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E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Observations and Lessons on Earthquake and Tsunami Risk
Mitigation in Padang, Indonesia
Nick Alexander, Degenkolb Engineers
Veronica Cedillos, GeoHazards International
Louise Comfort, University of Pittsburgh
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Reconnaissance Team Members
• EERI TeamDeierlein, Alexander, Cedillos, Hausler, Henderson, Comfort, Hart, Rudianto, Wijanto, Wood.
• Other US ParticipantsMooney & McGarr, USGSFranco, DiBarnaba, Sandoval Kizzee, Cabrera, Scawthorn
• InternationalAndalas UniversityITB UniversityIndonesian Society Geotech. Engrg.Nanyang Tech. UniversityNew Zealand Engineers
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Acknowledgements
NSF: EERI Learning From Earthquakes Program
with additional support from• Blume Earthquake Engineering Center, Stanford• Pacific Earthquake Engineering Research (PEER) Center• USGS• University of Pittsburgh, GSPIA• Team host organizations:
– Degenkolb Engineers– Forell Elsesser– Build Change– GeoHazards International– Risk Management Solutions, Inc.
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
History of Padang
Batang Arau River
Old City
City Center
Padang City 17th Century Trading Center Population 900,000 (20x growth since 1940) Capital of West Sumatra
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Impact – Road Damage
Sengara, I.W. et al., 2009
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Impact – Bridge Damage
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Impact – Foundation Damage
Provincial Public Works Building• 4 story, built 1976• Soft/Weak first story• Columns experienced 12” drift• Site experienced liquefaction• 100 m from Batang Arau River
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Impact – Utility and Lifeline Systems
• Airport– closed 3 hrs, regular ops 1 day
• Electric Power– distributed transformer damage– restored 20% within 5 days– fully restored within 8 days
• Phone/Communication– landlines OK, cell restored within days
• Water– 1 of 2 main supply pipes and 1 of 2
main distillation tanks ruptured– back to 60% within 2 weeks
• Port Facility– little damage, south of town
damaged water treatment
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Outline
• Building Types and Occupancies
• Acceleration Response vs Design Base Shear in Building Code
• Typical Building Damage & Collapse Mode
• Building Design & Construction in Padang
• Building Case Studies
• Summary of Buildings Performance
• Improving Buildings Performance
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Building Types and Occupancies
• Government Offices
• Schools
• Hospitals
• Commercial Buildings– Offices and Banks– Retail Malls– Hotels– Home-shops (Ruko)
• Residential Homes
Primarily Reinforced Concrete Frames with Brick Infill Walls
URM, Confined Masonry, Wood
Few Steel Moment Frames
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Comparison to Building Code
Building Code Requirements1970: Base shear = 0.1g, working stress design
1987: PGA = 0.25 – 0.36g, 2 soil types, inelastic R=4
2002: Similar to 1987, 3 soil types, capacity design
increase in short period spectral demands
Spectral Acceleration - 5% damping - NS component - stiff soil site
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 0.5 1 1.5 2
Spec
tral
Acc
eler
ation
(g)
Period (sec.)
