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How safe are our buildings and structures against earthquakes and winds ? Dr. Pennung Warnitchai Asian Institute of Technology

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How safe are our buildings and structures

against earthquakes and winds ?

Dr. Pennung Warnitchai Asian Institute of Technology

Where do earthquakes occur ?

Tectonic Plates

Tectonic Map of SouthEast Asia Seismicity Map of SouthEast Asia (1912-2007)

Ishii et al., 2005 Nature

The 26 Dec 2004 Megathrust EQ

Magnitude: 9.3

Rupture Length: 1200 km

http://staff.aist.go.jp/kenji.satake/Sumatra-E.html

Kamala Beach, Phuket

Tsunami Flooding

Maximum Water Level

One of the most devastating disasters for many countries surrounding Indian Ocean

Low-frequency but high-impact disaster caused by EQ

Improve public awareness of EQ risk

The Regional Integrated Multi-Hazard Early Warning System for Africa and Asia (RIMES)

Developed by ADPC, Located in the AIT campus

Tectonic Map of SouthEast Asia Seismicity Map of SouthEast Asia (1912-2007)

Haiti Earthquake (Jan 12, 2010) M 7.0, focal depth 13 km Downtown Port au Prince

Death Toll > 200,000

Yogyakarta Earthquake (2006) Magnitude = 6.2

Death Toll = 5,000

Christchurch Earthquake (February 22, 2011)

M 6.3, Death Toll > 200

Typical Commercial Concrete Buildings

Basic Problem : The majority of existing buildings are vulnerable to earthquake ground shaking !

3D-view generated by SAP2000 v10

Non-seismic Detailing

Strong Beam–Weak Column

Soft/Weak First Story

Torsional Irregularity

VULNERABILITY FACTORS

Elastic Dynamic Response (Modal Analysis)

Lateral-Torsional Movement (period = 0.50 sec)

17

Soft-story Collapse of Commercial/Residential Buildings in the 1999 Chi-Chi Earthquake (Taiwan)

The 1985 Michoacan Earthquake (Ms = 8.1)

The earthquake caused considerable destruction and loss of life in Mexico City, about 350 km from the EQ epicenter. The number of deaths was more than 10,000.

Seismic Risk of Tall Buildings from Distant Large Earthquakes

Earthquake Disaster in Mexico City (1985)

Much of the destruction was due to significant amplification of EQ ground motions by thick soft soil deposits.

Acceleration-Time Histories of EQ Ground Motions

Shake Table Experiment

Rock (No Amplification)

Very Stiff Soil

Stiff Soil (Moderate Amplification)

Moderately Soft Soil

Very Soft Soil (High Amplification)

Map showing Soil (Site) Conditions in Thailand (derived from digital elevation data—SRTM30 and boreholes data)

Seismic Risk in Bangkok due to Distant Large Earthquakes

1

0.86

0.850.81

0.76

0.73

0.7

0.64

0.620.56

0.52

0.49

0.42

0.40.35

0.32

0.28

0.22

0.17

0.11

0.08

0.04

0.030.03

0.010.0010

2468

1012141618202224262830323436384042444648505254

-1 -0.5 0 0.5 1

X1 = 3.23 sec

ช ัน้ที่1

0.88

0.89

0.82

0.78

0.74

0.66

0.66

0.62

0.57

0.53

0.49

0.47

0.41

0.37

0.32

0.27

0.23

0.17

0.11

0.05

0.05

0.020.02

0.020.020

2468

1012141618202224262830323436384042444648505254

-1 -0.5 0 0.5 1

Y1 = 4 sec

ช ัน้ที่

1

0.76

0.63

0.47

0.27

0.13

0.01-0.14

-0.26-0.36

-0.48

-0.52-0.54

-0.62-0.59

-0.58-0.54

-0.51

-0.39

-0.3

-0.19

-0.1

-0.060

-0.010

3

6

9

12

15

18

21

24

27

30

33

36

39

42

45

48

51

54

-1 -0.5 0 0.5 1

X2 = 0.95 sec

ช ัน้ที่1

0.79

0.64

0.5

0.28

0.12

0.05-0.19

-0.3-0.4

-0.47-0.53-0.54

-0.58-0.57-0.57

-0.51-0.44

-0.35

-0.3

-0.15

-0.08

-0.05-0.03-0.02-0.020

3

6

9

12

15

18

21

24

27

30

33

36

39

42

45

48

51

54

-1 -0.5 0 0.5 1

Y2 = 1.16 sec

ช ัน้ที ี่

Measurement of natural periods and vibration mode shapes of tall buildings in BKK

Y1 , T = 4.00 sec

Y2 , T = 1.16 sec X2 , T = 0.95 sec

X1 , T = 3.23 sec

Identification of Dynamic Properties of Bangkok Soil Basin by Array Microtremor Measurement

Large Size Array Microtremor Measurement (500 m – 1000 m)

Nonlinear Finite Element Model of Tall Buildings in BKK

Construction drawings of more than 200 tall buildings are being collected.

Their performance under extreme seismic events are being evaluated.

Damages and Losses in BKK from Possible Earthquake Scenarios

?

Satellite Image of a Typhoon

Hundreds of kilometers in Diameter

Typhoon = Hurricane = Cyclone = Tropical cyclone with surface wind speeds > 120 km/hr

Max. Typhoon winds may reach 320 km/hr.

World Map of Tropical Storm Hazard (Tropical Cyclones, Hurricanes, Typhoons)

Thunderstorm

•Small-scale wind: Kilometers in diameter •Produce lightning flashes

World Map of Lightning Hazard

Large Billboard Structures

Collapse of a large billboard (50 m high) in Bangkok during a severe thunderstorm in June 2002

Several large billboards in Bangkok were completely destroyed by severe thunderstorms on 28th June 2007

TU-AIT Boundary Layer Wind Tunnel Laboratory

A Scale Billboard Model In Wind Tunnel

Wind

Fx (Drag force)

Fz (Vertical force)

My (Overturning moment)

Mz (Torsion) Mx

(Transverse moment )

Fy (Side force)

High Frequency Force Balance Technique

Wind tunnel test on a scale billboard model To determine wind-induced forces

Drag

e

Drag

Drag x e = Torsion

A 40-m Tall Buddha Statue in Kanchanaburi Province

Wind Tunnel Model Test of The 70-story Gramercy Residence Building with the presence of all surrounding buildings (Manila, Philippines)

Key Issues for Wind Tunnel Model Tests • Wind-induced vibration in top floors

causing motion sickness

• Maximum wind pressure for cladding design

• Resonant amplification of structural response

• Effect of nearby buildings on wind loads

The 70-story Gramercy Residence Building

CAARC Building Model (180 m x 45 m x 30 m)

Simultaneous Dynamic Pressure Measurement

Dynamic Wind Pressure on CARRC Building

Thank You

Dr. Pennung Warnitchai Leader of Civil and Infrastructure Engineering Group School of Engineering and Technology