NTU Seminar Actions Wanted Deador Live Euro Code

Prof Tan Kang Hai (PhD, PEng)

Email: [email protected]

Director of Protective Technology Research Centre (PTRC)

Division of Structures & Mechanics

School of Civil & Environmental Engineering

Actions Wanted: Dead or Live

1

Basis of Structural Design to EC0

mailto:[email protected]



1. National Implementation and Annex

2. EC0

3. Load combinations

4. Global imperfections

5. Worked Examples

6. Summary

2

Content

3

EN 1990 … Eurocode : Basis of Structural Design

EN 1991 … Eurocode 1: Actions on Structures

EN 1992 … Eurocode 2: Design of Concrete Structures

EN 1993 … Eurocode 3: Design of Steel Structures

EN 1994 … Eurocode 4: Design of Composite Steel and Concrete Structures

EN 1995… Eurocode 5: Design of Timber Structures

EN 1996 … Eurocode 6: Design of Masonry Structures

EN 1997… Eurocode 7: Geotechnical Design

EN 1998 … Eurocode 8: Design of Structures for Earthquake Resistance

EN 1999 … Eurocode 9: Design of Aluminum Structures

EC0

EC1

EC2

EC3

EC4

EC5

EC6

EC7

EC8

EC9


4

EC0

EC1

EC2

EC3

EC4

EC5

EC6

EC7

EC8

EC9

Linkage between the Eurocodes


5

EN 1990: Basis of Structural Design (EC0)

EN 1991: Actions on Structures (EC1)

EN 1993: Design of Steel Structures (EC3)

EN 1991-1

EN 1991-2

EN 1991-3

Traffic loads

on bridges

Actions induced

by cranes & machinery

EN 1991-1.1

Density,

self-weight

& imposed loads

EN 1991-1.2

Actions on

structures

exposed to fire

EN 1991-1.3

Snow

loads

EN 1991-1.4

Wind

loads

EN 1991-1.5

Thermal

actions

EN 1991-1.6

Actions

during

execution

EN 1991-1.7

Accidental actions

due to impact

and explosion

EN 1993-1

EN 1993-1.1

General rules and rules for

Buildings

EN 1993-1.2

Structural

Fire

Design

EN 1993-1.3, EN 1993-1.4, EN 1993-1.5,

EN 1993-1.6, EN 1993-1.7, EN 1993-1.8,

EN 1993-1.9, EN 1993-1.10, etc.

etc.

6

EN 1991 part Published

EN 1991-1-1 Densities, self weight, imposed loads for buildings 2002

EN 1991-1-2 Actions on structures exposed to fire 2002

EN 1991-1-3 Snow loads 2003

EN 1991-1-4 Wind actions 2005

EN 1991-1-5 Thermal actions 2003

EN 1991-1-6 Actions during execution 2005

EN 1991-1-7 Accidental actions 2006

EN 1991-2 Traffic loads on bridges 2003

EN 1991-3 Actions induced by cranes and machinery 2006

EN 1991-4 Silos and tanks 2006


Codes that relate to actions


7

EN 1993-1.1:2004

Common rules for

Buildings and civil

Engineering structures

EN 1990:2002

EN 1991-1.1:2002

Density,

Self-weight

& imposed loads

Basis of

Structural Design

BS EN 1993-1.1:2005

Eurocode 3: Design of steel

structures – Part 1-1: General rules

and rules for buildings

BS EN 1990:2002

BS EN 1991-1.1:2002

Eurocode1: Part 1-1: General Actions –

Densities, self-weight

& imposed loads for buildings

Eurocode - Basis of

Structural Design

NA to BS EN 1993-1.1:2005

UK National Annex for EC2

NA to BS EN 1990:2002

NA to BS EN 1991-1.1:2002



NA to SS EN 1990:2008

Singapore National Annex for EC0

NA to SS EN 1991-1.1:2008


NA to SS EN 1993-1.1:2008


Structural Eurocodes are accepted from 1 Apr 2013, and co-exist for two years with the current

Singapore/British Standards. Structural Eurocodes will be the only prescribed structural design standards

from 1 Apr 2015. At the end of the two-year co-existence period on 1 Apr 2015, the SS/BS will be

withdrawn from the Approved Document.


