Rapid Screening of Buildings for Seismic Retrofit Assessment

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Rapid Screening of Buildings for Seismic Retrofit
Assessment
Murat Saatcioglu PhD,P.Eng. Professor and
University Research Chair Department of Civil
Engineering The University of Ottawa Ottawa, ON
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Why Seismic Screening?

• Seismic retrofitting may be very costly
• Before a decision is made, seismic assessment is
  required.
• Before undertaking a detailed seismic assessment,
  a rapid screening of buildings may be in order.
• NRC developed Manual for Screening of Buildings
  for Seismic Investigation

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Seismic Screening

• NRC Screening Manual is dated 1993. It has been
  revised recently at the request of PWGSC to
  conform to NBCC 2005 Seismic Hazard
• Seismic screening provides a simple tool to a
  community or authority to easily identify
  buildings that might pose a risk of life or
  injury, or severe curtailment of community
  services in the event of a damaging earthquake

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Seismic Screening

• Seismic screening is conducted by a simple
  inspection without the cost of a detailed
  analysis of every building in a given region
• Buildings that receive high score and is thus
  identified to be potentially hazardous require
  further investigation
• NBCC Appendix K recommends that buildings that
  have seismic resistance of 60 and lower relative
  to the current code requirement may be retrofitted

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Seismic Screening

• The 60 value is a trigger value and does not
  indicate that seismically deficient buildings
  should be retrofitted to have 60 capacity
• Once the decision to retrofit is made, it is
  advisable to improve the building performance up
  to the current standards expected from new
  buildings
• Cost and performance should be weighed against
  each other before a decision is made

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Seismic Screening

• The following has to be evaluated
• Seismicity(A) The maximum earthquake motion
  expected for the location of the building
  (seismic zone).
• Soil Conditions(B) Soft soils amplify earthquake
  motions and damage buildings.
• Type of Structure(C) The type of lateral force
  resisting system (LFRS) is important to assess
  potential seismic damage.

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Seismic Screening

• The following has to be evaluated (Contd)
• Building Irregularities(D) This applies
  primarily to weaknesses in configuration like
  soft storeys and captive columns.
• Non-Structural Hazards(F) Non-load-bearing
  components of the building, such as block
  partitions, may fall on people or interfere with
  rescue operation.

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Seismic Screening

• The following has to be evaluated (Contd)
• Design NBC Buildings designed to recent building
  codes are less vulnerable than buildings designed
  to older versions of the code.
• Building Importance(E) The consequences of
  failure are more severe for post-disaster
  buildings and critical facilities. Also, risk in
  densely populated buildings is higher.

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Seismic Screening Form
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Seismic Priority Index
Structural Index (SI) ABCDE Non-Structural
Index (NSI) BEF Seismic Priority Index (SPI)
SI NSI

• The scores should be used for the purpose of
  ranking
• SI or NSI of 1.0 to 2.0 indicate full compliance
  with the code.
• SPI lt 10 indicates low priority
• SPI 10 20 indicates medium priority
• SPI gt 20 indicates high priority
• SPI gt 30 potentially hazardous

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Thank You..
Questions or Comments?