Seismic Design to EC8

1

Seismic Design to EC8

Jack Pappin, Arup, Hong Kong

Topics

• Seismic hazard

• Site response / Liquefaction

• Design of buildings to EC8

• Foundation design to EC8

• Other ground effects

2

Ground motion

Plate tectonics

3

Observed seismicity

Seismic activity 1990 to 1999 within 100km of the surface: Source USGS website

Section through South America

Plate tectonics

4

Earthquake mechanism

Time = 0

Time = 100 years

Time = 101 years

Slippage causing Energy release

Earthquake effects

ModerateIntensity

LowIntensity

HighIntensity

5

MSK Intensity scale

III - Weak Felt indoors by a few people

V - Strong Buildings tremble, unstable objects overturned

VI - Slight damage Slight damage to a few brick buildings

VII - Building damage Large cracks in weak buildings, slight to r.c. building

VIII - Some destruction Partial collapse of weak buildings, a few slopes fail

IX - General damage Large cracks in r.c. buildings, liquefaction observed

X - General destruction Most brick buildings collapse, many landslides

XI - Catastrophe Most buildings collapse

XII - Landscape changes Practically all structures destroyed

IV - Largely observed Felt indoors by many people, doors and dishes rattle

II - Very weak Recorded by instruments

Intensity 7Newcastle 1989

6

Intensity 9Taiwan 1999

Magnitude

Magnitude is a measure of the size (or energy release) of the earthquake.

Each unit increase in magnitude scale is about a three times increase in ground motion for the same distance from the event. It is also about a 30 times increase in energy release.

7

MagnitudeEnergyRelease

Step 2 - Calculation

Ground motion

Step 1 - desk study

8

Step 1 - desk study

M8.5 and 7.9 Southern Sumatra Earthquakes of 12 September 2007 and M7.0 of 13 September 2007

9

Seismic Hazard of Western Indonesia – April 2008

What measure should be used to define ground motion

Intensity - measure of peak observed damage potential

Peak motions - acceleration, velocity or displacement

Ground motion

10


ROCK SOIL

Ground motion

12 Sep 2007 Sumatra

11

Frequency content - response spectra

What measure should be used to define ground motion

Intensity - measure of peak observed damage potential


Ground motion

Response spectrum

12

30 Sep 2009 Sumatra

30 Sep 2009 Sumatra

13

Ground motion - Calculation

Key information for a seismic hazard assessment

Seismic source zonesActive faultsAreas of diffuse seismicity

Attenuation relationshipThe behaviour of a measure of groundmotion as a function of the distancefrom the source of energy, (EERI 1984).

Attenuation relationship

Example for Peak Ground Acceleration

Distance (km)

Pea

k gr

ound

Acc

eler

atio

n (g

)

101 100 1000

1.0

0.5

0

M = 7.5

M = 6.5

M = 5.5

Magnitudemeasure of the size (or energy release) of the earthquake.

14

Example of Response Spectra from an event at 10km in the Western USA

Fundamental Period (sec)

Pea

k gr

ound

Acc

eler

atio

n (g

)

10 2

1.0

0.5

0

M = 7.5

M = 5.5

M = 6.5 for Eastern USA

M = 6.5

Attenuation relationship

Variability of Attenuation relationship

100

10Distance from energy source (km)

Pea

k ac

cele

ratio

n (%

g)

1

10

6

40

100

15

Ground motion - Calculation

2 basic methods to determine design ground motion

to determine the ground motion at the site due to maximum expected earthquakes

Deterministic

Probabilistic to determine the ground motion at the site which has a desired annual probability of being exceeded

For each source the maximum magnitude that is expected is estimated.

Deterministic seismic hazard analysis

STEP 2 - distance determination

R3R1

R2

Source 2

Source 1 Source 3

Site

STEP 1 - source model

M1 M3

M2

R1

STEP 3 - attenuation

M3

M2

M1

Distance

STEP 4 - report

Y =

Y3

Y1

Y2

R2R3

Controllingearthquake

16

Probabilistic seismic hazard analysis

Source 2

Source 1 Source 3

Site

STEP 1 - source model

R

R

R

STEP 2 - rate of earthquake activity

Magnitude M

3

21

STEP 3 - attenuation

M = 6

Distance R

M = 7

STEP 4 - result for all M and R

Parameter value y*

7

Aerial photography

Field mappingGround investigation data

Hard copy geological maps

ArcInfo export geological maps

Satellite imagery (IKONOS)

GIS

Maps

Hazards

Geohazard studies

17

Geology & tectonicsGeomorphologySlip ratesObserved seismicity

Seismic source zones and activity rates

Fault sources -

Geology & tectonicsObserved seismicityObserved seismicity

Areal sources -

2. Instrumental dataComplied by by several agencies e.g. ISC, USGS.Recent data is more complete

since 1920 for M > 6since 1963 for M > 4.5

1. plus 2. = Earthquake catalogue

Observed seismicity

1. Historical dataBased on Intensitymore recent data is more complete

18

Tectonic structure

Kuala Lumpur

-7.5

-5.0

-2.5

0.0

2.5

5.0

7.5

10.0

95.0 97.5 100.0 102.5 105.0 107.5 110.0

Longitude

La

titu

de

5 to 5.4

5.5 to 5.9

6 to 6.9

7 to 7.9

8 to 8.9

9

500km

19

Subduction zone model

0

100

200

300

0 100 200 300 400 500 600 700 800

Distance (km)

