Rcs1-Chapter2-Standards

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Reinforced Concrete

Structures 1 - Eurocodes

RCS 1

Professor Marwan SADEKhttps://www.researchgate.net/profile/Marwan_Sadek

https://fr.slideshare.net/marwansadek00

Email : [email protected]

If you detect any mistakes, please let me know at : [email protected]

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PLAN – RCS1

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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

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Selected ReferencesFrench 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 lesbâtiments 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, TheInstitution of Structural Engineers, BCA, 2006. A. J. Bond (2006), How to Design Concrete Structures using Eurocode 2, Theconcrete centre, BCA, 2006.https://usingeurocodes.com/

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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

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CHAPTER 2

Evolution of the STANDARDS – LIMIT STATES

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1. Introduction – Design standards

2. Eurocodes

3. EC0 / Semi –probabilistic methods

4. Limit states

5. Actions – Eurocode 1

6. Combinations of Actions (SLS- ULS)

Annexes

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Design standards / History

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Admissible stresses : BA45, BA60, CCBA68

( Safety factor applied on the resistance of materials, + use of linear elastic model)

Limit states : BAEL 83, BAEL 91, modifiée 99

other: ACI, BS, SIA

Eurocodes (EC2 –Reinforced & Prestress Concrete) : limit state

concept used in conjunction with a partial factor method

1. Introduction 2. Eurocodes 3. EC0/Semi probabilism 4. Limit States 5. Actions 6. Combinations of Actions

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The EUROCODES

The EN Eurocodes are a series of 10 European Standards, EN

1990 - EN 1999, providing a common approach for the design of

buildings and other civil engineering works and construction

products

Three official languages (English, French, German)

These european standards « EUROCODES » are intended to

harmonize the design regulations inside the European union.


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The clauses of EUROCODES are composed of the Principles and

Application Rules :

The Principles, identified by the letter (P) comprise the general

statements and definitions for which there is no alternative, as well

as requirements and analytical models for which no alternative is

permitted unless specifically stated.

The Application Rules are generally recognized rules which

comply with the Principles and satisfy their requirements.

NOTE :The Eurocodes are applicable for the design of new structures, but the principles, the basicrequirements and the application rules of EN1990 are applicable for the structural appraisal ofexisting construction, in developing the design of repairs and alterations or in assessing changesof use.

The EUROCODES


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EUROCODES establish fundamental requirements in order to reach an appropriate

level of performance in terms of structural reliability mainly :

The structural SAFETY OF PEOPLE

The SERVICEABILITY and FUNCTIONING of the structure

The STRUCTURAL INTEGRITY in accidental situations

The DURABILITY, with regard to environmental conditions

The EUROCODES


LIST OF EUROCODES

Nb of StandardsBasis of structural design EC 0 2ACTIONS EC 1 10CONCRETE EC 2 4STEEL EC 3 20COMPOSITE EC 4 3TIMBER EC 5 3MASONARY EC 6 4GEOTECHNIC EC 7 2EARTHQUAKE EC 8 6ALUMINIUM EC 9 5

NOTA : The 10 Eurocodes constitute a group of 59 parts ( 30 until 2005)


Links between EUROCODES

Structural safety, service-

ability and durability

Actions on structures

Design and detailing

Geotechnics & Earthquake

EN 1991

EN 1990

EN 1992 EN 1993 EN 1994

EN 1995 EN 1996 EN 1999

EN 1997 EN 1998

The EUROCODES


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Typical Layout

• National Title Page

• National Foreword

• EUROCODE – MAIN TEXT

• NORMATIVE ANNEXES

• INFORMATIVE ANNEXES

• NATIONAL ANNEX

(Professional rules)

European STANDARD

French Standard

NATIONAL STANDARDS IMPLEMENTING EUROCODES


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EUROCODE 2 French Standard NF EN 1992

DESIGN OF CONCRETE STRUCTURES:

EN 1992-1-1 : General rules, and rules for buildings (2005)

FNA - French National Annex (2007)

Professional recommendations (2007)

EN 1992-1-2 : Structural fire design

EN 1992-2 : Reinforced and prestressed concrete bridges

EN 1992-3 : Liquid retaining and containing structures


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The EUROCODES for the design of RC buidings

EUROCODE Part D’EUROCODE TITRE ET/OU OBJET

EN 1990 – Basis of structural designMain part

Fundamental requirements. Design principle at Limit states using the partial factor method.

AnnexeA1 Combinations of actions – application for buildings

EN 1991 : Eurocode 1 – Actions on structures

Part 1-1 Densities, self-weight, imposed loads for buildings

Part 1-2 Actions on structures exposed to fire.

Part 1-3 General actions - Snow loads

Part 1-4 General actions - Wind actions

Part 1-5 General actions - Thermal actions

Part 1-6 General actions - Actions during execution.

