Terms, Definitions and Symbols

​

3.1 Terms and definitions

For the purposes of this document, the terms and definitions given in EN 1990 and the following apply.

​

3.1.1

​

anchoring mortar

mortar based on organic or inorganic binder, or a mixture of these, installed at a fluid or paste consistency with the aim to anchor reinforcing steel bars in a drilled hole in concrete structures and to transfer the axial forces in the reinforcing steel bar to the concrete structure

​

3.1.2

​

beam

linear member subject primarily to flexure and shear with cross-section width not exceeding 4 times its cross-section depth (otherwise it should be considered as a slab) and an effective span of not less than 3 times the cross-section depth

​

3.1.3

​

biaxial bending

simultaneous bending about two principal axes

​

3.1.4

​

braced members or systems

structural members or subsystems, which in analysis and design are assumed to be stabilised by bracing members and hence, not contributing to the overall horizontal stability of a structure Note 1 to entry: Unbraced members are not stabilized by bracing members.

​

3.1.5

​

bracing members or systems

structural members or subsystems, which in analysis and design are assumed to contribute to the overall horizontal stability of a structure

​

3.1.6

​

buckling

failure due to instability of a member or structure under compression buckling or flexural buckling

​

3.1.7

​

buckling load

load at which buckling occurs; for isolated elastic members, it is synonymous with the Euler load

​

3.1.8

​

carbon steel

weldable non-alloy reinforcing steel

​

3.1.9

​

chord

compression or tension part of a member idealised as having a narrow width and which interacts with adjacent membrane elements through longitudinal shear

​

3.1.10

​

column

linear member subjected primarily to axial compression forces, with cross-section width not exceeding 4 times its cross-section depth (otherwise it should be considered as a wall) and the length is at least 3 times the cross-section depth

​

3.1.11

​

compression field

region of a stress field where concrete is subjected to uniaxial compressive stresses

​

3.1.12

​

confinement reinforcement

reinforcement which can increase the uniaxial concrete compressive strength and the deformation capacity through the favourable effect of transverse compressive stresses or can reduce the required anchorage length by preventing cover spalling Note 1 to entry: It can consist of stirrups, links, U-bars, headed bars or hoops placed perpendicular or at an angle to the axis of the member. Note 2 to entry: Confinement reinforcement can reduce the design anchorage length if it is anchored into the body of the section.

​

3.1.13

​

couplers

steel reinforcement products used for the mechanical splicing of steel reinforcing bars

​

3.1.14

​

cover, concrete

distance between the surface of a reinforcement bar or tendon (including links and stirrups and surface reinforcement where relevant) and the nearest concrete surface

​

3.1.15

​

cover, minimum

minimum value of the concrete cover provided in order to ensure (i) safe transmission of bond forces, (ii) protection of the steel against corrosion (durability)

​

3.1.16

​

cover, nominal

specified value of the concrete cover defined as a minimum cover plus an allowance in design for deviation

​

20

​

3.1.17

​

crack formation phase

phase of the cracking process which occurs when stresses exceed the cracking resistance and in which the full crack pattern is not yet developed, typically it is the type of cracking due to imposed deformations with large crack spacings, and for which an increase in the imposed strain will not increase crack width but instead it will form new cracks

​

3.1.18 crack width, calculated

calculated crack width at surface of member

​

3.1.19

​

creep, basic

creep occurring in concrete when there is no moisture transfer with the surrounding environment

​

3.1.20

​

creep, drying

creep, additional to basic creep, occurring in concrete when there is moisture transfer with the surrounding environment, the total creep is the sum of basic and drying creep

​

3.1.21

​

deep beam

beam for which the effective span $l_{\text {eff }}$ is less than 3 times the overall cross-section depth $h$

​

3.1.22

​

deformation capacity

ability of a member or part of it or a structure to deform while maintaining its resistance

​

3.1.23

​

damp patch

area which, when touched, might leave a light film of moisture on the hand but no droplets of water (i.e. beading)

​

3.1.24

​

diaphragm

planar member able to resist in-plane forces

​

3.1.25

​

effective tension area

concrete area in tension around reinforcement within which the crack opening is effectively controlled by the reinforcement (area of concrete that needs to be subject to tension up to the tensile resistance of concrete to produce a new crack)

​

3.1.26

​

effective depth

in a cross-section, distance from the extreme compression fibre to the centroid of the resultant force of the longitudinal tension reinforcement

​

3.1.27

​

effective length

length used to account for the shape of the deflection curve; it can also be defined as buckling length, i.e. the length of a pin-ended column with constant axial force, having the same cross-section and buckling load as the actual member

​

3.1.28

​

European Technical Product Specification

• European Product Standard (EN), or
• European Technical Assessment (ETA) based on a European Assessment Document (EAD), or
• product documentation based on a transparent and reproducible assessment that complies with all requirements of the relevant EAD

​

3.1.29

​

execution specification

document covering all drawings, technical data and requirements necessary for the execution of a particular project

​

3.1.30

​

exposure resistance classes

classes for defining the resistance of concrete against corrosion induced by carbonation (XRC) or by chlorides (XRDS) and damage caused by freeze/thaw attack (XRF)

​

3.1.31

​

external tendon

tendon external to the concrete, either within the depth of the cross-section or on the surface of the crosssection

​

3.1.32

​

first order effects

action effects calculated without consideration of the effect of structural deformations, but including geometric imperfections

​

3.1.33

​

flat slab

slab supported directly by columns, can be solid, ribbed or waffle

​

3.1.34

​

general anchorage zone

zone in which the tendon force is dispersed over the member cross-section until a linear stress distribution may be assumed

​

3.1.35

​

headed bar

reinforcing bar with head attached at one or both ends

​

3.1.36

​

hook

end part of a reinforcement, bent at not less than $135^{\circ}$

​

3.1.37

​

hoop

closed reinforcement or spiral reinforcement enclosing longitudinal reinforcement in compression members

​

3.1.38

​

indented reinforcement

reinforcing steel with at least two rows of indentations, which are uniformly distributed over the entire length

​

3.1.39

​

internal force

resultant of stresses in cross-section of a member (axial force, shear force, bending moment, torsion)

​

3.1.40

​

internal tendon

tendon which is placed inside the concrete either with bond or without bond to the concrete

​

3.1.41

​

isolated member

member for which no load redistribution to adjacent members is possible

​

3.1.42

​

isolated precast element

precast element for which no load redistribution to adjacent members is possible

​

3.1.43

​

lattice girder

two dimensional or three dimensional metallic structure comprising an upper chord, one or more lower chords and continuous or discontinuous diagonals which are welded or mechanically connected to the chords

​

3.1.44

​

lightweight aggregate concrete

concrete having a closed structure and an oven-dry density of not less than $800 \mathrm{~kg} / \mathrm{m}^{3}$ and not more than $2000 \mathrm{~kg} / \mathrm{m}^{3}$, consisting of or containing a proportion of artificial or natural lightweight aggregates having a particle dry density of less than $2000 \mathrm{~kg} / \mathrm{m}^{3}$

​

3.1.45

​

linear member

structural element, straight or curved, with one dimension significantly larger than the others (such as beams and columns)

​

3.1.46

​

link

reinforcement bent to form single or multiple legs that surrounds longitudinal reinforcement, if provided in the form of links these can be closed or open with sufficient anchorage at their ends Note 1 to entry: See also “Stirrup” which has a similar definition as “Link”, but does not include single leg Z- or C -shaped reinforcement.

​

3.1.47

​

local anchorage zone

zone in the immediate vicinity of the tendon anchorage or coupling device in which the tendon force is transmitted from the anchorage or coupling device to the concrete

​

3.1.48

​

loop

U-shaped reinforcement where both legs transmit their forces to other reinforcement or to concrete through bond

​

3.1.49

​

main reinforcement

in one-way slabs, the bending reinforcement placed in the direction perpendicular to the supports, in other members the longitudinal reinforcement with the largest overall capacity

​

3.1.50

​

membrane

planar member subjected primarily to in plane forces

​

3.1.51

​

nodal region

region of a stress field where the force is transferred amongst concurrent compression fields and/or ties

​

3.1.52

​

node

point of intersection of struts and/or ties transferring forces amongst them

​

3.1.53

​

nonlinear analysis

analysis method using models that account for mechanical and geometrical non-linear behaviour

​

3.1.54

​

ordinary reinforcement

reinforcement which is not prestressed, where not specified otherwise, it is made of reinforcing steel

​

3.1.55

​

plain reinforcement

reinforcement with a smooth surface

​

3.1.56

​

plain or lightly reinforced concrete members

structural concrete members having no reinforcement (plain concrete) or less reinforcement than the minimum amounts as defined in Clause 12

​

3.1.57

​

planar member

structural member with a dimension in one direction (depth) significantly smaller than those in the other directions (width) with width / depth > 4 (such as slabs, walls and shells)

​

3.1.58

​

pocket (or socket) foundation

member (precast, cast-insitu or partly precast) forming a tight pit for embedding the bottom of a precast column, fixed with infilled cast-insitu concrete

​

3.1.59

​

post-installed reinforcing steel system

deformed straight reinforcing steel bar and anchoring mortar installed using tools for drilling and preparing the hole (e.g. roughening and cleaning) as well as for injection of the mortar (e.g. dispenser, nozzles, piston plug, if applicable)

​

3.1.60

​

post-tensioning

prestress technique which consists in applying the prestress to tendons positioned in a hardened concrete member within a complete assembly of anchorages, sheathing with coating (for unbonded applications) or ducts to be grouted (for bonded applications)

​

3.1.61

​

precast concrete element

factory produced or site manufactured element cast and cured in a place other than its final location in the structure

​

3.1.62

​

precast concrete product

concrete element manufactured in accordance with a product standard by an industrial process under a factory production control system and protected from weather conditions during production

​

3.1.63

​

precast structure

structure assembled from precast concrete elements, connected to ensure the required structural integrity

​

3.1.64

​

prestress

effect of prestressing process, namely, internal forces in the sections and the deformations of the structure BS EN 1992-1-1:2023 EN 1992-1-1:2023 (E)

​

3.1.65

​

prestressing process

process of prestressing consists in applying forces to the concrete structure and the tendons

​

3.1.66

​

prestressed reinforcement

reinforcement made of strands, wires or bars subjected to a prestressing process, where not specified otherwise, it is made of prestressing steel

​

3.1.67

​

pre-tensioning

process by which tendons are stressed before and remain stressed during their embedment in cast concrete

​

3.1.68

​

pre-tensioning tendon

tendon in which the prestressed reinforcement is embedded in and bonded directly to concrete

​

3.1.69

​

reinforcement

assembly of bars and/or tendons, prestressed (prestressed reinforcement) or not (ordinary reinforcement), embedded in or connected to concrete members, which, where not specified otherwise, is made of steel and is bonded to the concrete

​

3.1.70

​

ribbed reinforcement

reinforcing bars with at least two rows of ribs uniformly distributed over the entire length

​

3.1.71

​

ribbed slab

slab with narrow ribs spanning in one direction

​

3.1.72

​

second order effects

additional action effects caused by structural deformations

​

3.1.73

​

secondary reinforcement

in one-way slabs, the bending reinforcement placed in the direction parallel to the supports

​

3.1.74

​

shear reinforcement, shear assemblies

stirrups, links, headed bars or bent-up bars specifically placed to resist action effects caused by shear and torsion

​

3.1.75

​

shell

planar member, either plane or curved, that carries both in-plane and out of plane forces Note 1 to entry: Cylindrical shells are simply curved, spherical shells are double curved.

​

3.1.76

​

shrinkage, basic

shrinkage occurring in concrete when there is no humidity transfer with the surrounding environment Note 1 to entry: Basic shrinkage is also known as autogenous shrinkage.

​

3.1.77

​

shrinkage, drying

shrinkage, additional to basic shrinkage, occurring in concrete when there is humidity transfer with the surrounding environment Note 1 to entry: The total shrinkage is the sum of basic and drying shrinkage.

​

3.1.78

​

slab

planar member loaded primarily perpendicularly to its plane for which the minimum panel dimension is not less than 4 times the overall thickness, possibly acting also as diaphragm

​

3.1.79

​

slab, solid

slab without voids or ribs

​

3.1.80

​

spiral reinforcement

continuously wound reinforcement in form of a helix, cylindrical or prismatic

​

3.1.81

​

stabilized cracking

phase of the cracking process in which the crack pattern is fully developed and an increase in the actions will normally result in an increase in the crack opening Note 1 to entry: This type of cracking is typically associated with applied external loads, when such loads are sensibly above the cracking loads.

​

3.1.82

​

stainless steel

stainless reinforcing steel in accordance with EN 10370

​

3.1.83

​

stirrup

reinforcement bent to form double or multiple legs that surrounds longitudinal reinforcement Note 1 to entry: Stirrups can be closed or open with sufficient anchorage at their ends.

​

3.1.84

​

stress field

stress state in a structure equilibrating the external actions

​

3.1.85

​

strut

resultant of a compression field, part of a strut-and-tie model

​

3.1.86

​

strut-and-tie model

model composed of the resultant forces of a stress field with struts for the compression fields and ties for the tension reinforcement

​

3.1.87

​

support, direct

bearing by contact forces pushing against the member

​

3.1.88

​

support, indirect

support with local tensile stresses in the supporting member caused by applied loads

​

3.1.89

​

technical documentation of post-tensioning system

documentation containing all information relevant for design and construction of post-tensioned structures in accordance with this Eurocode

​

3.1.90

​

tendon

in post-tensioned applications, the tendon is a complete assembly consisting of anchorages, prestressing steel (strand, wire, bar), and sheathing with coating for unbonded applications or ducts with grout for bonded applications; in pre-tensioned applications, the tendon is an individual element of prestressed reinforcement

​

3.1.91

​

tendon protection level

designation of a class or level of corrosion protection provided to tendons

​

3.1.92

tie tension member as part of a strut-and-tie model representing concentrated or distributed reinforcements

​

3.1.93

​

transverse reinforcement

reinforcement arranged perpendicular to the bar considered Note 1 to entry: In linear members it can consists of stirrups, links or hoops enclosing the longitudinal reinforcement considered; in planar member it consists of straight reinforcement parallel to the free surface.

