Reinforced Concrete Structures 1 - Eurocodes

Marwan SADEK 1
Reinforced Concrete
Structures 1 - Eurocodes
RCS 1
Professor Marwan SADEK
https://www.researchgate.net/profile/Marwan_Sadek
https://fr.slideshare.net/marwansadek00
Email : marwansadek00@gmail.com
If you detect any mistakes, please let me know at : marwansadek00@gmail.com

Marwan SADEK 2
PLAN – RCS1
M. SADEK
Ch 1 : Generalities – Reinforced concrete in practice
Ch 2 : Evolution of the standards – Limit states
Ch 3 : Mechanical Characteristics of materials – Constitutive
relations
Ch 4 : Durability and Cover
Ch 5 : Beam under simple bending – Ultimate limit state ULS
Ch 6 : Beam under simple bending – serviceability limit state SLS
Ch 7 : Section subjected to pure tension

Marwan SADEK 3
Selected References
French BAEL Code (91, 99)
 Règles BAEL 91 modifiées 99, Règles techniques de conception et de calcul des
ouvrages et constructions en béton armé, Eyrolles, 2000.
 J. Perchat (2000), Maîtrise du BAEL 91 et des DTU associés, Eyrolles, 2000.
 J.P. Mougin (2000), BAEL 91 modifié 99 et DTU associés, Eyrolles, 2000.
 ….
EUROCODES
 H. Thonier (2013), Le projet de béton armé, 7ème édition, SEBTP, 2013.
 Jean-Armand Calgaro, Paolo Formichi ( 2013) Calcul des actions sur les
bâtiments selon l'Eurocode 1 , Le moniteur, 2013.
 J. M. Paillé (2009), Calcul des structures en béton, Eyrolles- AFNOR, 2009.
 Jean Perchat (2013), Traité de béton armé Selon l'Eurocode 2, Le moniteur,
2013 (2ème édition)
 Manual for the design of concrete building structures to Eurocode 2, The
Institution of Structural Engineers, BCA, 2006.
 A. J. Bond (2006), How to Design Concrete Structures using Eurocode 2, The
concrete centre, BCA, 2006.
https://usingeurocodes.com/
M. SADEK

Marwan SADEK 4
In addition to Eurocodes, the references that are mainly
used to prepare this course material are :
 Thonier 2013
 Perchat 2013
 Paillé 2009
Some figures and formulas are taken from
 Cours de S. Multon - BETON ARME Eurocode 2 (available on internet)
 Cours béton armé de Christian Albouy
M. SADEK

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Chapter IV
Durability and Cover
M. SADEK
1. Exposure Classes
2. Structural Classes
3. Cover
4. Detailing of Members / Reinforcement

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1.Exposure Classes 2. Structural Classes 3. Cover 4. Detailing for members
 Introduction : Optimization of durability
The cover is the distance between the surface of the
reinforcement closest to the nearest concrete surface.
It should be sufficient in order to guarantee :
 the protection of the steel against corrosion;
 the safe transmission of bond forces;
an adequate fire resistance.

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 The cover of steel and the characteristics of the surrounding
concrete are principal parameters that permit to control the
longevity of the structures.
 Introduction : Optimization of durability

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Exposure CLASSES
18 classes - EC2

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Exposure classes related to environmental conditions in
accordance with EN 206-1

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DIFFERENCE between the classifications of
NF EN 206-1 & EC 2 (PAILLÉ 2009)
 We should make the distinction between the classification relative to the concrete
(NFEN206-1) and that relative to the steel cover (EC2) function of the exposure condition.
The criterion is not always the same.

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DIFFERENCE between the classifications of
NF EN 206-1 & EC 2 (PAILLÉ 2009)

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Indicative strength classes for durability
(NF EN 206-1)

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 Design working life
Design working
life category
Indicative
design
working life
(years)
F
NA Examples
1 10 10 Temporary structures
2 10-25 25
Replaceable structural parts, e.g. gantry girders,
bearings
3 15-30 25
Agriculture and similar structures
4 50 50 BUILDING STRUCTURES AND OTHER COMMON
STRUCTURES
5 100 100 Monumental building structures, bridges and other civil
engineering structures

