6th International Disaster and Risk Conference IDRC 2016 Integrative Risk Management - Towards Resilient Cities. 28 August - 01 September 2016 in Davos, Switzerland

1. 6th International Disaster and Risk Conference IDRC Davos 2016

2. SEISMIC RISKSEISMIC RISK
Seismic risk created due to seismic hazard and
vulnerability of the structural city elements.
Seismic Hazard is a natural phenomenon that has
potential to cause destruction.
Vulnerability is the inability to resist a hazard or to
Therefore: respond risk= Seismic Hazard x Vulnerability
Seismic risk is the probability of harm to human life
and physical elements.
Therefore Seismic Risk has the following FACTORS:
(i)-HAZARD
(ii)-VULNERABILITY

3. Location of Tehran: Alborz mountains, which
form part of the Alps-Himalayan zone.
High seismic historical seismic data: Several
strong earthquakes with return periods of about
180 years.
The features of the main active faults in the
megacity of Tehran can be summarized as
follows:
•Mosha Fault
•North Tehran Fault
•South and North Ray Faults
TEHRAN MEGACITY MICROZONATIONTEHRAN MEGACITY MICROZONATION

4. In 2011, Shakib et al., proposed seismic risk reduction
program for the megacity of Tehran. The program
consisted of the assessment of seismic hazard,
vulnerability, and risk for a mitigation plan of the new
and existing urban elements. It also, included a public
training program aimed at facilitating the involvement
of the community and to promote their alertness and
awareness by participating in various earthquake
preparedness activities
H. Shakib; S. Dardaei Joghan; and M. Pirizadeh
“Proposed Seismic Risk Reduction Program for the Megacity of Tehran, Iran, "Natural Hazards
Review, Vol. 12, No. 3, August 1, 2011. ASCE

6. In 2012, Shakib, and Dardaei, Proposed seismic risk
reduction program for lifelines in the megacity of
Tehran. In this study, a master plan of a seismic risk
reduction program for lifelines of the city was
presented. They evaluated each system to identify its
vulnerability for life safety and service disruption and
established priorities for risk reduction strategies, to
mitigate the vulnerabilities. They also, proposed a
“lifelines council” to provide a mechanism for
managing the program. They mentioned that the
program needed a comprehensive planning in order to
clarify the details of action plan of the program.
H. Shakib; S. Dardaei Joghan
“Proposed Seismic Risk Reduction Program for lifelines in the Megacity of Tehran”, 4th
International Disaster and Risk Conference IDRC Davos 2012.

8. Literature on the subject
 Aryman-1981
Seismic behavior of buried pipelines; relative displacement
between pipe and soil; less Inertia force
 O'Rourke-1990
Wave propagation and permanent deformation of ground
 Hindy and Novak-1979
Maximum stress created when pipe subjects to axial excitation

9. 0.12cr
t
D
ε = 0.4 0.8cr
t t
D D
ε< <

10. Buckling of buried pipelines
Beam shape buckling for low buried pipe
Mitsoia et al.,-2007
With increase of diameter critical strain
increases also,
1
1
0.2
2
0.2
4 n n
cr n
KDI n
A
ε
ε
σ
 
 ÷
+  
=  ÷
 

11. In 2016 Shakib and Jahangiri were investigated the efficiency
and sufficiency of some IMs for evaluating the seismic
response of buried steel pipelines. Six buried pipe models with
different diameter to thickness and burial depth to diameter
ratios, and different soil properties were subjected to an
ensemble of 30 far-field earthquake ground motion records.
Pipes were modeled using shell elements while equivalent
springs and dashpots were used for modeling the soil. Several
ground motion intensity measures were used to investigate
their efficiency and sufficiency in assessing the seismic
demand and capacity of the buried steel pipelines in terms of
engineering demand parameter measured by the peak axial
compressive strain at the critical section of the pipe.
H. Shakib; V.Jahangiri
“Intensity measures for the assessment of the seismic response of buried steel pipelines“,
Bulletin of Earthquake Engineering, April 2016, Volume 14, Issue 4, pp 1265–1284

12. PIPE AND SOIL MODELLING
Nonlinear soil springs
The finite element method is used for the modeling and
nonlinear dynamic analysis of the investigated buried
pipelines. The pipe is modeled using shell elements that are
well-suited for large rotation and large strain nonlinear
applications. The surrounding soil is modeled using bilinear
spring elements in axial, transverse and vertical directions, as
illustrated in Fig. below and equivalent dashpots in
aforementioned directions as representation of soil damping.
Assumed
stress-
strain
relation of
the steel
pipe
material

