Gutenberg Richter

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SIXTH FRAMEWORK PROGRAMME PRIORITY FP6-2002-INCO-MPC-1

“EARTHQUAKE PROTECTION OF HISTORICAL BUILDINGS BY REVERSIBLE MIXED TECHNOLOGIES”

Instrument: Specific Targeted Research Project Thematic Priority: FP6-2002-INCO-MPC-1 Start date of project: 1st October 2004 Duration: 36 months

Contribution of UTCB to the Workpackage 3

RISK ANALYSIS Date of preparation: August 5, 2005 Author(s): Dan Lungu, Cristian Arion, Radu Vacareanu Organisation: Technical University of Civil Engineering Bucharest,

Structural Safety & Natural Hazards Research Centre WP Leader: Organisation: Project coordinator: Federico M. Mazzolani Organisation: Department of Structural Analysis and Design,

University of Naples “Federico II”, Italy

Revision [draft]

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1. Seismic Hazard of Romania Seismic zones of Romania are given in the map of Figure 1 according to simplified original classification of Dr. Cornelius Radu.

Figure 1. Seismic zones of Romania end the epicenters of earthquakes during the period 984 - 2001

The map of maximum observed seismic intensities in Romania for a time interval ranging from 1091 to 1980 is presented in Figure 2. According the map, the maximum seismic intensity observed in Bucharest over almost one thousand years is VIII+.

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Figure 2. Map of maximum observed seismic intensities in Romania, 1091-1980

In Figure 3 is illustrated the present seismic zonation of Romania, Bulgaria, Ukraine and

Republic of Moldova. The general pattern of the map (which is based on deterministic macroseismic observations) as well as the content of the table describing the conversion of seismic intensity into ground acceleration are self-explanatory. They clearly suggest the need for harmonization of seismic macrozonation maps and prove the need for a joint zonation of the seismic hazard in the influence area of the Vrancea source. A NATO project with this subject is under way.

Figure 3. Macroseismic zonation for Vrancea source

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Figure 4. Present seismic zonation (2005) of Romania corresponding with MRI=50 yr. Two catalogues of earthquakes occurred on the territory of Romania were compiled,

more or less independently, by Radu (1974, 1980, 1995) and by Constantinescu & Marza (1980, 1995). The Radu’s catalogue is more complete, even the majority of significant events are also included in the Constantinescu & Marza catalogue. The magnitude in Radu catalogue is the Gutenberg-Richter magnitude, MGR (Gutenberg & Richter, 1954). Table 1. Radu Catalogue of major historical Vrancea earthquakes, I0 ≥ 9 (in Design of structures in seismic zones: Eurocode 8 - Worked examples, 1997)

Nr.

Date Time (GMT)

Intensity (max) Io

Magnitude MG-R MS

Radu’s source

h:m:s Radu Others Radu Others 1 1196 Feb 13 07: (8) 8-9 9/CM (6.7) 7.2 7.3/CM 7.0/KS RT, R 2 1230 May 10 07: (8-9) 9+ 8.5/CM (6.9)7.4 7.1/CM 7.1/KS RT, R, N3 1446 Oct 10 04: 8 8.5/CM 8-9/RT 6.7 7.3/CM 7.3/KS 6.9/RT RT, R 4 1471 Aug 29 10-11: (8) 9 9/CM 8-9 KS (6.9) 7.4 7.3/CM 7.1/KS RT, R 5 1516 Nov 8 12: 9 9/CM 8/KS 7.2 6.8/KS RT, R 6 1620 Nov 8 13-14: (8-9)9 9/CM 8/KS (6.9)7.2 7.3/CM 6.5/KS RT 7 1679 Ian29?/Aug 9 (8) 6 9/CM (6.7) 5.5 7.3/CM 6.8/KS RT 8 1681 Aug 18 (00)01: 9 8/CM (6.7)7.4 6.8/CM 6.8/KS RT 9 1738 May 31/ Jun 11 10-11: (8-9) 9 9.5/CM (6.9)7.4 7.5/CM 7.0/KS RT, R 10 1802 Oct 26 10:55 9 10/CM 7.5 7.7/CM 7.4/KS R 11 1838 Jan 23 18:45 8 9/CM 6.7 7.3/CM 6.9/KS R