Part 1-7 General actions - Accidental Actions

EN 1992 : Eurocode 2 – Design of concrete structures Part 1-1 General rules, and rules for buildings

Part 1-2 Structural fire design

EN 1997 : Eurocode 7 – Geotechnical design Part 1 General rules - Design of foundation

EN 1998 : Eurocode 8 – Design of structures for earthquake resistance

Part 1 General rules, seismic actions and rules for buildings.

Part 5 Foundations, retaining structures and geotechnical aspects


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L’EUROCODE 0 : BASIS OF STRUCTURAL DESIGN


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Several factors are likely to affect the safety of a construction

• Definition of the applied actions (Actions)

• Properties of the materials

• Definition of the internal forces (Effect of actions)

• Methods and design assumptions

• Execution method / qualification of employees

Safety


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Origin of Probabilism

A limit state could be reached due to combined effect of several random factors

of uncertainties. The basic idea of probabilism is to limit the probability of

reaching a limit state by taking into account the random character of :

Uncertainty in material property

Uncertainty in representative values of actions

Model uncertainty in actions and action effects (internal forces M,

N, T ..)

Model uncertainty in structural resistance


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SEMI-PROBABILISTIC Method in conjunction with Partial factor

of safety (Actions, resistance, effects)

LIMIT STATE CONCEPT

The design method at « Limit State » apply the partial factor ofsafety on the material Resistance and on the Actions (and theireffect)


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Check using the PARTIAL FACTOR METHOD

Fd : design value of the Action

Fk : Characteristic value of the Action

Frep : Representative value of the Action

f : partial factor for the Action accounting for model uncertainties and

dimensional variations

ψ = ψ0, ψ1 ou ψ2 (factors of combinations)

1) Design values of actions (Fd)


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2) Design Value of the effect of the action (Ed)

ad : Design values of geometrical data

Sd : Partial factor associated with the uncertainty of the action and/or

action effect model

Check using the PARTIAL FACTOR METHOD


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Check using the method of partial factors

3) Design value of a material property (Xd)

Xk : Characteristic value of a material property

: mean value of the conversion factor that take in account the scale

effect, humidity, temperature ..

m : Partial factor for a material property

(ex : 1.5 the concrete, 1.2 pour the steel)


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Semi – Probabilistic Method


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INDICATIVE DESIGN WORKING LIFE

DESIGN WORKINGLIFE CATEGORY

Indicative design

working life (years)

FNA EXAMPLES

1 10 10Temporary structures

2 10-25 25 Replaceable structural parts, e.g. gantry girders,

3 15-30 25Agriculture and similar structures

4 50 50 Buildings structures and other common structures

5 100100 Monumental building structures, bridges and other civil

engineering structures

The design working life should be specified. Table 2.1 of EN 1990 proposes:


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PRINCIPLE OF

LIMIT STATE DESIGN


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PRINCIPLE OF LIMIT STATE DESIGN

A limit state is a condition of a structure beyond which it no

longer fulfills the relevant design criteria.

Ultimate Limit State (ULS)

Serviceability Limit State (SLS)


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Ultime Limit State (ULS)

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Maximum capacity of the structure (people and structural safety)

Exceeding ULS Immediate Collapse

Based on Eurocodes, We distinguish the following ULS:

1. Loss of static equilibrium of the structure or any part (EQU)

2. Internal failure or excessive deformation of the structure or structural

members (STR)

3. Failure or excessive deformation of the ground (GEO)

4. Fatigue failure (FAT)


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1. Loss of static equilibrium (EQU)

Ex : Sliding or Overturning of a retaining Wall : earth pressure,

friction …


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2. Structural failure (STR)

2.a) Résistance of materials:

Failure of one or several structural elements even if the global

equilibrium is ok (beam subjected to bending or shear..)


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2. Structural failure(STR)

2.b) Elastic instabilities : Buckling of columns, lateral torsional

buckling of beams


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Serviceability Limit State - SLS

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The SLS are associated with conditions of normal use. They concern

the functioning of the structure, confort of people.

Strain, vibration, cracking..

We distinguish the following SLS:

1. Stress limitation (Steel & Concrete)

2. Crack control (crack width)

3. Deflection control

Other : Vibration, Thermal or sound insulation…


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1. Stress limitation in Steel and Concrete: In order to limit the

longitudinal cracks, micro cracks or high creep ..

Serviceability Limit State - SLS1. Introduction 2. Eurocodes 3. EC0/Semi probabilism 4. Limit States 5. Actions 6. Combinations of Actions

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2. Crack Control : Cracks should not be unsightly or wide

enough to lead to durability problems. It depends on several

parameters (steel-concrete bond, minimum cover..)

Definition of Exposure Classwmax 0.4, 0.3 ou 0.2 mm


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3. Deflection control (Appropriate limiting values of deflection)


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ACTIONS (LOADS)

Eurocode 1

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ACTIONS (Loads)(EN 1991 – Part 1)

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Forces induced by the applied loads and/or imposed deformation

to a construction.

Different sources :

Permanent load

Variable Load (Live load)

Climate load

Imposed deformation : Temperature variation,

soil settlement ..

