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Eurocode Actions
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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
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
1. National Implementation and Annex
4
EC0
EC1
EC2
EC3
EC4
EC5
EC6
EC7
EC8
EC9
Linkage between the Eurocodes
1. National Implementation and Annex
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
1. National Implementation and Annex
Codes that relate to actions
1. National Implementation and Annex
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
UK National Annex for EC1
UK National Annex for EC0
NA to SS EN 1990:2008
Singapore National Annex for EC0
NA to SS EN 1991-1.1:2008
Singapore National Annex for EC1
NA to SS EN 1993-1.1:2008
Singapore National Annex for EC3
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.
1. National Implementation and Annex
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.
3. Load combinations
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
3. Load combinations
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)
3. Load combinations
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);
3. Load combinations
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
3. Load combinations
23
3. Load combinations
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
3. Load combinations
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 ±
4. Global imperfections
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
4. Global 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
4. Global imperfections
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.
4. Global imperfections
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.
4. Global imperfections
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)
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
Equation 6.10 STR (Set B)
38
Load case 5. For min positive moment 1-2
1P
1.00Gk +1.5Qk
1.00Gk
Equation 6.10 STR (Set B)
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