CEN/TS 19103:2021

SLOVENSKI STANDARD
01-februar-2022
Evrokod 5: Projektiranje lesenih konstrukcij - Projektiranje sovprežnih konstrukcij
iz lesa in betona - Splošna pravila in pravila za stavbe
Eurocode 5: Design of Timber Structures - Structural design of timber-concrete
composite structures - Common rules and rules for buildings
Eurocode 5: Berechnung und Konstruktion von Holzbauten - Bemessung und
Berechnung von Holz-Beton-Verbundbauteilen - Allgemeine Regeln und Regeln für den
Hochbau
Eurocode 5 : Conception et calcul des structures en bois - Calcul des structures mixtes
bois-béton - Règles communes et règles pour les bâtiments
Ta slovenski standard je istoveten z: CEN/TS 19103:2021
ICS:
91.010.30 Tehnični vidiki Technical aspects
91.080.20 Lesene konstrukcije Timber structures
91.080.40 Betonske konstrukcije Concrete structures
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CEN/TS 19103
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
November 2021
TECHNISCHE SPEZIFIKATION
ICS 91.010.30; 91.080.40
English Version
Eurocode 5: Design of Timber Structures - Structural
design of timber-concrete composite structures - Common
rules and rules for buildings
Eurocode 5 : Conception et calcul des structures en Eurocode 5: Berechnung und Konstruktion von
bois - Calcul des structures mixtes bois-béton - Règles Holzbauten - Bemessung und Berechnung von Holz-
communes et règles pour les bâtiments Beton-Verbundbauteilen - Allgemeine Regeln und
Regeln für den Hochbau
This Technical Specification (CEN/TS) was approved by CEN on 25 July 2021 for provisional application.

The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to
submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard.

CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS
available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in
parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 19103:2021 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
0 Introduction . 5
1 Scope . 7
1.1 Scope of CEN/TS 19103 . 7
1.2 Assumptions . 7
2 Normative references . 7
3 Terms, definitions and symbols . 8
3.1 Terms and definitions . 8
3.2 Symbols and abbreviations . 9
4 Basis of design .15
4.1 General rules .15
4.2 Principles of limit state design .15
4.3 Basic variables .16
4.4 Verification using the partial factor method .21
5 Materials .22
5.1 Quasi-constant environmental conditions .22
5.2 Variable environmental conditions.23
6 Durability .23
6.1 General .23
6.2 Timber decking for composite slabs in buildings .23
6.3 Resistance to corrosion .23
7 Structural analysis .24
7.1 Modelling of the composite structure .24
7.2 Propping .28
8 Ultimate limit states .28
8.1 General .28
8.2 Beams and slabs – Verification of cross-sections .28
8.3 Walls .33
9 Serviceability limit states .33
9.1 General .33
9.2 Deflection .33
9.3 Vibration .34
9.4 Cracking of concrete .34
10 Connections .36
10.1 General .36
10.2 Mechanical properties obtained from test .36
10.3 Mechanical properties determined according to this Technical Specification .36
10.4 Detailing .43
11 Detailing and execution .43
11.1 General .43
11.2 Detailing of the cross-section.44
11.3 Detailing of the shear connection and influence of execution .44
Annex A (informative) Yearly variations of moisture content averaged over the timber
cross-section for timber-concrete composite structures under variable
environmental conditions . 46
A.1 Use of this Annex . 46
A.2 Scope and field of application . 46
A.3 Yearly variations of timber moisture content . 46
Annex B (informative) Calculation of the effect of inelastic strains . 49
B.1 Use of this Annex . 49
B.2 Scope and field of application . 49
B.3 Effective bending stiffness . 50
B.4 Bending moment in the concrete slab (sub. 1) and the timber beam (sub. 2) . 52
B.5 Axial forces . 52
B.6 Shear force in the connection due to shrinkage . 53
Annex C (informative) Experimental determination of the load-carrying capacity and
stiffness of timber to concrete connections . 55
C.1 Use of this Annex . 55
C.2 Scope and field of application . 55
C.3 Specimen configuration . 55
C.4 Testing protocol . 56
C.5 Determination of mechanical properties . 57
Bibliography . 58

European foreword
This document (CEN/TS 19103:2021) has been prepared by Technical Committee CEN/TC 250
“Structural Eurocodes”, the secretariat of which is held by BSI. CEN/TC 250 is responsible for all
Structural Eurocodes and has been assigned responsibility for structural and geotechnical design matters
by CEN.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under Mandate M/515 issued to CEN by the European Commission
and the European Free Trade Association.
