Seismic Vulnerability of lifelines

doi:10.21203/rs.3.rs-2082022/v1

The North of Algeria is located in a seismic zone, then earthquakes are probably the most likely natural disaster that would lead to major lifeline disruption. The adequate operation of lifelines is vital for the economic development of regions under moderate to high seismic activity. After an earthquake, the proper operation of all vital systems is necessary, for instance hospitals for medical attention of the wounded and highways for communication and assistance for victims.

In this work we apply the knowledge of pipeline vulnerability to the water supply system, and sanitary sewer pipelines (waste water), in Constantine city (Algeria).

Lifeline

Earthquake

vulnerability

Pipelines

Seismic vulnerability is a measurement of a structure’s seismic endurance, the vulnerability–damage ratio allowing to estimate the damage suffered by the structure as a result of a ground movement.

When seismic risk and potential damage are known, it is possible to calculate the seismic hazard. The seismic hazard is defined as the level of damage multiplied by the losses in structural systems. There are three ways to mitigate seismic hazard: decreasing seismic risk, decreasing vulnerability or decreasing the level of losses.

In order to estimate the vulnerability of lifelines and identify the systems of a region, it is necessary to measure the size and distribution of structures. Additionally, these kinds of studies enable to determine the steps to follow in order to reduce seismic hazards.

Despite the advancement in Seismic Engineering, technology, and new materials, in recent earthquakes (Loma Prieta, 1989; Northridge, 1994; and Kobe, 1995) the interruption in roads, communications and otherlifelines wasthe main cause of injuries, traffic problems, and breaks inenergy systems. The Northridge earthquake has been the most important one in terms of economic losses, mainly due to the interruption in the communication and transportation systems.

In this work, the main objective is to determine the seismic hazard for lifelines in Constantine city.

The estimation of lifeline seismic vulnerability is obtained by calculating direct damage and economic losses, using the following procedures: (1) calculation of seismic risk by estimation of seismic movements, (2) inventory of damage data for each system, and (3) determination of vulnerability curves as a function of seismic intensity.

The survival of lifelines depends on their behavior during the ground movement; generally, this behavior is characterized by means of empirical data. The studies of the response of lifeline systems during earthquakes, as well as the calculation of their behavior, are based on their structural characteristics. Therefore, the studies on lifelines vulnerability are based on experimental data rather than on theoretical studies.

Several works [1-2]describe the determination of the direct damage produced by an earthquake according to the following steps:

For all seismic scenarios it is necessary to calculate the intensity for each mesh cell within the region.
Designation of the magnitude and determination of special zones (as faults or distinct kind of soils) for each model.
Calculation of damages for each cell in the system and development of the damage curve.
Determination of direct damage due to the earthquake and collateral causes.

The MSK scale used to assess the intensity of an earthquake by observing the damage to buildings and the testimony of people. The MKS intensity (I) of the ground motion in the study area is evaluated at I=9.27.

This method is very simple, as the above equationsestimate the break rate of a pipeline rate of a pipelinewithout considering relevant pipe characteristics. It can beused when there is no detailed pipeline informationavailable and a very rough assessment of the loss is needed.[3]

$$\text{ log}Y=1.837\left(I\right)-14.065 Poor soil condition$$

$$\text{log}Y=1.717 \left(I\right)-14.221 Average soil condition$$

$$\text{ log}Y=1.522\left(I\right)-14.045 Good soil condition$$

Y

is the number of breaks/km of lifeline.

I

is the MKS intensity of the ground motion at the section being evaluated.

The following results were obtained applying Wang‘s model (Wang et al., 1991) to Constantine lifelines for correspond soil type.

