damage assessment methodology developed for tcip · 2019-11-08 · damage assessment methodology...

DAMAGE ASSESSMENT METHODOLOGY DEVELOPED FOR

TCIP Alper Ilki, Omer Halici, Eren Kupcu, Mustafa Comert, Cem Demir

Istanbul Technical University, Civil Engineering Faculty

International Workshop on Advances in Assessment and Modeling of Earthquake Loss, 4-5 November 2019, Istanbul

Contents

• Outline of the Present TCIP Damage Assessment Method

• Literature Review to Check/Update Damage Modifiers

• Repair Methods for Earthquake Damaged Structural Members

• Performance of Earthquake Damaged-and-Repaired Structural Members

• The Damage Threshold for Repairability

• Conclusions and Future Works

2

Contents







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Outline of the Present TCIP Damage Assessment Method

• Post-earthquake seismic damage evaluation of buildings after a major earthquake can easily become a major challenge since the number of buildings that require damage assessment can reach to tens of thousands

• On the other hand, relatively faster qualitative assessment approaches based on experience of the expert can be biased when combined with the post-eq psychology

• The experts tend to stay on the safe side and designate buildings with heavier than actual damage classes

• The classification of damages in buildings also determines the pace of the recovery stage, overestimation of damage causes loss of time and money

• Thus, an accurate and rapidly applicable quantitative damage assessment method based on measurable parameters is required considering the number of buildings and the insufficient number of qualified inspectors 4

Outline of the Present TCIP Damage Assessment Method • For this purpose, in 2003* (after the destructive 1999 Marmara Earthquakes), a quantitative post-eq

damage assessment methodology was developed for the Turkish Catastrophe Insurance Pool (TCIP, DASK in Turkish),

• The developed TCIP methodology aims to evaluate the damages in reinforced concrete (RC) and masonry structures

• The method was modified in 2015 to include a first quick inspection stage for identifying sligthtly or heavily damaged low- and medium-rise buildings with floor area less than 400 m2

• In scope of the method, the experts of TCIP (who may not be civil engineers if the number of buildings to be investigated is high), visit the building and make observations and measurements from the exterior and interior of the building

* H. Boduroglu, P. Ozdemir, A. Ilki

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Post-Earthquake Damage Assessment

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Non-damaged

Cosmetic Damage

Slight Damage

Moderate Damage

Severe Damage

Partial or Total Collapse

Repairable Irrepairable

Building Damage ?

Outline of Present TCIP Damage Assessment Method

7

Unclassified

Heavily Damaged

Exterior Assessment

Slightly Damaged

Moderately Damaged

Severely Damaged

Interior Assessment

Based on Japanese Residual Energy Dissipation Capacity Approach


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Initial Assessment

•Low- and mid-rise buildings that form the majority of all buildings are evaluated •Can be performed by experts who are not civil engineers •Slightly and heavily damaged building will be identified (app. 80-90% of all)

Expert Assessment

• Buildings not categorized in the initial assessment stage are to be evaluated by civil engineers.


• Step 1

Check for partial or total collapse

• Step 2

Check if the residual I.D.R. > 0.02

• Step 3

Check if the structure is tilted more than 3° from the base

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“Heavily Damaged” Yes



Exterior Assessment


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Damage Type

Residual Crack Width Compression Damage Damage

Modifier Type O - - 0.00 Type A ≤0.5 mm - 0.15 Type B 0.5 mm< w ≤3 mm Cover Crushing 0.35 Type C >3 mm Cover Spalling 0.65

Type D - Buckling of Reinforcement, Core Crushing 1.00

Interior Assessment

Initiate the assessment at the most damaged story


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Interior Assessment

< 400 m2

n < 8 No

Is the plan area ≤ 400m2 and number of

stories above the ground ≤ 8 ?

Yes Is the number of vertical

columns/shear walls with “Type C” and “Type D” damage is greater than 10% of the total number of

vertical members?

No

Yes

Calculate WDR

No

Determine the number of columns and shear walls

at that story

Heavily Damaged

Is the number of vertical column shear walls with “Type B” damage is less than 10% of the total number of vertical members, and the remaining

members are either “Type A” or “Type O”?

Slightly Damaged

Yes

[ ] 1000

00.165.035.015.0×

++++×+×+×+×

=DCBA

DCBAWDR


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Interior Assessment Damage

Type Damage Modifier

Type O 0.00

Type A 0.15

Type B 0.35

Type C 0.65

Type D 1.00 0, A, B, C, D are the total cross-sectional are of the vertical members in the relevant damage type Damages of beams can also be included to be considered if widespread and heavy beam damages are available.