This document has been drafted to be used in conjunction with relevant execution, material, product and
test standards, and to identify requirements for execution, materials, products and testing that are relied
upon by this document.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United
Kingdom.
0 Introduction
0.1 Introduction to the Eurocodes
The Structural Eurocodes comprise the following standards generally consisting of a number of parts:
— 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 aluminium structures;
— New Eurocodes under development.
0.2 Introduction to EN 1995 (all parts)
(1) EN 1995 (all parts) applies to the design of buildings and civil engineering works in timber (solid
timber, sawn, planed or in pole form, glued laminated timber or wood-based structural products, e.g.
LVL) or wood-based panels jointed together with adhesives or mechanical fasteners. It complies with the
principles and requirements for the safety and serviceability of structures and the basis of design and
verification given in EN 1990.
(2) EN 1995 (all parts) is concerned only with requirements for mechanical resistance, serviceability,
durability and fire resistance of timber structures. Other requirements concerning thermal or sound
insulation, for example, are not considered.
(3) EN 1995 (all parts) is subdivided into various parts:
— EN 1995-1 General;
— EN 1995-2 Bridges.
(4) EN 1995-1 “General” in itself does not exist as a physical document, but comprises the following two
separate parts:
— EN 1995-1-1 General – Common rules and rules for buildings;
— EN 1995-1-2 General – Structural fire design.
EN 1995-2 refers to the General rules in EN 1995-1-1.
This document supplements EN 1995.
0.3 Verb forms used in this Technical Specification
The verb “shall” expresses a requirement strictly to be followed and from which no deviation is permitted
in order to comply with the Eurocodes.
The verb “should” expresses a highly recommended choice or course of action. Subject to national
regulation and/or any relevant contractual provisions, alternative approaches may be used/adopted
where technically justified.
The verb "may” expresses a course of action permissible within the limits of the Eurocodes.
The verb “can” expresses possibility and capability; it is used for statements of fact and clarification of
concepts.
0.4 National annex for CEN/TS 19103
This document provides values within notes, indicating where national choices can be made. Therefore,
a national document implementing CEN/TS 19103 can have a National Annex containing all Nationally
Determined Parameters to be used for the assessment of buildings and civil engineering works in the
relevant country.
National choice is allowed in CEN/TS 19103 through the following subclauses:
• 4.3.1.2(5)   Average timber moisture content due to the environmental conditions
• 4.4.1.1  Partial factor for shrinkage action
• 4.4.1.2  Partial factor for temperature action
• 4.4.1.2  Partial factor for moisture content action
• 4.4.2    Partial factor for connection shear strength
National choice is allowed in CEN/TS 19103 on the application of the following informative annexes:
• Annex A  Yearly variations of moisture content averaged over the timber cross-section for timber-
concrete composite structures in variable environmental conditions
The National Annex can contain, directly or by reference, non-contradictory complementary information
for ease of implementation, provided it does not alter any provisions of the Eurocodes.
1 Scope
1.1 Scope of CEN/TS 19103
(1) CEN/TS 19103 gives general design rules for timber-concrete composite structures.
(2) It provides requirements for materials, design parameters, connections, detailing and execution for
timber-concrete composite structures. Recommendations for environmental parameters (temperature
and moisture content), design methods and test methods are given in the Annexes.
(3) It includes rules common to many types of timber-concrete composite, but does not include details
for the design of glued timber-concrete composites, nor for bridges.
NOTE For the design of glued timber-concrete composites or bridges alternative references are available.
(4) It covers the design of timber-concrete composite structures in both quasi-constant and variable
environmental conditions. For ease of use, it provides simple design rules for quasi-constant
environmental conditions and more complex rules for variable environmental conditions.
1.2 Assumptions
(1) The general assumptions of EN 1990 apply.
(2) CEN/TS 19103 is intended to be used in conjunction with EN 1990, EN 1991 (all parts), EN 1992 (all
parts), EN 1994 (all parts), EN 1995 (all parts), EN 1998 (all parts) when timber structures are built in
seismic regions, and ENs for construction products relevant to timber structures.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
NOTE See the Bibliography for a list of other documents cited that are not normative references, including
those referenced as recommendations (i.e. in ‘should’ clauses), permissions (‘may’ clauses), possibilities ('can'
clauses), and in notes.