De

pth

(km

)

5.0 to 5.45.5 to 5.96.0 to 6.97.0 to 7.98.0 to 8.99

Kuala Lumpur

Activity with depth for subduction events

0 50 100 150 200

0-20

20-30

30-40

40-60

60-80

80-100

100-130

130-160

160-200

200-250

250-300

Dep

th (

km)

number of events

20

Seismic activity in Subduction

0.001

0.01

0.1

1

10

4 5 6 7 8 9

Magnitude (M)

Ann

ual n

umbe

r of

eve

nts

> M

1800

1920

1964

Design

0.001

0.01

0.1

1

10

100

4 5 6 7 8 9

Magnitude (M)

Ann

ual n

umbe

r of

eve

nts

> M

1800

1920

1964

Design10

to 4

0km

40 to

100

km

0.001

0.01

0.1

1

10

4 5 6 7 8 9

Magnitude (M)

Ann

ual n

umbe

r of

eve

nts

> M

1920

1964

Design

100

to 2

00km

0.001

0.01

0.1

1

10

4 5 6 7 8 9

Magnitude (M)

Ann

ual n

umbe

r of

eve

nts

> M

1964

Design

200

to 3

00km

Sumatra Fault model

-7.5

-5.0

-2.5

0.0

2.5

5.0

7.5

10.0

95.0 97.5 100.0 102.5 105.0 107.5 110.0

Longitude

La

titu

de

5 to 5.4

5.5 to 5.9

6 to 6.9

7 to 7.9

Series9

Series10

21

Sumatra Fault model

0

100

200

300

0 100 200 300 400 500 600 700 800

Distance (km)

De

pth

(km

)

5.0 to 5.4

5.5 to 5.9

6.0 to 6.9

7.0 to 7.9

Kuala Lumpur

Sumatra Fault Area to the north

and east of the Sumatra Fault

Subduction zone

Sumatra fault activity rates

0.001

0.01

0.1

1

10

4 5 6 7 8 9

Magnitude (M)

An

nu

al n

um

be

r o

f eve

nts

> M

1800 - 2005

1920 - 2005

1964 - 2005

17mm/yr slip

Background

Total

22

93 96 99 102 105 108 111-12

-9

-6

-3

0

3

6

9

12

SumatraFault M

alay Peninsula

52 mm/yr

(N10oE)

57 mm/yr

Seulimeum

Renun

Dikit

Semangko

Palembang

Pekan Baru

Penang

Singapore

Latit

ude

(o ) Barumun

Medan

Sumani

Longitude (o)

Sumatra

Subduction

EurasianPlate

Indian-AustralianPlate 60 mm/yr

(N17oE)

500 km0

Sumatra

Java

Kuala Lumpur

Ground-Motion Attenuation Relationships for Sumatra Earthquakes

Developed by Megawati (NTU, Singapore)

Attenuation Subduction earthquakes (Megawati 2006)

0.001

0.01

0.1

1

10

0 200 400 600 800 1000

Distance (km)

1 se

con

d R

SA

(m

/s2)

9

8

7

6

5

Standard deviation = * 1.8

23

Attenuation Sumatra Fault earthquakes (Megawati 2006)

0.001

0.01

0.1

1

10

0 200 400 600 800 1000

Distance (km)

1 s

ec

on

d R

SA

(m

/s2 )

9

8

7

6

5

Standard deviation = * 2.6

Normal distribution

0

0.2

0.4

0.6

0.8

1

-3 -2 -1 0 1 2 3

Standard deviations from mean

Lik

elih

oo

d

24

Calculated response spectra

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.01 0.1 1 10

Period (sec)

Sp

ec

tral

Ac

ce

lera

tio

n (

m/s

2)

2% in 50 year

10% in 50 year

50% in 50 year

5% damping

13

63

11

3

16

3

21

3

26

3

31

3

363

413

463

51

3

56

3

613

663

713

763

813

863

9.25

8.25

7.25

6.25

5.25

0

2

4

6

8

10

% C

on

tib

uti

on

to

Haz

ard

Distance (km)Magnitude (M)

2% in 50 year (0.2sec)

De-aggregation2% in 50 year

0.2 second period

1833 type event

Subduction 0 to 40km deep



Sumatra Fault

Northeast Sumatra

Sunda Plate

13

63

113

163

213

263

313

363

413

463

513

563

613

663

713

763

813

863

9.25

8.25

7.25

6.25

5.25

0

2

4

6

8

10

12

Distance (km)Magnitude (M)

2% in 50 year (1s)

1 second period

13

63

113

163

213

263

313

363

413

463

513

563

613

663

713

763

813

863

9.25

8.25

7.25

6.25

5.25

0

2

4

6

8

10

12

14

16

18

20

Distance (km)Mag

2% in 50 year (5s)5 second period

25

Scenario events

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.01 0.1 1 10

Period (sec)