8

Nationally Determined Parameters (NDPs)

1500 NDPs in the Eurocode suite

355 NDPs in EN 1991

New definitions:

9

Clause Traditional definitions New definitions

1.5.3.1 Forces (load)/ imposed deformations Actions

1.5.3.2 Shear force, moment, stress, strain Action effects

1.5.3.3 Dead load (DL) Permanent actions (Gk)

1.5.3.4 Live load (LL), wind load Variable actions (Qk)

Live load Imposed loads

2. EC0

A structure shall be designed to have adequate:

- Structural resistance (ultimate limit state)

- Serviceability (serviceability limit state)

- Durability (serviceability limit state)

- Fire resistance (fire limit state)

- Robustness (accidental limit state)

10

2. EC0

Design for Ultimate Limit States (ULS)

Design for Serviceability Limit States (SLS)

The structure to be designed to satisfy:

Ed Rd

The structure to be designed to satisfy:

Ed Cd

Actions and Environmental Influences

Material and Product Properties

Design working life

11

2. EC0

12

Ultimate Limit States (ULS)

Serviceability Limit States (SLS)

LIMIT STATES

These refer to those associated with:

(1) collapse or failure, and generally govern the

strength of the structure or component;

(2) loss of equilibrium or stability of the structure

as a whole*.

(*): As the structure will undergo severe

deformation prior to reaching collapse conditions,

these states are regarded as ultimate limit states.

They will necessitate replacement of the structure

or element.

ULS is governed by strength and stability of

structures or members.

These refer to conditions of the structure in use,

including deformation, cracking and vibration

which:

(1) damage the structural or non-structural

elements (finishes, partitions, etc.) or the contents

of buildings (such as machinery);

(2) cause discomfort to the occupants of

buildings;

(3) affect adversely appearance, durability or

water and weather tightness.

SLS is generally governed by he stiffness of the

structure and the detailing of reinforcement.

These refer to states beyond which the structure infringes an agreed performance criterion

2. EC0

13

Persistent Situations

Transient Situations

Seismic Situations

Accidental Situations

DESIGN SITUATIONS

These refer to

conditions of normal

use.

Normal use includes

possible extreme

loading conditions from

wind, snow, imposed

loads, etc

Related to the design

working life of the

structure.

.

These refer to

temporary conditions of

the structure, in terms of

its use or its exposure,

e.g. during construction

or repair.

Much shorter than the

design working life

Refer to exceptional

conditions applicable to

the structure when

subjected to seismic

events.

These refer to

exceptional conditions

e.g. due to fire,

explosion, impact or

local failure.

Refer to relatively short

period.

FUNDAMENTAL COMBINATIONS FAILURE MODES AT ULS: EQU, STR, GEO, FAT

2. EC0

14

EQU

STR

FAT

GEO

MAJOR FAILURE MODES at ULTIMATE LIMIT STATES TO BE CONSIDERED FOR A DESIGN SITUATION:

Loss of static

equilibrium of the

structure or any part of it

considered as a rigid

body, where:

(1) minor variations in

the value or the spatial

distribution of actions

from a single source are

significant, and

(2) the strengths of

construction materials

or the ground do not

govern.

Internal failure or

excessive deformation

of the structure or

structural members,

including columns,

footings, piles,

basement walls, etc.,

where the strength of

construction materials of

the structure governs;

Fatigue failure of the

structure or structural

members.

Failure or excessive

deformation of the

ground where the

strength of soil or rock

are significant in

providing resistance;

2. EC0

Ultimate limit states: Three common failure states

15

2. EC0

16

Classification of Actions

2. EC0

17

Combination Value 0Qk

Frequent Value 1Qk

Quasi-permanent Value 2Qk

OTHER REPRESENTATIVE VALUES OF VARIABLE ACTIONS:

For:

1) ULS and

2) Irreversible SLS

3) Apply to non-leading variable

actions

(consider the reduced probability

of simultaneous occurrences of

two or more independent variable

actions.)