13. These spring elements represent soil stiffness based on
suggestions of the American Lifeline Alliance (2001).
Schematic representation of pipe-soil system and
boundary condition are illustrated in the Fig.
Schematic representation of the buried pipeline model

14. Candidate Intensity MeasuresCandidate Intensity Measures

15. EarthquakeEarthquake
RecordsRecords
Vs (m/s) PGA(g) R(km) Magnitude Event No.
213.4 0.13 46 6.8 Borrego Mtn, 1968 (117 El Centro Array #9) 1
274.5 0.09 33.4 6.5 Friuli, 1976 (Codroipo) 2
274.5 0.35 22 6.53 Imperial Valley, 1979 ( Delta) 3
256 0.08 21.4 6.9 Kobe,1995 (OSAJ) 4
312 0.34 22.5 6.9 Kobe,1995 (Kakogawa) 5
274.5 0.13 30.7 7.51 Kocaeli, 1990 (Iznik) 6
271.4 0.14 69.2 7.28 Landers, 1992 (Amboy) 7
207.5 0.09 36.1 7.28 Landers, 1992 (Palm Springs Airport) 8
370.8 0.04 96 7.28 Landers, 1992 (Riverside Airport) 9
271.1 0.17 52.7 6.93 Loma Prieta, 1989 (APEEL 2E Hayward Muir Sch) 10
198.7 0.25 77 6.93 Loma Prieta, 1989 (Emeryville - 6363 Christie) 11
209.9 0.21 30.8 6.93 Loma Prieta, 1989 (Palo Alto - 1900 Embarc.) 12
295 0.17 20.8 6.93 Loma prieta,1989 (Coyote Lake Dam (Downst)) 13
316.5 0.21 22.8 6.61 San Fernando, 1971 (LA - Hollywood Stor FF) 14
274.5 0.2 24 6.77 Spitak, 1988 (Gukasian) 15
338.5 0.07 33.1 6.36 Coalinga, 1983 (Parkfield - Gold Hill 2E) 16
345.4 0.127 63 7.28 Landers,1992 (Fort Irwin) 17
249.9 0.13906 22 6.53 Imperial Valley, 1979 (El Centro Array #13) 18
354.4 0.11889 89.7 7.28 Landers,1992 (Boron Fire Station) 19
281.6 0.13409 30.5 6.93 Loma prieta,1989 (Halls Valley) 20
308.9 0.13681 32.2 6.36 Coalinga, 1983 (Parkfield - Vineyard Cany 3W) 21
336.5 0.12805 50.1 6.53 Imperial Valley, 1979 (Coachella Canal #4 ) 22
284.8 0.19158 39.9 6.93 Loma Prieta, 1989 (Fremont - Emerson Court ) 23
190.1 0.32929 58.7 6.93 Loma Prieta, 1989 (SF Intern. Airport ) 24
236.6 0.14652 48.7 6.36 Coalinga, 1983 (Parkfield - Cholame 5W) 25
352 0.06851 80.4 6.5 Friuli, 1976 (Conegliano) 26
356.4 0.05268 46.3 6.9 Irpinia, 1980 (Bo0vino) 27
302 0.03853 96.8 6.61 San Fernando, 1971 ( Colton - So Cal Edison) 28
205.8 0.24693 28.3 6.7 Superstitn Hills(B), 1987, 5061 Calipatria Fire Station 29
259.6 0.10134 39.3 6.33 Victoria, 1980 (SAHOP Casa Flores) 30

16. Initial soil stiffness per unit length of the pipe and theInitial soil stiffness per unit length of the pipe and the
displacement at maximum soil forcedisplacement at maximum soil force
Model Initial soil stiffness per unit length of the pipe (N/mm2(
Displacement at maximum soil force per unit length of pipe
(mm(
Axial direction
Transverse
direction
vertical direction Axial direction Transverse
direction
vertical direction
Uplift
Bearing
Uplift Bearing
M1 12.24 107.79 43.09 234.29 5 53.4 35.6 35.6
M2 17.47 136.22 43.09 346.25 5 76.2 38.6 50.8
M3 26.94 130.32 40.91 1583.9 3 72.2 15 61
M4 49.78 101.72 88 90.76 10 52.1 81.2 81.2
M5 95.57 234.06 269.92 201.16 9 63.5 101.6 101.6
M6 133.28 375.7 300 330.86 8 61 122 122

17. In brief, based on the investigated models, it can be
concluded that for pipes buried in soils with initial
axial stiffness less than 50 N/mm2 per unit length of
the pipe, followed by RMSd are the
optimal IMs in terms of both efficiency and
sufficiency. For pipes buried in soils with initial axial
stiffness higher than 95N/mm2 per unit length of the
pipe the only sufficient and efficient IM is
Sufficiency of with respect to
magnitude and distance for M1
Comparison of EDP-IM plots for M6