Sp

ectr

al A

cce

lera

tio

n (

m/s

2)

2% in 50 year 10% in 50 year 50% in 50 year

Subd M9.3@530 * 1.9 Subd M9.0@530 * 1.7 Subd M8.7@550 * 1

Sum Flt M8@400 * 6 Sum Flt M8@400 * 3.5 Sum Flt M8@400 * 1.5

Local M6@130 * 2.3 Local M6@210 * 2 Local M6@240 * 1

5% damping

Incorporation of uncertainty

Example of a logic tree analysis

Attenuation Magnitude Maximummodel distribution magnitude

0.18

26

Time histories

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.01 0.1 1 10

Period (sec)

Sp

ectr

al A

ccel

erat

ion

(m

/s2)

2% in 50 year 10% in 50 year 50% in 50 year

2% in 50yrs - Short 10% in 50yrs - Short 50% in 50yrs - Short

2% in 50yrs - Long 10% in 50yrs - Long 50% in 50yrs - Long

5% damping

Time histories

Time [sec]4038363432302826242220181614121086420

Acc

eler

atio

n [m

/se

c2]

0.3

0.25

0.2

0.15

0.1

0.05

0

-0.05

-0.1

-0.15

-0.2

-0.25

T im e [ s e c ]8 0 07 5 07 0 06 5 06 0 05 5 05 0 04 5 04 0 03 5 03 0 02 5 02 0 01 5 01 0 05 00

Acc

ele

ratio

n [m

/sec

2]

0 . 2

0 . 1 5

0 . 1

0 . 0 5

0

- 0 . 0 5

- 0 . 1

- 0 . 1 5

- 0 . 2

T im e [s e c ]8 0 07 5 07 0 06 5 06 0 05 5 05 0 04 5 04 0 03 5 03 0 02 5 02 0 01 5 01 0 05 00

Acc

eler

atio

n [m

/sec

2]

0 .2

0 .1 5

0 .1

0 .0 5

0

- 0 .0 5

- 0 .1

- 0 .1 5

0.3

0.25

0.2

0.15

0.1

0.05

0

-0.05

-0.1

-0.15

-0.2

-0.25

Long Period

Short Period Same scale

27

2% in 50 year bedrock motion

0

1

2

3

4

5

6

7

0.01 0.1 1 10

Period (sec)

Sp

ec

tra

l A

cc

ele

rati

on

(m

/s2 )

Hong Kong

Kuala Lumpur

New York (IBC2006)

5% damping

28

USGS catalogue since 1972 - 0 to 50 km depth


29



30

Section R1

31

Section R2

Section R3

32

Magnitude recurrence plots

0

1

2

0.01 0.1 1 10

Bed

rock

Sp

ectr

al a

ccel

erat

ion

(m

/s2)

Structural period (s)

Semporna

Sandakan

Kota Kinabalu

Kuala Lumpur

Penang

Kuantan

Kuching

10% in the next 50 year bedrock response spectra

5% damping

33

Comparison with Eurocode 8 rules (3.2.1(4))

0.15 0.4 2

Comparison with Eurocode 8 rules (for bedrock)

34

0

1

2

0.01 0.1 1 10

Sp

ectr

al a

ccel

erat

ion

(m

/s2)


Semporna

Sandakan

Kota Kinabalu

Kuala Lumpur

Penang

Kuantan

Kuching

Seismic design not required

Seismic design

required with ductile

detailing


5% damping

Concern with seismicity near to KL

35

Events observed since 2004

2.2 2.7 3.2 3.7 4.2

0.1

1

10

Annual excee

dance rate

Magnitude

10% in the next 50 year bedrock response spectra

0

1

2

0.01 0.1 1 10

Sp

ectr

al a

ccel

erat

ion

(m

/s2)


Kuala Lumpur

KL with local events


Seismic design


detailing

36

Bedrock

?

Site Response

• 2 week visit two weeks after the event

Mexico City - 1985

37

Mexico City - 1985

Earthquake source

Mexico City

EpicentreMagnitude 8.1

D

D

D

38

Mexico City

5 km

Mexico City

5 km

39

Television studio

Mexico City

5 km

40

Recorded ground motion

Recorded ground motion

41

Response spectra

Observed building damage

43%

42

Notable non-damage

Lake bed ground conditions

43

Cyclic triaxial testing of lake bed clay

Nottingham University

Response spectra

44

IBC 2000+ Classification of soil profile types

The upper 30m of the soil profile are considered

Soil Profile Shear wave SPT Undrained shearType velocity (m/sec) N value strength (kPa)

A - Hard rock >1,500 - -

B - Weak to medium rock 750 - 1,500 - -

C - Dense stiff soil 375 - 750 > 50 > 100

D - Medium dense firm soil 180 - 375 15 - 50 50 - 100

E - Loose soft soil < 180 < 15 < 50

F - Deep soft soils that require site specific investigations

Site Response Effects – US approach

IBC 2000+ Soil amplification factors

Site Response Effects

Approximate Peak Ground Acceleration (g)