For:

1) ULS involving accidental actions,

and

2) Reversible SLS

3) Apply to leading variable action

(e.g. for buildings, the frequent value

is chosen so that the time it is

exceeded is 0.01 of the reference

period of 50 years)

For:

1) ULS involving accidental

actions, and

2) Reversible SLS

3) Used for calculation of long-

term effects.

(e.g. for loads on building floors,

the quasi-permanent value is

chosen so that the proportion of

the time it is exceeded is 0.50 of

the reference period.)

2. EC0

18

Permanent

Actions

Variable Action

(leading)

Prestress

Actions

Variable Actions

(accompanying)

G,j Gk,j Q,1 Qk,1

P Pk

Q,i 0,i Qk,i

Accidental

Actions

Eq. (6.10) (for EQU, STR, GEO of persistent and transient design situations)

“+”

COMBINATION OF ACTIONS FOR DESIGN AT ULTIMATE LIMIT STATES (ULS)

“+” “+” “+”

G,j Gk,j Q,1 0,1Qk,1

P Pk

Eq. (6.10a) (for STR, GEO of persistent and transient design situations) AND

“+” “+” “+” “+”

j G,j Gk,j Q,1 Qk,1

P Pk

Eq. (6.10b) (for STR, GEO of persistent and transient design situations)

“+” “+” “+” “+”

Q,i 0,i Qk,i

Q,i 0,i Qk,i

Notes: (1) j is sub-index for permanent action, j1; i is sub-index for accompanying variable actions, i>1;

(2) The symbol “+“ implies “to be combined with”;

(3) The symbol implies “the combined effect of”;

(4) The symbol is a reduction factor for unfavourable permanent action G, in the range of 0.8 to 1.0;

(5) The less favourable of Eq.(6.10a) and Eq.(6.10b) is used for STR and GEO design situations.


In BS 5950, a structure is first designed for the

fundamental load combination (DL + LL) and is then

checked for other load combinations (DL + LL + W)

with reduction load factors

In EC3, all combinations of actions (or load cases) are

equally important.

19


20

Persistent Situations

Transient Situations

Seismic Situations

Accidental Situations

For EQU, STR, GEO:

Equation (6.10)

For STR, GEO:

Equation (6.10a) &

Equation (6.10b)

For EQU, STR, GEO:

Equation (6.10)

For STR, GEO:

Equation (6.10a) &

Equation (6.10b)

Equation (6.12b)

Equation (6.11b)

FUNDAMENTAL COMBINATIONS

COMBINATION OF ACTIONS FOR DESIGN AT ULTIMATE LIMIT STATES (ULS)

Note: Fatigue verification (FAT) is not included in EC0 Clause 6.4

Characteristic Combination

Frequent Combination

Quasi-permanent Combination

Equation (6.14b)

Equation (6.15b) Equation (6.16b)

COMBINATION OF ACTIONS FOR DESIGN AT SERVICEABILITY LIMIT STATES (SLS)


21

DISTINCTION BETWEEN Eqs. (6.10), (6.10a) and (6.10b)

1. In Eq.(6.10a), all other variable actions Qi are taken into account with their combination value (0,iQk,i);

2. In Eq.(6.10b), Q1 is identified as a leading action (Qi are taken into account as accompanying actions), but a

reduction factor j is applied to the unfavourable permanent actions Gj;

4. These can be referred to Reliability Methods

3. Eqs. (6.10a) and (6.10b) will always give a lower design value for load effect than the use of (Eq.6.10);


Equation 6.10:

Comparison of partial factors

Design situations BS 5950 EC3 With one variable action

(Live load) 1.4DL + 1.6LL 1.35Gk + 1.5Qk

With one variable action

(Wind load) 1.4DL + 1.6W 1.35Gk + 1.5Wk

With two variable actions

(Wind & live loads) 1.2DL + 1.2LL + 1.2W

1.35 Gk + 1.5 Qk + 0.75Wk

Or 1.35 Gk + 1.05 Qk + 1.5Wk

0.7x1.5Qk 0.5x1.5Wk

Leading variable action

22


23


Ultimate states Combinations of actions

Eq. (6.10)

For EQU, STR, GEO

1.35 Gk + 1.5 Qk + 1.5*0.5Wk

Or 1.35 Gk + 1.05 Qk + 1.5Wk

Eq. (6.10a)

For STR, GEO

1.0 Gk + 1.5*0.5Wk +1.5*0.7 Qk

1.0 Gk + 1.5*0.5Wk

Eq. (6.10b) For STR, GEO

0.925*1.35Gk + 1.00Gk +1.5Wk +1.5*0.7 Q

(adverse) (favourable)

Equation 6.10a,b

24


25

• Variance of dimensions of a structure or a

member

• Lack of verticality of a structure and straightness

or flatness of a member

Global and local imperfections

e0

h h

b ±


26

• Global imperfections

of frames or bracing systems – Cover lack of verticality for frames or straightness of

structure restrained by bracings

• Local (member) imperfections

of individual members – Cover lack of straightness or flatness of a member

and residual stresses of the member

Global and local imperfections


V1

V2

V1

V2

V1

V2

27

Global imperfections

• In general, the sway imperfections are introduced into

analysis as corresponding horizontal loadings Hi = Vi

• For frames, sway imperfections may be disregarded

• so that their contribution to internal forces is negligible


EdEd VH 15.0

• The structure is assumed with inclination θl, given by:

where: θ0 is the basic value (θ0 = 1/200)

• αh is the reduction factor for height

where l is the total height of the structure in m and

• αm is the reduction factor for number of members:

where m is the number of vertically continuous members in the

storey contributing to the total horizontal forces on the floor.


29

Local imperfections by and LT

• Usually local imperfections are covered in global

analysis through reduction factors and LT

in member checks;

• Unless the frame is sensitive to 2nd order effects

– a member has at least

one moment resistant end joint

– and has simultaneously high slenderness

given in Eurocode 3, eq. 5.8.


Identify the critical load combinations for the ultimate limit state design of the beam

below using fundamental combinations given in Table A1.2(A) (Set A) and Table

A1.2(B) (Set B) of EN 1990. Assume that the beam is subject to permanent loads

(characteristic value: Gk kN/m), imposed loads (characteristic value: Qk kN/m) and a

permanent point load P kN at the end of the cantilever arising from dead loads of the

external wall.

Example 1. Load combination for cantilever beams

30

P

1 2

5. Worked examples

Static equilibrium (EQU) for building structures should be

verified using the design values of actions in Table

A1.2(A) EC0 (Set A).

The fundamental load combination to be used is:

When considering stability (EQU), a distinction between

the favorable and unfavorable effects needs to be made.

, , ,1 ,1 , 0, , 1G j k j Q k Q i i k iG Q Q i

31

5. Worked examples

Annex A1. Application for buildings

32

NA to BS EN 1990:2002

For verifying static

equilibrium for building

structures

5. Worked examples

33

1.10P

1 2

Load case For potential uplift at 1

0.9Gk

1.1Gk+1.5Qk

Equation 6.10 EQU (Set A)

When considering strength (STR) which does not involve geotechnical

actions, the strength of elements should be verified using load

combination Set B (Table A1.2(B) EC0).

Two options are given. Either combination (6.10) from EN 1990 or the

less favourable of equations (6.10a) and (6.10b) may be used.

34

5. Worked examples

35

• In the ‘single source principle’ for permanent actions in EC0, all

permanent actions from one source are assigned the same value of

partial factor in any one load combination. This principle is applied only

to STR and GEO and not to EQU state.