​

3.1.94

​

unbonded tendon

tendon for post-tensioned members where bond of the prestressed reinforcement to the member is permanently prevented by encasing it in sheathing with soft filler or by placing the tendon outside the concrete section (see external tendon)

​

3.1.95

​

waffle slabs

slab with narrow ribs spanning in both directions

​

3.1.96

​

wall

planar member subjected primarily to in plane forces, with cross-section width exceeding 4 times its thickness (otherwise it should be considered as a column) and the height is at least 3 times the section thickness

​

Terms and definitions in Annex I

​

3.1.97

​

corrosion penetration depth

loss in cross-sectional radius of a bar due to homogeneous corrosion (not pitting corrosion or localized zones)

​

3.1.98

​

pitting corrosion

form of localised corrosion that leads to the creation of cavities or holes in the metal

​

Terms and definitions in Annex J

​

3.1.99

​

adhesive

material that possesses enough adhesive strength to join CFRP reinforcement to a concrete surface

​

3.1.100

​

adhesively bonded CFRP reinforcement

externally or Near Surface Mounted CFRP reinforcement bonded to concrete using adhesive to provide a longitudinal shear connection

​

3.1.101

​

CFRP bar

thermally hardened, unidirectional CFRP reinforcement industrially manufactured in various shapes used as NSM reinforcement

​

3.1.102

​

Carbon Fibre Reinforced Polymer

​

CFRP

fibre-polymer composite material comprising industrially manufactured carbon fibres embedded in a polymer matrix

​

3.1.103

​

Carbon Fibre Reinforced Polymer (CFRP) system

composite comprising carbon fibres with an accompanying adhesive material that is bonded to an adequately prepared concrete strata for the purpose of strengthening a structural concrete component

​

3.1.104

​

concrete cover separation

failure mode occurring at the end of adhesively bonded reinforcement, where a shift in tensile force may detach the concrete cover and the entire adhesively bonded reinforcement

​

3.1.105

​

externally bonded reinforcement

EBR adhesively bonded CFRP reinforcement installed externally to a concrete surface

​

3.1.106

​

externally bonded stirrups

externally bonded CFRP system, embracing the member in closed or U-shaped form

​

3.1.107

​

Near Surface Mounted (NSM) reinforcement

adhesively bonded CFRP bar installed in slots cut into the existing concrete cover zone

​

3.1.108

​

sheets

textile surface structure comprising dry parallel fibre bundles arranged in one or more directions

​

3.1.109

​

slot

small recess cut into the concrete cover zone with predetermined dimensions along the member filled with adhesive in which adhesively bonded CFRP strips or bars (NSM) are embedded

​

3.1.110

​

strip

thermally hardened, unidirectional CFRP reinforcement industrially prefabricated in various rectangular flat shapes used as NSM or EBR reinforcement

​

Terms and definitions in Annex $L$

​

3.1.111

​

Steel Fibre Reinforced Concrete

​

SFRC

concrete to which steel fibres are included into the concrete matrix to achieve post cracking residual strength

​

3.1.112

​

residual flexural strength

stress at the outer most tension layer of a SFRC cross-section in bending corresponding to a certain crack width determined using linear elastic material behaviour and the assumption that plane sections remain plane during bending

​

3.1.113

​

residual tensile strength

uniaxial tensile stress corresponding to a certain crack opening derived from the residual flexural strength using design rules provided in Annex L

​

3.1.114

​

residual strength class

classification that defines the response of a SFRC beyond the cracking strain of concrete. This class defines the strength of the SFRC concrete without additional reinforcing bars or prestressing

​

3.1.115

​

ductility class

classification that is defined by the ratio between the residual flexural strengths at $\mathrm{CMOD}_{1}$ and $\mathrm{CMOD}_{3}$

​

Terms and definitions in Annex $\mathbf{R}$

​

3.1.116

​

Fibre Reinforced Polymer

​

FRP

fibre-polymer composite material comprising industrially manufactured fibres embedded in a polymer matrix

​

3.1.117

​

fibre reinforced polymer (FRP) reinforcement

assembly of profiled or roughened fibre reinforced polymer reinforcement bars, embedded in or connected to concrete members

​

3.2 Symbols and abbreviations

For the purposes of this document, the following symbols apply.

​

3.2.1 Latin upper case letters

A	Correction factor
$A_{\mathrm{c}}$	Cross-sectional area of concrete
$A_{\mathrm{cc}}$	Compressive area
$A_{\text {c,eff }}$	Effective concrete area
$A_{\text {cc }}$	Area of confinement core of partially loaded area
$A_{\mathrm{c} 0}$	Loaded area in partially loaded area
$A_{\mathrm{c} 1}$	Contributing area in partially loaded area
$A_{\text {e }}$	Equivalent area of reinforcement

$A_{\text {gt }}$	Elongation at maximum force
$A_{\mathrm{k}}$	Area enclosed by centrelines of connecting walls of cross section
$A_{\mathrm{p}}$	Cross-sectional area of prestressed reinforcement
$A_{\text {p,red }}$	Reduced cross-sectional area of prestressing steel
$A_{\mathrm{s}}$	Cross-sectional area of ordinary reinforcement
$A_{\text {sc }}$	Cross-sectional area of longitudinal reinforcement in the compression chord; confinement reinforcement
$A_{\mathrm{s}, \mathrm{conf}}$	Cross-sectional area of one leg of confinement reinforcement
$A_{\mathrm{s}, \text { confx }}, A_{\mathrm{s}, \text { confy }}$	Value of $A_{s, \text { conf }}$ in the $x$ and $y$-directions, respectively
$A_{\text {sf }}$	Cross-sectional area of the transverse reinforcement in a flange
$A_{\text {si }}$	Cross-sectional area of bonded reinforcement across interface
$A_{\text {sint }}$	Robustness reinforcement in flat slabs
$A_{\text {sl }}$	Effective area of tensile reinforcement
$A_{\mathrm{s}, \min }$	Minimum cross-sectional area of reinforcement
$A_{\mathrm{s}, \min , \mathrm{h}}$	Minimum amount of horizontal reinforcement
$A_{\mathrm{s}, \min , \mathrm{v}}$	Minimum amount of vertical reinforcement
$A_{\mathrm{s}, \min , \mathrm{w} 1}$	Area of minimum reinforcement to be placed at the most tensioned face of the section part under consideration to control cracking
$A_{\mathrm{s}, \min , \mathrm{w} 2}$	Area of minimum reinforcement to be placed at the least tensioned face of the section part under consideration to control cracking
$A_{\mathrm{s}, \text { web }}$	Reinforcement area to be provided in the web over a height limited by the neutral axis and the centroid of reinforcement with a spacing not exceeding 300 mm , to control cracking
$A_{\text {st }}$	Cross-sectional area of longitudinal reinforcement in the tension chord; transverse reinforcement
$A_{\text {std }}$	Tie down reinforcement in laps of headed bars
$A_{\text {st } \text { min }}$	Minimum transverse reinforcement
$A_{\mathrm{s}, \mathrm{v}}$	Amount of vertical reinforcement
$A_{\text {sw }}$	Cross-sectional area of shear reinforcement
$A_{\text {sw, min }}$	Minimum cross-sectional area of shear reinforcement
$A_{\mathrm{s}, \mathrm{req}, \mathrm{span}}$	Amount of required flexural non-prestressed reinforcement
$C$	Coefficient for fatigue strength of concrete under compression
$C_{\mathrm{m}}$	Coefficient used to obtain an equivalent constant moment to calculate second order effects in elements with differing end moments
$D_{\mathrm{h}}$	Diameter of a circular hoop or spiral reinforcement (defined by the bar’s axis)
$D_{\text {lower }}$	Smallest value of the upper sieve size $D$ in an aggregate for the coarsest fraction of aggregates in the concrete permitted by the specification of concrete [EN 206]
$D_{\text {max }}$	Declared value of the upper sieve size $D$ of the coarsest fraction of aggregates actually used in the concrete [EN 206]

$D_{\text {upper }}$	Largest value of the upper sieve size $D$ in an aggregate for the coarsest fraction of aggregates in the concrete permitted by the specification of concrete [EN 206]
$E$	Effect of actions
$E_{\text {cd }}$	Design value of modulus of elasticity of concrete
$E_{\text {c,eff }}$	Effective modulus of elasticity of concrete accounting for creep deformations
$E_{\text {cm }}$	Secant modulus of elasticity of concrete
$E_{\mathrm{c}, 28}$	Secant modulus of elasticity of concrete at age of 28 days
$E_{\mathrm{p}}$	Design value of modulus of elasticity of prestressing steel
$E_{s}$	Design value of modulus of elasticity of ordinary reinforcing steel
EI	Bending stiffness
$E I_{\text {eff }}$	Effective bending stiffness
$E_{t}$	Action effect (force or stress) at time $t$
$E_{\mathrm{t}=0}$	Internal force or stress at time $t=0$
$E_{\text {wc }}$	Force or stress assuming the structure was built without changes in the support conditions
F	Action
$F_{\text {cd }}$	Design value of the compression force in a compression chord or in a strut (compression positive)
$F_{\mathrm{d}}$	Design value of an action
$\Delta F_{\mathrm{d}}$	Design value of the change of the axial force in the flange over the length $\Delta x$
$F_{\text {Ed }}$	Design value of actions
$F_{\text {Ed,2 }}$	Fictitious magnified horizontal force to account for global second order effects
$F_{\text {Ed,sup }}$	Design support reaction due to the loads applied on the beam or the slab
$F_{\text {fat }}$	Relevant fatigue action (e.g. traffic load or other cyclic load)
$F_{\mathrm{H}, 0 \mathrm{Ed}}$	First order horizontal force due to wind, imperfections etc.
$F_{\mathrm{H}, 1 \mathrm{Ed}}$	Fictitious horizontal force
$F_{\mathrm{H}, \mathrm{i}}$	Transverse force representing a geometrical imperfection
$F_{\text {td }}$	Design value of the tension force in a tension chord or tie or in the transverse reinforcement
$F_{\text {Vi }}$	Vertical load to calculate $F_{\mathrm{H}, \mathrm{i}}$
$F_{\text {VB }}$	Buckling load of the bracing structure
$F_{\text {VBB }}$	Flexural buckling load of a cantilever, restricted by the floors, with base rotation
$F_{\text {VBS }}$	Buckling load due to localised lateral storey deformations
$F_{\text {VEd }}$	Total design vertical load on the bracing structure and the members braced by it
$F_{\text {Rd }}$	Design value of the resistance of a tie or of a tension chord
$G_{\mathrm{cd}}$	Design value of the elastic shear modulus
$G_{\mathrm{k}}$	Characteristic value of a permanent action

H	Distance between the points of application of two aligned forces
I	Second moment of area of concrete section
$I_{c r}$	Second moment of area of cracked concrete section
$I_{\mathrm{g}}$	Second moment of area of the gross concrete cross-section
$J\left(t, t_{0}\right)$	Creep function or creep compliance, representing the total stress-dependent strain per unit stress
$L$	Total height of the building above the base
$L_{x}, L_{y}$	Spans of slab in x - and y -directions
M	Bending moment in linear members
$M_{01}, M_{02}$	First order end moments, including effect of imperfections such that $\left\|M_{02}\right\| \geq\left\|M_{01}\right\|$
$M_{0 \text { Ed }}$	Maximum first order moment due to the fundamental load combination, including the effect of imperfections
$M_{0 \text { Eqp }}$	Maximum first order moment due to the quasi-permanent load combination
$M_{2}$	Nominal $2^{\text {nd }}$ order moment
$M_{\text {cr }}$	Cracking moment of the section in presence of the simultaneous axial force $N_{\mathrm{Ed}}$, which may be calculated on the basis of the concrete tensile strength $f_{\mathrm{ctm}}$ assuming linear stress distribution and neglecting any contribution from reinforcement
$M_{\text {Ed }}$	Design value of the applied internal bending moment
$M_{\text {Edy }}$	Design moment about $y$-axis, including second order moment, where relevant
$M_{\text {Edz }}$	Design moment about $z$-axis, including second order moment, where relevant
$M_{\text {Rd }}$	Moment capacity
$M_{\text {Rdy, } \mathrm{N}}$	Moment resistance about $y$-axis for the given axial force
$M_{\text {Rdz,N }}$	Moment resistance about $z$-axis for the given axial force
$M_{\text {rep }}$	Cracking moment with extreme fibre tension reaching the relevant tensile strength for sections without prestressing
$M_{\mathrm{R}, \min }$	Bending strength of the section with $A_{\mathrm{s}, \min }$ in presence of the simultaneous axial force $N_{\mathrm{Ed}}$
$M_{\text {y }}$	Moment when strain in tension reinforcement equals $\varepsilon_{\text {yd }}$
$\Delta M_{\text {Ed }}$	Reduction in the design support moment for a beam or slab continuous over a support that can be considered to provide no restraint to rotation; additional moment to calculate chord forces
$N$	Axial force in linear members ; number of load cycles
$N^{*}$	Number of load cycles corresponding to $\Delta \sigma_{\text {Rsk }}$
$N_{\mathrm{a}}$	Axial force in column above floor or diaphragm
$N_{\text {B }}$	Elastic buckling load (Euler)
$N_{\mathrm{b}}$	Axial force in column below floor or diaphragm
$N_{\text {Ed }}$	Design value of the applied axial force
$N_{\text {Edw }}$	Design value of the axial force in the web
$N_{\text {obs }}$	Number of lorries per year