Soi

l Am

plifi

catio

n F

acto

r

E

D

CBA

0

1

2

3

4

0 0.1 0.2 0.3 0.4 0.5 0.6

Short period motion (0.2 sec)

Soft soil

Hard Rock

Long period motion (1 sec)

E

DCBA

45

Eurocode classificationIBC

Eurocode classification

46



0

1

2

3

0.1 1 10

So

il am

plif

icat

ion

fac

tor


EC8 : 10% in 50 year bedrock response spectra

Class D

Class C

Class B

47


0

1

2

3

0.1 1 10

So

il a

mp

lifi

cati

on

facto

r



Class D

Class C

Class B

IBC 2000+ Soil amplification factors

Approximate Peak Ground Acceleration (g)

D

C

B

0

1

2

3

4

0 0.1 0.2 0.3 0.4 0.5 0.6

Short period motion (0.2 sec)

Soft soil

Hard Rock

Long period motion (1 sec)

D

CB

Oasys SIREN site response analysis

Soil Surface

Bedrock

Output motion

F

= F

Input motion

48

Gsec

Gmax or G0

Soil shear behaviour

G0

Gsec

Backbone curve

log

Gsec

G0

1.0Modulusreduction curve

G0(ij) = vs(ij)2 where G0(ij) is the elastic shear modulus

is the bulk density of soil andvs(ij) is the shear wave velocity through soilVs(vh)

Vs(hh)

Vs(hv)

v

h1

h2

Soil triaxial specimen

Bender element

1

1

2 2

33

Mid-plane pore pressure probe

Porous stone

Bender element (vs(vh))

Base pedestal

Bender element embedded in base platen

Bender element (vs(hv))

Bender element (vs(hh))

Bender element probe

Mid-plane pore pressure probeBender element probe

Hall-effect gauge (radial)Hall-effect gauge (axial)

49

Cyclic shear strain (%)

Gsec

G0

1.0

010.0001 0.001 0.01 0.1 10

10.0001 0.001 0.01 0.1 10

Dam

ping

rat

io (

%)

0

10

2030

PI =0

50

15

100

200

Variation with strain

Geophysical methods for G0

Up hole Down hole

G0 = VS2

Cross hole - simple Cross hole - accurate

50

Down hole seismic cone testing

Oasys SIREN is a computer programme for a non-linear model which solves the one dimensional site response problem in the time domain using the explicit finite difference method.

Soil Surface

Output motion

F

= F

Input motion

Bedrock

Displacement

51

Site Class Definition – EC8

Class C profiles, 10% in 50-year ground motion, long period

0

1

2

3

4

5

6

7

0.01 0.1 1 10

Period (s)

Sp

ectr

al R

atio

CK1OR4BH3 Alex RdBH 2 Alex RdBH ARN5BH ARN1BH 1936-3BH 799-TB8BH 2111-5BH 1263-4BH 1808-6BH 91F-86BH 703-69ABH 1222-6BH 460-14BH 2122-15BH 348-31Average

+2 Sigma+1 Sigma

Average

-1 Sigma-2 Sigma

Class E profiles, 10% in 50-year ground motion, long period

0

1

2

3

4

5

6

7

8

9

0.01 0.1 1 10

Period (s)

Sp

ect

ral R

atio

BH 233-11BH 1982-25BH 1754-4BH 1626-25BH 1627-23BH 1144-505-1BH 24B-PP2BH 144K-5BH 2131-2BH 1493-13BH 262-D19BH 424-9DTL/20/PZS/VSTDTL/31/VSTDTL/43/PZM/VSTDTL/45/VSTM2019M2020Average

+2 Sigma+1 Sigma

Average

-1 Sigma-2 Sigma

Spectral Ratios

B

D

52

Resulting Spectra

10% in 50 year - Long period

0

0.5

1

1.5

2

0.1 1 10Period (s)

Sp

ect

ral A

ccel

erat

ion

(m

/s/s

)

Bedrock

Site Class C

Site Class D

Site Class E

Site Class F

B

C

D

S

Displacement spectra

10% in 50 year - Long period

0.01

0.1

1

0.1 1 10Period (s)

Sp

ectr

al D

isp

lace

me

nt

(m)

Bedrock

Site Class C

Site Class D

Site Class E

Site Class F

B

C

D

S

53

Design spectra

0

1

2

0.1 1 10

Structural Period (s)

Sp

ec

tra

l A

cc

ele

rati

on

(m

/s2 )

Site Class B

Site Class C

Site Class D

Site Class E

Site Class F

B

C

D

S

Bedrock

Spectral ratios

0

1

2

3

4

5

0.1 1 10

Sp

ectr

al R

atio

Period T

10% in 50 year spectral ratios

Site Class B

Site Class C

Site Class D

Site Class S

0

1

2

3

0.1 1 10

So

il am

plif

icat

ion

fac

tor



Class D

Class C

Class B

54

Eurocode classification for KL / Penang

0

1

2

0.1 1 10

Sp

ectr

al A

ccel

erat

ion

(m

/s2)


10% in 50 year design spectra

Site Class C

Site Class D

Site Class S

C Equation

D Equation

E Equation

C 1.6 0.4 1.1 10.4D 2.5 0.9 1.6 4.6

S1 3.2 1.6 2.4 2.4

ag = 0.175 m/s2

0

1

2

0.01 0.1 1 10

Sp

ectr

al a

ccel

erat

ion

(m

/s2)