Marwan SADEK 15
Structural classes (6 Classes S1S6)
 Classe S4 : The recommended Structural Class (design
working life of 50 years) is S4, for buildings and common civil
engineering structures
 The bridges are classified in the the class S6 (4+2), for a design
working life of 100 years (Increase class by +2)
The class may be reduced function of design working
life, the strength class, and the binder type
(Table 4.3.NF, NA)

Marwan SADEK 16
Criterion Exposure Class
XO XC1 XC2, XC3 XC4
XD1 / XS1 /
XA1
XD2 / XS2 /
XA3
XD3 / XS3 /
XA3
Design
working life
100 years, Increase class by 2
25 years and less, Reduce class by 1
Strength
Class
C 30/37 C 30/37 C 30/37 C 35/45 C 40/50 C 40/50 C 45/55
If the strength is greater, Reduce class by 1
C 50/60 C 50/60 C 55/67 C 60/75 C 60/75 C 60/75 C 70/85
If the strength is greater, Reduce class by 2
Binder type
- C 35/45 C35/45 C 40/50 - - -
-
Concrete with CEM I
with fly ashes
- - -
Reduce class by 1
Compact
Cover
Reduce class by 1
Obtaining compactness in the cover zone concerns for example :
Steel form work, precast elements ..

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 Nominal cover cnom
 cnom : nominal cover
 cmin : minimum cover
cdev : allowance in design for deviation (Recommended value FNA = 10 mm)
(Recommended value FNA = 0)
 Note : the Calculation should be conducted for longitudinal and transverse steel

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 cmin,b : minimum cover due to bond requirement
(if dg>32)
 1 bar
 Bundle of nb barres
cmin,b =

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 cmin,dur : minimum cover due to environmental conditions
requirements with regard to durability for reinforcement steel in accordance
with EN 10080 (Table 4.4 N - NF EN 1992-1-1)

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 Raft foundation
The cover of a reinforced concrete raft cast directly against soil, the cover
should be at least 75 mm (65 mm FNA).
This value could be reduced to 40 mm (30 mm ANF) concrete cast against
prepared ground (including blinding)

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Some detailing requirements
(Constructional details)

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 Overlapping and anchorage of reinforcement (SBA2)
Transverse Steel
Bad practice very
common in lebanon !!

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 Minimum permissible mandrel diameter for bent bars avoid damage
to reinforcement
 Other criterion : Avoid concrete damage (SBA2),
For this second condition we can reach quickly a value > 10 
( The obtained value with EC2 are higher than those obtained with the previous French code BAEL)

x 2m
nomc
mandrin de cintrage
mdiamètre:
t
sdbt
5y
point de départ de
l'ancrage
45°
nomct 
t
2/c tnom  
 For civil engineering constructions and in case of a good bond condition,
when the tensile force (at the origin of the bar bent) is lower than 75% of the
maximum design force (bt0.75fyd), the mandrel diameter could be taken
m=10 .

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 Horizontal and Vertical spacing between bars (EC2, 8.2)
(the concrete can be placed and compacted satisfactorily for the development of
adequate bond)
(dg=2.5 cm in general)
The bars should be placed symmetrically
to avoid any additional excentricity

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 Reinforcing bars are in tension and therefore should never be bent around an
inside corner beams. They can pull straight !!

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Expansion joint
o Lmax = 25 à 30 m for Lebanon
o Top of the foundation
Construction joint
o in case of high differential settlement
 Lmax
 Lmax

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EXAMPLE
Developed length for stirrups:
o m=5  (6    16)
o with straight length : max(10 ; 70 mm) (90°)
 Carefull : When using other value of m, we obtain different values of developed length

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 Bundle of bars
 the bars should be of the same characteristics (type and grade).
Bars of different sizes may be bundled provided that the ratio of diameters
does not exceed 1,7.
 Where two touching bars are positioned one above the other, and where
the bond conditions are good, such bars need not be treated as a bundle
[EC2 - 8.9.1(4)]

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 Bundle of bars
 In design, the bundle is replaced by a notional bar having the same
sectional area and the same centre of gravity as the bundle.
o nb ≤ 4 for vertical bars in compression and for bars in a
lapped joint
o nb ≤ 3 for all other cases. (tension)

Marwan SADEK 31
 Determination of cover for longitudinal and transverse steel
 Steel ratio including longitudinal and transversal steel
(column , beam section)
Exercises

Reinforced Concrete Structures 1 - Eurocodes

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