$N_{\text {Rd }}$	Design value of axial resistance
$N_{\text {Rd,0 }}$	Design value of axial resistance without accompanying moments
$N_{\text {Vd }}$	Design value of the sum of the additional axial forces in the tension and in the compression chords due to shear in a cross-section
$N_{\text {years }}$	Design service life of bridge
$P$	Prestressing force
$P_{\mathrm{d}}$	Design value of the prestressing force
$P_{\mathrm{k}}$	Characteristic value of the prestressing force
$\bar{Q}$	Factor for traffic type
$Q_{\mathrm{k}, \mathrm{i}}$	Characteristic variable action
$Q(\mathrm{t})$	Total amount of hydration heat
$R$	Resistance
$R_{\mathrm{ax}}$	Restraint factor
$R_{\mathrm{ax}, 1}$	Restraint factor corresponding to the boundary conditions present after concreting
$R_{\mathrm{ax}, 2}$	Restraint factor corresponding to the boundary conditions present when the maximum temperature drop is expected to occur
$R_{\mathrm{ax}, 3}$	Restraint factor corresponding to the boundary conditions prevalent during the development of drying shrinkage
$R_{\text {cr }}$	Cracking risk
$R_{\mathrm{d}}$	Design value of the resistance
$R_{\mathrm{e}}, R_{\mathrm{p} 0,2}$	Tensile yield strength of reinforcing steel
$R_{\text {ea,cr }}$	Project parameter related to the admissible risk of cracking
RH	Relative humidity of the ambient environment in %
$R H_{\text {eq }}$	Internal relative humidity of concrete at equilibrium, accounting for self-desiccation in high performance concrete
$R_{\mathrm{m}}$	Structural resistance based on a non-linear verification performed using the mean values of the material properties and the nominal geometrical dimensions; tensile strength of reinforcing or prestressing steel
$R_{\text {min }}$	Minimum radius of curvature of tendons
$R_{\mathrm{p} 0,1}$	Tensile yield strength of prestressing steel
$S$	First moment of area above and about the centroidal axis
$S_{\text {Ed }}$	Individual design actions for interaction formula
$S_{\text {Rd }}$	Individual design resistances for interaction formula
$S_{\mathrm{s}}$	First order moment of area of the required tension and compression reinforcements with respect to the centroid of the gross cross-section
$T$	Torsional moment; tension force in lapped headed bars
$T_{0}$	Temperature of the restraining structure
$T_{1}, T_{2}$	Tension forces in legs of U-bar loops

$T_{\text {ci }}$	Temperature of fresh concrete
$T_{\mathrm{c}, \max }$	Maximum temperature in concrete due to hydration heat
$T_{\text {Ed }}$	Design value of the applied torsional moment
$T_{\text {col }}, T_{\mathrm{i}}, T_{\mathrm{p}}, T_{\mathrm{v}}$	Tensile force in horizontal ties to columns, internal, peripheral and vertical ties
$T_{\text {max }}$	Maximum temperature during heat treatment
$\Delta T_{\text {min }}$	Long term maximum temperature drop
$T_{\text {Rd,c }}$	Design value of axial resistance related to concrete failure in laps using U-bar loops
$T S_{\mathrm{Mu}}$	Tension stiffening effect at ultimate limit state
$T S_{\text {My }}$	Tension stiffening effect at yield
$V$	Shear force in linear members
$V_{\text {bcd }}$	Design shear force carried by the bottom chord
$V_{\text {Ed }}$	Design shear force in the section considered
$V_{\text {Edi }}$	Shear force acting parallel to the interface
Vol	Volume of traffic (tonnes/year/track)
$\Delta V_{\text {Ed }}$	Portion of shear force which may be subtracted from $V_{\text {Ed }}$ due to favorable circumstances
$V^{*}{ }_{\mathrm{R}}$	Coefficient of variation of structural resistance
$V_{\text {Rd,hog }}$	Resistance provided by hogging reinforcement in flat slabs
$V_{\text {Rd,int }}$	Resistance of flat slabs without shear reinforcement for robustness
$V_{\text {Rd,w,int }}$	Resistance of flat slabs with shear reinforcement for robustness
$V_{\text {tcd }}$	Design shear force carried by the top chord

​

3.2.2 Latin lower case letters

$a$	Distance; geometrical data; distance from concrete surface to the centre of the outside layer of reinforcement (Figure 9.3)
$a_{\mathrm{cs}}$	Effective shear span with respect to the control section
$a_{\mathrm{cs}, 0}$	$a_{\text {cs }}$ without considering effect of prestressing or external load
$a_{\mathrm{F}}$	Projection of a foundation from the column face
$a_{\mathrm{i}}$	Amplitude of buckling shape to be considered as an imperfection for bucking analysis of arches
$a_{1}$	Distance by which moment curve is shifted to account for shear effect
$a_{\mathrm{N}}$	Exponent governing the shape of the simplified skew bending interaction diagram
$a_{\mathrm{p}}$	Distances between the centre of the support area and the point of contraflexure in slabs under concentrated loads
$a_{\text {pd }}$	Parameter for calculating the punching shear resistance based on $a_{\mathrm{p}}$
$a_{\mathrm{p}, \mathrm{x}}, a_{\mathrm{p}, \mathrm{y}}$	Maximum distances from the centre of the support area to the two points (on the $x$ - and on the $y$-axis, respectively) where the bending moments $m_{\mathrm{Ed}, \mathrm{x}}$, respectively $m_{\mathrm{Ed}, \mathrm{y}}$, are zero
$a_{\mathrm{q}}$	Distance between concentrated forces pushing against each other

$a_{\mathrm{s}, \text { min }}$	Minimum interface reinforcement along edges of composite slabs
$a_{\mathrm{v}}$	Mechanical shear span
$a_{\mathrm{v}, 0}$	$a_{\mathrm{v}}$ without considering effect of prestressing or external load
$a_{\mathrm{x}}$	Distance from concrete surface to the centre of the outer reinforcement layer in the x direction
$a_{y}$	Distance from concrete surface to the centre of the outer reinforcement layer in the $y$ direction
$a, b$	Dimensions of load introduction block
$a_{0}, b_{0}$	Dimensions of loaded area $A_{\mathrm{c} 0}$
$a_{0, \text { red }}, b_{0, \text { red }}$	Reduced dimensions of loaded area due to eccentrically applied load
$a_{1}, b_{1}$	Dimensions of contributing area $A_{\mathrm{c} 1}$
$a_{\mathrm{h}}, b_{\mathrm{h}}$	Dimensions of rectangular head of headed bars
$a_{\delta}$	Deformation parameter considered which may be, for example, a strain, a curvature, or a rotation or even a deflection
$a_{\mathrm{I}}, a_{\mathrm{II}}$	Value of $\alpha_{\delta}$ calculated for uncracked and fully cracked conditions, respectively
$b$	Overall width of a cross-section, or actual flange width in a T or L beam
$b_{0}$	Length of control perimeter at face of supporting area
$b_{0,5}$	Length of control perimeter at a distance of $0,5 d_{\mathrm{v}}$ from column edge
$b_{0,5, \mathrm{~s}}$	Control perimeter placed at the location of the shear reinforcement perimeter
$b_{0,5 \text { out }}$	$b_{0}$ for the verification outside the shear reinforced area
$b_{\mathrm{b}}$	Geometric mean of the minimum and maximum overall widths of the control perimeter
$b_{\mathrm{c}}$	Width of a strut
$b_{\text {cs }}$	Maximum width of the confined concrete core at confinement reinforcement
$b_{\text {csx }}, b_{\text {csy }}$	Value of $b_{\mathrm{cs}}$ in the $x$ and $y$-directions, respectively
$b_{\text {e }}$	Width of element
$b_{\text {eff }}$	Effective width of flange in T, L or box sections
$b_{\text {ef,hog }}$	Effective width for consideration of hogging reinforcement in flat slabs
$b_{\mathrm{i}}$	Distance between longitudinal reinforcement bars fixed by confinement reinforcement
$b_{\mathrm{s}}$	Width of the support strip
$b_{\mathrm{w}}$	Minimum width of the cross-section between tension and compression chords and neutral axis
$b_{\mathrm{w}, \text { nom }}$	Nominal web width due to the disturbance of ducts
$c$	Concrete cover of reinforcement (to the surface of the bar, $\geq c_{\text {nom }}$ ). In 9.2 it refers to the bar which is closest to the concrete surface
$c_{1 / \mathrm{r}}$	Factor considering curvature distribution
$C_{\text {act }}$	Actual concrete cover
$C_{\mathrm{d}}$	Nominal value of the concrete cover for designing the anchorage length

$c_{\mathrm{d}, \text { conf }}$	Nominal value of $c_{\mathrm{d}}$ in presence of confinement
$C_{\text {min }}$	Minimum concrete cover $c$ provided to ensure sufficient bond strength and protection against corrosion
$C_{\text {min, } \mathrm{b}}$	Minimum concrete cover $c$ due to bond requirement
$C_{\text {min,dur }}$	Minimum concrete cover $c$ due to durability requirement
$C_{\text {nom }}$	Nominal value of the concrete cover $c$ which is specified in drawings and is basis for calculating fire resistance
$\Delta c_{\mathrm{abr}}$	Additional minimum cover for abrasion
$\Delta c_{\mathrm{dev}}$	Allowance in design for deviation of the concrete cover
$\Delta c_{\text {dur,red1 }}$, $\Delta c_{\text {dur,red2 }}$	Reduction of minimum cover for use of additional concrete protection
$\Delta c$	Additional reduction or addition to cover
$\Delta c_{\min , 30}$	Reduction of minimum cover for structures with design life of 30 years
$\Delta c_{\text {min, exc }}$	Reduction of minimum cover for superior compaction or curing
$\Delta c_{\text {min,p }}$	Additional minimum cover for prestressing tendons
$C_{\mathrm{s}}$	Clear distance between parallel reinforcement bars
$C_{\mathrm{u}}$	Effective width of concrete area carrying tensile forces due to the deviation of curved chords
$c_{\mathrm{V}}$	Parameter to determine $d_{\mathrm{v}, \text { out }}$
$C_{\mathrm{v} 1}, C_{\mathrm{v} 2}$	Coefficients for the shear resistance at interfaces
$c_{\mathrm{v} 1, \mathrm{fat}}$	Coefficients for the shear resistance at interfaces under fatigue action
$C_{\mathrm{X}}, C_{\mathrm{y}}, C_{\mathrm{yb}}$	Concrete covers to reinforcement measured in $x$ and $y$ direction and at bends, respectively
$d$	Effective depth of a cross-section
$d_{\mathrm{d}}$	Design value of the effective depth
$d_{\text {dg }}$	Size parameter describing the crack and the failure zone roughness taking account of concrete type and its aggregate properties
$d_{\text {key }}$	Height of shear key
$d_{\text {nom }}$	Nominal value of the effective depth determined on the basis of $c_{\text {nom }}$
$d_{\mathrm{p}}$	Effective depth of the prestressed reinforcement
$d_{\mathrm{s}}$	Effective depth of the ordinary reinforcement
$d_{\mathrm{v}}$	Shear-resisting effective depth of the reinforcement at the first and second shear reinforcement perimeter
$d_{\mathrm{v}, \text { out }}$	$d_{\mathrm{v}}$ outside of the second reinforced perimeter
$d_{\mathrm{vx}}, d_{\mathrm{vy}}$	Shear-resisting effective depth of the reinforcement in $x$ and $y$ direction, respectively
$d_{\mathrm{x}}, d_{\mathrm{y}}$	Effective depth of the reinforcement in $x$ and $y$ direction, respectively
$e$	Eccentricity
$e_{\mathrm{a}}, e_{\mathrm{b}}$	Eccentricity of applied load in partially loaded area

