2d-0067

The 17th World Conference on Earthquake Engineering

17th World Conference on Earthquake Engineering, 17WCEE
Sendai, Japan - September 13th to 18th 2020
Paper N° C002182
Registration Code: S-A00954

REPRODUCTION SIMULATION OF 1995 KOBE EARTHQUAKE BY
EARTHQUAKE DAMAGE SIMULATIONS IN EXPRESSWAY NETWORK
M. Hattori (1), H. Ohishi (2), M. Shinohara(3), M. Nakamura(4) , K. Magoshi(5)(1)

Hanshin Expressway Technology Center, hattori_m@tech-center.or.jp
Hanshin Expressway Technology Center, oishi@tech-center.or.jp(3)
Hanshin Expressway Company Limited, masatsugu-shinohara@hanshin-exp.co.jp(4)
Earthquake Engineering Research Center Inc, nakamura@eerc.co.jp(5)
Earthquake Engineering Research Center Inc, magoshi@eerc.co.jp(2)

Abstract
Earthquake damage simulations in expressway network targeted major earthquakes in the future has been researched in
Hanshin Expressway. This simulations target all Hanshin Expressway route. So, it can evaluate the bridge damage
conditions in route units or span units. If damaged piers can be predicted by the earthquake damage simulation, it ispossible to clarify the piers where we should conduct the seismic reinforcement. In addition, if amount of step
displacement on the road surface can be predicted, it is possible to clarify the places where we should prepare
equipment to eliminate the steps.
This earthquake damage simulation system is divided into three stages. Every earthquake simulation delivers thesimulation results.
Step 1 : Deep ground response analysis (from epicenter to engineering foundation)
Step 2 : Shallow ground response analysis (from engineering foundation to pier foundation)
Step 3 : Structural response analysis
In this study, 1995 Kobe earthquake was tried to reproduce by using this earthquake damage simulation to verify thissimulation accuracy. As a result, the damage dispersion of the actual structures at 1995 Kobe earthquake and thisreproduction simulation were coincided. Therefore, this simulation was confirmed the accuracy.
In addition, earthquake damage simulations targeted various epicenter were conducted, such as Nankai Troughearthquake and Uemachi earthquake. It was clarified that this simulation system is possible to evaluate pier damages
and the amount of step displacement before earthquakes.

Keywords: earthquake damage simulation, expressway network, 1995 Kobe earthquake© The 17th World Conference on Earthquake Engineering- 2d-0067 -2d-0067

The 17th World Conference on Earthquake Engineering

17th World Conference on Earthquake Engineering, 17WCEE
Sendai, Japan - September 13th to 18th 2020

1. Introduction
On Hanshin Expressway, seismic retrofit projects have been conducted after 1995 Kobe earthquake, i.e.
strengthening of bridge piers, ensuring adequate seating of girders and improving bridge restrainers. In
addition, earthquake damage simulations in expressway network targeted major earthquakes in the future has
been also researched as one of efforts for preventing and mitigating disasters. These simulations target all
Hanshin Expressway route. Therefore, it can evaluate the bridge damage conditions in route units or section
units. If damaged piers can be predicted by the earthquake damage simulation, it is possible to clarify thepiers where we should conduct the seismic reinforcement. In addition, if amount of step displacement on theroad surface can be predicted, it is possible to clarify the places where we should prepare equipment toeliminate the steps.
In this study, 1995 Kobe earthquake was tried to reproduce by using this earthquake damage
simulation to verify this simulation accuracy. In addition, earthquake damage simulations targeted various
epicenter were conducted, such as Nankai Trough earthquake and Uemachi earthquake. In this paper, thesesimulation results were reported at the current level.

2. Method of earthquake damage simulations in expressway network
As shown in Fig. 1, this earthquake damage simulation system is divided into 3 steps. Step 1 is “Deepground response analysis” which evaluate transmission of earthquake ground motions from epicenter to baseground surface for seismic design. Step1 results (such as acceleration response values at base ground surface
for seismic design) are passed to Step 2. Step 2 is “Shallow ground response analysis” which evaluate
amplification of earthquake ground motions from base ground surface for seismic design to each of pierfoundations. In Step 2, 1-dimensional non-linear dynamic analyses for shallow grounds below each of pierfoundations are conducted. Step 2 results (such as accelerations response values just below pier foundations)are passed to Step 3. Step 3 is "Structural response analysis" which evaluate seismic behavior of bridges.
Step 3： Structural response analysis

Step 2: Shallow ground response analysis

Step 1: Deep ground response analysis

Fig. 1 – Method of the arthquake damage simulation in expressway network
Table 1 shows the current analysis methods and analysis models. There are some analytical methods
and analytical models in each of the steps. We will improve the accuracy level of analytical methods andanalytical models sequentially in the future.