Semporna

Sandakan

Kota Kinabalu

Kuala Lumpur

Penang

Kuantan

Kuching


Seismic design


detailing


5% damping

55

Comparison with IBC rules

0

1

2

0.1 1 10

Sp

ec

tra

l ac

ce

lera

tio

n (

m/s

2 )


IBC: (2/3 2% in 50 year) response spectra

KL Rock

KL Soil C

KL Soil D

KL Soil S

seismic design not required

Seismic design required with no

ductility

Seismic design required with

ductility


0

1

2

0.1 1 10

Sp

ect

ral a

cce

lera

tion

(m

/s2 )


IBC: (2/3 2% in 50 year) response spectraBedrock

Kuala Lumpur

Kota Kinabalu

Semporna



ductility

56


0

1

2

3

0.1 1 10

Sp

ec

tra

l ac

ce

lera

tio

n (

m/s

2 )


IBC: (2/3 2% in 50 year) response spectraSoil Class D

Kuala Lumpur

Kota Kinabalu

Semporna



ductility

Comparison with Eurocode 8 rules (with soil)

0

1

2

0.01 0.1 1 10

Bed

rock

Sp

ectr

al a

ccel

erat

ion

(m

/s2)


Semporna

Sandakan

Kota Kinabalu

Kuala Lumpur

Penang

Kuantan

Kuching

Group D ; S = 1.35

Semporna D

KK D

KL D

57

0

1

2

3

0.01 0.1 1 10

Sp

ec

tra

l ac

ce

lera

tio

n (

m/s

2 )


10% in 50 year response spectraSoil Class D

Kuala Lumpur

Kota Kinabalu

Semporna

EC 8 Ductile

EC 8 Design

Comparison with EC 8

Possible EC8 Zoning map for Malaysia

58

0

1

2

0.01 0.1 1 10

Sp

ectr

al a

ccel

erat

ion

(m

/s2)


Semporna

Sandakan

Kota Kinabalu

Kuala Lumpur

Penang

Kuantan

Kuching


Seismic design


detailing


5% damping


0

1

2

0.1 1 10

Sp

ectr

al A

ccel

erat

ion

(m

/s2)



Site Class C

Site Class D

Site Class S

C Equation

D Equation

E Equation

C 1.6 0.4 1.1 10.4D 2.5 0.9 1.6 4.6

S1 3.2 1.6 2.4 2.4

ag = 0.175 m/s2

59

Possible EC8 Zoning map for Malaysia

8%g6%g

<4%g

<4%g

Liquefaction

60

Liquefaction

Liquefaction

61

Liquefaction

Philippines 1989

Turkey 1999Liquefaction

62

No Liquefaction

BUTWhen you are designing the structure,

can you rely on liquefaction happening?

Turkey 1999

Liquefaction

Standard method of assessing the likelihood of liquefaction

500 10 20 30

0.2

40

0.1

0.3

0.4

0.5

Corrected SPT N value (N1)

Ave

rage

pea

k sh

ear

stre

ss /

ver

tical

effe

ctiv

e st

ress

Percent fines (%) 35 15 <5

No Liquefaction

Liquefaction

0

Note: figure applies for a magnitude 7.5 earthquake

Liquefaction

63

Estimation of shear stress

10 0.2 0.4 0.6

15

0.8

20

10

5

0

Stress reduction factor rd

Dep

th (

m)

25

Modify soil Densify VibroflotationDynamic compactionDisplacement piling

Stabilise GroutingImprove drainage

Liquefaction

How to overcome

64

Vibro-replacement

Ground Improvement

• Typical methods include stone columns, dynamic compaction, grouting, soil cement mixing, dewatering.

• Suitability of method must be checked by field trials.

• For example stone columns do not work well with a high fines content (>15%).

Modify soil Densify VibroflotationDynamic compactionDisplacement piling

Stabilise GroutingImprove drainage

Change foundation FloatPile

Liquefaction

How to overcome

65

Liquefaction

How to overcome: Float

Liquefied soil

Shear failure

Basement void

66

Liquefaction

How to overcome: Pile

Liquefied soil Ductile detailing

Liquefaction - Lifelines

Loose backfillFlow of

liquefied soil

Jet grout walls

Flotation

Stone columns

Hashash et al, 2001

67

Building Design to EC8

134

Background to Eurocodes

• Set of unified design codes bringing together structural, civil, and geotechnical disciplines

• Adopted by all 28 member states of the European Union

• Conflicting national standards withdrawn by March 2010

• Main objective is:

“the elimination of technical obstacles to trade and the harmonisation of technical specifications”

(European Committee for Standardisation)

68

How are they Organised?