$e_{0}$	First order eccentricity
$e_{2}$	Second order eccentricity
$e_{\mathrm{b}}$	Eccentricity of the resultant of shear forces with respect to the centroid of the control perimeter
$e_{\mathrm{b}, \mathrm{x}}, e_{\mathrm{b}, \mathrm{y}}$	Components of $e_{\mathrm{b}}$ in $x$ and $y$ direction, respectively
$e_{\mathrm{d}, \text { min }}$	Minimum eccentricity due to uncertainties related to modelling and analysis
$e_{\mathrm{i}}$	Additional eccentricity covering the effects of geometrical imperfections
$e_{\mathrm{p}}$	Eccentricity of the axial forces related to the centroid of the section at control section, positive when the eccentricity is on the side of the flexural reinforcement in tension
$e_{\text {tot }}$	Total eccentricity
$e_{\mathrm{y}}{ }^{\prime}, e_{\mathrm{z}}{ }^{\prime}$	Dimensionless eccentricity along the $y$-axis and $z$-axis, respectively
$f_{\text {bcd }}$	Design resistance of bedding material
$f_{\text {bm,req }}$	Required minimum mean bond strength of post-installed bar
$f_{\mathrm{c}}$	Compressive strength of concrete
$f_{\text {cd }}$	Design value of concrete compressive strength
$f_{\text {cd,c }}$	Design value of strength of confined concrete
$f_{\text {cd,fat }}$	Design value of concrete fatigue strength
$f_{\text {cd,pl }}$	Design value of plain concrete compressive strength
$\Delta f_{\mathrm{cd}}$	Design value of strength increase due to transverse compressive stress or confinement
$f_{\mathrm{ck}}$	Characteristic concrete cylinder compressive strength at age $t_{\text {ref }}$
$f_{\mathrm{ck}, \mathrm{ref}}$	Value of $f_{\text {ck }}$ at reference age $t_{\text {ref }}$
$f_{\mathrm{ck}, 28}$	Value of $f_{\mathrm{ck}}$ at reference age of 28 days
$f_{\mathrm{cm}}$	Mean concrete cylinder compressive strength at age $t_{\text {ref }}$
$f_{\mathrm{cm}}(t)$	Mean concrete cylinder compressive strength at age $t$
$f_{\text {cmp }}$	Mean compressive strength of concrete after heat curing
$f_{\mathrm{ct}}$	Tensile strength, highest stress reached under concentric tensile loading
$f_{\text {ctd }}$	Design value of the tensile strength of concrete
$f_{\text {ctd,pl }}$	Design value of plain concrete tensile strength
$f_{\text {ct,eff }}$	Mean value of the tensile strength of the concrete effective at the time when cracking may first be expected to occur;
$f_{\text {ctk; } 0,05}$	Characteristic axial tensile strength of concrete (5 % fractile)
$f_{\text {ctk; } 0,95}$	Characteristic axial tensile strength of concrete (95 % fractile)
$f_{\mathrm{ctm}}$	Mean axial tensile strength of concrete at age $t_{\text {ref }}$
$f_{\text {ctm ,fl }}$	Mean flexural tensile strength of concrete
$f_{\mathrm{p}}$	Actual tensile strength of prestressing steel
$f_{\text {pd }}$	Design yield strength of prestressing steel
$f_{\mathrm{pk}}$	Characteristic tensile strength of prestressing steel

$f_{\mathrm{p} 0,1 \mathrm{k}}$	Characteristic 0,1 % proof-stress of prestressing steel
$f_{\mathrm{r}}$	Relative flexibility of rotational restraints at the ends of a support
$f_{\mathrm{R}}$	Minimum relative rib area of reinforcing steel
$f_{\mathrm{Rd}}$	Design value of bearing strength
$f_{\mathrm{s}, \mathrm{eff}}$	Tensile stress in reinforcement when $M_{\mathrm{Rd}}$ is reached
$f_{\mathrm{t}}$	Tensile strength of reinforcement
$f_{\text {tdx }}, f_{\text {tdy }}$	Tensile strength provided by reinforcement in membrane elements in x - and y directions, respectively
$f_{y}$	Yield strength of reinforcement
$f_{\text {yd }}$	Design yield strength of reinforcement
$f_{\mathrm{yk}}$	Characteristic value of yield strength of reinforcement or, if yield phenomenon is not present, the characteristic value of $0,2 \%$ proof strength
$f_{\text {ywd }}$	Design yield strength of shear reinforcement
$f_{0,2 \mathrm{k}}$	Characteristic 0,2 % proof-stress of reinforcement
$h$	Overall depth of a cross-section or of a part of a cross-section
$h_{\text {col }}$	Largest side length of column
$\boldsymbol{h}_{\mathbf{c}, \text { eff }}$	Height of the effective concrete area around reinforcement
$h_{\mathrm{D}}$	Hydrostatic head
$h_{\mathrm{F}}$	Foundation depth;
$h_{\mathrm{f}}$	Thickness of a flange at the junction with the web
$h_{\mathrm{n}}$	Notional size of concrete member
$i$	Radius of gyration
$i_{\text {s }}$	Radius of gyration of total group of reinforcement
$i_{\mathrm{y}}, i_{\mathrm{z}}$	Radius of gyration with respect to $y$-axis and $z$-axis, respectively
$k$	Coefficient; Factor
$k$	Ratio related to strain hardening of reinforcement
$k_{\mathrm{b}}, k_{\mathrm{b}, \text { simpl }}$	Coefficient for bond conditions
$k_{\text {bend }}$	Parameter accounting for the bend angle $\alpha_{\text {bend }}$
$k_{\mathrm{b}, \mathrm{pi}}$	Bond efficiency factor
$k_{\mathrm{c}}$	Coefficient reflecting the extent of cracking and the effect of non-linear material properties in the bracing system
$k_{\text {cip }}$	Factor considering increased uncertainty and variability in $\gamma_{\mathrm{C}}$ for concrete geotechnical members
$k_{\text {conf, } b}, k_{\text {conf,s }}$	Effectiveness factor for confinement
$k_{\text {cp }}$	Coefficient accounting for casting effect on bond conditions
$k_{\mathrm{c}, \mathrm{pl}}$	Coefficient to determine the design compressive strength of plain concrete
$k_{\mathrm{dc}}$	Coefficient for moment resistance depending on ductility class of reinforcement

$k_{\text {dowel }}$	Factor depending on the roughness of the interface
$k_{\text {duct }}$	Coefficient for calculating the nominal web width due to the disturbance of ducts
$k_{E}$	an adjusting factor for the modulus of elasticity of concrete considering the type of aggregates.
$k_{\mathrm{f} 1}, k_{\mathrm{f} 2}$	Stress exponent in $S$ - $N$ curves
$k_{\mathrm{fl}}, k_{\mathrm{fl}, \text { simpl }}$	Coefficient for type of loading (axial versus flexure)
$k_{\mathrm{h}}$	Coefficient which allows for the effect of non-uniform self -equilibrating stresses, which lead to a reduction of the apparent tensile strength
$k_{\text {int }}$	Coefficient to calculate resistance for robustness
$k_{\mathrm{I}}$	Coefficient to accounting for the effect of cracking, for tension stiffening and for the fact that creep deformations are less than proportional to the creep coefficient in cracked sections
$k_{\mathrm{Ib}}$	Factor for calculating the design anchorage length
$k_{\text {Is }}$	Factor to increase anchorage to lap length
$k_{N}$	Coefficient to consider beneficial effect of eccentric tendons on punching shear resistance in prestressed slabs
$k_{\mathrm{p}}$	Exponent to model the evolution of relaxation with time
$k_{\mathrm{pb}}$	Shear gradient enhancement coefficient for punching
$k_{\text {pp }}$	Coefficient accounting for the influence of axial forces on the shear slenderness of slabs submitted to concentrated forces
$k_{\mathrm{r}}$	In the context of second order effects, correction coefficient for equilibrium curvature depending on axial force
$k_{\mathrm{s}}$	Coefficient accounting for the effect of cracking on the shrinkage deflection
$k_{\text {st }}$	Resistance factor of the transverse reinforcement in laps using U-bar loops and headed bars
$k_{\text {surf }}$	Factor considering effect or ratio of actual cover / minimum cover
$k_{\mathrm{t}}$	Coefficient accounting for the effect of the nature and duration of the load on tension stiffening effects for cracking
$k_{\text {tc }}$	Coefficient considering the effect of high sustained loads on concrete compressive strength
$k_{\text {Temp }}$	Coefficient accounting for the reduction in temperature from $t_{1}$ to $t_{2}$
$k_{\mathrm{t}, \mathrm{pl}}$	Coefficient to determine the design tensile strength of plain concrete
$k_{\mathrm{tt}}$	Coefficient considering the effect of high sustained loads on concrete tensile strength
$k_{\mathrm{v}}$	Factor depending on roughness of interface
$k_{\mathrm{vp}}$	Coefficient considering effect of axial force
$k_{\mathrm{w}}$	Factor converting the mean crack width into a design crack width
$k_{1}$	Factor considering effect of axial force and eccentricity
$k_{1 / \mathrm{r}} k_{1 / \mathrm{r}, \mathrm{simpl}}$	Coefficient accounting for increase of crack width due to curvature
$k_{\mu}$	Unintentional angular displacement for internal tendons (per unit length)

$k_{\sigma}$	Ratio of concrete stress to $0,4 f_{\mathrm{cm}}$, used to account for non-linear creep
$k_{\sigma 1}, k_{\sigma 2}$	Coefficient for determining $\sigma_{\mathrm{s}, \mathrm{lim}}$
$k_{\varphi}$	In the context of second order effects, correction coefficient for equilibrium curvature accounting for creep
$l($ or $L)$	Length; span
$l_{0}$	Effective length of the member
$l_{0 \mathrm{~b}}$	Distance $l_{0 \mathrm{~b}}$ between points of zero moment
$l_{0 \mathrm{t}}$	Distance between torsional restraints
$l_{\text {aw }}$	Half wavelength of the buckling mode with the lowest buckling load
$l_{\mathrm{bd}}$	Design value of anchorage length of reinforcing steel
$l_{\mathrm{bdn}}$	Part of the anchorage length in the nodal region
$l_{\mathrm{bd}, \mathrm{pi}}$	Design anchorage length of post-installed reinforcing steel
$l_{\text {bd,tot }}$	Design anchorage length measured along the centre line of bars with bends and hooks in tension
$l_{\text {bpd }}$	Anchorage length of pretensioning tendon
$l_{\text {disp }}$	Dispersion length of effect of pretensioning tendon
$l_{\mathrm{pt}}$	Transmission length of pretensioning tendon
$l_{\mathrm{s}}$	Actual lap length
$l_{\text {sd }}$	Design value of lap length of reinforcing steel
$l_{\mathrm{w}}$	Clear height of the member
$l_{\mathrm{w}, \mathrm{p}}$	Length of passing crack
$m$	Number of load bearing members in one storey that bear a significant part of the vertical load
$m_{\text {Ed }}$	Design value of the applied internal bending moment per unit width in planar members
$m_{\text {Edx }}, m_{\text {Edy }}$	Value of $m_{\mathrm{Ed}}$ in the $x$ and $y$-directions, respectively
$m_{\text {Edxy }}$	Design value of the applied internal torsion moment per unit width in planar members
$m_{\text {Rd }}$	Design value of the flexural strength per unit width of a planar member resisting positive moments
$m_{\text {Rd }}{ }^{\text {}}$	Design value of the flexural strength per unit width of a planar member resisting negative moments (value positive)
$m_{\text {Rdx }}, m_{\text {Rdy }}$	Value of $m_{\mathrm{Rd}}$ in the $x$ and $y$-directions, respectively (without the influence of torsion moments)
$m_{\mathrm{Rdx}}{ }^{\prime}, m_{\mathrm{Rdy}}{ }^{\prime}$	Value of $m_{\mathrm{Rd}}{ }^{\prime}$ in the $x$ and $y$-directions, respectively (without the influence of torsion moments)
$n$	Non-dimensional axial force
$n_{\mathrm{b}}$	Number of anchored bars or pairs of lapped bars in the potential splitting failure surface
$n_{\mathrm{c}}$	Number of legs of confinement reinforcement crossing the potential splitting failure surface

$n_{\mathrm{i}}$	Number of acting stress cycles for stress level i
$n_{\mathrm{s}}$	Number of storeys
$n_{\text {st }}$	Proportion of traffic crossing bridge simultaneously
$n_{\text {trans }}$	Number of transverse bars in the bend
$n_{1}$	Number of layers with bars anchored at the same point in the member
$n_{2}$	Number of bars anchored in each layer
$n_{\sigma}$	Exponent to consider effect of steel stress on anchorage length
$p$	Water pressure
$p_{\text {Rd }}$	Maximum transverse bearing stress on tendon
$\Delta p$	Water pressure difference between the ends of a passing crack
$q$	Leakage rate through cracks
$q_{\mathrm{d}}$	Distributed load
$q_{\text {ed }}$	Design value of variable load
$r$	Radius of curvature
$r_{\text {inf }}$	Factor to account for variation in prestress in serviceability and fatigue verifications when prestressing is favourable
$r_{\mathrm{m}}$	Ratio of end moments $\left\|r_{\mathrm{m}}\right\| \leq 1,0$
$r_{\text {sup }}$	Factor to account for variation in prestress in serviceability and fatigue verifications when prestressing is unfavourable
$1 / r$	Curvature at a particular section
$s$	Spacing of the shear reinforcement or confinement reinforcement measured along the longitudinal axis of the member
$S_{\mathrm{c}}$	Spacing of the confinement reinforcement along the bar to be anchored
$S_{\mathrm{f}}$	Spacing of transverse reinforcement
$S_{0}$	Distance from the column face to the axis of the first perimeter of punching reinforcement
$S_{1}$	Spacing between shear links in radial direction
$S_{\mathrm{C}}$	Coefficient for different early strength development of concrete and concrete strength
$s_{\mathrm{L}}$	Spacing of longitudinal ribs
$S_{\text {T }}$	Spacing of transverse ribs
$S_{1}$	Centre-to-centre spacing of longitudinal bars
$S_{1, \text { surf,max }}$	Maximum spacing of surface reinforcement in beams with downstand
$S_{\text {bu,max }}$	Maximum longitudinal spacing of bent-up bars
$S_{\text {max,col }}$	Maximum spacing of transverse reinforcement along the column
$S_{l, \text { max }}$	Maximum longitudinal spacing of shear assemblies/stirrups
$S_{\text {slab,max }}$	Maximum spacing of bars for slabs
$s_{\text {stir,max }}$	Maximum spacing for torsion assemblies / stirrups

