Development of earthquake vulnerability curves of key building

types in the Philippines

Global Earthquake Model (GEM) Workshop

Nanyang Technological University, Singapore

July 1, 2013

Eric Augustus J. Tingatinga, Benito M. Pacheco, Jaime Y. Hernandez Jr., Ulpiano P. Ignacio Jr., Fernando Germar, Romeo Eliezer Longalong, William Mata, Marie Claire Pascua, Raniel Suiza, Liezl Raissa Tan

UPD-Institute of Civil Engineering

PRESENTATION OUTLINE

• Introduction and review of building typology

• Computational vulnerability curves

• Empirical vulnerability curves

• Heuristic vulnerability curves

• Summary

01 Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

INTRODUCTION

Source: Pacheco (2012)

VULNERABILITY

VULNERABILITY –the ratio of the cost of damage to the cost of structure and finishes, on a scale of 0 to 1. Vulnerability curve is a lognormal commulative distribution function with two parameters (mean and beta).

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Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

METHODS

1. COMPUTATIONAL Method (analytical method) • Use nonlinear static pushover

2. EMPIRICAL Method • Post-earthquake visual surveys

• Earthquake damage reports

3. HEURISTIC Method (based on experts’ opinion)

4. HYBRID Approach

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Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

What have we done so far?

Vibrametrics (2003) developed analytical and heuristic vulnerability of “typical” buildings in Metro Manila.

MMEIRS (JICA, PHIVOLCS, and MMDA 2004) reported empirical vulnerability curves of buildings in Metro Manila.

UPD-ICE (2011, 2012) in collaborative research project with PAGASA, PHIVOLCS, OCD, and Geoscience Australia called “Development of vulnerability curves of key buildings types in Greater Metro Manila Area, Philippines.”

UPD-ICE involvement in the ASEAN Earthquake Model (AEM).

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Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

BUILDING TYPOLOGY

• Material used for construction

• Structural type

• Age or vintage of construction

• Number of floors

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* Similar to HAZUS types

Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

BU

ILDIN

G TY

PO

LOG

Y &

SCO

PE

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Computational Earthquake Vulnerability Curves

Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

Methodology

• Building database populated with assumed site conditions, e.g., soil type and proximity to fault.

• Buildings designed and analyzed for different levels of ground shaking using ETABS.

• Capacity Spectrum Method was used.

• Fragility curves for four damage states (slight, moderate, extensive, and complete) are derived.

• Vulnerability curves are developed using assumed damage indices.

Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

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NSP Analysis

PERFORMANCE POINTS

PROBABILITY OF EXCEEDANCE

CURVE FITTING

FRAGILITY CURVES

BUILDING DATABASE

DAMAGE STATE EVALUATION

THRESHOLD VALUES

Capacity Spectrum Method DEMAND

SPECTRUM

(High Rise)

CMP Analysis

Computational

Method

(Low and Mid

Rise)

Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

Fragility Curve

0

0.25

0.5

0.75

1

0 0.3 0.6 0.9 1.2

Pro

bab

ility

of

Exce

ed

ance

PGA (g)

Computational Fragility Curves in PGA

Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

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Vulnerability Curve

0

0.25

0.5

0.75

1

3 5 7 9 11

Dam

age

Rat

io

MMI

C1-L : Computational

Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

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Empirical Earthquake Vulnerability Curves

Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

Methodology

1. Collection of building damage observations due to recent/historical earthquakes (PHIVOLCS & GA, 2012).

2. Classification and extraction of useful data for the building types.

3. Assignment, based on the descriptions of building damage for several earthquakes, of damage ratio for each recorded earthquake intensity.

4. Development of the vulnerability curve for each type

Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

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Data for MWS

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Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

MWS Vulnerability Curve

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Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

Heuristic Earthquake Vulnerability Curves

METHODOLOGY

Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

HEURISTIC METHOD

• Surveys conducted during

• ASEP Summit (June 2012), 22 respondents

• NEC-PETD Seminar (Aug. 2012), 15 respondents

• Specialists estimated the damage ratios of each building type to different levels of ground shaking (MMI V-IX). The estimates are weighted by years of experience.

• Vulnerability curve parameters are determined by fitting a lognormal CDF to the points.

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Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

Survey form

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Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

Heuristic Vulnerability Curve Development

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IV V VI VII VIII IX XI

Damage Ratio

(Weighted Mean)0 0.04 0.12 0.25 0.42 0.57 1

MMI

Summary

Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

Vulnerability Curves Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

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Wood and Masonry Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

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Concrete Building Types Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

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Steel Building Types Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

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Summary

1. Pre-, low and high code computational curves do not reveal significant difference in vulnerability of buildings of different vintages.

2. Heuristic curves imply the following relative vulnerability

3. Empirical method needs data that is systematically reported and compiled.

masonry < wood < concrete < steel

more vulnerable less vulnerable

Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

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REFERENCES • JICA, PHIVOLCS, & MMDA. (2004). “Earthquake Impact Reduction Study for Metropolitan

Manila. Manila,” Philippine Institute of Volcanology and Seismology.

• Saedi, A., Deck, O. & Verdel, T. (2009). Development of building vulnerability functions in subsidence regions from empirical methods. Engineering Structures 31, p. 2275-2286.

• Giovinazzi S. & Lagomarsino S., (2002). “A Methodology for the Vulnerability Analysis of Built-up Areas,” Proceedings of the International Conference on Earthquake Loss Estimation and Risk Reduction, Bucharest, October 2002. Italy: University of Genoa.

• Pacheco, B.M., Hernandez Jr. H., Ignacio Jr. U., Tingatinga, E.A., Tan, L.R., Pascua, M.C., Suiza R.M., Longalong, R.E., Mata, W., Zarco, M.H.. (2011). “Development of earthquake vulnerability curves for key building types in Iloilo City,” Proceedings, Philippines Institute of Civil Engineers National Conference, Cagayan De Oro, Nov. 2011.

• ASEP (2010),“National Structural Code of the Philippines (NSCP).” Volume 1, 6th edition.

• UPD-ICE (2011).“Development of Vulnerability Curves of Key Building Types in the Philippines.” Technical Report, Institute of Civil Engineering, University of the Philippines, Diliman, Quezon City.

• UPD-ICE (2012).“Development of Vulnerability Curves of Key Building Types in Greater Metro Manila Area.” Progress Report, Institute of Civil Engineering, University of the Philippines, Diliman, Quezon City.

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Global Earthquake Model (GEM) Workshop, NTU Singapore, July 1, 2013

Acknowledgments

Thank you for listening!