18. Eagle
eyes
view of
Tehran

19. Main steps in the probabilistic Hazard analysis
1-Seismic source characteristics 2-Return period of each source
3-Effects of earthquake on the site 4-Determination of the Hazard of the site

20. Design EarthquakeDesign Earthquake

21. Earthquake RecordsEarthquake Records
Earthquake Station Data Source Record/Component PGA (g( PGV (cm/s( PGD (cm(
Chi-Chi, Taiwan 1999/09/20 TCU046 CWB CHICHI/TCU046-W 0.133 39.8 37.37
Northridge 1994/01/17 127 Lake Hughes #9 USGS NORTHR/L09090 0.217 10.1 2.77
WhittierNarrow
1987/10/01
24399 Mt Wilson - CIT Seis
Sta
CDMG WHITTIER/A-MTW090 0.186 4.6 0.21
Friuli, Italy 1976/05/06 20:0 8012 Tolmezzo FRIULI/A-TMZ000 0.351 22.0 4.1
Loma Prieta 1989/10/18 47379 Gilroy Array #1 CDMG LOMAP/G01090 0.473 33.9 8.03
Palm Spring 1986/07/08 Whitewater Trout Farm USGS PalmWhite//W09090 0.186 4.6 0.21
Tabas, Iran 1978/09/16 73 Sedeh TABAS/SED-T1 0.027 4.1 4.91

22. Pipeline Modeling

24. Verification

25. V
e
r
i
f
i
c
a
t
i
o
n
Lanzano-2014
Diametrer-1 m
Thickness-8 mm
European
standard

26. Effect of Pipe Diameter
Pipe dia
1.0 m
1.5 m
2.0 m
)kg)Shear force
)Kg.cm)Bending
Moment
Effect of Dia
446 9951 1m dia 1
560 13160 1.5dia 2
666 14286 2.0dia 3

27. Effect of Pipe Buried Depth
Buried Depth
2.0 m
4.0 m
6.0 m
)kg)Shear force
)Kg.cm)Bending
Moment
Effect of Depth
455 4180 2.0 1
446 9951 4.0 2
432 3722 6.0 3

28. Effect of Pipe Thickness
pipe thick
10 mm
20 mm
30 mm
)kg)Shear force
)Kg.cm)Bending
Moment
Effect of
Thickness
446 9951 10mm 1
1129 26176 20mm 2
1456 31275 30mm 3

29. Effect of soil type
Soil type
100 m/s
300 m/s
600 m/s
)kg)Shear force
)Kg.cm)Bending
Moment
Soil type
446 9951 100m/s 1
393 5537 300m/s 2
261 2821 600m/s 3

30. Conclusion
1- The force on a buried pipe increases as the diameter
of the pipe increases. The rate of this increase is not
linear with the increase of the buried pipe’s diameter.
2- The force on the buried pipe decreases as the buried
depth of the pipe increases.
3- As the thickness of the pipe increases the force on
the buried pipe also increases.
4- The capacity of the pipe is highly dependent on its
thickness. That is, as the thickness of the pipe
increases the damage to it considerably decreases.

31. THANKTHANK
YOUYOU

32. AbstractAbstract
As a natural disaster, earthquake phenomenon carries enormous physical and
emotional costs on human societies yearly. Therefore it needs to receive special
attention and research. So far many researchers and decision makers have tried to
address this subject in order to predict its harmful consequences, propose appropriate
solutions, facilitate its management, and reduce its destructive impacts. Seismic risk
reduction necessitates comprehension and control of two factors; namely, seismic
hazard and vulnerability. A region of Tehran mega-city was chosen to assess the
seismic risk level considering these factors. This is done through providing the existing
conditions of buried pipelines. Plane strain sections of buried pipelines are selected for
the purpose of the study. Seven earthquake records related to the region were chosen
based on the mechanism of the fault, soil type and the distance between the site
location and the selected fault. The earthquake records were scaled according to the
results of the seismic hazard analysis, and the design spectra were proposed. On the
other hand, the periods of the buried pipelines and surrounding soil system were
evaluated through free vibration analyses. Then, the time history analyses of pipe-soil
system subjected to the earthquake records were carried out. Eventually, the pipeline
section stress under the effect of axial, shear and bending forces for three types of
pipelines with different diameters under ensemble earthquake records were calculated
and compared with the capacity stress. As a result, the level of the seismic risk of the
buried pipelines was drawn. With this in mind, some solutions were presented to
decrease the seismic risk of buried pipelines for urban areas.
Keyword: Seismic Risk Assessment, Buried Pipelines, City Regions
.