1)
EN 1990:2002 , Eurocode - Basis of structural design
EN 1991 (all parts), Eurocode 1: Actions on structures
EN 1991-1-5:2003, Eurocode 1: Actions on structures - Part 1-5: General actions - Thermal actions
2)
EN 1992-1-1:2004 , Eurocode 2: Design of concrete structures - Part 1-1: General rules and rules for
buildings
EN 1993-1-8, Eurocode 3: Design of steel structures - Part 1-8: Design of joints
EN 1994-1-1:2004, Eurocode 4: Design of composite steel and concrete structures - Part 1-1: General rules
and rules for buildings
1) As impacted by EN 1990:2002/A1:2005.
2) As impacted by EN 1992-1-1:2004/A1:2014.
EN 1994-2:2005, Eurocode 4 - Design of composite steel and concrete structures - Part 2: General rules and
rules for bridges
3)
EN 1995-1-1:2004 , Eurocode 5: Design of timber structures - Part 1-1: General - Common rules and rules
for buildings
EN 14592, Timber structures - Dowel-type fasteners - Requirements
3 Terms, definitions and symbols
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 1990, EN 1995-1-1 and the
following apply.
3.1.1
continuous fastener
fastener that is continuous along the length of the timber component
3.1.2
connection
any device or system formed of connected parts and an associated fastener or fasteners as well as, where
applicable, notches, which resists slip and transfers the related shear force at the interface between
timber and concrete
Note 1 to entry: Examples include dowel-type fasteners of any material, notches, plates and continuous fasteners,
any of which can be either mechanically fixed or bonded.
Note 2 to entry: Staples fall beyond the scope of this standard.
3.1.3
inelastic strain
strain which is caused not by stresses but by shrinkage, swelling or thermal expansion, for example
3.1.4
moisture content
mass of water in wood, expressed as a percentage of its oven-dry mass
3.1.5
quasi-constant environmental conditions
environmental conditions where
— timber is installed close to its expected moisture content in use mc and
use
— for softwood timber, the variation of average moisture content in use (Δmc, see Formula (4.5)) does
not exceed 6 % and
— the temperature variations of the air do not exceed 20 °C
Note 1 to entry: The indoor conditions of a heated building are a typical example of quasi-constant conditions.

3) As impacted by EN 1995-1-1:2004/A1:2008 and EN 1995-1-1:2004/A2:2014.
3.1.6
shrinkage of concrete
decrease in dimension of a piece of concrete due to the hardening process
3.1.7
shrinkage of timber
decrease in dimension of a piece of timber due to reduction of moisture content
3.1.8
swelling of timber
increase in dimension of a piece of timber due to increase of moisture content
3.1.9
thermal expansion
linear thermal expansion between given temperatures
3.1.10
variable environmental conditions
conditions that do not comply with quasi-constant environmental conditions
Note 1 to entry: Typical examples where variable environmental conditions can be experienced are balconies,
unheated roof spaces and outdoor covered and uncovered spaces.
3.2 Symbols and abbreviations
For the purposes of this document, the symbols given in EN 1995-1-1 and the following apply.