$S_{\text {tr,max }}$	Maximum transverse spacing of shear legs
$S_{\mathrm{r}}$	Spacing of shear links in the radial direction
$S_{\text {r,m,cal }}$	Calculated mean crack spacing when all cracks have formed or where not all cracks have formed, the maximum length along which there is slip between concrete and steel adjacent to a crack
$S_{\text {r,m,cal,x, }} S_{\text {r,m,cal,y }}$	Calculated mean crack spacing in the $x$ direction and in the $y$ direction, respectively
$S_{\mathrm{t}}$	Average spacing of shear links in the tangential direction at the investigated control perimeter; spacing of transverse reinforcement along the bar to be anchored
$s_{\mathrm{x}}$	Bar spacing in a group of headed bars
$t$	Thickness of a strut; length over which the support reaction is distributed
$t$	Time being considered, age of the concrete
$\Delta t$	Time interval
$t_{\text {eff }}$	Effective wall thickness
$t_{\text {eq }}$	Equivalent time to consider effect of heat treatment loss of prestress
$t_{\text {fac }}$	Tensile force in horizontal ties to walls
$t_{\mathrm{p}}$	Duration of heat curing
$t_{0}$	Age of concrete when the event under consideration occurs (prestressing, settlement, start of drying, loading age)
$t_{0, \text { adj }}$	Concrete age at loading adjusted for strength class of cement and temperature
$t_{0, \mathrm{~T}}$	Temperature-adjusted concrete age at loading
$t_{1}$	Time when the maximum concrete temperature due to heat hydration is reached
$t_{2}$	Time when concrete starts to develop tensile stresses
$t_{\mathrm{c}}$	Age of concrete when support conditions change
$t_{\text {crit }}$	Critical time for early-age cracking. Time at which thermal equilibrium with the restraining structure is achieved (within $2^{\circ} \mathrm{C}$ ) and the greater part of basic shrinkage has already developed
$t_{\text {dor }}$	Dormant time, e.g. time from concreting until stresses begin to develop
$t_{\text {ref }}$	Age of concrete at which the concrete strength is determined in days
$t_{\mathrm{s}}$	Age of concrete at the beginning of drying
$t_{\mathrm{T}}$	Temperature-adjusted concrete age in days
$u$	Perimeter of concrete cross-section, having area $A_{\mathrm{c}}$
$\nu_{\text {Ed }}$	Principal out of plane shear force per unit width in planar members
$\nu_{\text {Ed,x }}, \nu_{\text {Ed,y }}$	Out of plane shear force in planar members on the cross-sections perpendicular to the $x$ and $y$ direction, respectively
$W_{\mathrm{k}, \text { cal }}$	Calculated crack width
$w_{\mathrm{k}, \mathrm{cal}, 1}$	Crack width at end of a through-crack, where the crack is wider
$W_{\mathrm{k}, \text { cal }, 2}$	Crack width at end of a through-crack, where the crack is thinner
$W_{\mathrm{k}, \text { cal,e }}$	Equivalent width of a passing crack, of variable width

$w_{\mathrm{k}, l i m, 1}$	Limiting crack width for water-tightness
$w_{\text {lim,cal }}$	Limiting crack width to be compared with the calculated crack width $w_{\mathrm{k}, \mathrm{cal}}$
$x$	Depth of the neutral axis at serviceability limit state
$\Delta x$	Length under consideration for shear transfer
$X_{\text {cs }}$	Distance between the neutral axis and the axis of confinement reinforcement
$X_{g}$	Depth of neutral axis of uncracked section
$x, y, z$	Coordinates
$X_{\text {min }}$	Minimum depth of the compression zone to guarantee water-tightness in elements subjected to flexure
$X_{\text {sb }}$	Depth of the compression zone assuming a stress block
$X_{\mathrm{u}}$	Depth of the neutral axis at ultimate limit state
$Z$	Inner lever arm of internal forces for shear design
$Z_{\text {cp }}$	Distance between the centroid of the concrete section and the tendons
$Z_{\text {red }}$	Reduced depth of section at segment joint due to joint opening

​

3.2.3 Greek letters

$\alpha$	Angle; ratio
$\alpha$	Inclination of reinforcement across interface
$\alpha_{\text {bend }}$	Bend angle
$\alpha_{\mathrm{bs}}$	Coefficient accounting for the effect of the strength class of cement on basic shrinkage
$\alpha_{\mathrm{c}}$	Function to determine tangent modulus of elasticity of concrete
$\alpha_{\mathrm{c}, \text { th }}$	Coefficient of thermal expansion of concrete
$\alpha_{\mathrm{ds}}$	Coefficients accounting for the effect of the strength class of cement on drying shrinkage
$\alpha_{\mathrm{e}}$	Modular ratio, $\alpha_{\mathrm{e}}=E_{\mathrm{s}} / E_{\mathrm{c}}$
$\alpha_{\mathrm{e}, \mathrm{ef}}$	Modular ratio, $\alpha_{\text {e,ef }}=E_{\mathrm{s}} / E_{\text {c,eff }}$
$\alpha_{\mathrm{fcm}}$	Coefficient accounting for the effect of concrete strength on time evolution of drying creep
$\alpha_{\mathrm{h}}$	Reduction coefficient for length or height
$\alpha_{\mathrm{lb}}$	Factor accounting for cracks along post-installed bar
$\alpha_{\mathrm{m}}$	Reduction coefficient for number of members
$\alpha_{\text {NDP, b, }} \alpha_{\text {NDP, } \mathrm{d}}$	Coefficient to determine basic shrinkage and drying shrinkage, respectively
$\alpha_{\mathrm{R}}$	Sensitivity factor for the reliability of the resistance
$\alpha_{\text {RA }}$	Substitution rate of recycled concrete aggregates
$\alpha_{\text {SC }}$	Exponent accounting for the strength class of cement on the adjusted loading age
$\alpha_{\mathrm{s}, \mathrm{th}}$	Coefficient of thermal expansion of reinforcement
$\alpha_{\mathrm{v}}$	Angle between the principal shear force and the $x$-axis

$\alpha_{\mathrm{w}}$	Angle between shear reinforcement and the member axis perpendicular to the shear force
$\alpha_{1}, \alpha_{2}$	Coefficients for determination of transmission length
$\alpha_{3}$	Coefficient for determination of anchorage length considering type of verification (fatigue or other)
$\alpha_{\mu}$	Sum of the absolute values of angular displacements over a distance for the calculation of prestressing losses due to friction
$\beta_{\text {tgt }}$	Target value of reliability index
$\beta_{\text {new }}$	Ratio of longitudinal force in new concrete due to composite action
$\beta_{\text {incl }}$	Angle of inclined cross-sections for determining the shear resistance in case of direct: strutting in deep beams or in presence of concentrated loads near to the support
$\beta_{\mathrm{bc}, \mathrm{fcm}}$	Coefficient accounting for the effect of concrete strength on the basic creep coefficient
$\beta_{\text {bc,t-t0 }}$	Coefficient describing the evolution with time of basic creep and accounting for age of loading
$\beta_{\mathrm{bs}, \mathrm{t}}$	Coefficient describing the evolution with time of basic shrinkage
$\beta_{\mathrm{c}}$	Coefficient which depends on the distribution of $1^{\text {st }}$ and $2^{\text {nd }}$ order moments
$\beta_{\mathrm{cc}}(t)$	Coefficient for determining the compressive concrete strength which depends on the age of the concrete $t$
$\beta_{\mathrm{dc}, \mathrm{fcm}}$	Coefficient accounting for the effect of concrete strength on the drying creep coefficient
$\beta_{\mathrm{dc}, \mathrm{RH}}$	Coefficient accounting for the effect of relative humidity on the drying creep coefficient
$\beta_{\mathrm{dc}, \mathrm{to}}$	Coefficient accounting for the effect of age of loading on the drying creep coefficient
$\beta_{\mathrm{dc}, \mathrm{t}-\mathrm{t} 0}$	Coefficient describing the evolution with time of drying creep and accounting for the effect of notional size and age at loading
$\beta_{\mathrm{ds}, \mathrm{t}-\mathrm{ts}}$	Coefficient describing the evolution with time of drying shrinkage and accounting for the effect of notional size
$\beta_{\mathrm{e}}$	Coefficient accounting for concentrations of the shear forces along a control perimeter
$\beta_{\text {Eul }}$	Euler coefficient
$\beta_{\text {fck }}$	Coefficient accounting for concrete strength and slenderness, used in the nominal curvature method
$\beta_{\mathrm{h}}$	Coefficient accounting for the effect of notional size and concrete strength on the time development of drying creep
$\beta_{\mathrm{p}}$	Angle between the tendon and the axis of the member, for the sign, the angle indicated in Figure 8.4 is positive
$\beta_{\text {RH }}$	Coefficient accounting for the effect of relative humidity on drying shrinkage
$\beta_{\mathrm{t}}$	Coefficient to account for duration of loading or of repeated loading on average strain
$\gamma$	Partial factor (safety and serviceability)
$\gamma\left(t_{0, \text { adj }}\right)$	Exponent accounting for the influence of age of loading in the time development of drying creep
$\gamma_{\mathrm{C}}$	Partial factor for concrete

$\gamma_{\text {CE }}$	Partial factor for the modulus of elasticity of concrete
$\gamma_{\mathrm{F}}$	Partial factor for actions, also accounting for model uncertainties and dimensional variations
$\gamma_{\text {Ff }}$	Partial factor for fatigue actions
$\gamma_{\mathrm{m}}$	Partial factor for a material property
$\gamma_{\mathrm{P}}$	Partial factor for prestressing actions $P$
$\gamma_{\mathrm{P}, \text { fav }}, \gamma_{\mathrm{P}, \text { unfav }}$	Partial factor for favourable and unfavourable prestress effects
$\gamma_{\Delta \mathrm{P}, \text { sup },} \gamma_{\Delta \mathrm{P}, \text { inf }}$	Partial factors for change in stress in unbonded prestressing tendons associated with deformation of the member
$\gamma_{\mathrm{Q}}$	Partial factor for variable actions $Q$; also accounting for model uncertainties and dimensional variations
$\gamma_{\mathrm{R}}{ }^{*}$	Global resistance factor accounting for the uncertainties related to the material properties, geometrical dimensions and the resisting model
$\gamma_{\text {Rd }}$	Partial factor associated with the uncertainty of the resistance model
$\gamma_{\mathrm{S}}$	Partial factor for reinforcing or prestressing steel
$\gamma_{\text {sh }}$	Partial factor for shrinkage action
$\gamma_{\mathrm{v}}$	Partial factor for shear and punching resistance without shear reinforcement
$\gamma_{\text {water }}$	Specific weight of water
$\gamma_{\theta}$	Partial factor for model uncertainty
$\delta$	Deflection
$\delta_{0, \mathrm{Eqp}}$	Maximum short-term horizontal deflection due to the quasi permanent load combination determined assuming uncracked cross-sections
$\delta_{\text {Ed }}$	Maximum short-term horizontal deflection due to the fundamental load combinations from a first order analysis determined assuming uncracked cross-sections
$\delta_{\text {loads }}$	Linear elastic deflection due to the relevant combination of actions
$\delta_{\mathrm{M}}$	Ratio of the redistributed moment to the elastic bending moment
$\delta_{\varepsilon c \mathrm{~s}}$	Linear elastic deflection due to shrinkage
$\varepsilon_{\mathrm{c}}$	Compressive strain in the concrete
$\varepsilon_{\mathrm{c} 1}$	Strain at maximum stress
$\varepsilon_{\mathrm{c} 2}$	Compressive strain in the concrete at the peak stress $f_{\mathrm{c}}$
$\varepsilon_{\mathrm{c} 2, \mathrm{c}}$	Value of $\varepsilon_{\mathrm{c} 2}$ in case of confined concrete
$\varepsilon_{\text {cbs }}$	Basic shrinkage strain
$\varepsilon_{\text {cbs,fcm }}$	Notional basic shrinkage coefficient, accounting for the effect of concrete strength and strength class of cement on basic shrinkage
$\varepsilon_{\mathrm{ci}}\left(t_{0}\right)$	Elastic strain due to a constant stress $\sigma_{\mathrm{c}}\left(t_{0}\right)$ applied at time $t_{0}$
$\varepsilon_{\mathrm{cc}}\left(t, t_{0}\right)$	Creep strain due to a constant stress $\sigma_{\mathrm{c}}\left(t_{0}\right)$ applied at time $t_{0}$
$\mathcal{E}_{\text {cds,fcm }}$	Notional drying shrinkage coefficient, accounting for the effect of concrete strength and strength class of cement on drying shrinkage