Observations: (i) Abbreviations of Radu’s sources:R - Radu Catalogues, 1971 & 1974, RT - Radu & Torro Catalogue, 1986, N - Nikonov Catalogue, CM - Constantinescu & Marza Catalogue, 1980, KS - Kondorskaya & Shebalin Catalogue, 1977 (ii) Radu’s initial (1980) estimation of intensity and magnitude are given in parenthesis (...); (iii) Radu’s underlined values for I0 intensities denote the most probable value; (iv) I0 is maximum MSK-64 intensity.

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Table 2. Catalogue of major historical crustal (surface) earthquakes in Romania

IoIntensity (MSK)

MG-R

Mw Moment

Magnitude

Date Lat.

N°

Long.

E°

h Focus depth km Catalog C. Radu INFP, 2002

1550 Oct. 26 45.4 24.6 IX 7.2 1829 July 1 47.5 22.2 35 6.2

1879 Oct. 10 44.7 21.7 7 VIII 5.3 5.3 1901 Apr. 02 45.5 20.75 18 VII 5.0 5 1916 Jan. 26 45.4 24.6 21 VIII 6.4 1959 May 29 45.65 21.2 5 VII-VIII 5.0 5 1991 Jul. 12 45.38 21.05 11 VIII 5.7 5.6 1991 Jul. 18 44.90 22.35 12 VIII 5.6 5.6 1991 Dec. 02 45.45 21.12 9 VIII 5.6 5.5

The magnitude in Constantinescu & Marza catalogue was the surface magnitude, MS,

later tacitly assimilated as MGR (Marza, 1995). Example of Romanian earthquakes Catalogue for the most severe i.e. subcrustal Vrancea source in Romania and the most energetic century i.e. XX-century is given in Table 3. Table 3. Catalogue of subcrustal Vrancea earthquakes (Mw ≥ 6.3 ) occurred during the 20th century

RADU Catalogue, 1994

MARZA Catalogue,

1980

www.infp.roCatalogue,

1998

Date Time (GMT) h:m:s

Lat. N°

Long. E°

h, km I0 MGR Mw I0 Ms Mw

1903 13 Sept 08:02:7 45.7 26.6 >60 7 6.3 - 6.5 5.7 6.3 1904 6 Feb 02:49:00 45.7 26.6 75 6 5.7 - 6 6.3 6.6 1908 6 Oct 21:39:8 45.7 26.5 150 8 6.8 - 8 6.8 7.1 1912 25 May 18:01:7 45.7 27.2 80 7 6.0 - 7 6.4 6.7 1934 29 March 20:06:51 45.8 26.5 90 7 6.3 - 8 6.3 6.6 1939 5 Sept 06:02:00 45.9 26.7 120 6 5.3 - 6 6.1 6.2 1940 22 Oct 06:37:00 45.8 26.4 122 7 / 8 6.5 - 7 6.2 6.5 1940 10 Nov 01:39:07 45.8 26.7 1501) 9 7.4 - 9 7.4 7.7 1945 7 Sept 15:48:26 45.9 26.5 75 7 / 8 6.5 - 7.5 6.5 6.8 1945 9 Dec 06:08:45 45.7 26.8 80 7 6.0 - 7 6.2 6.5 1948 29 May 04:48:55 45.8 26.5 130 6 / 7 5.8 - 6.5 6.0 6.3 1977 4 March 2) 19:22:15 45.34 26.30 109 8 / 9 7.2 7.5 9 7.2 7.4 1986 30 Aug 21:28:37 45.53 26.47 133 8 7.0 7.2 - - 7.1 1990 30 May 10:40:06 45.82 26.90 91 8 6.7 7.0 - - 6.9 1990 31 May 00:17:49 45.83 26.89 79 7 6.1 6.4 - - 6.4 1) Demetrescu’s original (1941) estimation: 150Km; Radu’s initial estimation (1974) was 133 km 2) Main shock

