specified in cases where a statistical distribution is

not known.

NOTE 1 Values are given in the various Parts of EN 1991.

PORTSMOUTH, NOTE 2 The characteristic value of climatic actions is based upon the probability of 0,02 of its time-

varying part being exceeded for a reference period of one year. This is equivalent to a mean return period

of 50 years for the time-varying part. However in some cases the character of the action and/or the se-

lected design situation makes another fractile and/or return period more appropriate.

A

(8) For accidental actions the design value should be specified for individual projects.

d

OF NOTE See also EN 1991-1-7.

copy:UNIVERSITY A

(9) For seismic actions the design value should be assessed from the characteristic

Ed

A

value or specified for individual projects.

Ek

NOTE See also EN 1998.

(10) For multi-component actions the characteristic action should be represented by

groups of values each to be considered separately in design calculations.

Licensed 31

EN 1990:2002 (E)

4.1.3 Other representative values of variable actions

(1)P Other representative values of a variable action shall be as follows :

Q , used for the verification of

(a) the combination value, represented as a product 0 k

ultimate limit states and irreversible serviceability limit states (see section 6 and An-

nex C) ; Q

(b) the frequent value, represented as a product , used for the verification of ulti-

1 k

mate limit states involving accidental actions and for verifications of reversible

serviceability limit states ;

NOTE 1 For buildings, for example, the frequent value is chosen so that the time it is exceeded is 0,01 of

the reference period ; for road traffic loads on bridges, the frequent value is assessed on the basis of a

return period of one week.

BSI Q

NOTE 2 The infrequent value, represented as a product , is used for the verification of certain

1,infq k

© serviceability limit states specifically for concrete bridge decks, or concrete parts of bridge decks. The

Copy, infrequent value, defined only for road traffic loads (see EN 1991-2) thermal actions (see EN 1991-1-5)

and wind actions (see EN 1991-1-4), is based on a return period of one year.

Q

(c) the quasi-permanent value, represented as a product , used for the verification

Uncontrolled 2 k

of ultimate limit states involving accidental actions and for the verification of reversible

serviceability limit states. Quasi-permanent values are also used for the calculation of

long-term effects.

NOTE For loads on building floors, the quasi-permanent value is usually chosen so that the proportion of

the time it is exceeded is 0,50 of the reference period. The quasi-permanent value can alternatively be

determined as the value averaged over a chosen period of time. In the case of wind actions or road traffic

12/07/2004, loads, the quasi-permanent value is generally taken as zero.

4.1.4 Representation of fatigue actions

(1) The models for fatigue actions should be those that have been established in the

relevant parts of EN 1991 from evaluation of structural responses to fluctuations of loads

PORTSMOUTH, performed for common structures (e.g. for simple span and multi-span bridges, tall slender

structures for wind).

(2) For structures outside the field of application of models established in the relevant

Parts of EN 1991, fatigue actions should be defined from the evaluation of measurements

or equivalent studies of the expected action spectra.

OF NOTE For the consideration of material specific effects (for example, the consideration of mean stress

copy:UNIVERSITY influence or non-linear effects), see EN 1992 to EN 1999.

4.1.5 Representation of dynamic actions

(1) The characteristic and fatigue load models in EN 1991 include the effects of accel-

erations caused by the actions either implicitly in the characteristic loads or explicitly by

applying dynamic enhancement factors to characteristic static loads.

Licensed NOTE Limits of use of these models are described in the various Parts of EN 1991.

32 EN 1990:2002 (E)

(2) When dynamic actions cause significant acceleration of the structure, dynamic

analysis of the system should be used. See 5.1.3 (6).

4.1.6 Geotechnical actions

(1)P Geotechnical actions shall be assessed in accordance with EN 1997-1.

4.1.7 Environmental influences

(1)P The environmental influences that could affect the durability of the structure shall

be considered in the choice of structural materials, their specification, the structural con-

cept and detailed design.

BSI NOTE The EN 1992 to EN 1999 give the relevant measures.

(2) The effects of environmental influences should be taken into account, and where

© possible, be described quantitatively.

Copy, 4.2 Material and product properties

Uncontrolled (1) Properties of materials (including soil and rock) or products should be represented

by characteristic values (see 1.5.4.1).

(2) When a limit state verification is sensitive to the variability of a material property,

upper and lower characteristic values of the material property should be taken into ac-

count.