$\varepsilon_{\mathrm{cm}}$	Mean strain in the concrete between cracks at the same level of $\varepsilon_{\text {sm }}$
$\varepsilon_{\mathrm{cs}}$	Shrinkage strain
$\varepsilon_{\text {cu }}$	Ultimate compressive strain in the concrete
$\varepsilon_{\text {cu,c }}$	Value of $\varepsilon_{\text {cu }}$ in case of confined concrete
$\varepsilon_{\text {cds }}$	Drying shrinkage strain
$\varepsilon_{\mathrm{c} \sigma}\left(t, t_{0}\right)$	Time-dependent strain due to a constant stress $\sigma_{\mathrm{c}}\left(t_{0}\right)$ applied at time $t_{0}$
$\varepsilon_{\mathrm{c} \sigma}\left(t, \sigma_{\mathrm{c}}\right)$	Time-dependent strain due to a stress history $\sigma_{\mathrm{c}}(t)$
$\mathcal{E}_{\text {free }}$	Imposed strain
$\varepsilon_{\text {imp }}$	Imposed strain in element
$\varepsilon_{\mathrm{p}}$	Strain in the prestressing steel
$\varepsilon_{\mathrm{p}(0)}$	Strain difference between prestressing steel and surrounding concrete
$\Delta \varepsilon_{\mathrm{p}}$	Strain increase in the prestressing steel
$\mathcal{E}_{\text {restr }}$	Strain developing in restrained element
$\varepsilon_{\mathrm{s}}$	Strain in reinforcing steel
$\varepsilon_{\text {sm }}$	Mean strain in the reinforcement closest to the most tensioned concrete surface under the relevant combination of actions, including the effect of imposed deformations and taking into account the effects of tension stiffening. Only the additional tensile strain beyond the state of zero strain of the concrete at the same level is considered
$\varepsilon_{\text {ud }}$	Design strain of reinforcing and prestressing steel at maximum load
$\varepsilon_{\text {uk }}$	Characteristic strain of reinforcement or prestressing steel at maximum load
$\varepsilon_{\text {yd }}$	Design yield strain of reinforcement
$\varepsilon_{\mathrm{x}}$	Average strain in x-direction, of the flexural chords under tension and compression
$\varepsilon_{\mathrm{xt}}, \varepsilon_{\mathrm{xc}}$	Strain in flexural chords under tension and compression
$\varepsilon_{1}$	Value of the maximum principal tensile strain in concrete
$\varepsilon_{2}$	Value of maximum principal compressive strain in membrane element
$\zeta$	Distribution coefficient allowing for tension stiffening at a section
$\zeta_{\mathrm{f}}$	Reduction factor for fatigue strength of bent bar
$\eta$	Ratio of strains used to define stress strain model
$\eta_{1}$	Coefficient for determination of transmission length of pretensioning tendon accounting for position during concreting
$\eta_{\mathrm{c}}$	Strength reduction coefficient for shear resistance $\tau_{\text {Rd,c }}$
$\eta_{\mathrm{cc}}$	Factor to account for the difference between the undisturbed compressive strength of a cylinder and the effective compressive strength that can be developed in the structural component
$\eta_{\mathrm{cc}, \mathrm{fat}}$	Value of $\eta_{\text {cc }}$ for fatigue actions
$\eta_{\text {lw,Ec }}$	Coefficient related to $E_{\mathrm{c}}$ in lightweight concrete
$\eta_{\text {lw,fc }}$	Coefficient related to $f_{\mathrm{c}}$ in lightweight concrete
$\eta_{\text {lw,fct }}$	Coefficient related to $f_{\mathrm{ct}}$ in lightweight concrete

$\eta_{\mathrm{pm}}$	Coefficient accounting for the influence of membrane forces due to restrained deformations on the shear slenderness of slabs submitted to concentrated forces for existing structures
$\eta_{\mathrm{s}}$	Strength reduction coefficient for the contribution of the shear reinforcement
$\eta_{\text {sys }}$	Coefficient accounting for the performance of punching shear reinforcing systems
$\eta_{\text {visc }}$	Dynamic viscosity
$\theta$	Angle between the compression field and the member axis; rotation under bending moment
$\theta_{\text {cf }}$	Spreading angle of a concentrated force
$\theta_{\text {cs }}$	Angle between the compression field and a tie
$\theta_{\mathrm{f}}$	Angle between the compression field in a flange and the longitudinal axis
$\theta_{\text {fat }}$	Angle between the compression field and the member axis under fatigue actions
$\theta_{\mathrm{i}}$	Inclination representing a geometrical imperfection
$\theta_{\text {min }}$	Minimum allowed value of $\theta$
$\Theta_{\text {Rd }}$	Rotation capacity
$\Theta_{\text {Ed }}$	Rotation demand
$\lambda$	Slenderness ratio $l_{0} / i$
$\lambda_{\mathrm{c}}$	Correction factor to calculate upper and lower stresses of damage equivalent stress spectrum caused by LM71
$\lambda_{c, 0}, \lambda_{c, 1}, \lambda_{c, 2,3}, \lambda_{c, 4}$	Factor accounting for permanent stress, member type, traffic volume and design service life, number of loaded tracks
$\lambda_{\text {lim }}$	Limiting slenderness for isolated members below which second order effects may be neglected
$\lambda_{\mathrm{s}}$	Damage equivalent factor for fatigue
$\lambda_{\mathrm{s}, 1}, \lambda_{\mathrm{s}, 2}, \lambda_{\mathrm{s}, 3}, \lambda_{\mathrm{s}, 4}$	Factor accounting for member type, traffic volume, design service life, number of loaded lanes/tracks
$\lambda_{\text {y }}$	Slenderness ratio, $l_{0} / i_{y}$ with respect to the $y$-axis
$\lambda_{\mathrm{z}}$	Slenderness ratio, $l_{0} / i_{\mathrm{z}}$ with respect to the $z$-axis
$\mu$	Coefficient of friction between the tendons and their ducts
$\mu_{\mathrm{v}}$	Coefficient of friction at concrete interfaces
$\mu_{\mathrm{v}, \mathrm{fat}}$	Coefficient of friction at concrete interfaces for fatigue action
$v$	Strength reduction factor for concrete cracked due shear or other actions
$\nu_{\text {part }}$	Confinement factor of partially loaded area; factor for capacity of headed bars
$\xi$	Ratio of bond strength of prestressing and reinforcing steel
$\xi_{1}$	Adjusted ratio of bond strength taking into account the different diameters of prestressing and reinforcing steel
$\xi_{\mathrm{bc} 1}$	Adjustment parameter for basic creep to account for test results
$\xi_{\mathrm{bc} 2}$	Adjustment parameter for time development function of basic creep to account for test results

$\xi_{\text {bs1 }}$	Adjustment parameter for basic shrinkage to account for test results
$\xi_{\mathrm{bs} 2}$	Adjustment parameter for time development function of basic shrinkage to account for test results
$\xi_{\text {dc1 }}$	Adjustment parameter for drying creep to account for test results
$\xi_{\mathrm{dc} 2}$	Adjustment parameter for time development function of drying creep to account for test results
$\xi_{\mathrm{ds} 1}$	Adjustment parameter for drying shrinkage to account for test results
$\xi_{\mathrm{ds} 2}$	Adjustment parameter for time development function of drying shrinkage to account for test results
$\xi_{\mathrm{v}}$	Effective damping ratio (vibrations)
$\xi_{\mathrm{v}, \mathrm{st}}$	Structural component of effective damping ratio (vibrations)
$\rho$	Reinforcement ratio
$\rho_{\mathrm{c}}$	Oven-dry density of concrete in $\mathrm{kg} / \mathrm{m}^{3}$
$\rho_{\text {conf }}$	Ratio of the reinforcement providing confinement referred to the diameter of the bar to be anchored or spliced
$\rho_{\mathrm{i}}$	Ratio of bonded reinforcement across interface
$\rho_{\mathrm{l}}$	Reinforcement ratio for bonded longitudinal reinforcement in the tensile zone due to bending referred to the nominal concrete area $d \cdot b_{\mathrm{w}}$
$\rho_{\mathrm{l}, \mathrm{x},} \rho_{\mathrm{l}, \mathrm{y}}$	Value of $\rho_{1}$ in $x$-and $y$-directions, respectively
$\rho_{\text {min }}$	Minimum reinforcement ratio
$\rho_{\mathrm{p}}$	Tensile reinforcement ratio accounting for the different bond properties of reinforcing bars and prestressing tendons
$\rho_{\text {p,eff }}$	Tensile reinforcement ratio accounting for the different bond properties of reínforcing bars and prestressing tendons, referred to the effective concrete area
$\rho_{\mathrm{w}}$	Shear reinforcement ratio
$\rho_{\mathrm{w}, \text { min }}$	Minimum shear reinforcement ratio
$\rho_{\mathrm{w}, \text { stir }}$	Minimum ratio of shear and torsion reinforcement in the form of stirrups
$\rho_{\mathrm{x}}, \rho_{\mathrm{y}}$	Reinforcement ratio in x - and y -directions, respectively
$\rho_{1000}$	Value of relaxation loss (in %), at 1000 hours after tensioning and at a mean temperature of $20^{\circ} \mathrm{C}$
$\sigma_{1 \text { Ed }}$	Design value of principal tensile stress in uncracked concrete in pretensioned member
$\sigma_{\mathrm{a}}$	Stress range (2 $\sigma_{\mathrm{a}}$ )
$\sigma_{\mathrm{c}}$	Compressive stress in the concrete
$\sigma_{\text {cable }}$	Tensile stress in stay and extradosed cable
$\sigma_{\mathrm{cd}}$	Design value of compressive stress in the concrete
$\sigma_{\text {cd,max,equ }}$, $\sigma_{\mathrm{cd}, \text { min, equ }}$	Upper and lower stress of damage equivalent stress amplitude for $N=10^{6}$ cycles, respectively
$\sigma_{\mathrm{cd}, \text { max }, \mathrm{i},} \sigma_{\mathrm{cd}, \text { min }, \mathrm{i}}$	Maximum and minimum compressive stress in stress level i
$\sigma_{\text {cp }}$	Axial stress

$\sigma_{\mathrm{cp}, \mathrm{QP}}$	Stress in the concrete adjacent to the tendons, due to self-weight and initial prestress and other quasi-permanent actions where relevant.
$\sigma_{\mathrm{ct}}$	Tensile stress in concrete
$\sigma_{\mathrm{c} 2 \mathrm{~d}}$	Design value of the transverse stress in concrete due to confinement or minimum transverse compression stress due to external actions (compression positive)
$\sigma_{\mathrm{c}, \mathrm{lim}}$	Limited compressive stress for shear strength in plain concrete
$\sigma_{\text {ccd }}$	Design value of the mean compression stress perpendicular to a free surface near bars to be anchored or spliced
$\sigma_{\mathrm{d}}$	Design value of the average stress, tension positive
$\sigma_{\text {Edx }}, \sigma_{\text {Edy }}, \tau_{\text {Edxy }}$	Membrane stresses
$\sigma_{\mathrm{gd}}$	Design value of ground pressure
$\sigma_{\mathrm{n}}$	Compressive stress across interface
$\sigma_{\mathrm{p}}$	Stress in prestressing steel
$\Delta \sigma_{\mathrm{p}}$	Stress variation in prestressing tendon from state of zero strain
$\sigma_{\mathrm{p}, \text { max }}$	Maximum prestressing stress imposed at the active end by the jack
$\sigma_{\text {pd }}$	Design value of the stress in the tendon
$\sigma_{\text {pi }}$	Initial stress in prestressing steel
$\sigma_{\text {pk,inf }}$	Lower characteristic value of prestress
$\sigma_{\text {pk,sup }}$	Upper characteristic value of prestress
$\sigma_{\mathrm{p}, \mathrm{m}}(\mathrm{x}, \mathrm{t})$	Mean value of the prestressing stress after accounting for the immediate losses and the time-dependent losses at time $t$ and a distance $x$ from the active end
$\sigma_{\text {pm0 }}$	Tendon stress immediately after release
$\sigma_{\text {pm }, \infty}$	Long-term stress level in prestressing tendons at the state of zero (elastic) strain of the concrete at the same level
$\sigma_{\text {Rdu }}$	Design resistance of partially loaded area
$\sigma_{\mathrm{s}}$	Serviceability value of steel stress, determined on the basis of a cracked section
$\sigma_{\text {sd }}$	Design value of the reinforcing steel stress at the cross-section
$\sigma_{\text {sd }}{ }^{\prime}$	Maximum tensile stress in the reinforcing steel of headed bars developed by the head
$\sigma_{\mathrm{s}, \text { lim }}$	Limiting value of the serviceability steel stress in order to comply with a given limiting crack width
$\sigma_{\text {sr }}$	Stress in the tension reinforcement calculated on the basis of a cracked section under the loading conditions causing first cracking
$\sigma_{\text {swd }}$	Design value of the stress in the shear reinforcement
$\sigma_{\text {uk }}$	Characteristic breaking strength of stay and extradosed cable
$\Delta \sigma_{\text {freq }}$	Variation of tensile stress in stay or extradosed cable under frequent traffic loads
$\Delta \sigma_{\mathrm{p}, \mathrm{c}+\mathrm{s}+\mathrm{r}}$	Time dependent losses of prestress
$\Delta \sigma_{\mathrm{pd}}$	Design value of stress increase in tendon; design value of stress range in prestressing steel under fatigue load combination

