01. a summary of essential differences between ec2 and bs8110 code (2014 10 07)

1. A summary of essential

differences between EC2 and

BS8110

Prof Tan Kang Hai

Email: [email protected]

Director of Protective Technology Research Centre (PTRC)

School of Civil & Environmental Engineering All the rights of 11 lecture materials belong to Tan Kang Hai

1

mailto:[email protected]



• Which is the most challenging hurdle in migration from

BS8110 to EC2?

• What is the highest grade of concrete in EC2?

• How are notional horizontal loads represented in EC2?

• What are the essential differences in shear design

between BS 8110 and EC2?

• What is the main difference in column design in EC2?

QUIZ

2

Outline

Similarities and differences of BS8110 and EC2

Influence of material behaviour

Basis of design and load combination

Global geometric imperfections

Nonlinear versus linear elastic analysis

Shear design of beams and slabs

Design of columns

Detailing of members

3

Outline







Design of columns


4

- Ultimate limit state and serviceability limit state

- Permanent actions, imposed loads and wind loads

- Plane strain assumption for design of beams,

slabs, columns, and walls

- Linear elastic analysis

- Linear elastic analysis with limited distribution

- Plastic analysis

Similarities

of BS8110 and EC2

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

5

• EC2 is phenomenon-based code unlike the BS8110

• Entire code is based on reliability index

• Based on Model Concrete Code 1978 and 1990

1. Influence of material behaviour (Concrete grade

90/105)

2. Basis of design and load combination

3. Global geometric imperfections

4. Nonlinear versus linear elastic analysis

5. Shear design of beams and slabs

6. Design of columns

7. Detailing of members

Differences

between BS8110 and EC2 Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

6

Outline







Design of columns


7

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

max stress level for idealized curve must be below the max stress

of the schematic diagram for the same area under the curve

(3.15)

The design value of concrete compressive strength fcd is given by:

Where the factor allows for the difference between the

bending strength and the cylinder crushing strength of concrete,

and is the concrete material partial safety factor.

EC2 stress-strain relationships of

concrete under compression

8

ckck

c

ckcccd f

fff 567.0

5.1

85.0

5.1c

Class 1 Class 2 Class 3

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

Table 3.1 Strength and deformation

characteristics for concrete

9

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

EC2 stress-strain relationships of

reinforcing steel

k=ft/fy indicates ductility; the greater the k value, the longer is the

plateau or the plastic zone uk.

The design value of the modulus of elastic Es is 200 GPa. In

the ultimate limit state calculation, by taking a partial safety

factor of , design values of yield strength fyd and

yield strain of reinforcing steel are respectively computed as:

10

15.1s

y

yk

yk

yd ff

f 87.015.1

00217.0

1020015.1

105006

3

ss

yk

yE

f

11

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

Table C.1: Properties of reinforcement

Product form Bars and de-coiled

rods

Wire Fabrics Requirement or

quantile value (%)

Class A B C A B C -

Characteristic yield

strength fyk or f0.2k (MPa)

400 to 600

5.0

Minimum value of

k = (ft/fy)k

≥1.05

≥1.08

≥1.15

<1.35

≥1.05

≥1.08

≥1.15

<1.35

10.0

Characteristic strain at

maximum force, (%)

≥2.5

≥5.0

≥7.5

≥2.5

≥5.0

≥7.5

10.0

Bendability Bend/Rebend test -

Shear strength - 0.3 A fyk (A is area of wire) Minimum

Maximum

deviation

from nominal

mass

(individual

bar of wire)

(%)

Nominal

bar size

(mm)

≤8

>8

± 6.0

± 4.5

5.0

12

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

7.2.3 Tensile properties

The specified values for the tensile properties

are given in Table 4.

Table 4 – Characteristic tensile properties

Yield strength,

Re

MPa

Tensile/yield strength ratio,

Rm/Re

Total elongation at

maximum force, Agt

%

B500A 500 1.05a 2.5b

B500B 500 1.08 5.0

B500C 500 ≥1.15,<1.35 7.5

a Rm/Re characteristics is 1.02 for sizes below 8mm. b Agt characteristics is 1.0% for sizes below 8mm.

Values of Re specified are characteristic with p = 0.95.

Values of Rm/Re and Agt specified are characteristic with p = 0.90.

Calculate the values of Rm and Re using the nominal cross sectional area.

The absolute maximum permissible value of yield strength is 650 MPa.