Latin upper-case letters
A Area of cross-section 1
A Area of cross-section 2
A Area of longitudinal reinforcement in concrete flange
b
A Effective area of the concrete cross-section
conc,ef
A Area of longitudinal reinforcement in concrete flange
s
A
Area of transverse reinforcement in concrete flange
sf
A Area of the timber cross-section
tim
C
Coefficient which considers the interaction between vertical load q and inelastic
d
J,sls
strains in terms of slip in the joint
C Coefficient which correlates the inelastic strains with a fictitious load
p,sls
E Modulus of elasticity of cross-section 1
E Modulus of elasticity of cross-section 2
E Modulus of elasticity of concrete
conc
E Effective long-term modulus of elasticity of concrete
conc,fin
E Characteristic combination of actions
k
E Quasi-permanent combination of actions
q,per
E Fundamental combination of actions
u
E Design value of the modulus of elasticity of the steel reinforcement as given in
s
EN 1992-1-1:2004, 3.2.7
E Mean modulus of elasticity of timber parallel to the grain
tim
E Effective long-term modulus of elasticity of timber parallel to the grain
tim,fin
(EI) Bending stiffness of the cross-section i
i
(EI) Effective bending stiffness according to EN 1995-1-1:2004, Annex B
ef,EC5-AnnexB
(EI) Modified effective bending stiffness according to EN 1995-1-1:2004, Annex B,
ef,sls
which accounts for the interaction between vertical load and inelastic strains
F Characteristic axial withdrawal capacity of the fastener
ax,Rk
F
Estimated load-carrying capacity as defined in accordance with EN 26891 and
est
used in determining the mean slip modulus for ultimate limit states
F Characteristic load-carrying capacity in an Annex C test, as determined in
max
accordance with EN 26891
F Design load-carrying capacity for a notched connection
Rd
F Design tensile force between the timber and the concrete cross-section
t,Ed
F Design shear force per connection
v,Ed
F
Design load-carrying capacity per connection
v,Rd
F Characteristic connection shear strength
v,Rk
F Characteristic load-carrying capacity in shear per connection at time t
c
v,R,t ,k
c
I Moment of inertia of cross-section 1
I Moment of inertia of cross-section 2
I Moment of inertia of the timber cross-section
tim
K Stiffness of the connection
K
Maximum stiffness of the connection
max
K Minimum stiffness of the connection
min
K
Reference stiffness of connection
ref
K Slip modulus for serviceability limit states
ser
K Final slip modulus
ser,fin
K Mean slip modulus for serviceability at time t
c
ser,t
c
K Instantaneous slip modulus of the connection for ultimate limit states
u
K Final slip modulus for ultimate limit states
u,fin
K Slip modulus for ultimate limit states at time t
c
u,t
c
L Span of the beam
M(q + 0.8p ) Resulting bending moment due to external loads and part (80 %) of the fictitious
d sls
load equivalent to inelastic strains
M(q ) Resulting bending moment due to external load only
d
M Bending moment of component i
i
M Maximum bending moment in cross-section 2
max,2
M Bending moment in the timber cross-section
tim
N Axial force in cross-section i
i
N
Maximum axial force in cross-section 2
max,2
N Axial force in the timber cross-section
tim
T Initial average temperature in the concrete at time t
c
0,conc
T Initial average temperature in the timber at time t
c
0,tim
T Maximum temperature in the concrete (averaged over the cross-section)
max,conc
T Maximum temperature in the timber (averaged over the cross-section)
max,tim
T Minimum temperature in the concrete (averaged over the cross-section)
min,conc
T Minimum temperature in the timber (averaged over the cross-section)
min,tim
V Effective maximum shear force
max
V(q ) Resulting shear force due to external load
d
V
Ultimate slip determined in an Annex C test in accordance with EN 12512
u
X Design value of a strength property of timber or a wood-based product
d
Latin lower-case letters
a Distance
a spacing of fasteners parallel to the grain
a Distance from the centroid of cross-section 1 to the centroid of the effective
1↔c
composite cross-section
a Distance between the fastener and the unloaded edge
3c
a Distance between the fastener and the loaded edge
3t
a spacing of fasteners perpendicular to the grain
a Cross-sectional area of the transverse reinforcement of the concrete flange when
s
checking in-plane shear in the concrete
a Cross-sectional area of the longitudinal reinforcement of the concrete flange when
b
checking in-plane shear in the concrete
b Width of the concrete
conc
b Effective width of the concrete
conc,ef
b Notch width
n
b Width of the timber
tim
b Width of the timber element (in verification of concrete for in-plane shear)
w
c Minimum concrete cover for durability of steel reinforcement
min,dur
c Nominal concrete cover
nom
d Fastener diameter or rebar diameter
d Diameter of the aggregate
g
d Diameter of the concrete reinforcement bar diameter
r
f Design value of the compressive strength of concrete
cd
f Characteristic compressive cylinder strength of the concrete at 28 days
ck
f Design value of the tensile strength of concrete
ctd
f characteristic embedment strength of the concrete member for evaluation of the
c,h,2,k
load-carrying capacity based on the Johansen models
f
Effective design shear strength for the concrete
vcd
f Design shear strength of the timber member
v,t,d
f Design value of the yield strength of steel reinforcement
yd
h Nominal height of the connector
s,conn
h Thickness of the concrete flange
f
h Notch depth
n
k Deformation factor of timber
def
k ' Deformation factor for connections between concrete and timber
def
k Modification factor for duration of load and moisture content for timber strength
mod
