Introduction to Eurocode 2 - spata

08/10/2012

Eurocode Hierarchy

Introduction to Eurocode 2 SPATA Training

EN 1990 Basis of Design

Structural safety, serviceability and durability

EN 1991 Actions on Structures

Actions on structures

EN 1992 EN 1993 EN 1994 EN 1995 EN 1996 EN 1999

4 October 2012

Charles Goodchild BSc CEng MCIOB MIStructE

Concrete Steel Composite Timber Masonry Aluminium

EN 1997 Geotechnical Design

The Concrete Centre

EN 1998 Seismic Design

Design and detailing

Geotechnical & seismic design 4

Outline

Challenges of the Eurocodes • 58 Parts to Eurocodes plus National Annexes

•Setting the scene for the Eurocodes, • their format,

• Culture shock / steep learning curve

• their hierarchy,

• New symbols and terminology

• how they interact.

• Affects all materials

• An overview of Eurocode 2,

• Confusion over timescales

• highlighting changes from and

• Costs:

• comparing it to BS8110 • How it all fits together.

◦

Training

◦

Resources

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Setting the scene

Eurocodes: Timescales

Eurocodes are being/ will be used in:

BS 8110 and all old structural design British Standards have now been ‘withdrawn’. There will be a period of co-existence between our current codes and the Eurocodes.

• EU countries • EFTA Countries • Malaysia

CEN National Members

• Singapore

Austria Belgium Cyprus Czech Republic Denmark Estonia Finland France Germany Greece Hungary Iceland Ireland Italy Latvia Lithuania Luxembourg Malta The Netherlands Norway Poland Portugal Romania Slovakia Slovenia Spain Sweden Switzerland 3 United Kingdom

• Vietnam • Sri Lanka • Others?

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SPATA Training 4 Oct 2012 - Eurocode 2

DCLG letter: “Building Control will continue to consider the appropriate use of relevant standards on a case by case basis….. [The ‘traditional’] British Standards may not necessarily be suitable ….. in the medium and long term.” DCLG 2012 Consultation document – Eurocodes only in AD A by 2013? Scottish Technical Handbook: ‘The structural design and construction of a building should be carried out in accordance with the following Structural Eurocodes’. Insurers? Large projects? International projects? 6

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Format of the Eurocodes

Eurocodes: Timescales Highways:

Each Eurocode Contains: a. National front cover

HA IAN 124/11 July 2011

b. National forward 3 Implementation “Unless otherwise agreed with HA Project Sponsors/Project Managers and the Technical Approval Authority (TAA), Eurocodes must be used for the design of new and modification of existing highway structures (including geotechnical works), . . . .”

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Format of the Eurocodes

Opportunities • Most of Europe using the same basic design codes: ◦ ◦ ◦ ◦ ◦ ◦

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Each Eurocode Contains:

Increased market for UK consultants Increased market for UK manufacturers Reduced costs when working in several European markets Greater transferability of highly skilled staff Greater understanding of research, proprietary products etc. Reduce software development costs

a. National front cover b. National forward c. CEN front cover

• Technically advanced codes • Logical, organised to avoid conflicts between codes 8

Format of the Eurocodes

11

Format of the Eurocodes

(e.g. Eurocode 2) Each Eurocode Contains:

Each Eurocode Contains:

a. National front cover

a. National front cover b. National forward c. CEN front cover d. Main text and annexes (which must be as produced by CEN)

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SPATA Training 4 Oct 2012 - Eurocode 2

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Eurocode Hierarchy

Format of the Eurocodes Each Eurocode Contains:

These

a. National front cover

affect

b. National forward

concrete

c. CEN front cover

EN 1990 Basis of Design

design

d. Main text and annexes (which must be as produced by CEN) e. Annexes - can by normative and/or informative

EN 1991 Actions on Structures EN 1992 EN 1993 EN 1994 EN 1995 EN 1996 EN 1999

+ NA

EN 1997 Geotechnical Design

Concrete Steel Composite Timber Masonry Aluminium EN 1998 Seismic Design

+ NA

Structural safety, serviceability and durability Actions on structures

+ NA

Design and detailing

+ NAs

+ PDs

+ NA

Geotechnical & seismic design

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16

The Eurocodes

Format of the Eurocodes

• BS EN 1990 (EC0): Basis of structural design

National Annex (NA).