12/07/2004, (3) Unless otherwise stated in EN 1991 to EN 1999 :

– where a low value of material or product property is unfavourable, the characteristic

value should be defined as the 5% fractile value;

PORTSMOUTH, – where a high value of material or product property is unfavourable, the characteristic

value should be defined as the 95% fractile value.

(4)P Material property values shall be determined from standardised tests performed

under specified conditions. A conversion factor shall be applied where it is necessary to

convert the test results into values which can be assumed to represent the behaviour of

OF the material or product in the structure or the ground.

copy:UNIVERSITY annex D and EN 1992 to EN 1999

NOTE See

(5) Where insufficient statistical data are available to establish the characteristic values

of a material or product property, nominal values may be taken as the characteristic val-

ues, or design values of the property may be established directly. Where upper or lower

design values of a material or product property are established directly (e.g. friction

factors, damping ratios), they should be selected so that more adverse values would af-

fect the probability of occurrence of the limit state under consideration to an extent

Licensed 33

EN 1990:2002 (E)

similar to other design values.

(6) Where an upper estimate of strength is required (e.g. for capacity design measures

and for the tensile strength of concrete for the calculation of the effects of indirect ac-

tions) a characteristic upper value of the strength should be taken into account.

(7) The reductions of the material strength or product resistance to be considered re-

sulting from the effects of repeated actions are given in EN 1992 to EN 1999 and can

lead to a reduction of the resistance over time due to fatigue.

(8) The structural stiffness parameters (e.g. moduli of elasticity, creep coefficients) and

thermal expansion coefficients should be represented by a mean value. Different values

should be used to take into account the duration of the load.

BSI NOTE In some cases, a lower or higher value than the mean for the modulus of elasticity may have to be

taken into account (e.g. in case of instability).

© (9) Values of material or product properties are given in EN 1992 to EN 1999 and in the

Copy, relevant harmonised European technical specifications or other documents. If values are

taken from product standards without guidance on interpretation being given in

EN 1992 to EN 1999, the most adverse values should be used.

Uncontrolled (10)P Where a partial factor for materials or products is needed, a conservative value

shall be used, unless suitable statistical information exists to assess the reliability of the

value chosen.

NOTE Suitable account may be taken where appropriate of the unfamiliarity of the application or materi-

als/products used.

12/07/2004, 4.3 Geometrical data

(1)P Geometrical data shall be represented by their characteristic values, or (e.g. the case

of imperfections) directly by their design values.

PORTSMOUTH, (2) The dimensions specified in the design may be taken as characteristic values.

(3) Where their statistical distribution is sufficiently known, values of geometrical

quantities that correspond to a prescribed fractile of the statistical distribution may be

used.

OF (4) Imperfections that should be taken into account in the design of structural members

copy:UNIVERSITY are given in EN 1992 to EN 1999.

(5)P Tolerances for connected parts that are made from different materials shall be mu-

tually compatible.

Licensed 34 EN 1990:2002 (E)

Section 5 Structural analysis and design assisted by testing

5.1 Structural analysis

5.1.1 Structural modelling

(1)P Calculations shall be carried out using appropriate structural models involving

relevant variables.

(2) The structural models selected should be those appropriate for predicting structural

behaviour with an acceptable level of accuracy. The structural models should also be

appropriate to the limit states considered.

BSI (3)P Structural models shall be based on established engineering theory and practice. If

necessary, they shall be verified experimentally.

©

Copy, 5.1.2 Static actions

(1)P The modelling for static actions shall be based on an appropriate choice of the

Uncontrolled force-deformation relationships of the members and their connections and between

members and the ground.

(2)P Boundary conditions applied to the model shall represent those intended in the

structure.

(3)P Effects of displacements and deformations shall be taken into account in the con-

12/07/2004, text of ultimate limit state verifications if they result in a significant increase of the ef-

fect of actions.

NOTE Particular methods for dealing with effects of deformations are given in EN 1991 to EN 1999.

(4)P Indirect actions shall be introduced in the analysis as follows :

PORTSMOUTH, – in linear elastic analysis, directly or as equivalent forces (using appropriate modular

ratios where relevant) ;

– in non-linear analysis, directly as imposed deformations.

5.1.3 Dynamic actions

OF (1)P The structural model to be used for determining the action effects shall be estab-

lished taking account of all relevant structural members, their masses, strengths, stiff-

copy:UNIVERSITY nesses and damping characteristics, and all relevant non structural members with their

properties.

(2)P The boundary conditions applied to the model shall be representative of those in-

tended in the structure.