Eurocode Basis of Design

EN 1990

Eurocode 1

Actions on Structures

Eurocode 2

Design of Concrete Structures

Eurocode 3

Design of Steel Structures

Eurocode 4

Design of Composite Steel and Concrete Structures

Eurocode 5

Design of Timber

Structures

Eurocode 6

Design of Masonry

Structures

Eurocode 7

Geotechnical Design

Eurocode 8

Design of Structures for Earthquake Resistance

National Annex

Eurocode 9

Design of Aluminium Structures

From Bond & Harris

69

Eurocode 8 - Part 1: General Rules

Eurocode 8 – Parts 2 to 6

70

Eurospeak

Loads Actions

Dead Loads Permanent Actions

Imposed Loads

Variable Actions

‘Design Value’

Characteristic Value

Construction Execution

140

Eurospeak• Principles: Denoted by ‘P’ after the clause number – mandatory requirements

• Application Rules: Generally recognised rules that comply with the principles and satisfy their requirements

• Example

71

141

Eurostyle

• General, Non-prescriptive, Flexible

• “Performance Specification for Design”

Pros•Gives designer freedom to choose appropriate method•Economies are possible•Allows for evolving design methods•Can be applied to wide range of design situations in different locations

Cons•Can be daunting for those with little design experience•Less straightforward to use•Could be ambiguous

142

Design Philosophy

• Limit State Design is adopted in all Eurocodes

• Defined in EN 1990

• Fundamentally, all ULS and SLS shall be considered and verified where applicable

• Verification of Limit States should be carried out by either the partial factor, or probabilistic methods

• Important Considerations:- Design Working Life- Design Situations, e.g. normal use, transient, accidental, seismic

72

Limit State Design Philosophy

dd RE dMkrepFd aXFEE ;;

dMkrepFd aXFRR ;;

Probability of Failure (Eurocode Target <0.0001%)

Limit State Design Philosophy

Separation Calibrated by “partial factors”

73

145

The Partial Factor Method

Input ‘Characteristic’

Values

Material Parameters

Xk

Geometry

ak

Actions

Frep

‘Design’ Values

Material Parameters

Xk×γm =Xd

Geometry

ak +∆a = ad

Actions

Frep×γF = Fd

Calculation Model

Calculate Design

Resistance

Rd=f(Xd,ad)

Calculate Design Effect

of Actions

Ed=f(Fd,Xd,ad)

ULS verified?

Rd > Ed ?

146

q factor

displacement

force

elastic

Real behaviour

Sd

Design force (= elastic / q)

74

EC8 detailing DCL low ductility; q = 1.5

Lc

0.6Sc

Sb

Densified zones

Beam C

olum

n

Sc

Sb < 0.75x effective depth of beam

20 x minimum main bar diameterThe lesser of the column dimension400 mm

The larger of column dimensionLc larger of Length of lapped joints, minimum 3

transverse reinforcement bars

Diameter of transverse reinforcement bars not less than 6 mm or ¼ of the maximum diameter of the longitudinal bars

Sc min of

EC8 detailing DCM moderate ductility; q = 3.9

Lc

Sc

Lb

Sb

Densified zones

Beam

Column

Horizontal reinforcement in beam-column joints not less than that in the critical region of columns

24 times the stirrup diameter8 x smallest main bar diameterbeam depth / 4225 mm

Lb > beam depth

8 x minimum main bar diameterSc < minimum of half the width of the column confined concrete core

175 mm

1/6 clear height of the columnLc > maximum of Largest column section dimension

450mm

Note that the shear capacity of the beams and columns must be able to resist a shear force derived from the bending moment strength capacities considering actual reinforcement provided and material overstrength (material probable strength being higher than the design strength value)

Sb < minimum of

75

3 Storey building in KK

0.5M

M

M

Height (m)10.5

7

3.5

Lateral force distribution

10.5*0.5M = 5.3M

7*M = 7.0M

3.5*M = 3.5M

Sum = 15.8M

Period T = 0.05 * H0.75 = 0.29 s

For KK with Soil Class DLateral base shear = 0.85*Sa = 0.85*2.5*1.35 * 6% = 17% gLateral shear = 0.17*2.5M = 0.42M

Force

0.42*5.3/15.8 = 0.14M

0.42*7.0/15.8 = 0.19M

0.42*3.5/15.8 = 0.09M

Shear

28%

22%

17%


76

3 Storey building in KL

0.5M

M

M

Height (m)10.5

7

3.5

Lateral force distribution

10.5*0.5M = 5.3M

7*M = 7.0M

3.5*M = 3.5M

Sum = 15.8M

Period T = 0.05 * H0.75 = 0.29 s

For KL with Soil Class DLateral base shear = 0.85*Sa = 0.85 * 6% = 5% gLateral shear = 0.05*2.5M = 0.13M

Force

0.13*5.3/15.8 = 0.044M

0.13*7.0/15.8 = 0.058M

0.13*3.5/15.8 = 0.029M

Shear

9%

7%

5%


0

1

2

0.1 1 10

Sp

ectr

al A

ccel

erat

ion

(m

/s2)



Site Class C

Site Class D

Site Class S

C Equation

D Equation

E Equation

C 1.6 0.4 1.1 10.4D 2.5 0.9 1.6 4.6

S1 3.2 1.6 2.4 2.4

ag = 0.175 m/s2

77

Example building from Hong Kong – D11

• 15 storey residential

• H = 41m, W = 7200t

Mode shapes

0

5

10

15

20

25

30

35

40

-1 0 1 2

He

igh

t (m

)

