British Columbia has a population of 4.4 million people. There are over 800 schools in seismic areas and 80% of these are located in areas of high seismic hazard.The seismic hazard may be disaggregated into 3 categories, subduction, sub-crustal nd crustal earthquakes as shown in Fig.1. The se earthquakes are all generated by the subduction of the Juan de Fuca Plate beneath the North American Plate at a rate of 10mm year.
The performance of a building during an earthquake is expressed in terms of drift ratio. The performance standard required for establishing retrofit requirements may be either damage control or life safety. The allowable drit ratio for damage control is much less than that for life safety. For the school project the ministry of Education opted for life safety as the PBEE criterion for retrofit. For wood frame building the associated drift ratio is 4% and this still allows a significant drift margin against collapse. The adoption of a life safety standard allows more economical retrofits.
Drift ratios are estimate by nonlinear dynamic analysis of each of the generic school building types. Describe the procedure for calculation of the probability of drift exceedance. Need to discuss the reliability of any analysis.
B.C. School Retrofit Program - Liam Finn
1 B.C. School Retrofit Program $2.5 billion project + $ 7m research program at University of British ColumbiaKyoto Seminar 12-14 Jan 2010 Liam Finn
2 New Ideas for Economic Retrofit Deaggregation of hazard Performance – based design with drift ratio performance criterion IDA analyses of 31 generic school models 9m nonlinear analyses conductedSeismic performance calculator to access data Toolbox of retrofit options Kyoto Seminar 12-14 Jan 2010 Liam Finn
Context• BC’s population: 4.4 million• More than 800 schools in BC’s seismic risk areas• 80% of the schools located in high seismic risk areas (Victoria and Vancouver)
Methodology - Motions Earthquakes in Similar Tectonic SettingsCalifornia Peru & Chile Washington Mexico Japan Central-America
Methodology - Motions Characteristic Motion Histories 0.3 a) Crustal 0 -0.3 0.3 b) Time (Sec) SubcrustalAcceleration (g) 0 -0.3 0.3 c) Time (Sec) Subduction 0 -0.3 0 10 20 30 40 50 60 70 80 90 100 Time (sec)
Methodology - BasicsGuidelines Objective:Probability of Damage High Probability of Collapse Inter-storey Drift Deformation Aleatory Demand
Buildings – LDRSModeling School Building Shear Spring Model
Site Conditions Site Class DDense soil and Soft Rock Liquefiable Soil Site Class E
School InstrumentationObjectives:Provide early warning of quakeImprove quality and speed of post-earthquake damageassessment to ensure early access to safe schools1. 4 instruments per school for seismic response data. Reports to server at UBC Passive on site storage2. 1 Free field instrument linked to early warning network
Acknowledgement1. Professor Carlos Ventura and Professor Liam Finn2. UBC research team Dr. Freddy Pina Dr. Mehrtash Motammedi Bishnu Pandey Manuel Archila Jose Centeno3. British Columbia Ministry of Education4. Association of Professional Engineers and Geoscientists of British Columbia (APEGBC), Peter Mitchell (Project manager)5. Peer review committee Robert Hanson (FEMA John Sherstobitoff (Ausenco Sandwell) Farzad Naeim (John A. Martin&Associates) Dr. Ron DeVall (RJC) Michael Mehrain (URS Corporation John Wallace (Genivar) Clint Low (Bosh, Bohman Partners) Dr. Timothy White(Bosh, Bohman Partners)