2© The 17th World Conference on Earthquake Engineering- 2d-0067 -2d-0067

The 17th World Conference on Earthquake Engineering

17th World Conference on Earthquake Engineering, 17WCEE
Sendai, Japan - September 13th to 18th 2020

Table 1 – Current analytical methods and analytical models
earthquake response analysis which ground motions passed from
Step2 were inputted at below each of pier foundations
sequential nonlinear dynamic analysis (YUSAYUSA etc.)- available for large strain occurred- difficult to consider frequency characteristics
Statistical Green's function method- easy to calculate short period component of ground motions- impossible to calculate long period component of groundmotions

Structural response analysis
Shallow ground response analysis

Deep ground response analysis

3. Construction of analytical models
3.1 Deep ground response analysis model (Step1)
Fig.2 shows the fault model for 1995 Kobe Earthquake. Nozu et al. used this model and almost reproduced
1995 Kobe earthquake ground motion [1]. Statistical Green's function method was used in this reproduction
analysis. Analytical region was set at 400 km x 400 km centering on SMGA fracture point and was divided
with a 100m mesh.
Arima-Takatsuki fault

Depth (km)Osakako andHigashiosaka
RouteKobe Route

Fault of 1995 Kobe Earthquake

Asperity 2

Asperity 4

Asperity 1
Fracture point

Wangan RouteDistance of trabel direction (km)Uemachi fault(b) fracture point and asperities(a) fault distribution([1] Fig.9 quoted)

Fig. 2 – Fault model for 1995 Kobe Earthquake
Table 2 shows the details of its parameters. Unpublished parameters were set based on "Strong groundmotion prediction method for earthquakes with specified source faults” (“Recipe”) published by the
Headquarters for Earthquake Research Promotion [2].

3
© The 17th World Conference on Earthquake Engineering- 2d-0067 -2d-0067

The 17th World Conference on Earthquake Engineering

17th World Conference on Earthquake Engineering, 17WCEE
Sendai, Japan - September 13th to 18th 2020

Table 2 – the details of 1995 Kobe Earthquake fault model parameters
Name of fault
Position at southwest tip of fault
Average angle of fault travel direction θ (°)
Average angle of fault inclination direction δ (°)
Average angle of fault slip λ (°)

Fault length L (km)
Fault width W (km)
Fault section S (km2)
Head depth of fault Z0 (km)Moment of Earthquake (N・ m)
Magnitude of Earthquake Mw
Average amount of slip (m)Asperity1 Asperity2 Asperity4
34.616700 34.635673 34.688183
135.02940 135.05923 135.18803
N53
N53E
N233E
90
90
85
0
0
0
8
4.8
12.8
6.4
4.8
8
51
23
102
3.0
3.0
3.0
3.40E+17 1.30E+18 2.30E+18
6.0
5.6
6.2
0.7
0.4
0.7

3.2 Shallow ground response analysis model (Step2)
In the shallow ground response analysis, analytical models reproduced the ground structures at immediately
below each pier foundation. Ground constants of analytical models were set based on boring data in the
Kansai Geo-informatics database [3]. When the analytical models were built, the nearest boring data fromeach of pier foundations were used because boring data was limited [4]. In this study, shallow ground was
divided into 4 geological groups, alluvial sand (As), alluvial clay (Ac), diluvial sand (Ds) and diluvial clay
(Dc). Hyperbolic curve models were applied to each of groups and were set based on the triaxial test resultsin the Kansai Geo-informatics database.

3.3 Structural response analysis model (Step3)
Fig. 3 shows examples of the structural response analysis model by SeanFEM[5,6]. At this stage, structural
response analysis models of Kobe Route, Wangan Route, Kita-Kobe Route, Higashiosaka Route andOsakako Route were constructed. All route analytical models in Hanshin Expressway will be constructed in
2020.