Licensed 35

EN 1990:2002 (E)

(3) When it is appropriate to consider dynamic actions as quasi-static, the dynamic parts

may be considered either by including them in the static values or by applying equiva-

lent dynamic amplification factors to the static actions.

NOTE For some equivalent dynamic amplification factors, the natural frequencies are determined.

(4) In the case of ground-structure interaction, the contribution of the soil may be mod-

elled by appropriate equivalent springs and dash-pots.

(5) Where relevant (e.g. for wind induced vibrations or seismic actions) the actions may

be defined by a modal analysis based on linear material and geometric behaviour. For

structures that have regular geometry, stiffness and mass distribution, provided that only

the fundamental mode is relevant, an explicit modal analysis may be substituted by an

analysis with equivalent static actions.

BSI (6) The dynamic actions may be also expressed, as appropriate, in terms of time histo-

ries or in the frequency domain, and the structural response determined by appropriate

© methods.

Copy, (7) Where dynamic actions cause vibrations of a magnitude or frequencies that could

exceed serviceability requirements, a serviceability limit state verification should be

Uncontrolled carried out.

NOTE Guidance for assessing these limits is given in Annex A and EN 1992 to EN 1999.

5.1.4 Fire design

12/07/2004, (1)P The structural fire design analysis shall be based on design fire scenarios (see EN

1991-1-2), and shall consider models for the temperature evolution within the structure

as well as models for the mechanical behaviour of the structure at elevated temperature.

(2) The required performance of the structure exposed to fire should be verified by ei-

ther global analysis, analysis of sub-assemblies or member analysis, as well as the use of

PORTSMOUTH, tabular data or test results.

(3) The behaviour of the structure exposed to fire should be assessed by taking into ac-

count either :

– nominal fire exposure, or

– modelled fire exposure,

as well as the accompanying actions.

OF

copy:UNIVERSITY NOTE See also EN 1991-1-2.

(4) The structural behaviour at elevated temperatures should be assessed in accordance

with EN 1992 to EN 1996 and EN 1999, which give thermal and structural models for

analysis.

Licensed 36 EN 1990:2002 (E)

(5) Where relevant to the specific material and the method of assessment :

– thermal models may be based on the assumption of a uniform or a non-uniform tem-

perature within cross-sections and along members ;

– structural models may be confined to an analysis of individual members or may ac-

count for the interaction between members in fire exposure.

(6) The models of mechanical behaviour of structural members at elevated temperatures

should be non-linear.

NOTE See also EN 1991 to EN 1999.

5.2 Design assisted by testing

BSI (1) Design may be based on a combination of tests and calculations.

© NOTE Testing may be carried out, for example, in the following circumstances :

– if adequate calculation models are not available ;

Copy, – if a large number of similar components are to be used ;

– to confirm by control checks assumptions made in the design.

See Annex D.

Uncontrolled (2)P Design assisted by test results shall achieve the level of reliability required for the

relevant design situation. The statistical uncertainty due to a limited number of test re-

sults shall be taken into account.

(3) Partial factors (including those for model uncertainties) comparable to those used in

EN 1991 to EN 1999 should be used.

12/07/2004,

PORTSMOUTH,

OF

copy:UNIVERSITY

Licensed 37

EN 1990:2002 (E)

Section 6 Verification by the partial factor method

6.1 General

(1)P When using the partial factor method, it shall be verified that, in all relevant design

situations, no relevant limit state is exceeded when design values for actions or effects of

actions and resistances are used in the design models.

(2) For the selected design situations and the relevant limit states the individual actions for

the critical load cases should be combined as detailed in this section. However actions that

cannot occur simultaneously, for example due to physical reasons, should not be

considered together in combination.

BSI (3) Design values should be obtained by using :

- the characteristic, or

© - other representative values,

Copy, in combination with partial and other factors as defined in this section and EN 1991 to

EN 1999.

Uncontrolled (4) It can be appropriate to determine design values directly where conservative values

should be chosen.

(5)P Design values directly determined on statistical bases shall correspond to at least

the same degree of reliability for the various limit states as implied by the partial factors

given in this standard.

12/07/2004, 6.2 Limitations

(1) The use of the Application Rules given in EN 1990 is limited to ultimate and

serviceability limit state verifications of structures subject to static loading, including cases

where the dynamic effects are assessed using equivalent quasi-static loads and dynamic

amplification factors, including wind or traffic loads. For non-linear analysis and fatigue

PORTSMOUTH, the specific rules given in various Parts of EN 1991 to EN 1999 should be applied.