BS 4449:2005

+A2:2009

13

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

7.2.3 Tensile properties

BS 8666:2005 - Scheduling, dimensioning, bending and cutting of steel

reinforcement for concrete — Specification has been revised to incorporate:

(i) Shape codes available under BS EN ISO 3766:2003; (ii) Revised

notation in accordance with BS 4449:2005 and BS EN 10080:2005; (iii)

Revisions to BS 4449:2005 (including the omission of grade 250 and grade

460 reinforcement) (iv) The provisions of BS EN 1992-1-1 (including the

preclusion of wire to BS 4482:2004 for structural purpose).

.

14

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

BS system:

notation is T

Similar to BS specification

Outline







Design of columns


15

16

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

Leading variable action and accompanying variable action:

Comparison of partial factors for loading

Design situations BS 8110 EC2

With one variable action

(Live load) 1.4DL + 1.6LL 1.35Gk + 1.5Qk

With one variable action

(Wind load) 1.4DL + 1.6W 1.35Gk + 1.5Wk

With two variable

actions

(leading and

accompanying)

(Wind & live loads)

1.2DL + 1.2LL +

1.2W

1.35 Gk + 1.5 Qk + 0.75Wk

Or 1.35 Gk + 1.05 Qk + 1.5Wk

0.7x1.5Qk for office or

residential buildings

0.5x1.5Wk

(6.10)

Load combinations

according to EC0

17

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

Ultimate states Combinations of actions

Eq. (6.10)

For EQU, STR,

GEO

1.35 Gk + 1.5 Qk + 1.5*0.5Wk

Or 1.35 Gk + 1.05 Qk + 1.5Wk

Eq. (6.10a)

For STR, GEO

1.35 Gk + 1.5*0.5Wk +1.5*0.7 Qk

1.35 Gk + 1.5*0.5Wk

Eq. (6.10b)

For STR, GEO

0.925*1.35Gk + 1.5Wk +1.5*0.7 Qk

Or 0.925*1.35 Gk + 1.5Wk

To be applied together

(6.10a)

(6.10b)

For unfavourable

permanent

actions – single

source principle

in EC0 - Table

A1.2 (B) Set B

Load combinations

according to EC0

18

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

Load combinations

according to EC0

1.35Gk

1.35Gk + 1.5Qk

1.35Gk + 1.5Qk

1.0Gk

1.35Gk 1.35Gk

1.35Gk + 1.5Qk

Single source for Gk

1.4Gk + 1.6Qk

1.4Gk + 1.6Qk

1.4Gk + 1.6Qk

19

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

Load combinations

according to EC2 Cl 5.1.3

1.35Gk + 1.5Qk

1.0Gk 1.0Gk

Outline







Design of columns


20

21

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

• In EC2, there is no notional

horizontal load.

• Global geometric imperfections due

to out-of-plumbness of vertical

elements must be modelled by

equivalent loads in two design

situations:

Persistent design situations:

Possible extreme loading condition

of wind, imposed loads.

Accidental design situations: fire,

impact.

When to consider

geometric imperfections?

22

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

• Imperfection loads are quantified by three considerations:

Global analysis of building structures.

Analysis of isolated vertical members.

Analysis of floor diaphragms as horizontal elements

transferring forces to bracing members.

Only imperfection loads in global analysis are similar to

notional horizontal loads, although they are very different in

the way to be considered.

• Imperfections need not be considered for serviceability limit

states.

When to consider


23

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

• The structure is assumed with inclination θl, given by:

where: θ0 is the basic value (θ0 = 1/200)

• αh is the reduction factor for height

• αm is the reduction factor for number of members:

where m is the number of vertically continuous members

in the storey contributing to total horizontal forces on the

floor.

How to consider


24

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members • The imperfection on each floor may be represented by a

force acting on the floor where Na and Nb are the factored

axial forces above and below the floor considered. (see

EC3 Figure 5.3)

To design for slab

(member transferring

forces to bracing

elements)

How to consider


25

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

Lateral load case: in BS 8110: Hdesign = Max(HN, 1.2Wk)

However, in EC 2: Hdesign = 1.0 Hi + FWk

where Hi is horizontal loads for geometric imperfection

How to consider


Outline







Design of columns


26

27

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

First order elastic analysis: represents conditions at

normal service loads very well (Section 5.4)

First order elastic analysis with limited redistribution:

excluded nonlinearity, represents conditions at normal

service loads very well (Section 5.5)