(a) near Awaza Curve(b) near Tenpozan Junction

Fig. 3 – Examples of the structural response analysis model
Table 3 shows elements of the structural response analysis models. Super structurers were modeled bylinear elements. Steel bearings were reproduced the support conditions and rubber bearings were modeled by

4© The 17th World Conference on Earthquake Engineering- 2d-0067 -2d-0067

The 17th World Conference on Earthquake Engineering

17th World Conference on Earthquake Engineering, 17WCEE
Sendai, Japan - September 13th to 18th 2020

spring elements with equivalent rigidity. Piers were modeled by nonlinear elements. Pier foundations weremodeled by spring elements.
Table 3 – Elements of structural response analysis models
Superstructures linear beam element
Steel bearings : fixed or movable
Bearings
Rubber bearings : spring element(with goruping equivalent rigidity)
Piernonlinear beam element (groping)Pier foundation spring element (S-R model)

In this study, all piers in Hanshin Expressway were divided into 13 groups according to structuralconfiguration and diameter of the cross section, and the representative piers were selected from each of thegroups. The representative pier’s cross section was applied to that of piers divided into same group. Seismic
reinforcement has been conducted after 1995 Kobe Earthquake in Hanshin Expressway, i.e. steel piers werefilled with concrete or RC piers were wrapped by steel plates. The analysis models had unreinforcement
cross sections to reproduce structural condition at the time of the earthquake. In addition, as shown in Fig. 4,
Pilz piers collapsed at the earthquake were modeled based on the drawing at the time.

Dural box
girders withsteel deckBaseisolators(a) before the earthquake (Pilz pier)(b) after the earthquake

Fig. 4 – Cross-section before and after the earthquake

4. REPRODUCTION SIMULATION OF 1995 KOBE EARTHQUAKEThe reproduction simulation results of 1995 Kobe Earthquake are shown below. Further, this study onearthquake damage simulations in expressway network is in a research and development stage. The accuracyof the analysis results will be verified in the future.

4.1 Deep ground response analysis
Fig. 5 shows the maximum acceleration values distribution at the base ground surface for seismic design. It
is confirmed that maximum acceleration values calculated on Kobe Route because the point was near the
epicenter of 1995 Kobe Earthquake.

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The 17th World Conference on Earthquake Engineering

17th World Conference on Earthquake Engineering, 17WCEE
Sendai, Japan - September 13th to 18th 2020

Fig. 5 – the maximum acceleration values distribution at the base ground surface for seismic design

4.2 Shallow ground response analysis
Fig. 6 shows the maximum acceleration values distribution at the base ground surface for seismic design andthe ground surface below each of pier foundations. Although large accelerations at ground surface were
calculated on Kobe Route, the acceleration values at the ground surface were lower than at the base groundsurface for seismic design.

基盤波（並進 RSS
Accelerationsat）the base ground surface for seismic design

Accelerationsat）the ground surface
地表面波（並進 RSSHeightshows the maximum acceleration values※高さは最大加速度を表す※高さは最大加速度を表す
Heightshows the maximum acceleration values

Route路線名
namethe maximum
最大加速度(gal) acceleration values
湾岸線
Wangan
Route
1000
Kobe Route
神戸線
500
0
Osakako/Higashiosaka
大阪港・東大阪線

Route路線名
namethe maximum
最大加速度(gal) acceleration values
湾岸線
Wangan
Route
1000
Kobe Route
神戸線
500
0
Osakako/Higashiosaka
大阪港・東大阪線(a) at the base ground surface for seismic design(b) at the ground surface

Fig. 6 – the maximum acceleration values distribution
Fig.7 shows the time history accelerations at the ground surface of the actual observation record andthe reproduction analysis. Here, the observation record was recorded at Kobe-S observation station by theStrong Motion Earthquake observation in Japanese Ports [7]. This record was selected because it wasthought that the station was the nearest of all stations recorded at the earthquake ground motions. The
analysis results were picked up at the pier position close to Kobe-S observation station. The distance from
Kobe-S observation station to the objective point in reproduction analysis is about 330 m.
Fig.8 shows the acceleration response spectrum at the ground surface of the actual observation record
and the reproduction analysis. The NS and EW components of the observation record are dominant at aperiod of about 1.5 seconds. All components of the reproducibility analysis are dominant at a period of

