Japan Society of Civil Engineers,
July 1st, 2021

Xinzheng LU, Qingle Cheng, Yifan Fei, Yi Gu
Institute of Disaster Prevention and Mitigation
Department of Civil Engineering, Tsinghua University
Email: luxz@tsinghua.edu.cn
Website: www.luxinzheng.net
1

1. Introduction of M6.4 Yangbi earthquake
2. Field investigation
3. Prompt damage assessment using
RED-ACT
4. Other applications of RED-ACT
5. Conclusions
2

1. Introduction of M6.4 Yangbi earthquake
2. Field investigation
3. Prompt damage assessment using
RED-ACT
4. Other applications of RED-ACT
5. Conclusions
3nName: Yangbi earthquake

nMagnitude: 6.4 (CENC), 6.1 (USGS)

nTime: 2021-05-21, 21:48 (local time)

nLocation: Yangbi countyn3 dead, 28 injured

38 km
Dali City4

n

Ground motion
n260 setsn

Maximum PGA: 7.20 m/s/s

4.5 km

53YBX

5

n

Ground motion
n260 setsn

Maximum PGA: 7.20 m/s/s

n53YBX, 4.5 km

The corresponding peak ground acceleration (PGA) of the designearthquake (i.e., exceedance probability of 10% in 50 years) is 20061. Introduction of M6.4 Yangbi earthquake2. Field investigation
3. Prompt damage assessment using
RED-ACT
4. Other applications of RED-ACT
5. Conclusions
7n300 experts with 3 daysn

6 counties
Green placard
Yellow placard
Red placard

8

nSeismic Intensity
VIII (JMA: 5.5-5.9)
VII (JMA: 5.0-5.4)
VI (JMA: 4.5-4.9)

Green placard
Yellow placard
Red placard

9n

The buildings with formal seismic design and construction
have good seismic capacity

Slight damage
10n

The seismic capacity of rural buildings is generally weakPartially collapsed

11

nSeismic Reinforcement Project of Rural buildingsnSince 2004

n

Three strengthening method for rural buildings

Steel braces
between wood components to improve the integrity
12nSeismic Reinforcement Project of Rural buildings
nSince 2004

n

Three strengthening method for rural buildings

Steel diagonal braces

between wood components toimprove the overall deformation ability

Steel tie rods

between wood components toimprove the overall deformation ability13

nSeismic Reinforcement Project of Rural buildings
nSince 2004

n

Three strengthening method for rural buildings

Steel braces

Steel diagonal bracesnAbout 300 $ per buildingnInexpensive, simple and anti-collapse

Steel tie rods14

1. Introduction of M6.4 Yangbi earthquake
2. Field investigation
3. Prompt damage assessment usingRED-ACT
4. Other applications of RED-ACT
5. Conclusions
15

Conventional method

Proposed method

EQ
magnitude

EQ
magnitude
Much smaller
Uncertainty

Significant
Uncertainty

Building info.

EQ Intensity
Significant
Uncertainty

Uncertainty

Fragility curve
Significant
Uncertainty

LossGroundmotion

Building info.

Much smaller
Uncertainty

Uncertainty

Nonlinear timehistory analysis
Much smaller
Uncertainty

Loss16Densely-distributed
strong motion network

City-scale nonlinear
time-history analysis

Earthquake ground motion
Input

Actual ground motion records

Rapidly evaluate seismic damage

1+1>2!

M or e er atAccu

17

Recorded groundmotionCity-scale nonlinear
time-history analysis+Real-time Earthquake Damage Assessment
RED-ACT
Densely-distributed
strong motion
network

Building
inventory

Human feeling

Input

Ground motion
Ground motion
fieldCity-scalenonlinear timehistory analysis
Earthquakeinduced landslide

Building damage18

nWhat is City-scale nonlinear time-history analysis?
(NLTHA)

Input

Structural dynamics

Building
Earthquake ground motion
Seismic damage
Input

Structural dynamics
City19Structural dynamic models (Physics driven model)

The ground motion(recorded or simulated)

Structural dynamic models(multi-scale models)

Dynamic
response

Advantages• Strictly following the fundamental of structural dynamics• Accurately represent the features of individual buildings• Accurately represent the characteristics of earthquakes
Lu XZ, Guan H, Earthquake Disaster Simulation of Civil Infrastructures: From Tall Buildings to Urban Areas(2nd edition), Singapore: Springer, 2021.

20nMulti-scale structural dynamic models

Multi-story buildings

Sheardeformation
mode

Tall buildings

Flexural-shear
deformation
mode

Special buildings

Complexdynamicproperty
Beam/column
Fiber beam
element
Shear wall
Multi-layershell elements

MDOF shear model

MDOF flexural shear model

Moderate-fidelity models

Refined FE model

High-fidelitymodels

21Each parameter has a clear physical meaning

Empirical formula

Codes

Test data

RC frame
RC shear wall structures

Suitable fordifferent
countries…
Parameter determination and damage assessment for THA-based regional seismic damage prediction ofmulti-story buildings, Journal of Earthquake Engineering, 2016 22

nParameters adapted for Japan

Yield point
Wood structures

Vy   y k0h120

Ductility factor  7.2  3.6Y / 30 , Y  30  3.6, Y  30

RC structures

Vy   y  y 0.2mg

  7  5Y / 30 , Y  30  2, Y  30

Steel structures

Vy   y  y 0.2mg

  5  3Y / 30 , Y  30  2, Y  30

(Data source provided by Ji Dang)23

Validation
ExperimentnMonitoring

Vertical actuator Vertical actuator Vertical actuator
Constant axial
Constant axial Constant axial
loadingloadingloading
Rollers