First order inelastic analysis: Plastic analysis with no

geometrical nonlinearity (Section 5.6)

Second order elastic analysis: Effects of finite

deformation considered. Good representation of P- effect

(Section 5.7)

Second order inelastic analysis: Both geometrical and

material nonlinearities are considered. Model can faithfully

reflect the behavior of structures up to ultimate limit state

Different types of analysis

28

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

Source: Fig. 8.1 of Matrix Structural Analysis, Second Edition, William

McGuire, Richard H. Gallagher and Ronald D. Ziemian, John Wiley & Sons, Inc,

2000, ISBN 0-471-12918-6

e

Different types of analysis

Outline







Design of columns


29

30

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

Methodology

DC : the concrete acts as the

diagonal struts;

VT: the stirrups act as the

vertical ties;

BT: the tension reinforcement

forms the bottom chord;

TC: the compression

steel/concrete forms the top

chord.

= 21.80 ÷ 450 (strut angle)

(EC2 6.2.3(2))

(a) Beam and reinforcement

(b) Analogous truss

• EC2 uses The Variable Strut Inclination Method for shear

design.

• BS 8110 uses Truss Analogy with truss angle = 450

31

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

Comparison of shear design

• BS 8110

1. = 45o

2. BS 8110 compares shear

stresses.

3. The maximum shear

stress is limited to 5

N/mm2 or 0.8fcu,

whichever is the lesser.

4. The design shear force

must be less than the

sum of the shear

resistance of concrete

plus shear links.

• EC2

1. = 21.8o ÷ 45o

2. EC 2 compares shear forces.

3. The maximum shear capacity

of concrete VRd,max cannot be

exceeded.

4. Where the applied shear

exceeds the min shear

resistance of concrete VRd,c,

the shear reinforcement

should be capable of resisting

all the shear forces.

32

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

Punching shear design of slabs

Control perimeters

Basic control perimeter u1:

Outline







Design of columns


33

34

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

Differences in symbols

35

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

Differences in symbols

36

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

Differences in design

37

Similarities and

differences of

BS8110 and EC2

Influence of

material behaviour

Basis of design

and load

combination

Global geometric

imperfections

Nonlinear versus

linear elastic

analysis

Shear design of

beams and slabs

Design of columns

Detailing of

members

Differences in design

Outline







Design of columns


38

DESIGN ANCHORAGE LENGTH

For the effect of the form of the

bars assuming adequate cover

1=0.7~1.0 (in comp. is 1.0)

For the effect of concrete minimum

cover 2=0.7~1.0 (in comp. is 1.0)

For the effect of confinement by tied

transverse bars along the design anc.

length 3=0.7~1.0 (in comp. is 1.0)

For the effect of confinement by welded

transverse bars along the design anc. length

4=0.7

For the effect of confinement by transverse

pressure along the design anc. length 5=0.7

Basic anchorage length

Design stress of the bar:

Design ultimate stress:

For the quality of bond condition 1=0.7

(poor) - 1=1.0 (good)

For the bar diameter 2=1.0 for ≤32mm

2=(132-)/100 for >32mm

The design concrete tensile strength (<C60/75)

fctd=fctk,0.05/c


39

DESIGN ANCHORAGE LENGTH lbd


40

• Complex load combinations due to leading and accompanying

variable load cases;

• In EC0 - Eq 6.10 compared with Eq 6.10(a) and Eq 6.10(b).

• Definition of member types and the choice of suitable elements;

• Represent global geometrical imperfection load by horizontal

loads and consider in all ULS;

• Need to consider global second order effect unless structure

satisfies Clause 5.8.3.3;

• Calculation model should reflect realistic global and local

behaviour of the designed RC structure

• High strength concrete is permitted (above 50 MPa till 90 MPa);

• Mild steel 250 MPa is no longer allowed.

SUMMARY on Differences between BS and EC

41

• Which is the most challenging hurdle in migration from

BS8110 to EC2?

• What is the highest grade of concrete in EC2?

• How are notional horizontal loads represented in EC2?

• What are the essential differences in shear design

between BS 8110 and EC2?

• What is the main difference in column design in EC2?

QUIZ

42

Thank You!

43

01. a summary of essential differences between ec2 and bs8110 code (2014 10 07)

Documents

slabs design of columns

column design

ec2 similarities

differences of bs8110

bs8110 entire code

outline similarities

strength of concrete

bs8110 prof tan kang