k ' Modification factor for duration of load and moisture content for the strength of
mod
connections between concrete and timber
k Mean slip modulus for serviceability limit states, determined from Annex C tests in
s
accordance with EN 26891
k Coefficient for concrete, taking into account the effect of high sustained loads on
tc
compressive strength
l Notch length
n
l Distance between notches
s
l Length of timber in front of the notch
v
mc Moisture content of timber (averaged over the timber cross-section)
mc Moisture content of timber at time t
c
mc Maximum moisture content of timber during annual cycles
max
mc Minimum moisture content of timber during annual cycles
min
mc Expected moisture content of timber in use (mean over the year, averaged over the
use
timber cross-section)
mc Variation in moisture content over an annual cycle
var
p Fictitious vertical load which represents the effects of inelastic strains on the
sls
structure
s Effective spacing of the connections
ef
s
Spacing of the transverse reinforcement bars in the concrete slab when checking in-
f
plane actions in the concrete
s Longitudinal spacing of the fasteners when checking in-plane shear in the concrete
l
s Maximum spacing of the connections
max
s Minimum spacing of the connections
min
s Transverse spacing of the fasteners when checking in-plane shear in the concrete
t
t
A point in time
t The time when the concrete achieves the design strength or the time when the design-
imposed load is applied to the composite structure, whichever is the earlier
t Time for design for long-term condition
∞
t Time according to EN 13670:2009, 8.5(6) when curing and protection of the concrete
c
are complete
t Time of removal of props
p
t
Age of concrete at which drying shrinkage begins according to EN 1992-1-1:2004,
s
3.1.4(6)
q Design value of the external loads
d
u Mean ultimate slip
u,tc
w Crack width in concrete
k
w Recommended maximum crack width in concrete EN 1992-1-1:2004, Table 7.1N
max
z Distance between the centres of gravity of the cross-sections
Greek upper-case letters
ΔF Design longitudinal shear over a certain length of beam in verification of concrete for
d
in-plane shear (including diaphragm actions)
Δmc Total change over the annual cycle of the average timber moisture content due to
environmental conditions
-
Reduction in average moisture content in timber over the annual cycle with respect
Δmc
to the expected moisture content in use mc
use
+
Increase in average moisture content in timber over the annual cycle with respect to
Δmc
the expected moisture content in use mc
use
Δmc Timber moisture content variation (averaged over the timber cross-section) to be
calc
considered in the design
Δmc Difference between the average timber moisture content in use mc and the average
use
d
value mc at time t
0 c
ΔT Non-linear temperature difference component of the composite section
E
ΔT Temperature difference component about the z-z axis, with linear variation
MY
ΔT Temperature difference component about the y-y axis, with linear variation
MZ
Change in the average temperature of the concrete in the composite section from
-
ΔT
u,conc
initial to minimum
Change in the average temperature of the concrete in the composite section from
+
ΔT
u,conc
initial to maximum
ΔT Temperature variation of the cross-section i (1 or 2) to be considered in the design
u,i,calc
Change in the average temperature of the timber in the composite section from initial
-
ΔT
u,tim
to minimum
+ Change in the average temperature of the timber in the composite section from initial
ΔT
u,tim
to maximum
Δε Difference in inelastic strain between the timber part and the concrete part
Δx Length under consideration in verification of concrete for in-plane shear (including
diaphragm actions)
Greek lower-case letters
α Angle of a notch
α Coefficient of linear thermal expansion of concrete
c,T
α Coefficient of thermal expansion of the cross-section i
i,T
α Coefficient of linear moisture expansion of timber parallel to the grain
t,u
α Coefficient of linear thermal expansion of timber parallel to the grain
t,T
γ Composite factor of the concrete cross-section
γ Partial factor for shrinkage action
SH
γ
Partial factor for thermal action
T
γ Partial factor for moisture content action
u
γ Partial factor for connection shear strength
v
ε Shrinkage of concrete according to EN 1992-1-1:2004
conc
ε Effective shrinkage of concrete
ef,conc
ε Inelastic strain of the cross-section
i
Angle of the concrete strut
θ
ν
Strength reduction factor for concrete cracked in shear
ρ Mean value of timber member density
m
σ
Design compressive stress in the concrete member, caused by axial force and bending
conc,c,d
σ Design tensile stress in the concrete member, caused by axial force and bending
conc,t,d
τ Design longitudinal shear stress for verification of concrete for in-plane shear
Ed
φ Creep coefficient of the concrete
ψ Factor for combination value of yearly variations of average timber moisture content
0,mc
ψ Factor for frequent value of yearly variations of average timber moisture content
1,mc
ψ Factor for quasi-permanent value of average timber moisture content variations
2,mc
ψ Coefficient for the effect of composite action on the creep coefficient of the concrete
conc
cross-section
ψ Coefficient for the effect of composite action on the creep coefficient of the connection
conn
ψ Coefficient for the effect of composite action on the creep coefficient of the timber
tim
cross-section
4 Basis of design
4.1 General rules
(1) The design of timber-concrete composite structures shall be in accordance with the general rules
stated in EN 1990 and the supplementary provisions for timber-concrete composite structures stated in
this document.