The envelope of the peak ground acceleration (PGA, cm/s2) recorded in Romania during the last 3 strongest Vrancea earthquakes is interpolated in Figure 5. This clearly shows the directivity pattern (N45OE) of the subcrustal Vrancea sources activity.

http://www.infp.ro/

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21 22 23 24 25 26 27 28 29

48

47

46

45

44

Ukraine

Hungary Republic of Moldova

Yugoslavia

Bulgaria

BlackSea

Banat

Valahia

Moldova

Cris

Mures

Danube

Dobrogea

Prut

#

#

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#Satu-Mare

Craiova

Timisoara

Cluj-NapocaOradea

Bucuresti

Turnu Magurele Ruse

Iasi

Baia

Adjud

Peris

Bacau

Varna

Surduc

Barlad

Dochia

Onesti

Tulcea

Focsani

Istrita

Giurgiu

Otopeni

Pitesti

Kavarna

Campina

Branesti

Botosani

Chisinau

Calarasi

Carcaliu

Provadia

Cernavoda

Vrancioaia

Vidra Lotru

Krasnogorka

Muntele Rosu

Bolintin Vale

Vidraru Arges

TransilvaniaCahul

Shabla

Fetesti

Ramnicu Sarat1977

1986

1990

1940

86.6

79.197.2

45.8

14.3 26.1

11.5

50.9

82.0

90.8

36.2

48.2

32.9

93.6

33.6

61.5

297.1

109.4

186.9

157.2

208.6 150.8194.9

114.1

223.8

112.4112.2

132.0

168.6

136.6

212.8146.4

232.1

164.0

107.1100.4

158.6

#Constanta

Valenii de Munte

219.8

Ploiesti

Olt

#

100 0 100 200 Kilometers

ArcView GIS version 3.1, ESRI Inc. CA.

#· Epicenters of strong Vrancea events (Mw > 6.9)

Lungu, Aldea, 1999

N

EW

S

March 4, 1977

Mw=7.5h=109 km

Aug.30, 1986

May 30, 1990

Mw=7.2h=133 km

Mw=7.0h=91 km

Mw - moment magnitudeh - focus depth

200 - 300150 - 20075 - 1500 - 75

PGA, cm/s2

ROMANIA. Maximum peak ground acceleration PGA, cm/s2 recorded during 1977, 1986 and 1990 VRANCEA earthquakes

Seismic stations with free-field records:

& Bulgaria network

$ GEOTEC network&

# INCERC network% INFP network

R. of Moldova network

Figure 5. Maximum recorded peak ground acceleration during the last Vrancea strong events Based on the results of probabilistic seismic hazard assessment for Vrancea source (Lungu et al., 1995...2002) and taking into account the contributions from the crustal seismic sources around Romania, Figure 6 presents the proposed hazard map for the new code for design of earthquake resistant buildings in Romania, P100-2004. The map give the design peak ground acceleration, ag for the MRI=100 yr seismic event. In the case of Bucharest city for the MRI=475 yr seismic event ag is ≥0.35-0.4g as function of source depth, Table 4. Table 4. PGA in Bucharest

Maximum credible Vrancea magnitude Mw,max = 8.1

Focal depth, h, km 100 110 120 130 140 150

Mean recurrence interval, MRI, years 475

m 0.28 0.25 0.23 0.21 0.19 0.17 PGA, in g

m+1.0σ 0.46 0.42 0.38 0.34 0.31 0.28

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Bucharest MRI = 475 yr PGA≥ 0,35 g Tp = 1.6

Figure 6. Peak ground acceleration for design, ag for MRI=100 yr., P100-2004 code proposal

The response spectra in Figure 7 are recommended for Romania locations characterized by

various control period of response spectra: TC ≤ 0.7s, 0.7s < TC ≤ 1.0s, 1.0s<TC ≤ 1.6s during the MRI = 100 years Vrancea events.