Displacement

Normalised mode shapes

Mode 1

Mode 2

Mode 3

78

Modal contributions - KL

0

5

10

15

20

25

30

35

40

-5 0 5 10 15 20

Hei

gh

t (m

)

Displacement (mm)

Scaled mode shapes

RSS

Mode 1

Mode 2

Mode 3

0

5

10

15

20

25

30

35

40

-1 0 1 2 3

He

igh

t (m

)

Shear (MN)

Shear

RSS

Mode 1

Mode 2

Mode 3

0

5

10

15

20

25

30

35

40

-20 0 20 40 60 80 100

He

igh

t (m

)

Moment (MNm)

Moment

RSS

Mode 1

Mode 2

Mode 3

Modal contributions - KK

0

5

10

15

20

25

30

35

40

-10 0 10 20 30 40

He

igh

t (m

)

Displacement (mm)

Scaled mode shapes

RSS

Mode 1

Mode 2

Mode 3

0

5

10

15

20

25

30

35

40

-5 0 5 10

He

igh

t (m

)

Shear (MN)

Shear

RSS

Mode 1

Mode 2

Mode 3

0

5

10

15

20

25

30

35

40

-50 0 50 100 150 200

He

igh

t (m

)

Moment (MNm)

Moment

RSS

Mode 1

Mode 2

Mode 3

79

Modal contributions - Semporna

0

5

10

15

20

25

30

35

40

-10 0 10 20 30 40 50

He

igh

t (m

)

Displacement (mm)

Scaled mode shapes

RSS

Mode 1

Mode 2

Mode 3

0

5

10

15

20

25

30

35

40

-5 0 5 10 15

He

igh

t (m

)

Shear (MN)

Shear

RSS

Mode 1

Mode 2

Mode 3

0

5

10

15

20

25

30

35

40

-100 0 100 200 300

He

igh

t (m

)

Moment (MNm)

Moment

RSS

Mode 1

Mode 2

Mode 3

Shear

0

5

10

15

20

25

30

35

40

0 5 10 15 20 25

He

igh

t (m

)

Shear (%)

Shear (q = 1.5)

KL

KK

Semporna

80

Example building from Hong Kong – D17

• 53 storey residential

• H = 158m, W = 33000t

Mode shapes

0

20

40

60

80

100

120

140

160

-1 0 1 2

He

igh

t (m

)

Displacement

Normalised mode shapes

Mode 1

Mode 2

Mode 3

81

Modal contributions - KL

0

20

40

60

80

100

120

140

160

-50 0 50 100 150 200 250 300

He

igh

t (m

)

Displacement (mm)

Scaled mode shapes

RSS

Mode 1

Mode 2

Mode 3

0

20

40

60

80

100

120

140

160

-2 0 2 4 6 8 10

He

igh

t (m

)

Shear (MN)

Shear

RSS

Mode 1

Mode 2

Mode 3

0

20

40

60

80

100

120

140

160

-200 0 200 400 600 800 1000

He

igh

t (m

)

Moment (MNm)

Moment

RSS

Mode 1

Mode 2

Mode 3

Modal contributions - KK

0

20

40

60

80

100

120

140

160

-100 0 100 200 300

He

igh

t (m

)

Displacement (mm)

Scaled mode shapes

RSS

Mode 1

Mode 2

Mode 3

0

20

40

60

80

100

120

140

160

-5 0 5 10 15

He

igh

t (m

)

Shear (MN)

Shear

RSS

Mode 1

Mode 2

Mode 3

0

20

40

60

80

100

120

140

160

-500 0 500 1000 1500

He

igh

t (m

)

Moment (MNm)

Moment

RSS

Mode 1

Mode 2

Mode 3

82

Modal contributions - Semporna

0

20

40

60

80

100

120

140

160

-200 0 200 400 600

He

igh

t (m

)

Displacement (mm)

Scaled mode shapes

RSS

Mode 1

Mode 2

Mode 3

0

20

40

60

80

100

120

140

160

-10 0 10 20 30

He

igh

t (m

)

Shear (MN)

Shear

RSS

Mode 1

Mode 2

Mode 3

0

20

40

60

80

100

120

140

160

-500 0 500 1000 1500 2000 2500

He

igh

t (m

)

Moment (MNm)

Moment

RSS

Mode 1

Mode 2

Mode 3

Shear

0

20

40

60

80

100

120

140

160

0 5 10 15

He

igh

t (m

)

Shear (%)

Shear (q = 1.5)

KL

KK

Semporna

83

Foundation design

Failure Modes of Pad Foundations

SlidingBearing capacity

Overturning Structural

84

Failure by Sliding

Provided structure can hold itself together the only requirement is for No damageDesign checkSmall movement in 50% in 50 year ground motion

Failure by Bearing Capacity

Due to uncontrolled displacement the Life safety check will be required. If the structure could collapse as result of bearing failure of the foundation then the No collapse check is required. Design checkControlled displacement in the 10% in 50 year ground motion.Possibly required to check for failure 2% in 50 year ground motion.