measured
SNI-2002
SNI-1987
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Building Damage and Collapse
Story Collapse Complete Collapse
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Brick MasonryInfill Wall & NS Damage
Building Damage and Collapse
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Building Design & Construction
• Seismic Design Codes– Established by national committee (Jakarta)– First established 1970, updates in 1987 and 2002– Currently revising to model after U.S. IBC & ASCE 7
• Expertise of Local Professionals– Engineering education at university– Little professional development & continuing education in Padang– Little training/certification of contractors
• Code Compliance & Quality Assurance– Field observations and interviews suggest lack of compliance – Problems most significant with small projects and renovations– Common to other developing countries (lack of well established
process, insufficient resources to implement, lack of education)
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Building Case Studies
• SMK 9• M Djamil Hospital• Provincial Planning
Building• Ambacang Hotel• Hotel Mariani• Dutch Colonial &
Chinatown Buildings• Lasano Kampong Dalam
Village• Padang Ruko Buildings
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
SMK 9 School
• High School• 3 story, built 1997• Partial floor and stair
collapse• Weak/Captive Columns• 2 casualties (non-students)
• many students at time of EQ• EQ Drills teach duck and
cover• Students ran out of building• No student victims
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Sentral Plasa Raya Mall
• 3 story concrete frame/brick infill building built in 2005
• Back end collapsed• Brick infill failures• Non-structural
damageFRONT END
BACK END
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Sentral Plasa Raya Mall
• Heavy mass at the back end
• Column detailing:• Small ties with 90 degree
hooks
• Column failure at lap splice
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Provincial Planning Building
• 3 story, 1981-83• 1st Floor Collapse
– Configuration– Design and Detailing
• smooth bars
• small ties w/ 90 degree hooks
– Construction quality
• 2 Casualties– 80 occupants in building
during EQ
• Impact on rebuilding effort– Many files still in building
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
M Djamil Hospital
• Largest hospital in Padang (800+ beds)
• 13 buildings, only 1 building sustained major damage
• Outpatient Building– 3 stories, built in 1982– First floor collapsed– No casualties– Pounding between
segments
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
M Djamil Hospital
Vaulted roof at the atrium
Damage at the one end of the cross shape
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Ambacang Hotel
• Originally a 1900 Dutch 2-story masonry warehouse, later expanded to 5 stories• Both concrete & steel frames
• Irregular, no clear load path
• Partial story collapse at 2nd Floor of main building BEFORE EQ
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Ambacang Hotel
• Separate 6 story steel building (built in 2005) fully collapsed
• Poor moment frame connection detail• No continuity plate
• Weak way bending
• Slender columns
• 200 fatalities in the hotel (est.)
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Hotel Mariani
• 4-6 story 2006 steel building collapsed, 3-story 1963 concrete building damaged but survived
• One of few steel buildings in Padang• Weak axis column bending led to progressive collapse
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Hotel Mariani
Moment frame failed weak way
Building collapsed towards the back
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Dutch Colonial & Chinatown Districts
• 100+ year old buildings, adjacent to the river
• Unreinforced masonry buildings w/ wood roofs & floors
• Out-of-plane collapse
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Lasano Kampong Dalam Village
• Small village in hills outside of Pariaman
• URM, confined masonry• URM houses sustained
the most damage• Settlement resulted in
damage to several homes• Liquefaction
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Lasano Kampong Dalam Village
Confined Masonry Buildings
• Improved version of URM• Promoted in rural areas in
Indonesia• Reinforced concrete
element for confinement• Fairly well performance
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Ruko Buildings in Padang
• Ruko – very common in Padang
• 2 to 3-story tall • commercial & residential
• Stiffness irregularity• Various performance
• Some collapse some minor damage
• No comprehensive plan check
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Performance of Concrete Buildings
• Soft/weak story• Weak columns• Inadequate steel
reinforcement– not enough steel– nonconforming details
• Poor quality concrete• Insufficient lateral strength
and stiffness• Brittle architectural finishes
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Performance of Concrete Buildings
• Damage to older buildings is not unexpected
• Damage to newer buildings was greater than expected
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Performance of Steel Buildings
• Poor moment frame detailing– Weak way bending– Poor welding– Nonconforming to code
• Slender column sections for moment frame
• Insufficient strength and stiffness - significant drift
• Non-familiarity with steel design and construction in the area