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0

0.5

1

1.5

2

2.5

3

3.5

0 0.5 1 1.5 2 2.5 3 3.5 4oada T , s

There is an instrumental evidence, from both the 1977 earthquake and 1986 earthquake

that soil conditions in Bucharest are characterised by the long predominant period of ground vibration: Tg=1.4-1.6s. That Tg explains the long corner period of response spectra Tc=1.6s, in Figure 8. A tentative macrozonation of Tc in Romania territory, based on existing records is given in Figure 9.

Figure 8. INCERC seismic station in Eastern Bucharest. Normalised power spectral density for the NS comp. of the March 4, 1977 and August 30, 1986 earthquakes

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0 10 20 30Pulsatia ω, rad/s

Dens

itate

a s

40

la n

orm

atpe

ctra

aliz

a 4 Martie 1977, mp.NS 30 Aug. 1986, M=7.0, comp. NS

M=7.2, co

ωp =2 π/T p

INCERC Bucuresti

PSD

Peri

T B =0.07 T D =3

5.775/T 2

1.925/T

β 0 =2.75

T C =0.7s0

0.5

1

1.5

2

2.5

3

3.5

0 0.5 1 1.5 2 2.5 3 3.5 4Perioada T , s

T C =1.0s

2.75/T

β 0 =2.75

T B =0.1 T D =3

0.7s<Tc ≤ 1.0sξ =0.05 Tc ≤ 0.7s

ξ =0.05

8.25/T 2

0

0.5

1

1.5

2

2.5

3

3.5

0 0.5 1 1.5 2 2.5 3 3.5 4 T , sPerioada

TD =2

8.8/T 2

4.4/Tβ 0 =2.75

TB =0.16 T C =1.6s

1.0s<Tc ≤ 1.6s ξ= 0.05

Period T,s Period T,s

Figure 7. Normalised acceleration design spectra for various soil condition in Romania, P100-2004 code proposal

Period T,s

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Figure 9. Romania. Control period of response spectra, P100-2003

2. Vulnerable buildings in Romania

The major developments in four generations of seismic codes in Romania can be described as in Figure 10 when the history of overall seismic design coefficient, Cs for shear wall and frames structures in Bucharest is represented (1940-2002). The geometry of Cs is self explanatory.

One may note the gap of the Cs for flexible buildings and structures during the period 1963-1978.

However, even for rigid structures built during that period, the maximum Cs was about 2/3 of the present day Cs. It is emphasised that after the 1977 event, new ductility rules for RC structures were imported from US practice and incorporated into Romanian seismic codes, P100. According to the EUROCODE 8 requirements the rules were significantly improved after 1989.

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0.10.4

0.7

1

1.3

1.6

1.9

0

2

4

6

8

10

12

Seismicdesign

coefficient Cs , %

8-10

6-8

4-6

2-4

Year of code issue

Building period T , s

10 %8%

12.5 %10%

5 %

2.2%1.8%2%

Shear wallsFrames

0.3 s

1.5 s

Tc=1.5 s

19411945

199019921978

19811970

1963

7.5%7.5% 7.2%

6.8%

Tc=0.4 s

RIGID buildings

FLEXIBLE buildings

Ductile structures Non ductile buildings

Figure 10. Evolution of seismic design coefficient in Bucharest during period 1940-2003

Example of the vulnerable residential, hospital, schools, churches in important cities of Romania are given in the following:

Vulnerable residential buildings -from Ministry of Transports, Constructions and Tourism of Romania-

City

Number of vulnerable

buildings

Number of inhabitants

Bacau 6 208.643

Barlad 6 78.786

Braila 4 232.409

Brasov 8 312.481

Bucharest 123+ ... 2.011.305

Buzau 1 146.926

Campina 2 40.297

Iasi 49 347.606

Roman 1 81.731

Suceava 1 118.183

Targu-Mures 1 164.132 Vaslui 6 78.735

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Vulnerable school buildings -from Ministry of Education and Research of Romania-

