Recent Advances on the Increase of Resilience and Sustainability of School Infrastructure

，

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Seismic Retrofitting Program of School Buildings in Taiwan

DirectorNational Center for Research on Earthquake Engineering

ProfessorNational Taiwan University

Shyh-Jiann Hwang

February 24, 2021

• Established at National Taiwan University in 1990• Mission:

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x Pre-quake preparation – Disaster preventionx Emergency response – Disaster reductionx Post-quake recovery – Disaster relief

Introduction of NCREE

Outlines

• Introduction• Evaluation and Retrofitting

Technologies• School Retrofitting Program• Residential Building Program• Conclusion

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Introduction

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Vulnerability of School Buildings

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Taiwan 1999 Chi-Chi EQ

Mexico 1985 Mexico City EQ

Collapse of school buildings

School Building Retrofitted by PT Rods

0 1 2 3 4 5 6 7RF Drift Ratio(%)

0

500

1000

1500

2000

2500

3000

3500

Base

She

ar (k

N)

P.T. Retrofit Specimen Benchmark Specimen

1444

2985 at Roof Drift Ratio 0.98%

at Roof Drift Ratio 0.86%

Effectiveness of PT-Rod RetrofittingIn-situ school testing, Tainan, Taiwan (2007)

Evaluation and Retrofitting Technologies

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Screening

SimpleSurvey

Preliminary Evaluation

Detailed Evaluation

Screening Process

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Simple Survey (2009-2011)

Field investigation: • 3,721 public schools25,843 buildings

• 228 college students4,426 days per person

School building included:• Buildings constructed before 1999

• Buildings occupied by students or teachers

fA6

CAWA

Total Floor Area above 1st Floor

1st Floor Capacity

Seismic Index:fg

WWCCAwaAA

DemandCapacity

6WWuu�

fA6Demand

Capacity CA WA

Preliminary Evaluation

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Detailed EvaluationPerformance Based Engineering

Nonlinear Static AnalysisCapacity Spectrum

AnalysisPushover Analysis

Performance-Target Ground Acceleration Ap

Ap

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Modeling of Vertical Members

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V

ΔΔs

Vmn

ΔaΔe,mn

V

ΔΔn Δa

Vn

Vcr

Δcr

ShearPlastic Hinge

Flexural Plastic Hinge

Well known

In dispute

Shear critical column: low f’c, less transverse reinforcement

Short column

Shear wallColumn

Shear-Critical Vertical Members

Static Test

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Research on Seismic Capacity of Members

Shaking Table TestStatic Test

Columns WallColumn

-10 -5 0 5 10-800

-400

0

400

800

3DL

側力強度

(kN)

層間位移角(%)

實驗值分析值

Collapse Behavior of RC Column

1001

fAN

401

f401"4

1003

H cg

u

cn

tc

�c

X�U�

Elwood & Moehle (Spectra 2005; ACI 2005)

� �

¸¸¹

·¨¨©

§

T�T

T�

tandfAsNtan

tan1100

4H

cytstu

2

n

sΔ

aΔ

'

uV

0

V

u'sΔ aΔ

v

Nu

Flexural Shear

Shaking Table Tests for Column Collapse Behavior

18Yavari et al. (2010)

sΔ

bV

y'

V

'0

yV

n' aΔ蘇瑞翔等人(2007)

吳俊霖等人(2009)

Experimental Verification of Shear Strength

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test nV V

)(MPafcc

AVG = 1.20COV = 0.10

1.180.18

1.240.08

1.270.22

33 29 11 86 60

1.150.14

RC

'Displacement

V

'

V

Short Column Shear Wall Typical Column

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'

V

'

Shea

r St

reng

th

Displacement

V

Wall with Opening

Backbone Curves for Shear Critical Members

Softened Strut-and-Tie Model

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Test Setup of Monotonic Loading

2

1

Jacks

Pumps

Brace

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Test Video of Monotonic Loading

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Pseudo-Dynamic and Cyclic Tests Setup

Pseudo Dynamic Test (# 3), Courtesy of Dr. Min-Lang Lin

Hua-Lien (2005) Yun-Lin (2005)

Tao-Yuan (2006) Tainan (2007)

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-4 -2 0 2 4Story Drift (%)

-1500

-1000

-500

0

500

1000

1500

Base

She

ar (k

N)

In-Situ Tests of School Buildings –Verification of Pushover Analysis

Common Retrofitting Techniques

Jacketed column

Wing wall

Shear wall

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RC Wing Wall (2005) Composite Column (2006)

Steel Jacketing (2007)RC Jacketing (2007)

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In-Situ Tests of School Buildings –Verification of Retrofitting Methods

� Basic Methodology from ATC-13

Structural Properties

Plan, Dimensions, Section details,

Material strength, Soil condition

Seismic Magnitude

Damaged Conditions

Site PGA,Longitudinal PGA for individual building

Damage records,Definition of "damage"

Chi-Chi Earthquake Damage Database of School Buildings in Taiwan

NCREE-07-023Tu et al.