6© The 17th World Conference on Earthquake Engineering- 2d-0067 -2d-0067

The 17th World Conference on Earthquake Engineering

17th World Conference on Earthquake Engineering, 17WCEE
Sendai, Japan - September 13th to 18th 2020

around 0.2 seconds and 1.5 seconds. General piers have eigen period over 0.2 seconds in Hanshin
Expressway, the simulation results were similar to the observation record in period band of structural
response. However, in the NS and EW components of the observation record, the main motion continued forabout 5 seconds after the seismic motion reached the observation point, but in the reproduction analysis, themain motion continued for about 15 seconds. Therefore, the reproducible analysis evaluated the duration of
the ground motion longer than the observation record. It was thought that the parameter of the epicentermodel in the deep ground response analysis effect on the duration of the ground motion. Therefore, deep
ground response analysis with different parameters will be conducted to improve the accuracy of the groundmotion.

1000

0
-500
-1000
0

10

20

30

NS

500

加速度(gal)Acceleration (gal)Acceleration (gal)

加速度(gal)

1000

NS

500

0
-500
-1000
0

40

10

20

1000

0
-500
-1000
0

10

20

30

0

10

20

-1000
20

30

40

UD

500

加速度(gal)

加速度(gal)Acceleration (gal)Acceleration (gal)

0
-500

10

30

Time (s)
1000

0

40

-500
-1000

40

UD

500

30

0

Time (s)
1000

40

EW

500

加速度(gal)Acceleration (gal)Acceleration (gal)

加速度(gal)

1000

EW

500

30

Time (s)Time (s)

0
-500
-1000
0

40

10

20

Time (s)Time (s)(a) observation record(b) reproduction analysis

10000

1000

1000

応答スペクトル (gal)10000

Acceleration esponse spectrum (gal)Acceleration esponse spectrum (gal)

応答スペクトル (gal)Fig. 7 – The time history accelerations at the ground surface

100
10

NS
EW

1

UD

100
10

NS
EW

1

UD

Type
II-III Ⅱ
of design
earthquake ground motions
タイプ
-Ⅲ種地盤

Type II-III Ⅱ
of design
earthquake ground motions
タイプ- Ⅲ種地盤

0.1

0.1
0.1

1

Period
周期 (sec)
(s)

10

0.1

1
Period (sec)周期(s)(a) observation record(b) reproduction analysis

Fig. 8 – The acceleration response spectrum at the ground surface

7© The 17th World Conference on Earthquake Engineering- 2d-0067 -10

2d-0067

The 17th World Conference on Earthquake Engineering

17th World Conference on Earthquake Engineering, 17WCEE
Sendai, Japan - September 13th to 18th 2020

4.3 Structural response analysis
Fig.9 shows the deformation modes near Higashi-Kobe Bridge at about 12 second and 18 second
from occurring the earthquake. Fig.10 shows damage level criteria of piers along Kobe Route. Here,
5 ranks from As to D were set for the damage level criteria of pier capacity. The investigation
results at the time were classified based on the actual external damage after 1995 the earthquake.
The damage level criteria of them was determined by the policies as shown in Table-4. In
reproduction analysis, it was determined according to the maximum strains of longitudinal rebars,
those of concrete and the maximum shear capacity. Thresholds to class the damage level criteria
were set based on prevent examinations and the latest design specification [8-10]. Focusing on Pilz
piers along Kobe Route collapsed by 1995 Kobe Earthquake, it was classified as “As” in theinvestigation result. In the reproduction analysis results, it was classified as “As” although not allspans. Therefore, it was confirmed that there was a certain accuracy to class damage level criteria ofpiers under large earthquakes.

(a) about 12 sec.

(b) about 18 sec.