Number of vulnerable schools

City Requiring technical

assessment

Having a technical

report

Having technical

documents

Total

Bacau 1 - - 1 Barlad 11 - - 11 Brasov 7 2 - 9 Bucharest 13 7 2 22 Constanta - - 1 1 Craiova 2 - 5 7 Galati 1 2 - 3 Giurgiu 2 - - 2 Iasi 3 5 - 8 Pitesti - 1 1 2 Ploiesti 1 5 - 6 Sibiu 3 1 - 4 Vaslui 10 - - 10 Total 54 23 9 86

Vulnerable hospital buildings

-from Ministry of Health and Family of Romania-

Number of vulnerable hospitals

CITY Severely damaged. Requiring immediate technical assessment

Having a technical report

Approved project for retrofitting

Retrofitting in work

Total

Bacau 3 3 Barlad 2 2 Bucharest 13 16 6 10 45 Buzau 9 9 Constanta 7 7 Craiova 4 4 Focsani 2 2 Galati 6 2 1 9 Giurgiu 1 1 Iasi 21 17 2 5 45 Pitesti 2 7 9 Ploiesti 2 2 Sibiu 1 1 Targu-Mures 2 2 Vaslui 4 1 5

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Vulnerable buildings belonging to the cultural heritage Examples

Orthodox Churches damaged after major historical earthquakes in Bucharest

No. Name Address 1802 1838 1940 1977

1 Manastirea

Plumbuita, “de la Podul Colentinei”

Str. Plumbuita 58 severe

2 Manastirea Marcuta Str. Gentianei din Sos. Pantelimon severe

3 Doamnei (fosta manastire)

Intr. Bis. Doamnei 3, Calea Victoriei 28 medium

4 Sf. Gheorghe-Nou Bd. Bratianu 27 medium

5 Manastirea Antim Str. Mitropolitul Antim Ivireanu 29 light

6 Sf. Elefterie-Vechi Str. Sf. Elefterie 15C medium medium 7 Oborul-Vechi Str. Traian 204 medium medium 8 Sf. Pantelimon Str. Iancu Capitanu 24 severe 9 Popa Rusu Str. Popa Rusu 13-17 medium

10 Precupetii Noi Str. G-ral Ernest Brosteanu 12 medium

11 Doamna Ghica-Tei Str. Doamna Ghica 2 medium

12 Manastirea Sf. Spiridon-Nou Calea Serban Voda 29 medium

13 Sf, Nicolae Tabacu Calea Victoriei 180 medium medium

14 Sf. Nicolae-Selari Str. Blanari 16 / Intr. Selari collapse

15 Sf. Mina (Vergului) Str. C. F. Robescu 18A medium

16 Herastrau-Sfintii Apostoli Petru si

Pavel

Str. Nicolae Caranfil 28 medium

17 Dobroteasa Bd. Mircea – Voda 35B medium

18 Amzei Str. Biserica Amzei 12 light medium

19 Biserica si Scoala Sf. Silvestru Str. Silvestru 36 medium

20 Boteanu (cu Bradu) Str. Boteanu 8 medium severe

21 Popa Nan Str. Popa Nan 47 bis si Str. Gh. Costa-Foru 5 severe severe

22 Sfantul Apostol Andrei-Chitila II Sos. Chitilei 138 severe

23 Aparatorii Patriei II Str. Lunca Barzesti 3 medium

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51

6

2024

10 912

0

10

20

30

40

50

60

1550 1600 1650 1700 1750 1800 1850 1900 1950 2000

Bucharest Cultural heritage orthodox churches

Figure 11. Distribution by age of churches listed as cultural heritage

(Data source: National Institute of Historical Monuments Bucharest, 2004) The 87 churches from Bucharest listed by the Romanian Ministry of Culture as historic monuments (Source: National Institute of Historical Monuments Bucharest, 2004) are represented in Figure 11.