Earthquake, Fire


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ACTIONS (Loads)

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Fk : Characteristic value of an Action


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Classification of Actions

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1. Permanent Loads

2. Variable loads

3. Accidental loads


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1. Permanent loads (characteristic value Gk : low variability ,

represented by mean value, see Annex A for densities)

Self Weight of the structure

Weight of equipments : cladding, machines in industries

Weight, earth pressure, liquid pressure (constant level)

…

NOTE: In some cases, the variation in permanent load should be taken in account

(when the difference becomes significant)

Ex : asphalt pavement layer (± 20 %)


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2. Variable loads

imposed loads (or Live load) in a building or a bridge (Q)

Climatic Action : Wind (W), Snow (S))

Uniform or differential variation of temperature (T ou T)

Moving loads (Trucks, trains ..)

..


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3. Accidental Action FA

Non common, quick

Only at ULS

Accident of a truck on a bridge

Fire

Earthquake (E)


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Characteristic values of Imposed Loads (NF-EN 1991-1-1, 6.3)The Residential, social, commercial and administration areas in buildings are classified in Four categories (Table 6.1)


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Imposed loads in buildings (NF-EN 1991-1-1, 6.3)

qk (uniformly distributed load –general effect)

Qk (concentrated load impact on 50x50 mm²-local effect)

EC1

Example : Imposed loads on floors, balconies and stairs in buildings (Table 6.2)

FNA


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Example : : Imposed loads on floors, balconies and stairs in buildings

Additional load due to partition

movable partitions with a self-weight ≤ 1,0 kN/m wall length : qk = 0,5 kN/m²



In lebanon : It is recommended to take an additional load of partitions :

150 to 200 daN/m²


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Other aspects (see annexes)

Storage

Parking

Horizontal reduction factor

Vertical reduction factor

..


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Combinations of Actions (EC0)

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The assessment of internal forces (N, T, M) is done on the basis of

load combination

Combination ULS

Combination SLS


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Characteristic value of a permanent action Gk

Gk,sup Characteristic value of unfavourable Permanent action for the design of a

given element (Earth pressure on a retaining wall)

Gk,inf Characteristic value of favourable Permanent action for the design of a

given element (Earth pressure on a retaining wall) (soil Self weight on a

retaining wall)

Characteristic Value of the Action


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Characteristic value of a single variable action Qk

Combination value, 0Qk

Frequent value, 1Qk

Quasi-permanent value 2Qk

Characteristic Value of the Action


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Table A1.1 / EN1990 – Recommended values of factors for buildings

Characteristic Value of the Action1. Introduction 2. Eurocodes 3. EC0/Semi probabilism 4. Limit States 5. Actions 6. Combinations of Actions

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Combinations of Actions ULS (STR)

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1. Fundamental Combination

To simplify, for buildings

When considering the critical variable action

When considering leading and accompanying variable Actions

G : Partial factor for permanent actions G =1.35 if G unfavourable, 1, if favourable

Q,1 : Partial factor for variable action , Q,1 =1.5 for leading and accompanying variable Action


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2) Accidental Combination

Combinations of Actions ULS (STR)

3) Seismic Combination

Ad : design value of an accidentel action

1,1 : if fire

AEd :design value of action due to Earthquake ground motion


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1) Characteristic Combination :

Combinations of Actions SLS

2) Frequent Combination :

3) Quasi-permanent Combination


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Annexes

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Selected Parts of ANNEX A (EC1 – part 1.1)Construction materials -Tables A1 A12

Table A.1 - Concrete and mortar

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Selected Parts of ANNEX A (EC1 – part 1.1)Construction materials -Tables A1 A12

TableA.2 - Masonry

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ANNEX A (EC1 – part 1.1)

Table A.3 - Timber Table A.4 - Metals

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ANNEXE A (EC1 – Part 1.1)Table A.7 - Stored Materials

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Extracted parts (EC1 – part 1.1 - 6.3)

Storage Areas, Parking

Reduction Factors

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Extracted from (EC1 – Part 1.1) Characteristic values of imposed load

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Extracted from (EC1 – Part 1.1 - 6.3)

Characteristic values of imposed load

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The recommended value for the horizontal reduction factor for floors and roofs :

French National Annex

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The recommended value for the vertical reduction factor for columns

and walls

N : is the number of storeys (> 2) above the loaded structural elements from the same category

French National Annex

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Reminder about Units

Length en (m)

1 m = 100 cm

(precision in R.C: 1 cm / sometimes 0.5 cm)

(in steel structures : 1 mm)

Force (N)

10 N = 1 daN = 1 kg (kgf )

1 MN = 103 kN = 100 T (Tf)

Pressure /Stress (Pa)

1 Pa = 1 N/m²

1 MPa = 106 Pa = 1 N/mm²

1 MPa = 10 bars = 100 T/m²

1 bar = 1 kg/cm²

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Exercices

Load / m² on a slab

Combinations of actions SLS , ULS

Numerical example / Determination of maximum forces

Total load / Load on columns

Load on beam (/ m)

Rcs1-Chapter2-Standards

Education

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