Fig. 9 – The acceleration response spectrum at the ground surface

Damage level criteria

耐荷力ランク判定(被害調査結果)

Investigation

Pilz section

As

Investigation

A
B
C
D
18

18.5

19

19.5

20

20.5

21

21.5

Damage level criteria

耐荷力ランク判定(解析結果)

AnalysisAs

22

距離 (km)Pilz section
Analysis

A
B
C
D
18

18.5

19

19.5

20

20.5

21

21.5

22

距離 (km)(a) along Kobe Route(b) around Pilz section

Fig. 10 – damage level criteria of piers along8© The 17th World Conference on Earthquake Engineering- 2d-0067 -2d-0067

The 17th World Conference on Earthquake Engineering

17th World Conference on Earthquake Engineering, 17WCEE
Sendai, Japan - September 13th to 18th 2020

Table 4 – The policies for the damage level criteria
Rankdamage level
As Collapse or toppling, or equivalent damage
Damage affecting the load carrying capacity significantly and causing risk ofApotential life-threatening secondary disasters
B
C
D

amage affecting the load carrying capacity but allowing for temporary use aslong as it does not worsen any further during aftershocks or under live load
Damage with no adverse effects on the short-term load carrying capacity

Damage with no specific effects on the load carrying capacity

5. Damage evaluation by earthquake response simulations for various hypocenter
5.1 Assumed ground motion
Table 5 shows a list of ground motions assumed in this study. In this study, 4 inland active fault type
earthquake and 1 trench type earthquake were assumed. Uemachi Earthquake (South collapsed case andNorth collapsed case), Arima-Takatsuki Earthquake and 1995 Kobe Earthquake were targeted as inland
active fault type earthquake. Nankai Trough Earthquake was targeted as trench type earthquake.
Fig.2 shows the fault distribution of Uemachi Earthquake, Arima-Takatsuki Earthquake and 1995
Kobe Earthquake. The seismic center distribution and the fault parameters of the target earthquakes are
based on the Osaka Prefectural Natural Disaster Prevention Measures for Uemachi Earthquake and ArimaTakatsuki Earthquake [11]. Analytical region for Uemachi Earthquake and Arima-Takatsuki Earthquake
were set at 400 km x 400 km centering on SMGA fracture point and was divided with a 100m mesh.
Fig.11 shows the fault distribution of Nankai Trough Earthquake. The seismic center distribution andthe fault parameters of Nankai Trough was based on published data (land side case) by the Cabinet OfficeNankai Trough Great Earthquake Model Study Group [12]. Parameters that are not shown in the public
documents were set based on “Recipe”. The deep ground response analysis model was built based on J-SHIS
information (ver. 2017) [13]. Analytical region for Nankai Trough Earthquake was set at 500 km x 500 km
centering on SMGA fracture point and was divided with a 100m mesh.

Table 5 – Analysis case
Case
Earthquake ground motions
1 1995 Kobe earthquake
2 Uemachi fault earthquake (north fault case)
3 Uemachi fault earthquake (south fault case)
4 Arima-Takatsuki fault earthquake
5 Nankai Trough earthquake

Fig.11 – Fault model for Nankai Trough Earthquake

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The 17th World Conference on Earthquake Engineering

17th World Conference on Earthquake Engineering, 17WCEE
Sendai, Japan - September 13th to 18th 2020

5.2 Earthquake damage simulation results
Fig.12 shows the damage degree maps of pier capacity at each pier based on earthquake response simulations.
It was calculated that some piers along Wangan Route or Kobe Route were greatly damaged under 1995
Kobe Earthquake and Arima-Takatsuki Earthquake. It was also calculated that some piers along the entire
route were greatly damaged under Uemachi Earthquake (north failure case and south failure case). The
number of damaged piers under Nankai Trough earthquake was lower than other earthquakes.
Fig.12 also shows those of car runnability based on earthquake response simulations. As a result, it
was clarified that this simulation system is possible to evaluate pier damages and the amount of step
displacement before earthquakes.