6.3 Design values

6.3.1 Design values of actions

OF F F

(1) The design value of an action can be expressed in general terms as :

d

copy:UNIVERSITY (6.1a)

F F

d f rep

with :

F F (6.1b)

rep k

where :

Licensed 38 EN 1990:2002 (E)

F is the characteristic value of the action.

k

F is the relevant representative value of the action.

rep

is a partial factor for the action which takes account of the possibility of unfa-

f vourable deviations of the action values from the representative values.

is either 1,00 or , or .

0 1 2 A

(2) For seismic actions the design value should be determined taking account of the

Ed

structural behaviour and other relevant criteria detailed in EN 1998.

6.3.2 Design values of the effects of actions ) can be

(1) For a specific load case the design values of the effects of actions (E

d

BSI expressed in general terms as :

(6.2)

E E F a i

; 1

d Sd f i rep i d

, ,

©

Copy, where : is the design values of the geometrical data (see 6.3.4) ;

a

Uncontrolled d

is a partial factor taking account of uncertainties :

Sd in modelling the effects of actions ;

in some cases, in modelling the actions.

NOTE In a more general case the effects of actions depend on material properties.

12/07/2004, (2) In most cases, the following simplification can be made :

(6.2a)

E E F a i

; 1

d F i rep i d

, ,

with :

PORTSMOUTH,

(6.2b)

F i Sd f i

, ,

e.g.

NOTE When relevant, where geotechnical actions are involved, partial factors can be applied to

F,i

can be globally applied to the effect of the

the effects of individual actions or only one particular factor F

combination of actions with appropriate partial factors.

OF (3)P Where a distinction has to be made between favourable and unfavourable effects of

copy:UNIVERSITY permanent actions, two different partial factors shall be used ( and ).

G,inf G,sup

(4) For non-linear analysis (i.e. when the relationship between actions and their effects is

not linear), the following simplified rules may be considered in the case of a single

predominant action :

a) When the action effect increases more than the action, the partial factor should be

F

applied to the representative value of the action.

Licensed 39

EN 1990:2002 (E)

b) When the action effect increases less than the action, the partial factor should be

F

applied to the action effect of the representative value of the action.

NOTE Except for rope, cable and membrane structures, most structures or structural elements are in

category a).

(5) In those cases where more refined methods are detailed in the relevant EN 1991 to

EN 1999 (e.g. for prestressed structures), they should be used in preference to 6.3.2(4).

6.3.3 Design values of material or product properties

X

(1) The design value of a material or product property can be expressed in general

d

terms as :

X

BSI k

X (6.3)

d m

©

Copy, where :

X is the characteristic value of the material or product property (see 4.2(3)) ;

k

Uncontrolled is the mean value of the conversion factor taking into account

– volume and scale effects,

– effects of moisture and temperature, and

– any other relevant parameters ;

is the partial factor for the material or product property to take account of :

12/07/2004, m – the possibility of an unfavourable deviation of a material or product property

from its characteristic value ; .

– the random part of the conversion factor

(2) Alternatively, in appropriate cases, the conversion factor may be :

– implicitly taken into account within the characteristic value itself, or

PORTSMOUTH,

– by using instead of (see expression (6.6b)).

M m

NOTE The design value can be established by such means as :

– empirical relationships with measured physical properties, or

– with chemical composition, or

– from previous experience, or

– from values given in European Standards or other appropriate documents.

OF

copy:UNIVERSITY 6.3.4 Design values of geometrical data

(1) Design values of geometrical data such as dimensions of members that are used to

assess action effects and/or resistances may be represented by nominal values :

a a

= (6.4)

d nom

Licensed 40 EN 1990:2002 (E)

(2)P Where the effects of deviations in geometrical data (e.g. inaccuracy in the load

application or location of supports) are significant for the reliability of the structure (e.g.

by second order effects) the design values of geometrical data shall be defined by :

a a a (6.5)

d nom

where :

a takes account of :

– the possibility of unfavourable deviations from the characteristic or nominal

values ;

– the cumulative effect of a simultaneous occurrence of several geometrical de-

viations.

BSI

a 0

a a

NOTE 1 can also represent geometrical imperfections where = 0 (i.e., ).

d nom

© NOTE 2 Where relevant, EN 1991 to EN 1999 provide further provisions.

Copy, (3) Effects of other deviations should be covered by partial factors

– on the action side ( ), and/or

F

– resistance side ( ).