$\Delta \sigma_{\mathrm{pr}}$	Absolute value of the variation of stress in the tendons at location $x$, at time $t$, due to the relaxation of the prestressing steel
$\Delta \sigma_{\mathrm{p}, \text { ULS }}$	Increase of the stress from the effective prestress to the stress in the ultimate limit state for prestressed members with permanently unbonded tendons
$\Delta \sigma_{\mathrm{p}, \mu}$	Prestressing losses due to friction
$\Delta \sigma_{\text {Rsk }}$	Stress range resistance at $N^{*}$ cycles from relevant $S$ - $N$ curve
$\Delta \sigma_{\text {sd }}$	Design value of stress range in reinforcing steel under fatigue load combination
$\Delta \sigma_{\mathrm{s}, \max }$	Maximum reinforcing steel stress range under relevant load combination
$\Delta \sigma_{\text {s,equ }}$	Damage equivalent stress range for reinforcement
$\Delta \sigma_{\theta}$	Thermal loss induced by heat treatment
$\tau_{\mathrm{cp}}$	Shear stress in the concrete from acting shear force
$\tau_{\text {Ed }}$	Average acting shear stress over a cross-section
$\tau_{\text {Ed,i }}$	Design value of the shear stress at interfaces
$\tau_{\text {Rd }}$	Shear resistance governed either by yielding of shear reinforcement or crushing of concrete
$\tau_{\text {Rd,c }}$	Shear stress resistance of members without shear reinforcement (average shear stress over a cross-section)
$\tau_{\text {Rdc,min }}$	Minimum shear stress resistance allowing to avoid a detailed verification for shear (average shear stress over a cross-section)
$\tau_{\text {Rd,cs }}$	Shear stress resistance of planar members with shear reinforcement subjected to concentrated forces
$\tau_{\mathrm{Rd}, \mathrm{i}}$	Shear stress resistance at interfaces
$\tau_{\text {Rdm }}$	Shear stress resistance reduced by influence of transverse bending
$\tau_{\text {Rd,max }}$	Maximum shear stress resistance of planar members with shear reinforcement subjected to concentrated forces
$\tau_{\text {Rd,pl }}$	Design strength of plain concrete in shear
$\tau_{\text {Rd,sy }}$	Shear stress resistance governed by yielding of shear reinforcement
$\tau_{\mathrm{t}, \mathrm{i}}$	Torsional shear stress in wall i
$\tau_{\mathrm{t}, \mathrm{Rd}}$	Torsional shear stress resistance
$\tau_{\mathrm{t}, \mathrm{Rd}, \mathrm{sw}}, \tau_{\mathrm{t}, \mathrm{Rd}, \mathrm{sl}}$, $\tau_{\mathrm{t}, \mathrm{Rd}, \max }$	Torsional shear stress resistance governed by yielding of shear reinforcement, by yielding of longitudinal reinforcement or by crushing of the concrete in the compression field
$\phi$	Diameter of a reinforcing bar
$\phi_{\mathrm{b}}$	Equivalent diameter of a bundle of reinforcing bars
$\Phi_{\mathrm{c}}$	Diameter of confinement reinforcement
$\phi_{\text {duct }}$	Outer diameter of a post-tensioning duct
$\phi_{\text {eq }}$	Equivalent bar diameter for bond calculations when tensile reinforcement is composed by bars of different diameters
$\phi_{\mathrm{h}}$	Diameter of circular head of headed bar

$\phi_{\text {mand }}$	Mandrel diameter for bent reinforcement bars
$\phi_{\text {mand,min }}$	Minimum value of $\phi_{\text {mand }}$
$\phi_{\mathrm{p}}$	Nominal diameter of the pretensioning tendon
$\phi_{\mathrm{p}, \mathrm{eq}}$	Equivalent diameter of tendons
$\phi$	Diameter of transverse reinforcement between the bar to be anchored and the free surface; diameter of welded transverse bar
$\phi_{\text {trans }}$	Diameter of transverse bars within bend
$\phi_{\mathrm{w}}$	Diameter of of punching shear reinforcement
$\phi_{\mathrm{w}, \text { max }}$	Maximum diameter of punching shear reinforcement
$\Phi$	Factor taking into account eccentricity, including second order effects; dynamic factor for railway bridges
$\varphi$	Damage equivalent impact factor $\varphi_{\text {at }}$ or $\Phi$ for road and railway bridges
$\varphi\left(t, t_{0}\right)$	Creep coefficient, defining creep between times $t$ and $t_{0}$, related to elastic deformation at 28 days
$\varphi\left(50 \mathrm{y}, t_{0}\right)$	Creep coefficient after 50 years of loading
$\varphi_{0,05}, \varphi_{\mathrm{k} ; 0,05}$	Lower-bound value and characteristic value of creep coefficient corresponding to a 5 % cut-off, based on a normal distribution
$\varphi_{0,10}, \varphi_{\mathrm{k} ; 0,10}$	Lower-bound value and characteristic value of creep coefficient corresponding to a 10 % cut-off, based on a normal distribution
$\varphi_{0,90}, \varphi_{\mathrm{k} ; 0,90}$	Upper-bound value and characteristic value of creep coefficient corresponding to a 90 % cut-off, based on a normal distribution
$\varphi_{0,95}, \varphi_{\mathrm{k} ; 0,95}$	Upper-bound value and characteristic value of creep coefficient corresponding to a 95 % cut-off, based on a normal distribution
$\varphi_{\mathrm{bc}}\left(t, t_{0}\right)$	Basic creep coefficient
$\varphi_{\mathrm{dc}}\left(t, t_{0}\right)$	Drying creep coefficient
$\varphi_{\text {eff,b }}$	Effective creep ratio for local second order effects
$\varphi_{\text {eff,s }}$	Effective creep ratio for global second order effects
$\varphi_{\sigma}\left(t, t_{0}\right)$	Creep coefficient, adjusted for non-linearity due to concrete stresses above $0,4 f_{\mathrm{cm}}$
$\chi$	Aging coefficient which may be taken equal to 0,8 for long term calculations
$\omega$	Mechanical reinforcement ratio
$\omega_{\mathrm{r}}$	Required mechanical tension reinforcement ratio at mid-span to resist the moment due to the design loads (at support for cantilevers)

​

3.3 Symbols in Annex A

​

3.3.1 Latin upper case letters

$V_{i}$	Coefficient of variation of the variable $i$
$V_{R M}$	Coefficient of variation of the resistance

​

3.3.2 Latin lower case letters

$f_{\text {c,ais }}$	Actual insitu concrete compressive strength in the structure
$f_{\mathrm{c}, \mathrm{is}}$	Compressive strength of a core taken at a test location within a structural element or precast concrete component expressed in terms of the strength of a $2: 1$ core of diameter $\geq 75 \mathrm{~mm}$
$f_{y m}$	Mean value of yield strength of reinforcing steel or, if yield phenomenon is not present, the characteristic value of 0,2 % proof strength

​

3.3.3 Greek lower case letters

$\alpha_{\mathrm{R}}$	Sensitivity factor for the reliability of the resistance
$\beta_{\text {tgt }}$	Target value of reliability index
$\gamma_{\mathrm{M}}$	Partial material factor
$\mu_{i}$	Bias factor of the variable $i$ defined as ratio $X_{i, \mathrm{~m}} / X_{i, \mathrm{k}}$
$\eta_{\text {is }}$	Insitu factor of the concrete compressive strength defined as ratio $f_{\text {c,ais }} / f_{\mathrm{c}}$
$\mu_{\text {RM }}$	Bias factor of resistance

​

3.4 Symbols in Annex I

​

3.4.1 Latin upper case letters

AAR	Alkali-aggregate reaction
$A_{\text {sq }}$	Cross-sectional area of a square plain bar
$D_{\text {max }}$	Declared value of the upper sieve size of the coarsest fraction of aggregates used in concrete
$D E F$	Delayed ettringite formation
$P_{\mathrm{x}}$	Corrosion penetration depth
$V_{\text {fc,is }}$	Coefficient of variation of $f_{\mathrm{c}, \text { is }}$
$V_{\text {fc,is,lim }}$	Limit value of $V_{\mathrm{fc}, \mathrm{is}}$ for the adjustment of the partial factors for concrete
$V_{\text {fy }}$	Coefficient of variation of yield strength of reinforcement
$V_{\text {fy,lim }}$	Limit value of $V_{\text {fy }}$ for the adjustment of the partial factor for reinforcement
$V_{\mathrm{x}}$	Coefficient of variation of the material property $X$
$X_{\mathrm{k}}$	Characteristic value of the material property

​

3.4.2 Latin lower case letters

$b_{\mathrm{w}, i}, b_{\mathrm{w}, i-1}$, $b_{\mathrm{w}, i+1}$	Coefficients to evaluate $b_{\mathrm{w}}$ for shear resistance in case of shear reinforcement not fulfilling the maximum longitudinal spacing of shear assemblies/stirrups or bent-up bars given in Clause 12
$c_{\mathrm{f}}$	Additional distance with respect to concentrated loads of reaction forces acting on compression flanges
$c_{\text {min, xy }}$	Minimum value of concrete cover between $c_{\mathrm{x}}$ and $c_{\mathrm{y}}$ for designing the anchorage in case of low concrete cover

$d_{\text {sys }}$	Relevant depth considered for determination of $\eta_{\text {sys }}$
$f_{\text {ck }, \text { is }}$	Characteristic in-situ compressive strength of concrete cores expressed in terms of the strength of a $2: 1$ core of diameter $\geq 75 \mathrm{~mm}$ (5 % fractile)
$f_{\mathrm{ck}, \mathrm{ft}}$	Residual characteristic compressive cylinder strength of concrete
$f_{\text {ctk,is; } 0,05}$	Characteristic measured insitu axial tensile strength of concrete (5% fractile)
$k_{\text {lbs,c }}$	Coefficient for bond calculation in case of low concrete cover
$k_{n}$	Characteristic fractile factor for a sample size $n$
$k_{\mathrm{ns}}$	Coefficient for shear stress resistance of members with shear reinforcement
$k_{\text {part }}$	Coefficient for determining $\sigma_{\mathrm{Rdt}}$
$k_{\mathrm{vd}}$	Coefficient for shear stress resistance of members without shear reinforcement
$k_{\mu \mathrm{fc}}$	Parameter to be used to evaluate $f_{\mathrm{ck}}$ from $f_{\mathrm{ck}, i \mathrm{~s}}$ and that account for the representativeness of the insitu compressive concrete strength
$m_{x}$	Mean value of the variable $X$ from $n$ sample results
$n$	Number of test results
$s_{X}$	Estimated value of the standard deviation of the variable $X$ from $n$ sample results
$x_{i}$	Basic variable $i$

​

3.4.3 Greek lower case letters

$\gamma_{\text {def }}$	Partial factor covering uncertainties related to calculation of deformations
$\delta_{1}, \delta_{2}$	Coefficients for the design value of the reinforcement stress at the cross-section to be anchored by bond over $l_{\text {bd }}$ in case of bends and hooks
$\eta_{1} \eta_{2} \eta_{3} \eta_{4}$	Coefficients for the design anchorage length $l_{\mathrm{bd}}$ for plain bars
$\sigma_{\text {sd }}^{\prime}$	Design value of the reinforcement stress at the cross-section to be anchored by bond over $l_{\text {bd }}$ in case of bends and hooks
$\sigma_{\mathrm{Rd}, \mathrm{t}}$	Maximum design stress applied to partially loaded area not requiring transverse reinforcement
$\Delta \sigma_{\text {sd }}$	Design value of the reinforcement stress at the cross-section developed by bends and hooks
$\phi_{\text {sq }, \text { eq }}$	Equivalent bar diameter for bond calculation of square cross-section bars
$\psi$	Maximum rotation of slab around supporting area

​

3.5 Symbols in Annex J

​

3.5.1 Latin upper case letters

$A_{\mathrm{f}}$	Cross-sectional area of a CFRP system
$D$	Diameter of circular column section
$D_{\mathrm{eq}}$	Equivalent diameter of member with rectangular cross section
$E_{\mathrm{f}}$	Mean modulus of elasticity in longitudinal direction of ABR CFRP

$F_{\text {bfRd }}$	Design bond force resistance of the ABR CFRP
$F_{\text {bsm }}$	Bond strength per unit length
$F_{\text {fEd,cr }}$	Force in CFRP at first crack in the strengthened area
$F_{\text {f,NSM,max }}$	The maximum force in the NSM CFRP system, taking the shift of the tension envelope into account
$\Delta F_{f, \min }$	Minimum value of $\Delta F_{\mathrm{f}}$ under the fatigue load combination
$\Delta F_{f, \max }$	Maximum value of $\Delta F_{\mathrm{f}}$ under the fatigue load combination
$\Delta F_{\mathrm{f}}$	Force change in CFRP under the fatigue load combination
$\Delta F_{\text {fEd }}$	Difference in FRP tension force between cracks
$\Delta F_{\text {fEd,fat }}$	Design difference in the change in force in the CFRP system between cracks
$\Delta F_{\text {fRd,fat1 }}$	Fatigue resistance limited by an elastic response in the bond of the CFRP to the concrete surface
$\Delta F_{\text {frd,fat2 }}$	Fatigue resistance of the CFRP system subject to N* stress cycles
$\Delta F_{\text {fRd }}$	Bond resistance between cracks
$\Delta F_{\text {fE,equ }}$	Maximum difference in CFRP stress under the relevant load combination between cracks
$N^{*}$	Number of stress cycles
$V_{\text {Rd,cfE }}$	Design resistance against concrete cover separation

​

3.5.2 Latin lower-case letters

$a_{\mathrm{fE}}$	Distance from end of CFRP flexural strengthening to adjacent point of zero bending moment
$a_{\mathrm{r}}$	Distance of adhesively bonded CFRP reinforcement from free edge
$b_{\mathrm{f}}$	Width of the adhesively bonded CFRP reinforcement sheets or strips or square bars
$b_{\text {slot }}$	Width of slot for NSM CFRP reinforcement
$c_{\text {fat }}$	Reduction factor taking into account the stress cycles
$f_{\text {bfRd }}$	Design bond strength of the anchorage
$f_{\mathrm{bsm}}$	Mean bond stress of reinforcing steel
$f_{\text {ctm,surf }}$	Mean surface tensile strength of concrete
$f_{\text {Ack }}$	Characteristic compressive strength of the adhesive
$f_{\text {Atk }}$	Characteristic tensile strength of the adhesive
$f_{\text {fud }}$	Ultimate design short-term tensile strength of the ABR CFRP
$f_{\text {fuk }}$	Characteristic short-term tensile strength of the ABR CFRP
$f_{\text {fwd }}$	Design shear strength of the CFRP system
$\Delta f_{\text {fED }}$, $\Delta f_{\text {fED, max }}$	Difference and maximum difference in CFRP stress between cracks, respectively
$\Delta f_{\text {fk, } \mathrm{B}}$	Basic value of adhesive bond strength between cracks