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Performance of Masonry Buildings
• Unreinforced Masonry– Poor quality materials and workmanship– No confinement to prevent out-of-plane wall
failure
• Confined Masonry– Performed fairly well– Guidelines available for single family homes
but no code provision
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Improving Buildings Performance
• Proper enforcement & implementation of the Building Code– continuing education– quality assurance– training/certifications of contractors
• Building code provision for residential homes and ruko/homeshops
• Challenge to implement these in the re-construction effort
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Outline
• Tsunami Risk
• Preparedness Efforts
• Tsunami Evacuation during 9/30 Earthquake
• Performance of Tsunami Evacuation Structures
• Observations & Lessons Learned
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Tsunami Risk in Padang
One of the highest tsunami risks in the world
National Geographic Indonesia
Risk is a function of the hazard and exposure
Padang
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Tsunami Hazard in Padang
Killed more than half the population in Banda Aceh
Padang is exposed to a similar hazard from same fault
Indian Ocean TsunamiDecember 2004
After 2004 Tsunami
Before 2004 Tsunami
Banda Aceh
Banda Aceh
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Seismological Background
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Tsunami Mechanism
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Tsunami Mechanism
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
First big rupture on the Sundamegathrust occurred in 2004
The second big rupture occurred in March 2005
The third rupture occurred in a series of events, with an aftershock of M7.9
Northern part of Mentawai patch remains locked
Source: Kerry Sieh
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Vulnerable Terrain
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
• 900,000 people
• Almost 9,000/km2 at city center
• >½ the population lives within a 5 meter elevation– Mostly fishermen
• <30 minutes to evacuate
• Inundation distance ~2 km
Population Density and Distribution
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
• One of 6 cities designated to undertake earthquake and tsunami risk reduction after 2004
• Early warning systems• Planning evacuation routes• Education and evacuation drills
– “duck, cover, hold” – tsunami evacuation
• Over 50,000 people will still be unable to evacuate within < 30 minute tsunami arrival time
Preparedness Efforts in Padang
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Evacuation Structures | Examples
Refuge Structures: Designed to rise above the expected tsunami inundation level, and withstand the expected earthquake and tsunami forces; provides vertical evacuation
Bridges: Designed to be earthquake-resistant and serve as element of horizontal evacuation
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Evacuation Structures | Existing Buildings
• Regulation requires all buildings > 2 stories to serve as evacuation site during tsunami
• Existing Building Surveys– 5 different organizations– Based on location and capacity,
suitability not thoroughly considered– Seismic deficiencies not considered
• Buildings used as sites in evacuation simulations
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Tsunami Evacuation
• Most people evacuated after shaking
• Problems with evacuation plan – sometimes slow to initiate– traffic jams (1-2 hrs)– lack of information and coordination
• Little evidence of vertical evacuation• Roads and bridges generally intact• Performance of evacuation buildings
– 1/3 collapsed or heavily damaged– 3/4 had sufficient damage to be closed
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
High Ground
Coastline
Evacuation Structures | Bridges
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Evacuation Structures | LBA LIA
• 4 story language school
• First 2 stories collapsed
July 2009 October 2009
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Evacuation Structures | STBA Prayoga
• 4 story junior college
• Complete collapse
July 2009 October 2009
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Evacuation Structures | Plasa Andalas
• 4 story mall
• Partial collapse on 4th floor and fire
July 2009 October 2009
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Good Candidates for Evacuation
Indonesian Bank Complex• Tsunami evacuation
– large building– elevated site– terrace @ 20 m– on-site security
• Moderate EQ damage • Evacuation lessons
– public awareness – individuals must feel safe
& confident
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Good Candidates for Evacuation
• Major mosques in general are good candidates for evacuation– Large prayer area– Redundant structures– Better construction quality– Good accessibility– People tend to go to mosques
after disasters
• ~100 people evacuated to Masjid Taqwa after the earthquake
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Observations and Lessons• Overview of Damage
– Buildings– Bridges and Transportation– Utility Lifelines
• Deaths and Injuries• Resiliency of Padang City• Tsunami Evacuation
– Tsunami still a threat– Inadequate evacuation capacity – Evacuation structures are crucial
• Building Code provisions and enforcement• Rebuilding Better / Safer?
E E R I TECHNICAL BRIEFING ON SEPTEMBER 30, 2009 PADANG, INDONESIA EARTHQUAKE
Thanks!
Questions?