Uncontrolled M

NOTE Tolerances are defined in the relevant standards on execution referred to in EN 1990 to EN 1999.

6.3.5 Design resistance R

(1) The design resistance can be expressed in the following form :

d

12/07/2004,

X

1 1 k i

,

R R X a R a i

; ; 1 (6.6)

d d i d i d

,

Rd Rd m i

,

where :

is a partial factor covering uncertainty in the resistance model, plus geometric

PORTSMOUTH, Rd deviations if these are not modelled explicitly (see 6.3.4(2));

X i.

is the design value of material property

d,i

(2) The following simplification of expression (6.6) may be made :

OF X k i

,

R R a

; i 1 (6.6a)

d i d

copy:UNIVERSITY M i

,

where :

(6.6b)

M i Rd m i

, ,

may be incorporated in , see 6.3.3.(2).

NOTE i M,i

Licensed 41

EN 1990:2002 (E)

(3) Alternatively to expression (6.6a), the design resistance may be obtained directly from

the characteristic value of a material or product resistance, without explicit determination

of design values for individual basic variables, using :

R k

R (6.6c)

d M

NOTE This is applicable to products or members made of a single material (e.g. steel) and is also used in

connection with Annex D “Design assisted by testing”.

(4) Alternatively to expressions (6.6a) and (6.6c), for structures or structural members that

are analysed by non-linear methods, and comprise more than one material acting in

association, or where ground properties are involved in the design resistance, the following

expression for design resistance can be used :

BSI

1 m ,

1

R R X X a

; ; (6.6d)

d k i k i i d

1 ,

1 , ( 1

)

© M m i

,

1 ,

Copy, partial factors to the

NOTE In some cases, the design resistance can be expressed by applying directly M

individual resistances due to material properties.

Uncontrolled 6.4 Ultimate limit states

6.4.1 General

(1)P The following ultimate limit states shall be verified as relevant :

12/07/2004, a) EQU : Loss of static equilibrium of the structure or any part of it considered as a

rigid body, where :

– minor variations in the value or the spatial distribution of actions from a single

source are significant, and

– the strengths of construction materials or ground are generally not governing ;

PORTSMOUTH, b) STR : Internal failure or excessive deformation of the structure or structural mem-

bers, including footings, piles, basement walls, etc., where the strength of construc-

tion materials of the structure governs ;

c) GEO : Failure or excessive deformation of the ground where the strengths of soil or

rock are significant in providing resistance ;

OF d) FAT : Fatigue failure of the structure or structural members.

copy:UNIVERSITY NOTE For fatigue design, the combinations of actions are given in EN 1992 to EN 1999.

(2)P The design values of actions shall be in accordance with Annex A.

Licensed 42 EN 1990:2002 (E)

6.4.2 Verifications of static equilibrium and resistance

(1)P When considering a limit state of static equilibrium of the structure (EQU), it shall be

verified that :

E E (6.7)

d ,dst d ,stb

where :

E is the design value of the effect of destabilising actions ;

d ,dst

E is the design value of the effect of stabilising actions.

d ,stb

BSI (2) Where appropriate the expression for a limit state of static equilibrium may be

supplemented by additional terms, including, for example, a coefficient of friction between

© rigid bodies.

Copy, (3)P When considering a limit state of rupture or excessive deformation of a section,

member or connection (STR and/or GEO), it shall be verified that :

Uncontrolled

E R (6.8)

d d

where :

E is the design value of the effect of actions such as internal force, moment or a vector

d representing several internal forces or moments ;

12/07/2004, R is the design value of the corresponding resistance.

d

NOTE.1 Details for the methods STR and GEO are given in Annex A.

NOTE 2 Expression (6.8) does not cover all verification formats concerning buckling, i.e. failure that

happens where second order effects cannot be limited by the structural response, or by an acceptable

PORTSMOUTH, structural response. See EN 1992 to EN 1999.

6.4.3 Combination of actions (fatigue verifications excluded)

6.4.3.1 General

OF (1)P For each critical load case, the design values of the effects of actions (E ) shall be

d

determined by combining the values of actions that are considered to occur

copy:UNIVERSITY simultaneously.

(2) Each combination of actions should include :

– a leading variable action, or

– an accidental action.

(3) The combinations of actions should be in accordance with 6.4.3.2 to 6.4.3.4.

Licensed 43

EN 1990:2002 (E)

(4)P Where the results of a verification are very sensitive to variations of the magnitude of

a permanent action from place to place in the structure, the unfavourable and the

favourable parts of this action shall be considered as individual actions.