2 4

1620

16

29

4750

0

10

20

30

40

50

60

1550 1600 1650 1700 1750 1800 1850 1900 1950 2000

Bucharest All orthodox churches

Figure 12. Distribution by age of all orthodox churches

(Data source: Atlas Guide of religious buildings in Bucharest, Vol 1, 2, 3, 1999)

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3. Fragility functions for representative building types Table 5 lists the several typical modern model building in contemporary Romania. Table 5. Model building types in Romania

Height No. Label Description Range Typical Name Stories Stories Meters 1 2

RC1M RC1H

Concrete Moment Frame Mid-Rise High-Rise

4 - 7 8+

6 10

17.1 28.5

3 4

RC2M RC2H

Concrete Shear Walls Mid-Rise High-Rise

4 - 7 8+

6 10

17.1 28.5

The building capacity curve (also known as a push-over curve) is a plot of a building

lateral load resistance as a function of a characteristic lateral displacement (i.e., a force-deflection plot). It is derived from a plot of static-equivalent base shear versus building (e.g., roof) displacement. In order to facilitate direct comparison with earthquake demand (i.e. overlaying the capacity curve with a response spectrum), the force (base shear) axis is converted to spectral acceleration and the displacement axis is converted to spectral displacement.

The three control points that define model building capacity in Figure 13 are related to: • Design capacity • Yield capacity • Ultimate capacity

Sa

SdDy DuDd

Au

Ay

Ad

UltimateCapacity

YieldCapacity

DesignCapacity

Figure 13. Example Building Capacity Curve, HAZUS

The classification suggested by Park, Ang & Wen was adapted for the damage states, Table 6.

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Table 6. Range of damage index Damage state DI ≤ 0.1 None 0.1 < DI ≤ 0.25 Slight 0.20 < DI ≤ 0.40 Moderate 0.40 < DI < 1.00 Extensive DI ≥ 1.00 Complete

In RISK-UE project, example of building fragility curves for Slight, Moderate, Extensive and Complete structural damage states for above typical building types were computed. Example results are indicated in Figure 14, Figure 15 and Figure 16.

0.00

0.05

0.10

0.15

0.20

0.25

1941-1962 1963-1969 1970-1977 1978-1989 1989-2002

Seismic code period

Ay, '

g

RC1HRC2H

Figure 14. Yielding acceleration, Ay according to seismic code period

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0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

1941-1962 1963-1969 1970-1977 1978-1989 1989-2002

Seismic code period

Au, '

g

RC1HRC2H

Figure 15. Ultimate acceleration, Au according to seismic code period

RC1H, 1990-2002

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 10 20 30 40 5

SD , cm

P(>d

s|SD

)

0

Slight Moderate ExtensiveComplete

Figure 16. Fragility Curves for Slight, Moderate, Extensive and Complete Damage

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References JICA Technical Cooperation Project "Reduction of Seismic Risk for Buildings and Structures" with Romania, 2002-

2007, Ref.#7241011E0 P100-2004, draft code for design of earthquake resistant buildings in Romania. Vrancea Earthquakes. Tectonics, Hazard and Risk Mitigation, 1999. Contributions from the First International

Workshop on Vrancea Earthquakes, Bucharest, Romania, Nov.1-4, 1997, Wenzel, F., Lungu, D., Editors, Kluwer Academic Publishers, 374 p.

Arion, C., 2003. “Seismic Zonation of Romania considering the soil condition and seismic sources”. PhD Thesis UTCB, Bucharest, 181p.

Lungu D., Arion, C., Aldea A., “Seismic protection of the cultural heritage buildings“, oral presentation at The VIIth National Conference for protection of cultural heritage patrimony, Bucharest, March 31– April 2 2005.

Lungu D., Aldea A., Arion, C., Demetriu S.,Cornea T., 2000. Microzonage Sismique de la ville de Bucarest - Roumanie, Cahier Technique de l’Association Française du Génie Parasismique, No.20, p.31-63

Lungu, D., Cornea, T., Aldea, A., Zaicenco, A., (1997). Basic representation of seismic action. In: Design of structures in seismic zones: Eurocode 8 - Worked examples. TEMPUS PHARE CM Project 01198: Implementing of structural Eurocodes in Romanian civil engineering standards. Edited by D.Lungu, F.Mazzolani and S.Savidis.Bridgeman Ltd., Timisoara, p.1-60.

Radu, C. manuscripts, (1994). Catalogues of earthquakes occurred on Romanian territory during the periods 984-1990 and 1901-1994.

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