• BS EN 1991 (EC1): Actions on Structures • BS EN 1992 (EC2): Design of concrete structures •

BS EN 1993 (EC3): Design of steel structures

•

BS EN 1994 (EC4): Design of composite steel and concrete structures

•

BS EN 1995 (EC5): Design of timber structures

•

BS EN 1996 (EC6): Design of masonry structures

•

BS EN 1997 (EC7): Geotechnical design

•

BS EN 1998 (EC8): Design of structures for earthquake resistance

•

BS EN 1999 (EC9): Design of aluminium structures 17

Eurocode Basis of structural design

The National Annex provides: •

Values of Nationally Determined Parameters (NDPs) (NDPs have been allowed for reasons of safety, economy and durability)

• Example: Min diameter for longitudinal steel in columns min = 8 mm in text min = 12 mm in N.A.

•

The decision where main text allows alternatives

It gives the safety factors for actions and combinations of action for the verification of both ultimate and serviceability limit states.

• Example: Load arrangements in Cl. 5.1.3 (1) P

•

EN 1990 provides comprehensive information and guidance for all the Eurocodes, on the principles and requirements for safety and serviceability.

The choice to adopt informative annexes • Example: Annexes E [Strength class for durability] and J [particular detailing rules] are not used in the UK

•

Non-contradictory complementary information (NCCI) • TR 43: Post-tensioned concrete floors – design handbook 15

SPATA Training 4 Oct 2012 - Eurocode 2

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Eurocode: BS EN 1990 (EC0): Basis of design

Eurocode – EC0 Ultimate Limit State – Categories

Published 27 July 2002

The ULS is divided into the following categories:

Says that structures are to be designed, executed and maintained so that, with appropriate forms of reliability, they will:

EQU Loss of equilibrium of the structure.

Ed,dst ≤ Ed,stb

• Perform adequately under all expected actions

STR Internal failure or excessive deformation of the structure or structural member.

• Withstand all actions and other influences likely to occur during construction and use

Ed  Rd;

GEO Failure due to excessive deformation of the ground.

• Have adequate durability in relation to the cost • Not be damaged disproportionately by exceptional hazards

FAT Fatigue failure of the structure or structural members. 19

Eurocode – EC0

Eurocode: ULS Actions

Representative value of an action Design value of an action = Fd = F  Frep = F  (  FK ) where

FK = the characteristic value of action Frep =  FK - is the representative value  = Four values, namely, 1.0 or 0 or 1 or 2 Qk = Characteristic Value (of a variable action) 0 Qk = Combination Value 1 Qk = Frequent Value 2 Qk =Quasi-permanent Value

Design values of actions, ultimate limit state – persistent and transient design situations (Table A1.2(B) Eurocode) Comb’tion expression reference

Permanent actions Unfavourable

Favourable

Leading variable action

Eqn (6.10)

1.35 Gk k,j,sup γ G,j,sup G

1.0 GkGk,j,inf γG,j,inf

1.5 γQ,1 Q Qk,1 k,1

1.35 Gk k,j,sup Eqn (6.10a) γ G,j,sup G

1.0 GkGk,j,inf γG,j,inf

Eqn (6.10b) ξ0.925x1.35G γG,j,supGk,j,sup γ 1.0 GkGk,j,inf G,j,inf k

Accompanying variable actions Main(if any)

1.5 Qk,i γ 0,i Q k,i Q,i Ψ0,i 1.5 Ψ0,1QQk,1k γ Q,1Ψ0,1

γ Qk,1 1.5 Q,1 Q k,1

Generally for one variable action:

Others

1.5 Q k,i γ Q,i Ψ0,i k,i γ 1.5 Qk,i Q,i Ψ0,i Q k,i

1.25 Gk + 1.5 Qk

Provided: 1. Permanent actions < 4.5 x variable actions 2. Excludes storage loads

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Load arrangements to EC2 Greek Alphabet

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SPATA Training 4 Oct 2012 - Eurocode 2