NOTE This applies in particular to the verification of static equilibrium and analogous limit states, see

6.4.2(2).

(5) Where several effects of one action (e.g. bending moment and normal force due to self-

weight) are not fully correlated, the partial factor applied to any favourable component

may be reduced.

NOTE For further guidance on this topic see the clauses on vectorial effects in EN 1992 to EN 1999.

(6) Imposed deformations should be taken into account where relevant.

BSI NOTE For further guidance, see 5.1.2.4(P) and EN 1992 to EN 1999.

© 6.4.3.2 Combinations of actions for persistent or transient design situations (funda-

Copy, mental combinations)

(1) The general format of effects of actions should be :

Uncontrolled

E E G P Q Q j i

; ; ; 1 ; 1 (6.9a)

d Sd g j k j p q k q i i k i

, , ,

1 ,

1 , 0 , ,

(2) The combination of effects of actions to be considered should be based on

– the design value of the leading variable action, and

– the design combination values of accompanying variable actions :

12/07/2004, NOTE See also 6.4.3.2(4).

E E G P Q Q j i

; ; ; 1 ; 1 (6.9b)

d G j k j P Q k Q i i k i

, , ,

1 ,

1 , 0 , ,

(3) The combination of actions in brackets { }, in (6.9b) may either be expressed as :

PORTSMOUTH,

G P Q Q

"+" "+" "+" (6.10)

, k, j P Q,1 k,1 Q, i 0, i k, i

G j

j 1 i >

1

or, alternatively for STR and GEO limit states, the less favourable of the two following

expressions:

OF

(6.10a)

G P Q Q

" " " " " "

G j k j P Q k Q i i k i

, , ,

1 0 ,

1 ,

1 , 0 , ,

j i

1 1

copy:UNIVERSITY

(6.10b)

G P Q Q

" " " " " "

j G j k j P Q k Q i i k i

, , ,

1 ,

1 , 0 , ,

j i

1 1

Where :

"+ " implies "to be combined with"

implies "the combined effect of"

G

is a reduction factor for unfavourable permanent actions

Licensed 44 EN 1990:2002 (E)

NOTE Further information for this choice is given in Annex A.

(4) If the relationship between actions and their effects is not linear, expressions (6.9a) or

(6.9b) should be applied directly, depending upon the relative increase of the effects of

actions compared to the increase in the magnitude of actions (see also 6.3.2.(4)).

6.4.3.3 Combinations of actions for accidental design situations

(1) The general format of effects of actions should be :

E E G P A Q Q j i

; ; ; ( or ) ; 1 ; 1 (6.11a)

d k j d k i k i

, 1,1 2,1 ,

1 2 , ,

(2) The combination of actions in brackets { } can be expressed as :

BSI

(6.11b)

G P A Q Q

" " "+" "+" ( or ) "+"

1,1 2,1 2, i

k, j d k,1 k, i

© j 1 i 1

Copy,

Q Q

(3) The choice between or should be related to the relevant accidental

1,1 k,1 2,1 k,1

design situation (impact, fire or survival after an accidental event or situation).

Uncontrolled NOTE Guidance is given in the relevant Parts of EN 1991 to EN 1999.

(4) Combinations of actions for accidental design situations should either

A

– involve an explicit accidental action (fire or impact), or

– refer to a situation after an accidental event (A = 0).

12/07/2004, A

For fire situations, apart from the temperature effect on the material properties, should

d

represent the design value of the indirect thermal action due to fire.

6.4.3.4 Combinations of actions for seismic design situations

(1) The general format of effects of actions should be :

PORTSMOUTH,

E E G P A Q j i

; ; ; 1 ; 1 (6.12a)

d k j Ed i k i

, 2 , ,

(2) The combination of actions in brackets { } can be expressed as :

G P A Q

" " "+" "+" (6.12b)

2, i

OF , Ed k, i

k j

j 1 i 1

copy:UNIVERSITY 6.4.4 Partial factors for actions and combinations of actions

(1) The values of the and factors for actions should be obtained from EN 1991 and

from Annex A.

Licensed 45

EN 1990:2002 (E)

6.4.5 Partial factors for materials and products

(1) The partial factors for properties of materials and products should be obtained from

EN 1992 to EN 1999.