5. Worked examples

36

1.35P

Load case 2. For max reaction at 1

1 2

Load case 1 For max reaction at 2

1.35Gk+1.5Qk

1.35P

1 2

Equation 6.10 STR (Set B)


1.35Gk

1.35Gk+1.5Qk

1.35Gk+1.5Qk

37

1.35P

Load case 4. For max moment at 1-2

1 2

Load case 3. For max moment of cantilever

1.35Gk

1.35Gk+1.5Qk

1.35P

1 2

1.35Gk

1.35Gk+1.5Qk


38

Load case 5. For min positive moment 1-2

1P

1.00Gk +1.5Qk

1.00Gk


Identify the critical load combinations for the ultimate limit state design (STR - Set B)

of the 3-storey frame shown below. Assume that the frame is subjected to

permanent loads (characteristic value: Gk kN/m), imposed loads (characteristic

value: Qk kN/m), and wind load (characteristic value: Wk kN).

39 1 2

Example 2. Leading and accompanying Variable Actions

5. Worked examples

40

1 2

Load case 1(a). Treat the wind

load as leading VAR action

Design for columns (STR - Set B)

1.5Wk

1.5Wk

1.5Wk

1.35Gk+0.7(1.5Qk)

1.35Gk+0.7(1.5Qk)

1.35Gk+0.7(1.5Qk)

Load case 1(b). Treat the

imposed load as leading VAR action

1 2

0.75Wk

0.75Wk

0.75Wk

1.35Gk+ 1.5Qk

1.35Gk+1.5Qk

1.35Gk+1.5Qk

5. Worked examples

41

1 2

0.5(1.5Wk)

0.5(1.5Wk)

0.5(1.5Wk)

1.35Gk+1.5Qk

1.35Gk+1.5Qk

1.35Gk+1.5Qk

1 2

Load case 2(a). Treat the wind

load as leading VAR action

1.5Wk

1.35Gk+0.7(1.5Qk)

Design for columns (STR - Set B)

1.5Wk

1.5Wk

1.35Gk+0.7(1.5Qk)

1.35Gk+0.7(1.5Qk)

Load case 2(b). Treat the

imposed load as leading VAR action

5. Worked examples

42

Design for beams (STR - Set B)

1 2

Load case 3. Treat the imposed

load as dominant load without wind

1.35Gk+1.5Gk

1.35Gk+1.5Gk

1.35Gk+1.5Gk

5. Worked examples

43

• Imperfections for global linear analysis

VEd,1 VEd,2

loading

and

reactions

10000

24000

IPE 550

HE 340 B

12 kN/m'

40 kN 40 kN

imp 1

geometry

and

cross sections

HEd,2 HEd,1

5. Worked examples

Example 3. Horizontal action simulating global imperfections

44

• HEd = 0 i.e. < 0.15 VEd (consider )

• Sway imperfection for global analysis (imp 1):

0029.087.03

2

200

1mh0

10

22

hh

3

2min,h

87.02

115.0

115.0m

m

kN07.18024120029.01imp V

5. Worked examples

45

• Internal forces (loading + imperfections):

MEd [kNm] NEd [kN] VEd [kN]

MEd [kNm] NEd [kN] VEd [kN]

-374,6 387,1

-483,2 -183,5 -184,5

-38,7

-37,5 38,7

143,5 -483,2

144,5

5. Worked examples

46

• Local imperfections for global analysis only if simultaneously

(column concerned):

- exists moment resistant end joint: OK

- slenderness

In this case,

• Thus, local imperfections can be ignored in global analysis

and to be considered by factors and LT .

332105184

235170905050

3Ed

y,

.,

N

fA,

73.09.93

5.146/10000

1

y

5. Worked examples

Variable actions: leading and accompanying actions

Failure mode: EQU,STR, GEO and STR/GEO

Either Equation 6.10, OR 6.10(a) and 6.10(b) for STR

Persistent/Transient/Accidental/Seismic design situations

Imperfections significantly influence strength of structures

In general, need to introduce horizontal actions to simulate

equivalent geometrical imperfections in frames

Global and local imperfections should be considered

47

6. Summary

Thank You for your attention!

48

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