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Eurocode: Annex A

Load arrangements to EC2 alternative to UK NA

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Action

0

1

2

Category A: domestic, residential areas

0.7

0.5

0.3

Category B: office areas Category C: congregation areas

0.7 0.7

0.5 0.7

0.3 0.6

Category D: shopping areas Category E: storage areas Category F: traffic area (vehicle weight < 30 kN)

0.7 1.0

0.7 0.9

0.6 0.8

0.7

0.7

0.6

Category G: traffic area (30 kN < vehicle weight < 160 kN)

0.7

0.5

0.3

Category H: roofs Snow (For sites located at altitude H 20 > Agg + 5 Check max spacing between bars

EC2 - Flexure

Eurocode 2 - Flexure

essential design by hand z

As = MEd/fydz





d 1  1  3.53 K  0.95d * 2

where K = M/bd2fck

435 MPa = 500/1.15 =

For grades of concrete up to C50/60, εcu= 0.0035;

=1;

 = 0.8 ;

fcd = cc fck/ c = 0.85 fck/1.5 = 0.57 fck

z = d x z/d

fyd = fyk/1.15 = 435 MPa

Derived formulae include: z/d

= (1 + (1 + 3.529K)0.5] / 2

As K’

= MEd/(1.15 fykz ) = 0.207

(where K = M/bd2fck) ( = 1. But UK best practice limits x/d to 0.45 max44 which in turn limits K’ to 0.167)

EC2 - Flexure

Check Check Check Check

min reinforcement provided As,min > 0.26(fctm/fyk)btd (Cl. 9.2.1.1) max reinforcement provided As,max  0.04Ac (Cl. 9.2.1.1) min spacing between bars > bar > 20 > Agg + 5 max spacing between bars

Eurocode 2 – Beam shear

Design Flowchart

Strut inclination method

The following flowchart outlines the design procedure for rectangular beams with concrete classes up to C50/60 and grade 500 reinforcement

21.8 <  < 45

Carry out analysis to determine design moments (M)

K

Determine K and K’ from: M & K '  0.6  0.18 2  0.21 2 b d fck

Note:  =1.0 means no redistribution and  = 0.8 means 20% moment redistribution.

Yes

Beam singly reinforced

Is K ≤ K’ ?

No

Beam doubly reinforced – compression steel needed



K’

1.00

0.208

0.95

0.195

0.90

0.182

0.85

0.168

0.80

0.153

0.75

0.137

0.70

0.120

It is often recommended in the UK that K’ is limited to 0.168 to ensure ductile failure

SPATA Training 4 Oct 2012 - Eurocode 2

VRd, s 

Asw z f ywd cot  s

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Eurocode 2 vs BS8110: Shear

Eurocode 2 – Deflection

Safer!

Shear reinforcement density

The deflection limits stated to be: • Span/250 under quasi-permanent loads to avoid impairment of appearance and general utility

Eurocode 2: BS8110: VR = VC + VS

VRmax

Asfyd/s

• Span/500 after construction under the quasi-permanent loads to avoid damage to adjacent parts of the structure.

Test results VR

Less links!

Deflection requirements can be satisfied by the following methods:

(but more critical)

Minimum links

• Direct calculation (Eurocode 2 methods considered to be an improvement on BS 8110) . • Limiting span-to-effective-depth ratios

Shear Strength, VR

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EC2 - Shear

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Eurocode 2 – Flow chart for L/d

Design Flow Chart for Shear

Determine basic l/d including K for structural system

Determine vEd where: vEd = design shear stress [vEd = VEd/(bwz) = VEd/(bw 0.9d)]

Factor F1 for ribbed and waffle slabs only F1 = 1 – 0.1 ((bf/bw) – 1) ≥ 0.8

Determine the concrete strut capacity vRd when cot  = 2.5 vRd = 0.138fck(1-fck/250)

Is vRd > vEd? Yes

No

Factor F2 for spans supporting brittle partitions > 7m F2 = 7/leff

Determine  from:  = 0.5 sin-1[(vEd/(0.20fck(1-fck/250))]

Factor F3 accounts for stress in the reinforcement F3 = 310/s ≤ 1.5 where s is tensile stress under characteristic load or No As,prov /As,req’d

(cot  = 2.5)

Calculate area of shear reinforcement: Asw/s = vEd bw/(fywd cot )

No Is basic l/d x F1 x F2 x F3 >Actual l/d?