(2) The basic requirements of EN 1990:2002, Clause 2, are deemed to be satisfied for timber-concrete
composite structures when all the following are applied:
— Limit state design in conjunction with the partial factor method in accordance with EN 1990;
— Actions in accordance with EN 1991 (all parts);
— Action combinations in accordance with EN 1990;
— Resistances, durability and serviceability in accordance with this standard, EN 1992-1-1,
EN 1994-1-1 and EN 1995-1-1.
4.2 Principles of limit state design
(1) In addition to the general principles stated in EN 1995-1-1:2004, 2.2 the effects of construction
sequence and changes of environmental conditions should be considered where relevant for the design.
NOTE Refer to 4.3.1.2 for the effect of changes of environmental conditions, where relevant.
(2) Due to the different creep behaviours of the concrete, the timber and the connection system, the final
long-term stress distribution in the composite structure at ultimate limit state, due to the fundamental
combination of actions E , should be calculated by superimposing:
u
— the stress distribution in the long-term due to the quasi-permanent combination of actions E
q,per
calculated using the effective moduli of elasticity of concrete and timber and the
E E
conc,fin tim,fin
effective slip modulus of the connection K (refer to 4.3.2(7))
u,fin
and
— the instantaneous stress distribution due to the difference between the fundamental combination of
actions E and the quasi-permanent combination of actions E , calculated using the moduli of
u qper
elasticity of concrete E and timber E and the slip modulus of the connection K .
conc tim u
(3) Due to the different creep behaviours of the concrete, the timber and the connection system, the final
deformation of the composite structure at serviceability limit state, due to the characteristic combination
of actions E , should be calculated by superimposing:
k
— the total deformation in the long-term due to the quasi-permanent combination of actions E
q,per
calculated using the effective moduli of elasticity of concrete E and timber E and the
conc,fin tim,fin
effective slip modulus of the connection K (refer to 4.3.2(7))
ser,fin
and
— the instantaneous deformation due to the difference between the characteristic combination of
actions E and the quasi-permanent combination of actions E , calculated using the moduli of
k qper
E E K
elasticity of concrete and timber and the slip modulus of the connection .
conc tim ser
4.3 Basic variables
4.3.1 Actions and environmental influences
4.3.1.1 General – Quasi-constant environmental conditions
(1) Actions to be used in design shall be obtained from the relevant parts of EN 1991.
(2) Duration of load and moisture content should be taken into account in the design for mechanical
resistance and serviceability in accordance with EN 1995-1-1 and in accordance with this document.
NOTE Duration of load and moisture content affect the strength and stiffness properties of timber as well as
the strength and stiffness properties of the connection between timber and concrete.
(3) Shrinkage of concrete should be considered in design for verification of both the ultimate limit state
and the serviceability limit state. For timber-concrete composite structures with a cast-in-situ concrete
slab, the shrinkage of concrete should be calculated from the time of concrete curing t , irrespective of
c
whether the timber member is propped or not.
NOTE The calculation of the effects of concrete shrinkage is given in Annex B. Concrete shrinkage is regarded
as an inelastic strain applied to the timber-concrete composite structure.
(4) The increase in moisture content of the timber due to casting may be disregarded (see 11.1 (3)).