6.5 Serviceability limit states

6.5.1 Verifications

(1)P It shall be verified that :

C

E (6.13)

d d

BSI where :

© C is the limiting design value of the relevant serviceability criterion.

d

Copy, E is the design value of the effects of actions specified in the serviceability

d criterion, determined on the basis of the relevant combination.

Uncontrolled 6.5.2 Serviceability criteria

(1) The deformations to be taken into account in relation to serviceability requirements

should be as detailed in the relevant Annex A according to the type of construction

works, or agreed with the client or the National authority.

12/07/2004, NOTE For other specific serviceability criteria such as crack width, stress or strain limitation, slip

resistance, see EN 1991 to EN 1999.

6.5.3 Combination of actions

(1) The combinations of actions to be taken into account in the relevant design

PORTSMOUTH, situations should be appropriate for the serviceability requirements and performance

criteria being verified.

(2) The combinations of actions for serviceability limit states are defined symbolically

by the following expressions (see also 6.5.4) :

OF NOTE It is assumed, in these expressions, that all partial factors are equal to 1. See Annex A and

EN 1991 to EN 1999.

copy:UNIVERSITY a) Characteristic combination :

E E G P Q Q j i

; ; ; 1 ; 1 (6.14a)

d k j k i k i

, ,

1 0

, ,

in which the combination of actions in brackets { } (called the characteristic

combination), can be expressed as :

Licensed 46 EN 1990:2002 (E)

G P Q Q (6.14b)

"+" "+" "+"

k j

, k,1 0, i k, i

j i

1 1

NOTE The characteristic combination is normally used for irreversible limit states.

b) Frequent combination :

E E G P Q Q j i (6.15a)

; ; ; 1 ; 1

d k j k i k i

, 1

,

1 ,

1 2 , ,

in which the combination of actions in brackets { }, (called the frequent combination),

can be expressed as :

G P Q Q (6.15b)

"+" "+" "+"

k j

, 1,1 k,1 2, i k, i

j i

1 1

BSI NOTE The frequent combination is normally used for reversible limit states.

©

Copy, c) Quasi-permanent combination :

E E G P Q j i

; ; 1 ; 1 (6.16a)

Uncontrolled d k j i k i

, 2 , ,

in which the combination of actions in brackets { }, (called the quasi-permanent

combination), can be expressed as :

G P Q (6.16b)

"+" "+"

k j

, 2, i k, i

j i

1 1

12/07/2004, where the notation is as given in 1.6 and 6.4.3(1).

NOTE The quasi-permanent combination is normally used for long-term effects and the appearance of the

structure.

PORTSMOUTH, P P

(3) For the representative value of the prestressing action (i.e. or ), reference

k m

should be made to the relevant design Eurocode for the type of prestress under

consideration.

(4)P Effects of actions due to imposed deformations shall be considered where relevant.

OF NOTE In some cases expressions (6.14) to (6.16) require modification. Detailed rules are given in the

relevant Parts of EN 1991 to EN 1999.

copy:UNIVERSITY 6.5.4 Partial factors for materials

(1) For serviceability limit states the partial factors for the properties of materials

M

should be taken as 1,0 except if differently specified in EN 1992 to EN 1999.

Licensed 47

EN 1990:2002 (E) Annex A1

(normative)

Application for Buildings

A1.1 Field of application

1) This annex A1 gives rules and methods for establishing combinations of actions for

(

buildings. It also gives the recommended design values of permanent, variable and acci-

dental actions and factors to be used in the design of buildings.

NOTE Guidance may be given in the National annex with regard to the use of Table 2.1 (design working

life).

BSI A1.2 Combinations of actions

© A1.2.1 General

Copy, (1) Effects of actions that cannot exist simultaneously due to physical or functional

reasons should not be considered together in combinations of actions.

Uncontrolled NOTE 1 Depending on its uses and the form and the location of a building, the combinations of actions

may be based on not more than two variable actions.

NOTE 2 Where modifications of A1.2.1(2) and A1.2.1(3) are necessary for geographical reasons, these

can be defined in the National annex.

12/07/2004, (2) The combinations of actions given in expressions 6.9a to 6.12b should be used when

verifying ultimate limit states.

(3) The combinations of actions given in expressions 6.14a to 6.16b should be used

when verifying serviceability limit states.

PORTSMOUTH, (4) Combinations of actions that include prestressing forces should be dealt with as

detailed in EN 1992 to EN 1999.

A1.2.2 Values of factors

(1) Values of factors should be specified.

OF

NOTE Recommended values of factors for the more common actions may be obtained from Table

copy:UNIVERSITY A1.1.