85

Mexico City 1985

Failure by Overturning

If the structure could collapse due to overturning capacity failure then the No collapse check is required. Otherwise the only requirement is for No damage. For buildings on a raft failure could lead to collapse.Design checkSmall movement in 50% in 50 year ground motion.For a raft, required to check for failure in 2% in 50 year ground motion

86

Structural Failure

Due to uncontrolled displacement the Life safety check will be required. If the structure could collapse as result of structural failure of the foundation then the No collapse check is required. Design checkStructural integrity in the 10% in 50 year ground motion.Possibly required to check for failure 2% in 50 year ground motion.

Failure Modes of Piles - Vertical Loads

Stiff Clay

Soft Clay

Fill

87

Mexico City - 1985

Mexico City - 1985

88

Mexico City - 1985

Softclay

Sand

Building in Mexico City – 1 year later

89

Failure Modes of Piles - Vertical Loads

Stiff Clay

Soft Clay

Fill

Building in Taiwan - 1999

90

Building in Taiwan - 1999

The Hermes is built on a narrow site in Tokyo’s central Ginza district. It uses a new structural system that relieves seismic forces vertically through a lifting rear column at ground floor level, restrained by dampers.

This ‘stepping column’ system is able to move with the earthquake, thereby reducing forces and foundation and steelwork costs.

Yielding Piles - Hermes Tokyo

91

Case Study - Hermes Tokyo

Effects on Piles

92

Pile Failure - Lateral Loads

Bedrock

Stiff Clay

Soft Clay

Fill

500 250

Bending Moment (kNM)

Piles - Lateral Loads0 50 100 150

Horizontal displacement (mm)

Soil displacement from SIREN

Pile displacement

100 : 30combination rule

93

Case Study - LNG Tanks, Trinidad

Dynamic soil-pile-tank interaction study to assess loads in the piles and tank.• 1-D soil column modelled in Oasys LS-DYNA.• Took account of the effect of liquefaction.• Took account of stiffening effect of the piles.• Analysed the entire problem in one step.

Typical cross-section through the tank and foundation system


94

Driven Steel Tube Piles

Preferred Solution

Foundation Design Options• Foundation types considered included:

• Ground replacement.• Closely spaced stone columns.• Lowered foundation scheme.• Bored piles.• Driven piles (combined with stone columns).

• There was no clear cost advantage in any of the foundation types examined.


1-D Soil Model


95

Soil Column Analysis


Site Response Results


96

Soil-Pile Model


Effect of Piles on Response


97

Complete SSI Model


Analysis of Complete SSI System


98

Bending Moments in the Piles


Soil displacement

Effects on raking piles

99

Raking Piles

Raking Piles

100

Other ground effects

Bedrock

Effects on Railways / Basements

Stiff Clay

Soft Clay

Fill

0 50 100 150


101

Cut and cover tunnel box

68mm

A pseudo static Horizontal Acceleration (=3%g) is applied to whole model

68mm

results of pseudo static model

Horizontal earth pressures

102

Lifelines - Longitudinal Motion

• Maximum ground strain is Vm / C Where Vm is the peak ground velocity and

C is the propagation velocity

• If this strain is too large then further analysis is required

Lifeline (EA)

Elastic/plastic spring to model movement

between lifeline and soil

Point of applied ground motion displacement

O’Rourke and Liu, 1999

Observed Damage to Water Pipe Systems

0.01 0.02 0.05 0.1 0.2 0.5 1

1

0.5

0.2

0.1

0.05

0.02

0.01

0.005

0.002

0.001Pip

e D

amag

e R

atio

(re

pai

rs p

er k

ilom

etre

)

Peak Horizontal Particle Velocity (m/s)

103


Propagation Velocities

Measured apparent S - wave propagation velocities

Event Site conditionsC

(km/s)

Japan 23/1/68 60 m soft alluvium 2.9

Japan 1/7/68 60 m soft alluvium 2.6

Japan 9/5/74 70 m silty clay, sand &silty sand 5.3



San Fernando 9/2/71 Variable 2.1

Imperial Valley 15/10/79 > 300 m alluvium 3.8

Imperial Valley 15/10/79 > 300 m alluvium 3.7

Turkey 1999

Fault Rupture

104

Turkey 1999

Fault Rupture

Gölcük Stepover Fault(2.5m vertical movement)(0.7m horizontal movement)

D

U

Example -Factory inTurkey

105

Gölcük Stepover Fault(2.5m vertical movement)(0.7m horizontal movement)

Body Shop

D

U

Example -Factory inTurkey

Example - Factory in Turkey

Tilting of columns Differential settlement Lateral displacement

Damage to Body Shop

106

Fault Rupture - Lifelines

Elastic/plastic spring to model movement between

lifeline and soil

Point of applied ground motion displacement


Slope stability

107

Slope stability

Slope stabilityStandard method of considering down-slope movement

If Ac / Am is greater than 0.5 then movements are small

Ac is theaccelerationrequired to cause the slopeto have a factor of safetyof one

108

Bedrock

Slope Stability - Effects on Piles

0 50 100 150


500 250

Bending Moment (kNM)

Documents

Seismic Design to EC8