$\Delta f_{\text {flk, } \mathrm{C}}$	Increase of bond strength between cracks resulting from clamping from curvature of the beam
$\Delta f_{\text {frk }, \mathrm{F}}$	Increase of bond strength between cracks resulting from bond friction
$\Delta f_{\text {fRd }}$	Bond resistance between adjacent cracks
$h_{\mathrm{f}}$	Height of CFRP shear reinforcement crossing shear crack
$k_{\mathrm{cc}}$	Confinement factor for columns strengthened with CFRP
$k_{\mathrm{c}, \text { surf }}$	Coefficient considering the concreting position for estimation of surface tensile strength
$k_{\mathrm{e}}$	Confinement effectiveness factor for rectangular columns
$k_{\mathrm{f}}$	Coefficient for determining the effective thickness for a number of layers
$k_{\mathrm{h}}$	Confinement effectiveness factor for helical wrapping
$k_{\mathrm{f} 3}$	Exponent for determining factor for stress cycles
$k_{\mathrm{r}}$	Factor considering corner radius
$k_{\text {sys,b1, }}$	Product-specific system factor
$k_{\text {sys,b2, }}$
$k_{\text {sys,b3 }}$
$l_{\mathrm{bf}}$	Bond length of the adhesively bonded CFRP reinforcement
$l_{\text {bf,max,k }}$	Characteristic maximum value of effective bond length of ABR CFRP
$n_{\mathrm{f}}$	Number of CFRP layers
$r_{\mathrm{c}}$	Corner radius
$S_{\mathrm{f}}$	Centre to centre spacing of FRP strips
$s_{\text {f0k }}$	Maximum bond slip
$S_{\text {cr } \text { min }}$	Minimum spacing of bending cracks
$t_{\mathrm{f}}$	Nominal thickness of the adhesively bonded reinforcement
$t_{\text {slot }}$	Depth of slot for NSM CFRP reinforcement bar or strip

​

3.5.3 Greek lower-case letters

$\alpha_{\mathrm{bc}}$	Product-specific system factor for long-term behaviour of concrete
$\alpha_{\mathrm{bA}}$	Product-specific system factor for long-term behaviour of the adhesive
$\alpha_{\mathrm{f}}$	Angle formed between the CFRP system and longitudinal axis of a member in bending
$\alpha_{\text {fat2 }}$	Reduction factor for fatigue
$\beta_{1}$	Reduction factor for bond capacity taking account of anchorage length
$\beta_{\mathrm{f}}$	Angle formed between the CFRP system and the transverse axis of a column strengthened by CFRP confinement
$\gamma_{\mathrm{BA}}$	Partial factor for adhesively bonded CFRP reinforcement for bond
$\gamma_{\mathrm{f}}$	Partial factor for tensile strength of adhesively bonded CFRP reinforcement
$\varepsilon_{\text {fud }}$	Long-term design strain of adhesively bonded CFRP reinforcement
$\varepsilon_{\text {fuk }}$	Characteristic ultimate strain for the adhesively bonded CFRP reinforcement

$\eta_{\mathrm{f}}$	Reduction factor applied to the tensile stress of the EBR CFRP sheet or strip
$\Delta \sigma_{\mathrm{f}}$	Stress range of an NSM CFRP reinforcement subjected to fatigue
$\tau_{\text {bck }}$	Bond strength of concrete with NSM CFRP reinforcement strips
$\tau_{\text {bAk }}$	Bond strength of adhesive with NSM CFRP reinforcement strips
$\tau_{\text {bAd }}$	Design value of the shear stress resistance of adhesive
$\tau_{\text {Ed,f }}$	Design shear stress in adhesively bonded CFRP stirrups for shear induced crack separation
$\tau_{\text {f1k }}$	Maximum bond strength of adhesively bonded CFRP reinforcement
$\tau_{\text {Rd }}$	Design shear resistance of the member without shear strengthening
$\tau_{\text {Rd,CFRP }}$	Design shear resistance of a section with CFRP shear strengthening
$\tau_{\text {Rd,f }}$	Contribution of ABR CFRP shear strengthening to design shear resistance
$\phi_{\mathrm{f}}$	Diameter of NSM CFRP bars

​

3.6 Symbols in Annex L

​

3.6.1 Latin upper case letters

CMOD $_{1}$	$=0,5 \mathrm{~mm}$ is the crack width (Crack Mouth Opening Displacement) for which the characteristic residual flexural strength, $f_{\mathrm{R}, 1 \mathrm{k}}$, is determined (defined in EN 14651).
$C M O D_{3}$	$=2,5 \mathrm{~mm}$ is the crack width (Crack Mouth Opening Displacement) for which the characteristic residual flexural strength, $f_{\mathrm{R}, 3 \mathrm{k}}$, is determined (defined in EN 14651).
$A_{\text {ct }}$	Area of the tension zone ( $\mathrm{in} \mathrm{m}^{2}$ ) of the cross-section involved in the failure of an equilibrium system

​

3.6.2 Latin lower case letters

$f_{\mathrm{R}, 1 \mathrm{k}}$	Characteristic residual flexural strength at $C M O D_{1}=0,5 \mathrm{~mm}$ representing the residual strength class
$f_{\mathrm{R}, 3 \mathrm{k}}$	Characteristic residual flexural strength at $C M O D_{3}=2,5 \mathrm{~mm}$ representing the performance class
$f_{\text {Fts,ef }}$	Effective residual tensile strength for crack widths at the serviceability limit state accounting for fibre orientation
$f_{\text {Ft1,ef }}$	Effective residual tensile strength for crack width $=0,5 \mathrm{~mm}$ accounting for fibre orientation to be used in the constitutive law for bi-linear stress distribution
$f_{\text {Ftsd }}$	Design residual tensile strength for crack widths at the serviceability limit state accounting for fibre orientation
$f_{\text {Ft1d }}$	Design residual tensile strength for crack width $=0,5 \mathrm{~mm}$ accounting for fibre orientation to be used for bi-linear stress distribution
$f_{\text {Ft3,ef }}$	Effective residual tensile strength for crack width $=2,5 \mathrm{~mm}$ accounting for fibre orientation to be used in the constitutive law for bi-linear analysis
$f_{\text {Ftud }}$	Design value of the residual tensile strength accounting for fibre orientation
$f_{\text {Ftu,ef }}$	Effective residual tensile strength of SFRC for given crack width accounting for fibre orientation and volume effect
$f_{\text {Ft3d }}$	Design residual tensile strength for crack width $=2,5 \mathrm{~mm}$ accounting for fibre orientation to be used for bi-linear stress distribution

$k_{\mathrm{AS}}$	Parameter that limits the replacement of minimum longitudinal reinforcement by fibres
$k_{\text {dur }}$	Coefficient to determine the distance to which the residual tensile strength of SFRC shall be disregarded
$k_{\mathrm{F}}$	Coefficient to determine clear bar spacing as a function of the fibre length
$l_{\mathrm{cs}}$	Structural length used to convert the stress-crack width relationship of SFRC to a stressstrain relationship compatible with concrete design
$S_{\text {r,m,cal,F }}$	Mean crack spacing of SFRC members subject to bending
$W_{\mathrm{u}}$	Maximum crack opening accepted in the structural design

​

3.6.3 Greek letters

$\alpha_{\text {duct }}$	Coefficient to determine required $A_{\mathrm{s}}$ for which plastic analysis can be used without direct check of rotation capacity
$\alpha_{\mathrm{f}}$	Coefficient for determining $S_{r, m, c a l, F}$
$\gamma_{\text {SF }}$	Partial factor for SFRC in tension
$\eta_{\mathrm{cF}}, \eta_{\mathrm{sw}}, \eta_{F}$	Parameters expressing that the shear capacity contributions from steel fibres and ordinary reinforced concrete are not 100 % additive
$\varepsilon_{\text {Ftu }}$	Ultimate tensile strain for SFRC
$\varepsilon_{\text {Ftud }}$	Design tensile strain limit used for SFRC cross-sections with or without axial force according to 5.1.7 and 8.1.5
$\varepsilon_{F, 0}$	Equivalent strain value used to define the post-cracking constitutive law for non-linear analysis
$\kappa_{\mathrm{G}}$	Factor taking into account the size of the tensile zone involved in the failure state
$\kappa_{k \text {,max }}$	Factor defining the upper limit of the ratio between characteristic and mean residual flexural strengths
$\kappa_{0}$	Factor taking into account the orientation of the steel fibres in the concrete matrix in relation to the orientation of the principal tensile stress arising from the action effects
$\rho_{\text {Fw,min }}$	Minimum shear reinforcement ratio
$\tau_{\text {Rd,cF }}$	Design value of the shear strength of SFRC
$\tau_{\text {Rd,SF }}$	Design value of the shear strength of SFRC with shear reinforcement
$\tau_{\mathrm{t}, \mathrm{Rd}, \mathrm{swF}}$	Design value of the torsional resistance in the transversal direction
$\tau_{\mathrm{t}, \mathrm{Rd}, \mathrm{slF}}$	Design value of the torsional resistance in the longitudinal direction

​

3.7 Symbols in Annex R

​

3.7.1 Latin upper case letters

$A_{\mathrm{fl}}$	Cross-sectional area of longitudinal FRP reinforcement
$A_{\mathrm{f}, \text { surf }}$	FRP surface reinforcement
$C_{\mathrm{c}}, C_{\mathrm{e}}, C_{\mathrm{t}}$,	Long term strength reduction factor to account for temperature, for creep and for environmental conditions, respectively
$E_{\mathrm{fR}}$	Design value of modulus of elasticity of FRP-reinforcement
$E_{\text {fwR }}$	Design value of modulus of elasticity of FRP shear reinforcement

​

3.7.2 Latin lower case letters

$f_{\text {ftd }}$	Design tensile strength of FRP reinforcement
$f_{\text {ftk0 }}$	Characteristic tensile strength of FRP reinforcement at the rupture strain $\varepsilon_{f t k 0}$
$f_{\text {ftk,100a }}$	Characteristic long term tensile strength of FRP reinforcement
$f_{\text {bd100a }}$	Long term bond strength of FRP reinforcement
$f_{\text {fwk,100a }}$	Characteristic long term tensile strength of FRP shear reinforcement
$f_{\text {fwRd }}$	Design tensile strength of FRP shear reinforcement

​

3.7.3 Greek letters

$\alpha_{\text {FRP,th }}$	Coefficient of thermal expansion of FRP reinforcement
$\gamma_{\text {FRP }}$	Partial factor for FRP reinforcing material
$\varepsilon_{\mathrm{fRd}}$	Strain of FRP reinforcement at design tensile strength $f_{\text {ftd }}$
$\varepsilon_{\text {ftk,100a }}$	Long term rupture strain of FRP reinforcement
$\varepsilon_{\text {ftk0 }}$	Rupture strain of FRP reinforcement
$\varepsilon_{\text {fwRd }}$	Strain of FRP shear reinforcement at design tensile strength $f_{\text {fwRd }}$
$\tau_{\text {Rd.f }}$	Shear resistance of a member with FRP reinforcement
$\rho_{\text {lf }}$	Longitudinal reinforcement ratio for FRP reinforcement
$\sigma_{\mathrm{f}}$	Serviceability value of stress in the FRP reinforcement, determined on the basis of a cracked section
$\sigma_{\mathrm{f}, \text { limm }}$	Limiting value of the serviceability stress in the FRP reinforcement in order to comply with a given limiting crack width
$\sigma_{\mathrm{ftd}}$	Design value of stress in the FRP reinforcement at the cross-section
$\phi_{\mathrm{f}}$	Diameter of a FRP reinforcement bar

​

3.8 Abbreviations

AVCP	Assessment and Verification of Constancy of Performance.
CS, CN, CR	Classes of Concrete with Slow/Normal/Rapid strength development
CFRP	Carbon Fibre Reinforced Polymer reinforcement adhesively bonded to the concrete surface
ERC	Exposure Resistance Class
FPC	Factory Production Control
FRP	profiled or roughened glass or Carbon Fibre Reinforced Polymer reinforcement
GFRP	Glass Fibre Reinforced Polymer reinforcement
lg	Logarithm with basis 10
LWAC	Ligthweight Aggregate Concrete
PE	Polyethylene
n. a.	not applicable

SCM	Supplementary cementitious materials	B. 3
SFRC	Steel Fibre Reinforced Concrete
SLS	Serviceability Limit State
SSRC	Stainless Steel Resistance Class
ULS	Ultimate Limit State

​

3.9 Units

Angle	Degrees/Radians
E-Modulus	For unit dependent formulae, MPa is used.
Geometric data	For unit dependent formulae, mm is used.
Relative humidity	%
Stresses and material strengths	For unit dependent formulae, MPa is used.
Temperature	${ }^{\circ} \mathrm{C}, \mathrm{K}$
Time	Days unless otherwise stated

​

3.10 Sign conventions

(1) In general, forces, stresses and strains which result in an elongation of material have a positive and those which result in shortening have a negative sign. When compressive or tensile forces are indicated in a figure by a vector they have a positive sign when they are acting in the direction described by the vector. (2) All tensile and compressive material strengths are used with a positive sign. (3) Shortening due to shrinkage is considered positive.