4.3.1.2 General – Variable environmental conditions
(1) In variable environmental conditions, the provisions given in 4.3.1.2 shall apply in addition to the
provisions in 4.3.1.1.
(2) Due to the different linear expansion coefficients of timber and concrete, temperature differences
should be considered for verifications of both the ultimate limit state and the serviceability limit state. In
most cases, only the variations of the uniform temperature component in the concrete (ΔT ) and the
u,conc
timber ( ), as defined in Clause 4(3) of EN 1991-1-5:2003, need to be considered. The effects of the
ΔT
u,tim
linear and non-linear temperature difference components of the composite section (ΔT , ΔT and ΔT ),
MY MZ E
as defined in 4(3) of EN 1991-1-5:2003, may be neglected.
(3) The maximum and minimum temperature differences in the concrete and timber should be
calculated using Formulae (4.1) to (4.4):
+
∆=TT −T (4.1)
u,conc max,conc 0,conc
+
∆=TT −T (4.2)
u,tim max,tim 0,tim
and
−
∆TT= −T (4.3)
u,conc min,conc 0,conc
−
∆=TT −T (4.4)
u,tim min,tim 0,tim
where
+
is the change in the average temperature of the concrete in the composite section from
∆T
u,conc
initial to maximum;
is the maximum value of the average temperature in the concrete (refer to EN 1991-1-
T
max,conc
5:2003, Clause 5);
is the initial average temperature in the concrete at time t when the concrete has been
T c
0,conc
cured;
+
is the change in the average temperature of the timber in the composite section from
∆T
u,tim
initial to maximum;
is the maximum value of the average temperature in the timber (refer to EN 1991-1-
T
max,tim
5:2003, Clause 5);
is the initial average temperature in the timber at time t when the concrete has been
c
T
0,tim
cured;
NOTE If the initial temperatures when the structure is erected are unknown, reference can be made to
EN 1991-1-5:2003, Annex A.
−
is the change in the average temperature of the concrete in the composite section from
∆T
u,conc
initial to minimum;
is the minimum value of the average temperature in the concrete (refer to

T
min,conc
EN 1991-1-5:2003, Clause 5);
−
is the change in the average temperature of the timber in the composite section from
∆T
u,tim
initial to minimum;
is the minimum value of the average temperature in the timber (refer to
T
min,tim
EN 1991-1-5:2003, Clause 5).
(4) Shrinkage/swelling of timber in the longitudinal direction due to reductions/increases in moisture
content should be considered in design for verification of both the ultimate limit state and the
serviceability limit state. In general, shrinkage/swelling of the timber should be calculated by considering
only the variation over time of moisture content, averaged over the timber cross-section.
(5) When the timber is conditioned (see EN 1995-1-1:2004, 10.2) to the expected moisture content in
use mc , the annual variation of the average timber moisture content due to the environmental
use
conditions Δmc (see Formula (4.5)) should be taken into account:
+ -
— The increase (Δmc = Δmc/2 > 0) and the decrease Δmc = Δmc/2 < 0) with respect to the expected
moisture content in use mc should be considered.
use
NOTE 1 Guidance for the evaluation of the variation Δmc is given in Annex A.
Δmc mc− mc (4.5)
max min
where
is the maximum annual average timber moisture content;
mc
max
is the minimum annual average timber moisture content.
mc
min
— For structures in Europe, moisture content variations should be considered with a sign opposite to
that of the temperature variations
− −
+
NOTE 2 Δmc > 0; ΔT < 0 and ΔT < 0
u,conc u,tim
and
+ +
-
Δmc < 0; ΔT > 0 and ΔT > 0.
u,conc u,tim
mc
(6) When timber is not conditioned to the expected moisture content in use , in addition to
use
4.3.1.2(5), the difference between the average timber moisture content due to the environmental
conditions in use mc and the average value mc at the time t when the concrete was cured should
use 0 c
also be considered in design.
NOTE Annex B Formulae provide a method for calculation of the effects of temperature differences and
shrinkage/swelling of timber. In these Formulae, temperature difference, shrinkage of concrete and
shrinkage/swelling of timber are inelastic strains applied to the timber-concrete composite structure.
=
4.3.1.3 Load duration classes – Quasi-constant environmental conditions
(1) The load duration classes according to EN 1995-1-1 shall apply.
(2) The effect of concrete shrinkage on the timber-co
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