Check maximum spacing of shear reinforcement : s,max = 0.75 d For vertical shear reinforcement

Yes Check complete

Eurocode 2 – Beam shear essential design by hand

when vEd < vRd,cot  =2.5, then cot  = 2.5 ( = 21.8°) and

Asw/s = vEd bw/(fywd.2.5)

Shear fck vRd

cot  = 2.5

MPa

MPa

20 25 28 30 32 35 40 45 50

2.54 3.10 3.43 3.64 3.84 4.15 4.63 5.08 5.51

20.5

Structural system

K

Simply supported

1.0

End span

1.3

Internal span

1.5

Flat slab

1.2

Cantilever

0.4

fck = 30,

 = 0.50%

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SPATA Training 4 Oct 2012 - Eurocode 2

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Basic span/effective depth ratios

Span to depth ratio (l/d)

We can manipulate the Expressions for concrete struts so that

Increase As,prov or fck

Percentage of tension reinforcement (As,req’d/bd)

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EC2 Columns: Slenderness (2)

EC2 Columns: Design moments

& 2nd order moments: Effective length & F Actions

F

1st order moments:

First order moments

M01 = Min {|Mtop|,|Mbottom|} + ei Ned 

M02 = Max {|Mtop|,|Mbottom|} + ei Ned

Slenderness, 

where Effective length, l0



ei = Max {Io/400, h/30, 20}

M

(20 mm usually critical)

l0 = l

l0 = 2l l0 = 0,7l

l0 = l / 2

l0 = l

l /2 2l

Braced members:

For stocky columns:



F = 0,51

Design moment, MEd = M02



Yes SlenIs   lim? der No

 k1   k2   1  0,45  k1   0,45  k2 

Design Moments, MEd

Unbraced members:

F=

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  k k k1   k 2   max  1  10  1 2 ;  1     1  1  k   k1  k 2  2    1  k1  

EC2 Columns: Slenderness (7)

EC2 Columns: Slenderness (3)

& 2nd order moments

& 2nd order moments: Effective length & F

For Slender columns,

F: working out k (each end)

Actions

MEd = Max[M02, M 0e + M2, M01 + M 2/2]

k = relative stiffness = ( / M) (E / l) (From Eurocode 2)

First order moments

Where

M2 = nominal order moment M2 = NEd e2 where e2 = fn(deflection) 2nd

Effective length, l0

There are alternative methods for calculating eccentricity, e2, for slender columns

M0e + M2

M0e

E Ic lc k  0 .1 2E I b  lb

Slenderness limit, lim Yes SlenIs   lim? der No

Detailing

EC2 Columns: Slenderness

Actions First order moments

Slenderness limit, lim

Design Moments, MEd Calculate As Detailing

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EC2 Columns: Slenderness (4)

& 2nd order moments: Slenderness

& 2nd order moments: Effective length : F from k Actions

Slenderness  = l0/i

First order moments

where

Effective length, l0

= Fl . . . . . of which more later (or use BS8110 factors!} i = radius of gyration = (I/A)

 = 3.46 l0 / h  = 4 l0 / h

k

E Ic lc  0 .1 2E I b  lb

Slenderness limit, lim Yes SlenIs   lim? der No

Detailing 57

SPATA Training 4 Oct 2012 - Eurocode 2

First order moments Slenderness, 

F

Effective length, l0 Slenderness limit, lim

l0 = Fl And

Design Moments, MEd Calculate As

Actions

ki = relative stiffness each end

Slenderness, 

l0 = Effective length,

For a rectangular section, For a circular section,

lb,lc are the beam and column lengths

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Yes SlenIs   lim? der No

Ib,Ic are the beam and column uncracked second moments of area

Calculate As

Detailing

Effective length, l0

(From PD 6687: Background paper to UK NA)

Where:

Design Moments MEd

Calculate As

Slenderness, 

Alternatively...

