Seismic retrofit methods
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Transcript of Seismic retrofit methods
Seismic Retrofit:
Criteria, Weakness & Methods
Seismic Retrofit:
Criteria, Weakness & Methods
byPaul W. McMullin, SE, PhD
CRSA Green Brains SeminarJune 26, 2008
Seismic RetrofitSeismic Retrofit
Outline
Performance
Weaknesses
Options
Performance
Weaknesses
Options
SDEDC (1994)
Seismic RetrofitSeismic Retrofit
Life Safety Through the Eyes of an SE
GET PEOPLEOUT THE
DOOR ALIVE
GET PEOPLEGET PEOPLEOUT THE OUT THE
DOOR ALIVEDOOR ALIVE
Seismic RetrofitSeismic Retrofit
Life Safety Through the Eyes of an SE
The purpose of this code is to establish the minimum requirements to
safeguard the public health, safety and general welfare…
(IBC 2006, 101.3)
The purpose of this code is to establish the minimum requirements to
safeguard the public health, safety and general welfare…
(IBC 2006, 101.3)
Seismic RetrofitSeismic Retrofit
Life Safety Through the Eyes of an SE
Structural Code generally does not consider:
Building economics
Business interruption losses
Sustainability
Structural Code generally does not consider:
Building economics
Business interruption losses
Sustainability
Seismic RetrofitSeismic Retrofit
Building State After a Major Earthquake
Northridge EarthquakeMagnitude 6.7Estimated Economic
Loss $49.3 billion
Northridge EarthquakeMagnitude 6.7Estimated Economic
Loss $49.3 billion
PEER (2000)
Seismic RetrofitSeismic Retrofit
Building State After a Major Earthquake:
Northridge
SDEDC (1994)
Seismic RetrofitSeismic Retrofit
Building State After a Major Earthquake:
Northridge
FEMA (2000)
Seismic RetrofitSeismic Retrofit
Performance Based Seismic Design:
Basics
Next generation seismic design methodology
Originally developed by FEMA for existing buildings
Applicable for new design
Considers each element’s energy dissipation capacity
Next generation seismic design methodology
Originally developed by FEMA for existing buildings
Applicable for new design
Considers each element’s energy dissipation capacity
Seismic RetrofitSeismic Retrofit
Performance Based Seismic Design:
Pairing
Target Building Performance Levels
Ope
ratio
nal P
erfo
rman
ce
Leve
l (1-
A)
Imm
edia
te O
ccup
ancy
P
erfo
rman
ce L
evel
(1-
B)
Life
Saf
ety
Per
form
ance
Le
vel (
3-C
)
Col
laps
e P
reve
ntio
n P
erfo
rman
ce L
evel
(5-
E)
Ear
thqu
ake
Haz
ard
Leve
l
Once every 100 years Once every 250 years Once every 500 years Once every 2500 years
a e i
m
b f j n
c g k o
d h l p
Seismic RetrofitSeismic Retrofit
Performance Based Seismic Design:
Levels & Acceleration
Performance levelsOperationalImmediate OccupancyLife Safety (IBC)Collapse Prevention
Performance levelsOperationalImmediate OccupancyLife Safety (IBC)Collapse Prevention
Acceleration OptionsTypical
50%/50 (1/100 year)20%/50 (1/250 year)10%/50 (1/500 year)2/3 of 2%/50 (IBC)2%/50 (1/2500 year)
Any probability between those listed above
Acceleration OptionsTypical
50%/50 (1/100 year)20%/50 (1/250 year)10%/50 (1/500 year)2/3 of 2%/50 (IBC)2%/50 (1/2500 year)
Any probability between those listed above
Seismic RetrofitSeismic Retrofit
Common Damage
Seismic RetrofitSeismic Retrofit
Common Damage
Seismic RetrofitSeismic Retrofit
Common Weaknesses: Masonry
Unreinforced Masonry:Everything
Reinforced Masonry:(generally perform well)
Under-reinforcedUngrouted cellsConnections
Unreinforced Masonry:Everything
Reinforced Masonry:(generally perform well)
Under-reinforcedUngrouted cellsConnections
Seismic RetrofitSeismic Retrofit
Common Weaknesses: Concrete
Ductility is big issue:Continuous beam
reinforcingHoop spacingLap splices
Under-reinforced (primary)
Ductility is big issue:Continuous beam
reinforcingHoop spacingLap splices
Under-reinforced (primary)
Seismic RetrofitSeismic Retrofit
Common Weaknesses: Concrete
EQE (1999 Taiwan)
Seismic RetrofitSeismic Retrofit
Common Weaknesses: Timber
DETAILINGCross grain bendingContinuityShear transfer
Undersized Elements
Nail pattern too far apart
DETAILINGCross grain bendingContinuityShear transfer
Undersized Elements
Nail pattern too far apart
Seismic RetrofitSeismic Retrofit
Common Weaknesses: Steel
ConstraintFull penetration welds
Redundancy
Material Over strength
ConstraintFull penetration welds
Redundancy
Material Over strength
FEMA (2000)
Seismic RetrofitSeismic Retrofit
Common Weaknesses: Steel
ConstraintFull penetration welds
Redundancy
Material Over strength
ConstraintFull penetration welds
Redundancy
Material Over strength
FEMA (2000)
Seismic RetrofitSeismic Retrofit
Retrofit Options: Masonry
Unreinforced MasonryPost TensioningAdding PerforationsVertical Wall CoringSlottingShotcreteFiber Reinforced
Plastics (FRP)
Reinforced MasonryShotcreteFRP
Unreinforced MasonryPost TensioningAdding PerforationsVertical Wall CoringSlottingShotcreteFiber Reinforced
Plastics (FRP)
Reinforced MasonryShotcreteFRP
Seismic RetrofitSeismic Retrofit
Retrofit Options: Masonry
Seismic RetrofitSeismic Retrofit
Retrofit Options: Masonry
Seismic RetrofitSeismic Retrofit
Retrofit Options: Concrete
Shear Walls
Grade Beams
Steel or FRP Wrap of columns/ beamsApplication to flatsurface
Concrete jacketing (steel fiber reinforced)
Shear Walls
Grade Beams
Steel or FRP Wrap of columns/ beamsApplication to flatsurface
Concrete jacketing (steel fiber reinforced)
Seismic RetrofitSeismic Retrofit
Retrofit Options: Timber
Structural Panel overlay
Increased nailingSheet metal blocking
Steel Connectors (Simpson is our friend)
Structural Panel overlay
Increased nailingSheet metal blocking
Steel Connectors (Simpson is our friend)
Seismic RetrofitSeismic Retrofit
Retrofit Options: Timber
Seismic RetrofitSeismic Retrofit
Retrofit Options: Steel
Cover Plates
Shear Walls (steel or concrete)
Braced Frames out of Moment Frames
Cover Plates
Shear Walls (steel or concrete)
Braced Frames out of Moment Frames
Seismic RetrofitSeismic Retrofit
Preguntas?
Questions?Questions?