5.1. Results

Table 1

Results for water pipelines
Intensity	breaks/km	Length (km)	Wang et al (Total)
1	0.00	631	0.00
2	0.00		0.00
3	0.00		0.00
4	0.00		0.00
5	0.00		0.00
6	0.00		0.00
7	0.11		69
8	0.62		391
9.27	5.45		3440
10	19.08		12044
11	106.27		67083
12	591.70		373510

Table 2

Results for sewage pipelines
Intensity	breaks/km	Length (km)	Wang et al (Total)
1	0.00	34	0.00
2	0.00		0.00
3	0.00		0.00
4	0.00		0.00
5	0.00		0.00
6	0.00		0.00
7	0.11		3.75
8	0.62		21.14
9.27	5.45		185.89
10	19.08		650.81
11	106.27		3624.86
12	591.70		20182

The break rate of an underground pipeline extending through a liquefaction area differs depending upon the pipe material according to Eguchi’s study:[5]

Y = 1.5 material is Asbestos Cement (AC)

Y = 1.0 material is Cast Iron (CI)

Y = 0.8 material is Welded steel with Caulked joints(WSCJ)

Y = 0.7 material is welded steel with Gas-welded joints (WSGWJ)

Y = 0.1 material is Welded steel with Arc-welded joints

(WSAWJ)

Where Y is break/1000 feet.

6.1. Results

The following tables show the result of the damages in the lifelines (water and sewage).

Table 3

Results for water pipelines (asbestos cement)
Asbestos cement
Diameter (mm)	80	100	125	150	200	250
Length ( km)	3,06	4,61	0,3	10,41	1,19	4,17
Break/Km			4.92

Table 4

Results for water pipelines (cast ductile steel)
Cast ductile steel
Diameter (mm)			40	60		80		100		125
Length ( km)			/	0,06		15,32		96,73		2,12
Break/Km						3.28
150	175	200			250		300		350		400
68,355	2,2	32,15			18,25		26,38		9,62		12,21
Break/Km					3.28

Table 5. Results for water pipelines (cast steel gray)

Cast steel gray
Diameter (mm)	40	60	80	100	125
Length ( km)	0,45	1,55	13,63	12,83	1,64
Break/Km		3.28

150	175	200	250	300	350	400	800
6	1,71	6,3	5,273	1,8	0,92	0,73	0,33
			3.28

Table 6. Results for sewage pipelines (cement)

Cement	ColA	Col B	ColC	Col D North			ColD	Col E East	Col E –South-	Collector F	Collector G
Diameter (mm)	300	1000	800		1000	1600		600-1000	1200-1600	400-1000-1600	2000
Length ( km)	1.6	4.1	1.5	2.6			1.8	8.0	5.7	4.9	3.6
Break/Km				4.92

Kubo-Katayama proposed in 1975, the following empirical method to estimate the seismic loss of buried pipeline system in reference to the conditions of damage to pipelines by the earthquake in San Fernando (USA, 1971). [6]

Rfm = Rf * Cg * Cp * Cd

Rfm : Report damage (is the number of breaks/km of lifeline)

Rf: Report standard damage (breaks/km).

Rf = 1,7 * A^6.1 * 10^− 16 ---------- (maximum Rf = 2,0)

A: Pic ground acceleration (gal)

Cg : Modification coefficient

Cp: Modification coefficient of pipe material

Cd: Modification coefficient of pipe diameter

Table 7

Modification Coefficient «Cg»
Soil Type	P_L	C_g
Hard Soil	-	0,50
FirmSoil	P_L=0	1,00
Soft Soil	0 < P_L≤5	2,00
	5 < P_L≤15	2,90
	15 < P_L	4,70

Table 8

Coefficient (Cp * Cd)
Diameter Pipe Material Pipe	Ø ≤ 75 mm	75mm < Ø ≤ 150mm	150mm< Ø ≤250mm	250mm< Ø ≤450mm	450mm< Ø ≤ 1 000mm
asbestos cement	6,40	3,40	2,40	2,00	1,40	0,60
galvanized steel	2,70	1,70	1,10	1,00	0,90	0,40
concrete	2,00	1,50	0,90	0,50	0,40	0,20
precast concrete	0,13	0,10	0,07	0,05	0,03	0,02
Cast steel	1,70	1,30	1,00	0,60	0,40	0,20
Cast ductile steel	0,70	0,40	0,20	0,10	0,08	0,05
Cast steel gray	4,60	2,60	1,80	1,50	1,20	0,50
polyethylene	0,20	0,15	0,10	0,07	0,04	0,02
PVC pipe	2,10	1,40	1,00	0,80	0,60	0,30