Slenderness, 

Slenderness limit, lim

Yes SlenIs   lim? der No Design Moments, MEd

Slenderness  = l0/i

Calculate As Detailing 60

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EC2 Columns: Slenderness (5)

Eurocode 2: Column design

& 2nd order moments: Allowable Slenderness

Allowable Slenderness Actions

lim = 20ABC/n where: A = 1 / (1+0,2ef) ef is the effective creep ratio;

First order moments Slenderness, 

(if ef is not known, A = 0,7 may be used)

B = (1 + 2)  = Asfyd / (Acfcd) (if  is not known, B = 1,1 may be used) C = 1.7 - rm rm = M01/M02 M01, M02 are first order end moments, M02  M01 (if rm is not known, C = 0.7 may be used) n

Effective length, l0 Slenderness limit, lim Yes SlenIs   lim? der No

If using column charts we want: NEd/bhfck and MEd/bh2fck from which we get: Asfyk/bhfck

Design Moments, MEd Calculate As

= NEd / (Acfcd)

Detailing

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EC2 Columns: Slenderness (6)

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Eurocode 2: Column design

& 2nd order moments: Allowable Slenderness & C

lim = 20ABC/n 105 kNm

So we have NEd and MEd !!!!

Actions

105 kNm

105 kNm

Asfyk/bhfck = 1 ≡ As/bd = 6%

First order moments

for C30/37 concrete and B500 steel

Slenderness,  Effective length, l0 Slenderness limit, lim

105 kNm

-105 kNm

rm = M01/ M02 = 0 / 105 =0 C = 1.7 – 0 = 1.7

rm = M01/ M02 = 105 / -105 = -1 C = 1.7 + 1 = 2.7

rm = M01/ M02 = 105 / 105 =1 C = 1.7 – 1 = 0.7

Yes SlenIs   lim? der No Design Moments, MEd Calculate As Detailing

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EC2 – Detailing:

EC2 Columns: Slenderness (7)

Ultimate bond stress

& 2nd order moments If Slenderness > Allowable slenderness Then include nominal 2nd order moment, M2 M2 = NEd e2 where e2 = fn(deflection)

There are alternative methods for calculating eccentricity, e2, for slender columns

Actions First order moments Slenderness, 

The design value of the ultimate bond stress, fbd = 2.25 12fctd where fctd should be limited to C60/75 1 =1 for ‘good’ and 0.7 for ‘poor’ bond conditions 2 = 1 for   32, otherwise (132- )/100 Direction of concreting

Direction of concreting

Effective length, l0

M0e

M0e + M2

Slenderness limit, lim Yes SlenIs   lim? der No Design Moments MEd Calculate As Detailing

SPATA Training 4 Oct 2012 - Eurocode 2

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

a) 45º    90º Direction of concreting

250

c) h > 250 mm Direction of concreting  300

h

h

b) h  250 mm d) h > 600 mm unhatched zone – ‘good’ bond conditions hatched zone - ‘poor’ bond conditions

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Eurocode 2: relationships –

EC2 – Detailing: Design Anchorage Length, lbd

BS EN 1990 BASIS OF STRUCTURAL DESIGN

BS EN 1997 GEOTECHNICAL DESIGN

lbd = α1 α2 α3 α4 α5 lb,rqd  lb,min However:

BS 8500 Specifying Concrete

(α2 α3 α5)  0.7 lb,min > max(0.3lb; 15, 100mm)

NSCS DMRB?

BS EN 1991 ACTIONS ON STRUCTURES

BS EN 10138 Prestressing Steels

BS EN 1992

BS EN 10080 Reinforcing Steels

BS EN 206 Concrete BS EN 13670 Execution of Structures

DESIGN OF CONCRETE STRUCTURES

Part 1-1: General Rules for Structures Part 1-2: Structural Fire Design

NBS? Rail? CESWI?

EC2 – Detailing: Alpha values

BS EN 1994 Design of Comp. Struct.