Damage state of structures according to WDR;

0% ≤ WDR < 20% DS1 - ”Slightly Damaged” 21% ≤ WDR < 35% DS2 - “Moderately Damaged” 35% ≤ WDR DS3 - “Heavily Damaged”

Contents







13

Literature Review to Check/Update Damage Modifiers Similar to the Japanese JBDPA (2015) approach the lost energy dissipation capacity is

used for the definition of damage modifiers: 0.15 for A, 0.35 for B, 0.65 for C, and 1.0 for

D member damage classes

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Load

Displacement

Ed: Dissipated energy Er: Remaining

dissipation capacity

η = 𝐸𝐸𝑑𝑑𝐸𝐸𝑑𝑑+𝐸𝐸𝑟𝑟

Damage modifier is a measure of already dissipated energy as a percentage of total energy dissipation capacity

Literature Review to Check/Update Damage Modifiers In order to check the current modifier value data from 100 column tests compiled from

the literature.

Main difficulty: Crack widths are generally not reported.

Concrete compressive strength <20 MPa 20 MPa - 30 MPa >30 MPa Number of column tests 30 40 30 Axial load ratio < 20% 20%-40% > 40% Number of column tests 55 25 20 Long. Reinf. Ratio <1% 1% - 2% 2% - 4% Number of column tests 34 23 43 Long. bar type Deformed Plain Number of column tests 80 20 Main failure mode Flexural Shear Number of column tests 60 40

Literature Review to Check/Update Damage Modifiers

A B C D

Mean 0.90 0.71 0.60 0.10 St. Dev. 0.07 0.10 0.17 0.07 CoV 0.08 0.15 0.29 0.71 Points belove current value 6 4 5 0

Total number of tests 18 19 67 87

Contents







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Repairing Methods for EQ Damaged Structural Members

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Type A

Flexural Crack <=0.5mm

Shear Crack <=0.5mm

Type A Damage

- Remove Concrete fragments - Clean the dust particles inside the cracks with air compressor

Crack width

<0.05mm?

Widen the crack surfaces and patch with non-shrink

grout

Repair completed

Low viscosity epoxy injection Repair completed

Yes

No


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Type B

Cover Crushing

0.5 mm – 3 mm crack width

Type B Damage

Existence of cover

crushing?

Remove the crushed concrete. Clean and roughen the surface

Repair completed

Is reinforcement

revealed?

Yes Yes

Existence of crack?

No

Yes

The cover concrete needs to be recast (See the procedure

for Type C)

Patching with repair mortar

No

Repair completed

Epoxy injection

Crushing Removing the crushed cover and roughening the region

Patching application with repair mortar

Remove the concrete layer to the one diameter depth

behind long. bar


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Type C

Cover Spalling

Crack width > 3mm Cover spalling

Type C Damage

Existence of cover

crushing?

Remove the crushed concrete

Repair completed Yes

Existence of crack?

No

Yes

Patch the member with repair mortar

Repair completed

Crack width > 3mm ?

Low viscosity epoxy injection

Medium viscosity epoxy injection

Yes

No

No

Cover spalling Patching with repair mortar

Removing the concrete layer


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Type D

Core crushing and buckling of reinforcement

Residual shear deformation

Step 1

Present overlapping length

Damaged region

Suspending the structural system with temporary props

Step 2

Removing the crushed concrete in the damaged region and cutting the buckled reinforcement Step 3

Attaching new reinforcement

min 20 Φ

min 50Φ Stirrup spacing smax=100mm

Step 4

Casting concrete

Add the new reinforcement considering the sufficient anchorage and overlapping

length


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Type D Type D Damage

Remove the damaged concrete and cut the buckled bars

Add stirrups

Repair completed

Core crushing and buckling of reinforcement

Residual shear deformation

Suspend the structure with temporary props

Place the formwork and cast new concrete

1 2

3 4

5

Contents







23

Performance of EQ Damaged-and-Repaired Structural Members

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Literature Review Test Specimen

Type Repair Method

Reached displacement before repair

(x δy)

