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Performance-based Assessment and Retrofit of School Buildings in British Columbia, Canada
Michael FairhurstProf. Carlos E. Ventura, Prof. W. D. Liam Finn, Dr. Armin Bebamzadeh, Dr. Graham Taylor
MASc | The University of British Columbia, Canada (2014)
Graduate Student/Research Assistant | The University of British Columbia, Canada (2015 - Present)
The 5th Tongji-UBC Symposium on Earthquake Engineering “Facing Earthquake Challenges Together” May 4-8 2015, Tongji University Shanghai, China
2
Background
(courtesy of USGS)
BC population: 4.4 million
More than 800 schools in moderate to high seismic hazard
80% of schools in high seismic hazard (Victoria and Vancouver)
BC Ministry of Education launched seismic mitigation program
Address the highest priority needs
Cost and time efficient guidelines
University of British Columbia •Laboratory tests•Analytical development
Professionals •Local engineers•External peer review
Seismic Retrofit Guidelines-1st and 2nd Editions (2011, 2013)
Seismic Retrofit Guidelines-3rd Edition (2017)
3
Seismic Retrofit Guidelines
Performance-based Design
Reliance on Inelastic
Deformation
Probabilistic Analysis
Operational Shelter Life Safety CollapsePrevention
4
Seismic Retrofit Guidelines
Risk given Crustal EQs
Risk given Subduction EQs
Risk given Subcrustal EQs
-0.3
0
0.3
Time (Sec)
a)
-0.3
0
0.3
Time (Sec)
Acc
eler
atio
n (
g)
b)
0 10 20 30 40 50 60 70 80 90 100-0.3
0
0.3
Time (sec)
c)
Crustal
Subcrustal
Subduction
3 types of hazardPerformance-based
DesignReliance on
Inelastic Deformation
Probabilistic Analysis
Seismic Hazard Analysis
Seismic Records
Design Spectra
10 ground motions from each hazard source
SubductionHazard
SubcrustalHazard
5
Seismic Retrofit Guidelines
Performance-based Design
Reliance on Inelastic
Deformation
Probabilistic Analysis
Seismic Hazard Analysis
Seismic Records
Design Spectra
Probabilistic Nonlinear Dynamic Analysis
Lateral Deformation Resistance Systems
(LDRS)
Unreinforced Masonry Walls
(URM) Diaphragms
3 types of building elements are considered in the analysis:
Lateral Deformation Resistance Systems, LDRS (such as wood and concrete shear walls, concrete and steel frames, reinforced and unreinforced masonry walls) : 27 prototypes
Unreinforced masonry walls (URM): 5 prototypes
Flexible diaphragms (wood and steel deck diaphragms): 6 prototypes
Wide range of LDRS heights and resistances URM thicknesses and heights Diaphragm span lengths
6
Seismic Retrofit Guidelines
Performance-based Design
Reliance on Inelastic
Deformation
Probabilistic Analysis
Seismic Hazard Analysis
Seismic Records
Design Spectra
Probabilistic Nonlinear Dynamic Analysis
Lateral Deformation Resistance Systems
(LDRS)
Unreinforced Masonry Walls
(URM) Diaphragms
The cyclic force-deformation of prototypes are based on experimental results
7
Seismic Retrofit Guidelines
Performance-based Design
Reliance on Inelastic
Deformation
Probabilistic Analysis
Seismic Hazard Analysis
Seismic Records
Design Spectra
Probabilistic Nonlinear Dynamic Analysis
Lateral Deformation Resistance Systems
(LDRS)
Unreinforced Masonry Walls
(URM) Diaphragms
Incremental nonlinear dynamic analysis is performed for a wide range of ground motions and intensities
Risk is obtained by summing the contributions from all levels of shaking and each hazard type
Probability of Deformation Exceedance
SaSadDrdrCPDEDrdr
8
Seismic Retrofit Guidelines
Performance-based Design
Reliance on Inelastic
Deformation
Probabilistic Analysis
Seismic Hazard Analysis
Seismic Records
Design Spectra
Probabilistic Nonlinear Dynamic Analysis
Lateral Deformation Resistance Systems
(LDRS)
Unreinforced Masonry Walls
(URM) Diaphragms
Analysis is performed for a wide range of resistances and drifts.
Probability of DDL exceedance in 50 years PDE < 2%
Conditional probability of near failure drift (CDL) exceedance (CPDE) ≤ 25%
Probability of Deformation Exceedance
Life Safety Performance Objective for LDRS:
Required Resistance
Design Inelastic Deformation
9
Seismic Retrofit Guidelines
Performance-based Design
Reliance on Inelastic
Deformation
Probabilistic Analysis
Seismic Hazard Analysis
Seismic Records
Design Spectra
Probabilistic Nonlinear Dynamic Analysis
Lateral Deformation Resistance Systems
(LDRS)
Unreinforced Masonry Walls
(URM) Diaphragms
User friendly access to over 9 million pre-analyzed non-linear dynamic analysis results
Ability to perform risk analysis and provide retrofit resistance for different performance objectives
Probability of Deformation Exceedance
Required Resistance
Design Inelastic Deformation
Web-based Seismic Performance Analyzer
10
Seismic Retrofit Guidelines, 3rd Edition
New 2015 hazard modelConditional Spectra for ground motion
selection and scaling
0 1 2 3 4 50
1
2
3
4
Period (sec)
Sa
(g)
Selected Records
Target Spectrum
Mean of Selected Records
2.5 and 97.5 Percentiles
0 1 2 3 4 50
0.5
1
1.5
2
2.5
3
3.5
4
Period (sec)
Sa
(g)
Selected Records
Target Spectrum
Mean of Selected Records
2.5 and 97.5 Percentiles
Conditional Spectra for subduction earthquakes in Victoria, BC
Conditional Spectra for crustal earthquakes in Victoria, BC
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Seismic Retrofit Guidelines, 3rd Edition
Conditional Spectra for ground motion selection and scaling
Effect of conditioning period:
Victoria, Site Class C
UHS Tc = 0.2 sec Tc = 0.5 sec Tc = 1.0 sec
Prot/Height (mm) 3000 4500 3000 4500 3000 4500 3000 4500
W-1 27.8 - 25.4 - 24.6 - 25.5 -S-1 51.2 - 36.6 - 47.0 - 42.0 -S-5 37.0 - 29.3 - 35.0 - 32.3 -S-7 36.7 - 26.1 - 30.7 - 29.5 -S-8 48.5 - 33.9 - 39.2 - 37.7 -C-1 19.3 - 16.5 - 18.7 - 17.8 -C-4 36.0 - 27.5 - 29.7 - 30.1 -C-6 - 29.5 - 25.5 - 27.1 - 25.4M-3 42.4 - 31.6 - 32.6 - 33.5 -R-2 25.9 - 18.5 - 23.8 - 27.4 -
12
Seismic Retrofit Guidelines, 3rd Edition
New prototypes for more cost effective retrofit solutions:
“High-performance” wood and concrete shearwalls
More strict detailing requirements
13
Seismic Retrofit Guidelines, 3rd Edition
New prototypes for more cost effective retrofit solutions:
“High-performance” wood and concrete shearwalls
More strict detailing requirements
Thank you!
14
Certificate of Structural
Engineering Program