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Verification of Acceptance Criteria (35 Buildings)

0

0.5

1

1.5

2

Safe

Unsafe

CapacityDemand

Collapse Heavy Medium Small Slight

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CDR=

School Retrofitting Program

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Strategy for School Upgrading in Taiwan

Census

Evaluation

Design and

Construction

Dat

abas

eco

llect

ed b

y in

tern

et

Field Investigation

PreliminaryEvaluation

Detail Evaluation

Peer Review

Retrofit Design

RetrofitConstruction

Rebuild

Maintenance

Maintenance

Peer Review

Inspection

Safe

Unsafe

Safe

Unsafe

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Unification of Process

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• Complex Parties: governmental official, school teacher, engineer, constructor,student, parent

• Tight Schedule: annual budget, short construction period

• Unification Document: operation specification,contract document, design manual

Budget Control - Service Payment

New Construction

SeismicRetrofitting

Design Payment = Rate u Construction Fee

Design Payment = Rate u Floor Area

Innovation forQuality

Payment perQuantity

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Budget Control - Economic Methods

RC Column Jacketing RC Wing Wall RC Shear Wall

Isolated Device DamperSeismic Devices with Patents Ö Prohibited

Traditional Retrofitting Method Ö Encouraged

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Quality Control - Review and Inspection• Peer Review for Design

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School Staff

Constructor

Engineer

School Staff

Engineer

3 Reviewers

Budget Saving

32%100%

68%

• Inspection for Construction

Quality Control - Workshops• Workshops for Engineers, School Administrators,

Educational Officials

• Case Study

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Website and Database

https://school.ncree.org.tw

Database

• Data Collecting• News Announcement• Download Service• Exchange of Information

• Process monitoring• Decision making

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Epicenter

Junior High S.No retrofitting30km from epicenter

Vocational S.Retrofitted31km from epicenter

Kaohsiung Jia-Xian EQML = 6.4, March 4, 2010Retrofitting Effectiveness

Wing Wall

RC Wall 38

Cost of School Retrofitting in Taiwan

2

2

Retrofitting fee NT$ 2,250 /mActual Cost: = = Rebuilt fee NT$ 22,000 /m

10%

10%

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Census

Evaluation

Retrofitting

Under processing

Design

Data deadline： 2020.03.31

School Buildings Upgrading Projects

x Project span from 2009 to 2022x Upgrading rate by construction up to 37%

Build

ing

No.

27,241

17,780

10,353

1,328

8,710

0

5000

10000

15000

20000

25000

30000

Census Evaluation Design Retrofitting

Residential Building Program

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Earthquake Damages of Buildings with Soft and Weak First Story

11‐story Hotel2018 Hualien EQ

14‐story Condominium2016 Meinong EQ

12‐story Condominium2018 Hualien EQ

Characteristics of Damaged Buildings

• Older RC building

• Soft and weak first story

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Source : DEGENKOLB RECONNAISANCE TEAM2016 MEINONG TAIWAN EARTHQUAKE DEBRIEF

Interim Seismic Retrofit

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Building with soft first story

Removal of seismic deficiency

Prevent Building Collapse Immediately during Earthquake

City Building type Process Method

Tainan7-story

Condominium + 1F market

Open bidding Addition of external frames

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Interim Retrofitting Case – External Frames

Conclusion

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Features of Project• Field investigation• Advanced evaluation method• Screen and prioritization• Unified procedure• Budget and quality control• Website and database

NCREE

LocalGovernments

CentralGovernment

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Technology

Administration

Compulsory

Monitoring

Acknowledgementz Ministry of Education (MOE)z Ministry of Science and Technology (MOST)z National Applied Research Laboratories

(NARLabs)z Schools of Cheng Junior High, Kou-Hu

Elementary, Ruei-Pu Elementary and Guan-Miao Elementary

z County Governments of Hualien, Yunlin, Taoyuan and Tainan

z Universities of NTU, NTUST, NYUST, NCKU, NKFUST, NCTU, etc.

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Thank you for your attention