Apprx. Secant

Stiffness Ratio after

Repair

Apprx. Ultimate Strength

Ratio after Repair

Approx. Energy

Dissipation Capacity

after Repair

Marder (2018) Beam

Epoxy Inj. and Mortar Patching 3.4 0.88 1.04 Increased

Epoxy Inj. and Mortar Patching 5.4 0.79 1.07 Similar

Epoxy Inj. and Mortar Patching 5.4 0.85 1.07 Similar

Cuevas and Pampanin

(2017) Beam

Epoxy Injection 1.2 1.00 1.05 N/A

Epoxy Injection 2.2 0.90 1.05 N/A

Watanabe et al. (2004) Column

Epoxy Injection 3.0 0.81 1.04 Increased

Epoxy Injection 5.0 0.79 1.05 Increased

Mortar Patching 5.0 0.81 1.07 Increased

Mortar Patching 7.0 0.77 1.06 Reduced

Lehman et al. (2001)

Bridge Column Epoxy Injection 3.5 0.50 1.00 Similar

French et al. (1990)

Interior BC

Assembly

Epoxy Injection 4 0.85 1.01 N/A


Lee et al. (1976)

Exterior BC

Assembly



Celebi and Penzien (1973)

Beams

Epoxy Injection 3.5 N/A 1.11 N/A

Epoxy Injection 4 N/A 1.21 Reduced

Epoxy Injection 4 N/A 1.19 Reduced

Epoxy Injection 5 1.1 1.17 Reduced

Expanded from Marder (2018)

Load

Displacement

K0

KR

Approximated Yield

0,00

0,20

0,40

0,60

0,80

1,00

1,20

1,40

0,00 2,00 4,00 6,00 8,00

Rep

aire

d St

reng

th /

Und

amag

ed S

tren

gth

Maximum Displacement Ductility Prior to Repair

0

0,2

0,4

0,6

0,8

1

1,2

0,00 2,00 4,00 6,00 8,00

Rep

aire

d Se

cant

Stif

fnes

s / U

ndam

aged

Se

cant

Stif

fnes

s

Maximum Displacement Ductility Prior to Repair


25

Literature Review

Columns, further

experimental

study is needed

• Literature survey shows a trend that damaged-and-repaired specimens approximately

exhibit the same strength and ductility but slightly lower stiffness properties than

that of undamaged ones

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Performance-wise

Load

Displacement

Undamaged

Repaired


Contents







27

The Damage Threshold for Repairability

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Load

Displacement

Undamaged

Damaged

After Repair?

Performance-wise Cost-wise

Repair Cost

Benefit

Feasibility?


Can the repaired structure withstand

the same PGA?

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Performance-wise

Damage Type Stiffness Modifier

λK

Strength Modifier

λQ

Ductility Modifier

λD

Type A 0.90 1 1

Type B 0.80 1 1

Type C 0.80 1 1

0

0,2

0,4

0,6

0,8

1

1,2

1,4

1,6

0 0,1 0,2 0,3 0,4 0,5 0,6

Sae

& a

(g)

Sd & d (m)

Undamaged

Repaired


Three extreme cases have been compared with typical sub-standard undamaged

structures:

• Undamaged structure λK=1 (Effective stiffness)

• All columns λK=0.9 (Type A)

• All columns λK=0.8 (Type C)

• All columns λK=0.7 (for observation)

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Performance-wise Case Studies

Load

Displacement

KIeff

0

0,2

0,4

0,6

0,8

1

1,2

1,4

0 0,1 0,2 0,3 0,4 0,5 0,6

Sae

& a

(g)

Sd & d (m)

0

0,1

0,2

0,3

0,4

0,5

0,6

0 0,05 0,1 0,15 0,2

Sae

& a

(g)

Sd & d (m)


31

Performance-wise Case Studies Structure

Similar PGA capacity with the intact ones

Contents







32

Conclusions

• From the beginning (since 2003), the TCIP Post-EQ Damage Assessment Methodology has

been shaped to allow unbiased and accurate damage categorization of earthquake-stricken

buildings and continue to be developed with the recent site and laboratory observations

• Performance analyses showed that damaged-and-repaired buildings can theoretically have

similar PGA capacity with the intact ones

• Repairability threshold can be correlated with the repair cost rather than the structural

performance of repaired structures

• A link between WDR and repair cost needs to be defined for a clear repairability limit

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Future Works

• The relationship between the damage state and repair cost (structural +

nonstructural) for Turkey are being investigated:

– Structural analyses

– Statistical data from past eqs

• The seismic performance of damaged-and-repaired RC columns still needs further

research:

– A set of experimental tests will be carried out on repaired RC columns

– Stiffness, strength and ductility modifiers will be updated/validated accordingly

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Thank you for your attention

[email protected]

damage assessment methodology developed for tcip · 2019-11-08 · damage assessment methodology...

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