Case 1
兵庫県南部地震再現

Case 2
上町断層帯(北側ケース)

上町断層帯(南側ケー
Case 3ス)

Damage level criteria of pier capacity

Case 4有馬-高槻断層帯

南海トラフ
Case
5
*湾岸線のみ*only Wangan RouteCase 1Case 3

Case 2

Damage level criteria of car runnabilityabcdCase 5*only Wangan RouteCase 4

Fig. 12 – damage level criteria of pier capacity and car runnability
10© The 17th World Conference on Earthquake Engineering- 2d-0067 -2d-0067

The 17th World Conference on Earthquake Engineering

17th World Conference on Earthquake Engineering, 17WCEE
Sendai, Japan - September 13th to 18th 2020

6. Conclusion
In this study, 1995 Kobe earthquake was tried to reproduce by using this earthquake damage simulation to
verify this simulation accuracy. As a result, the damage dispersion of the actual structures at 1995 Kobe
earthquake and this reproduction simulation were coincided. Therefore, this simulation was confirmed theaccuracy.
In addition, earthquake damage simulations targeted various epicenter were conducted, such as Nankai
Trough earthquake and Uemachi earthquake. It was clarified that this simulation system is possible toevaluate pier damages and the amount of step displacement before earthquakes.
In this paper, we showed the simulation results in a research and development stage. In order toimprove prediction accuracy of this simulation system in the future, it is necessary to improve the level ofanalysis model for structural response analysis. It is also necessary to reevaluate the parameters using groundmotion analysis and thresholds determining the degree of damage.

7. Acknowledgments
This research is part of the joint research between Hanshin Expressway Co., Ltd. and the Earthquake
Engineering Research and Development Center Co., Ltd. on “joint research on earthquake response
simulation for Hanshin Expressway network under large earthquake. We thank all the parties concerned here.

8. References[1] Nozu A, Nagao T, Yamada M (2007): Site amplification factors for strong-motion sites in Japan based on spectral
inversion technique and their use for strong-motion evaluation. 7th Journal of JAEE, 2nd edition. (in Japanese)[2] The Headquarters for Earthquake Research Promotion (2016): Strong ground motion prediction method forearthquakes with specified source faults (“Recipe”) (in Japanese)[3] Kansai
Geo-informatics
network(2019):
KansaiGeo-informatics
net2005.jp/index/db01.html [Accessed Feb. 28, 2020] (in Japanese)

database,https://www.kg-[4] Kiryu S, Nogami Y, Sakai K, Murono Y (2014): A simple method of constructing ground model for evaluating
response of structure located in wide area. Journal of Japan Society of Civil Engineers, Ser.A1 (StructuralEngineering & Earthquake Engineering), Vol.70, Issue 4, 742-750. (in Japanese)[5] Seismic Analysis Research Inc. (2007): SeanFEM ver.1.22 Theoretical manual and validation. (in Japanese)[6] Nishikawa K, Yoshizuka M, Sakate M, Nonaka T (2006): Nonlinear seismic behaviors of a long-span suspension
bridge in major earthquakes. Journal of Structural Engineering, Vol.52A, 413-424. (in Japanese)[7] Ministry of Land, Infrastructure, Transport and Tourism: Strong-Motion Earthquake Records in Japanese Ports,
http://www.mlit.go.jp/kowan/kyosin/eq.htm [Accessed Feb. 28, 2020] (in Japanese)[8] Japan Road Association (2012): Specifications for Highway Bridges PartV Seismic Design (in Japanese)[9] Soda N, Yamada K, Kimizu T, Hirose T (2013): Performance test of natural rubber bearing ruptured according to
The 2011 off the Pacific coast of Tohoku Earthquake, Journal of Structural Engineering, Vol.59A, 516-526. (inJapanese)[10] Abe M, Yoshida J, Fujino Y, Morishige Y, Uno S, Usami S (2004): Experimental investigation of ultimate
behavior of metal bridge bearings under seismic loading, Journal of Japan Society of Civil Engineers, Issue773, 6378. (in Japanese)[11] Osaka Prefectural Government (2007): http://www.pref.osaka.lg.jp/kikikanri/keikaku_higaisoutei/index.html[Accessed Feb. 28, 2020] (in Japanese)[12] Cabinet Office Japan (2012): http://www.bousai.go.jp/jishin/nankai/model/ [Accessed Feb. 28, 2020] (in Japanese)

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17th World Conference on Earthquake Engineering, 17WCEE
Sendai, Japan - September 13th to 18th 2020[13] National Research Institute for Earthquake Science and Disaster Resilience (2017): Japan Seismic Hazard
Information Station, http://www.j-shis.bosai.go.jp/ [Accessed Feb. 28, 2020] (in Japanese)

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