Licensed 48 EN 1990:2002 (E)

Table A1.1 - Recommended values of factors for buildings

Action 0 1 2

Imposed loads in buildings, category (see

EN 1991-1-1) 0,3

0,5

0,7

Category A : domestic, residential areas 0,3

0,5

0,7

Category B : office areas 0,6

0,7

0,7

Category C : congregation areas 0,6

0,7

0,7

Category D : shopping areas 0,8

0,9

1,0

Category E : storage areas

Category F : traffic area, 0,6

0,7

0,7

vehicle weight 30kN

Category G : traffic area, 0,3

0,5

0,7

30kN < vehicle weight 160kN 0

0

0

Category H : roofs

Snow loads on buildings (see EN 1991-1-3)*

BSI Finland, Iceland, Norway, Sweden 0,70 0,50 0,20

Remainder of CEN Member States, for sites 0,70 0,50 0,20

© located at altitude H > 1000 m a.s.l.

Remainder of CEN Member States, for sites 0,50 0,20 0

Copy,

located at altitude H 1000 m a.s.l.

Wind loads on buildings (see EN 1991-1-4) 0,6 0,2 0

Temperature (non-fire) in buildings (see EN 0,6 0,5 0

Uncontrolled 1991-1-5)

NOTE The values may be set by the National annex.

* For countries not mentioned below, see relevant local conditions.

A1.3 Ultimate limit states

A1.3.1 Design values of actions in persistent and transient design situations

12/07/2004, (1) The design values of actions for ultimate limit states in the persistent and transient

design situations (expressions 6.9a to 6.10b) should be in accordance with Tables

A1.2(A) to (C). e.g.

NOTE The values in Tables A1.2 ((A) to (C)) can be altered for different reliability levels in the

National annex (see Section 2 and Annex B).

PORTSMOUTH, (2) In applying Tables A1.2(A) to A1.2(C) in cases when the limit state is very sensitive

to variations in the magnitude of permanent actions, the upper and lower characteristic

values of actions should be taken according to 4.1.2(2)P.

(3) Static equilibrium (EQU, see 6.4.1) for building structures should be verified using

OF the design values of actions in Table A1.2(A).

copy:UNIVERSITY (4) Design of structural members (STR, see 6.4.1) not involving geotechnical actions

should be verified using the design values of actions from Table A1.2(B).

(5) Design of structural members (footings, piles, basement walls, etc.) (STR) involving

geotechnical actions and the resistance of the ground (GEO, see 6.4.1) should be veri-

fied using one of the following three approaches supplemented, for geotechnical actions

and resistances, by EN 1997 :

Licensed 49


PAGINE

90

PESO

674.13 KB

AUTORE

vipviper

PUBBLICATO

+1 anno fa


DESCRIZIONE APPUNTO

EN 1990 establishes Principles and requirements for the safety, serviceability and durability of structures, describes the basis for their design and verification and gives guidelines for related aspects of structural reliability. EN 1990 is intended to be used in conjunction with EN 1991 to EN 1999 for the structural design of buildings and civil engineering works, including geotechnical aspects, structural fire design, situations involving earthquakes, execution and temporary structures.
Contents:
- principles of limit states design;
- basic variables;
- structural analysis and design assisted by testing;
- verification by the partial factor method;
- application for buildings;
- management of structural reliability for construction works;
- basis for partial factor design and reliability;
- analysis;
- design assisted by testing.


DETTAGLI
Corso di laurea: Corso di laurea in ingegneria civile
SSD:
A.A.: 2011-2012

I contenuti di questa pagina costituiscono rielaborazioni personali del Publisher vipviper di informazioni apprese con la frequenza delle lezioni di Tecnica delle costruzioni e studio autonomo di eventuali libri di riferimento in preparazione dell'esame finale o della tesi. Non devono intendersi come materiale ufficiale dell'università Mediterranea - Unirc o del prof D'assisi Ricciardelli Francesco.

Acquista con carta o conto PayPal

Scarica il file tutte le volte che vuoi

Paga con un conto PayPal per usufruire della garanzia Soddisfatto o rimborsato

Recensioni
Ti è piaciuto questo appunto? Valutalo!

Altri appunti di Tecnica delle costruzioni

Costruzioni zone sismiche
Appunto
Cemento - Collaudo
Appunto
Costruzioni - Sicurezza
Appunto
Costruzioni - DM 14 gennaio 2008
Dispensa