7.1. Results

Table 9

Results for water pipelines[7]
Intensity	Average breaks/km	Length (km)	Kubo-Katayama (Total break)
9.27	2.68	631	1691

Table 10

Results for sewage pipelines[7]
Intensity	Average breaks/km	Length (km)	Kubo-Katayama (Total break)
9.27	0.68	34	23

Table 11

Results for water pipelines
Method	Wang et al	Eguchi	Kubo-Katayama
break/km	5.45	3.28/4.92	2.68

Table 12

Results for sewage pipelines
Method	Wang et al	Eguchi	Kubo-Katayama
break/km	5.45	4.92	0.68

Comparisons of results obtained in this work are summarized in Tables 11 and 12. The results of the three methods are comparable despite the fact that they are based on the (03) different approaches.

The vulnerability of lifelines is a problem for which research has been conducted to try to quantify and predict the disorders that may occur in case of earthquake. The reliability of the estimate of damage to lifelines depends on the method used.

In this work, we made a comparison between three methods. The first method is that developed by “Eguchi” which is based on an empirical approach to estimate the damage by used of parameters such as: materials and soil type, While the second approach «Model proposed by Wang et al» is very simple, It can be used when there is no detailed pipeline information available and a very rough assessment of the loss is needed.

The third method is that developed by Kubo-Katayama, which is based on an empirical approach to estimate the damage by used of several parameters such as: materials, diameters, and soil type.

Comparisons of results obtained in this work are summarized in Tables 11 and 12. The results of the Eguchi and Wang methods are comparable despite the fact that they are based on two different approaches. But the results depends essentially different characteristics surrounding and intrinsic of these networks (soil and material used).Thus, the results by the methods of Eguchi and Kubo-Katayamathat uses the characteristic of networks are more reliable and more or less reflects the reality.

Although the use of the method of Wang et al is indispensable an emergency and the absence of precise information networks for rapid decision support.

ATC-13 (Applied Technology Council), Earthquake damage evaluation data for California, Redwood City (1985), CA, Report ATC-13
ATC-25 (Applied Technology Council), Seismic vulnerability and impact of disruption of lifelines in the coterminous United States,Redwood City (1991), CA, Report ATC-25
Wang LRL, Wang JCC, Ishibashi I. GIS applications in seismic loss estimation model for Portland (1991), Oregon water and sewer systems. US Geological Survey. Open File Report
Boukri M, Farsi M.N, Mebarki A, Belazougui M, Amellal O, Mezazigh B , Guessoum N, Bourenane H, Benhamouche A (2014),“Seismic Risk and Damage Prediction: Case of the Buildings in Constantine City (Algeria)”, Bulletin of Earthquake Engineering, February 2014, Volume12, No.1
Eguchi R T. Seismic Component Vulnerability Models for Lifeline risk Analysis. J. Wiggins Co. Technical Report No. 82-1396-22; 1983.
Katayama, T., Kubo, K., Sato, N. (1975). “Earthquake damage to water and gas distribution systems. Proc. U.S National Conference on Earthquake Engineering”, 18-20 June, Ann Arbor, USA
CGS (2012), (National Earthquake Engineering Research Centre –Algeria-), Vulnerability and Seismic Risk Assessment Study of Constantine City Report, Algeria

No competing interests reported.

Seismic Vulnerability of lifelines

Status:

Version 1

Abstract

Figures

1. Introduction

2. Estimation Of Lifelines Seismic Vulnerability

3. Analytical Approach To Estimate Damage

4. The Mks Intensity Scale

5. Method Proposed By Wang Et Al

5.1. Results

6. Method Proposed By Eguchi

6.1. Results

7. Method Proposed By Kubo-katayama

7.1. Results

8. Comparison Of Results

9. Conclusion

References

Additional Declarations

Status:

Version 1