BS EN 1998 SEISMIC DESIGN

BS EN 1992 Part 2: Bridges

BS EN 1992 Part 3: Liquid Ret. Structures

BS 4449 Reinforcing Steels BS EN 13369 Pre-cast Concrete 70

BS EN 13670 Specifications

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EC2 – Detailing

BS EN 13670 & NSCS

Curtailment of reinforcement Envelope of (M Ed /z +N Ed )

lbd

Acting tensile force

lbd

R esisting tensile force

lbd

al

lbd

Ftd

al Ftd lbd

lbd lbd

lbd

“Shift rule”

• For members without shear reinforcement this is satisfied with al = d • For members with shear reinforcement: al = (MEd/z) + 0.5VEd Cot  But it is always conservative to use al = 1.125d

SPATA Training 4 Oct 2012 - Eurocode 2

New Types of Finish

Types of Finish

Hierarchy of Tolerances

Hierarchy of Tolerances

Includes NA

Green Issues

as BS EN 13670

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Eurocode 2: relationships –

BS EN 1990 BASIS OF STRUCTURAL DESIGN

BS EN 1997 GEOTECHNICAL DESIGN

BS 8500 Specifying Concrete

BS EN 206 Concrete

NSCS

BS EN 13670 Execution of Structures

DMRB?

Technical publications (CCIP) BS EN 1998 SEISMIC DESIGN Concise Eurocode 2

BS EN 1991 ACTIONS ON STRUCTURES

BS EN 10138 Prestressing Steels

BS EN 1992

BS EN 10080 Reinforcing Steels

Rail?

RC Spreadsheets ‘How to’ compendium

DESIGN OF CONCRETE STRUCTURES

Part 1-1: General Rules for Structures Part 1-2: Structural Fire Design

BS 4449 Reinforcing Steels

NBS? BS EN 1994 Design of Comp. Struct.

CESWI?

Worked Examples

BS EN 13369 Pre-cast Concrete 73

BS EN 1992 Part 3: Liquid Ret. Structures

BS EN 1992 Part 2: Bridges

Eurocode 2 & the UK – what does it mean?

Concise Eurocode 2 for Bridges

ECFE – scheme sizing

Scheme design

Properties of concrete Precast Design Manual

Precast Worked Examples

www. eurocode2.info

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Concise Eurocode 2

A paper by Moss and Webster (BS8110 vs EC2, TSE 16/03/04) concluded:·

Clarity Clear references

• big impact

Comment

• learning curve

Design aids

• not wildly different from BS8110 in terms of the design approach. • similar answers • marginally more economic. • less prescriptive and more extensive than BS8110 • gives designers the opportunity to derive benefit from the considerable advances in concrete technology over recent years • believe that after an initial acclimatisation period, EC2 will be generally regarded as a very good code

.

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Flat slabs: Economic depths

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‘How to’ compendium

500 450

To BS8110

400

IL = 5 kN/m2

SLAB DEPTH, mm

350 300

To BS8110 incl 1.5 SDL

IL = 2.5 kN/m2

EC2: up to 15 mm shallower @ 6 m

To BS8110 incl 1.5 SDL

EC2: up to 25 mm shallower @ 9 m

250 200

5 to 7 % savings?

150 4.0

5.0

6.0

7.0

8.0

9.0

To EC2

10.0 11.0 12.0 SPAN, m

75

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Rev’d 12 May 10

SPATA Training 4 Oct 2012 - Eurocode 2

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Spreadsheets to BS EN 1992-1-1 (and UK NA)

Spreadsheets

TCC11 Element design TCC12 Bending and Axial Force TCC13 Punching Shear TCC14 Crack Width TCC21 Subframe analysis TCC31 One-way Solid Slabs (A & D) TCC31R Rigorous* One-way Solid Slab TCC32 Ribbed slabs (A & D) TCC33 Flat Slabs (A & D) (single bay) TCC33X Flat Slabs. Xls (whole floor) TCC41 Continuous beams (A & D) TCC41R Rigorous* Continuous Beams TCC42 (β) Post-tensioned Slabs & Beams (A & D) TCC43 Wide Beams (A & D) TCC51 Column Load Take-down & Design TCC52 Column Chart generation TCC53 Column Design TCC54 Circular Column Design TCC55 Axial Column Shortening TCC71 Stair Flight & Landing – Single TCC81 Foundation Pads TCC82 Pilecap Design

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Design Guidance New Concrete Industry Design Guidance is written for Eurocode 2 • TR 64 Flat Slab • TR43 PT • TR58 Deflections

Text books

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Introduction to Eurocode 2 Charles Goodchild, BSc CEng MCIOB MIStructE

The Concrete Centre www.concretecentre.com www.eurocode2.info 81

SPATA Training 4 Oct 2012 - Eurocode 2

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