Rollers

500

1440

1320

1320

Horizontal
actuator

2280

Agree well with experimentError of maximal drift:-4.6% (Proposed method)-2.8% (Period updated)

Parameter determination and damage assessment for THA-based regional seismic damage prediction ofmulti-story buildings, Journal of Earthquake Engineering, 2016

nLudian Earthquake (M 6.5), 2014, China

Actual damage of Longtoushan Town

Compare with actual damage and DPM method(DPM: Damage Probability Matrices)ü Agree well with actual damage
ü More accurate than the traditional DPM method
Parameter determination and damage assessment for THA-based regional seismic damage prediction ofmulti-story buildings, Journal of Earthquake Engineering, 2016 25

1. Explicit physical mechanism
2. Higher accuracy
3. Adaptive data resolutions

4. Intuitive and intelligible visualization
5. Death, Dollar, Downtime & Resilience
6. Various secondary disasters

Beijing CBD, 1679 Sanhe-Pinggu M8.0 Earthquake26

Beijing 2nd Adm Center (2017), Tongzhou
District (2018) & Daxing District (2019)

Taiyuan (2017)

Xiong’An (2017)

New Beichuan (2018)

Tangshan (2016) 27

Earthquake secondary fire

San Francisco Bay Area, M 7.0 Earthquake of Hayward Fault
1,843,351 buildings, Courtesy NHERI SimCenter28

nNear-real-time prompt assessment for regional EQILs

Module 1: Generation of theground motion field

Module 2: Model parameters
determination

Module 3: Newmark sliding
block analysis

Strong-motion network
Elevation (m)3754

ac-12aαNewmark sliding block method
Recorded ground motion

Digital elevation modelmtpapbpyscsm

Simulated ground motion

sssuvavbvi
wb

Lithology data

Display the result of EQILs

Near-real-time prompt assessment for regional earthquake-induced landslides using recorded groundmotions, Computers & Geosciences, 2021 29

RED-ACTVIII (JMA: 5.5-5.9)
VII (JMA: 5.0-5.4)
VI (JMA: 4.5-4.9)
None and slight damage
Moderate damage
Extensive and collapse

30nCompared with actual damage
VIII (JMA: 5.5-5.9)

None and slight damage

VII (JMA: 5.0-5.4)

Moderate damage

VI (JMA: 4.5-4.9)

Extensive and collapse

Green placard
Yellow placard
Red placardField investigation

RED-ACTØ 300 experts

Ø 1 student

Ø 3 daysØ < 1 h after getting ground motion
31

n

EQILs assessment
Our method: high probabilityn PAGER: low probabilityn Agree well with actual damagenLandslide location

沟头箐, Goutouqing

Our method
Wald et al., 2010. PAGER--Rapid assessment of an earthquake’s impact.

PAGER
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1. Introduction of M6.4 Yangbi earthquake
2. Field investigation
3. Prompt damage assessment using
RED-ACT
4. Other applications of RED-ACT
5. Conclusions
33

nJiuzhaigou Earthquake (M 7.0), 2017, China• < 2 h after getting ground motion• < 5 h after earthquake

Predictions ofsome agencies

Our prediction

Site investigation report“Hundreds casualties”, “Very small possibility“Tens of thousands ofof collapse”
collapse”“73,671 damaged,76 collapsed”

Agree well

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nFukushima Earthquake (M 7.3), 2021, JapannField investigation: small possibility of collapsenCollapsed (全壊): 32, Extensive damage (半壊): 259

RED-ACT

NIED-CRSUSGS PAGER

Predictions ofsome agencies

Very small possibilityof collapse

50~500 buildings will
Required a regional or
collapse in a large area national level response

消防庁災害対策本部. 福島県沖を震源とする地震による被害及び消防機関等の対応状況（第16報）

35

nChina, USA, Japan, Italy, New Zealand, etc.
Since 2016, significant earthquakes around the world
Domestic 65, Abroad 51

2018 M7.0 Anchorage
earthquake2019 M7.1 Ridgecrest
earthquake

Last updated: 2021/6/15

China Earthquake
Networks Center

played a critical role
< 2 h after getting ground motion< 1 h after getting ground motion36

1. Introduction of M6.4 Yangbi earthquake
2. Field investigation
3. Prompt damage assessment using
RED-ACT
4. Other applications of RED-ACT
5. Conclusions
37

Recorded ground
City-scale nonlinear+motion
time-history analysis
Real-time Earthquake Damage
Assessment (RED-ACT)
EQ
magnitude
Determinate

Accurate ground motion

Determinate

Accurate structural dynamicequations

Groundmotion

Building info.
Uncertainty

City-scale timehistory analysis

Limited
Uncertainty

LossAdvantages

Accurate seismic damage
assessment

38

Prof. Lieping Ye, Aizhu Ren
Dr. Zhen Xu, Xiao Lu, Chen Xiong,X Zeng, Y Tian, ZB Yang
B Han, QL Cheng, DL Gu, CJ Sun
Prof. Mengtan Gao,
Yanxiang Yu
China Earthquake
CH Fu, XC Lin
Administration

Prof. KH Law

Prof. S Mahin,
Dr. F McKenna
Dr. M Schoettler
Prof. J Dang

Stanford University39

Thank you
for your attention!
www.luxinzheng.net
luxz@tsinghua.edu.cn
40