Post on 08-Jan-2023
SEISMIC STRENGTHENING OF BUILDINGS AND SEISMIC INSTRUMENTATION -TWO PRIORITIES FOR SEISMIC RISK
REDUCTION IN ROMANIA
D. Lungu1,2 , A. Aldea2, S. Demetriu2 and I. Craifaleanu1
Abstract
According to the number of people lost in earthquakes during XXth century as well as in a single (March 4, 1977) earthquake during this century (1574 people, including 1424 in Bucharest), Romania can be ranked the 3rd country in Europe, after Italy and Turkey. Romania is followed by the former Yugoslavia and by the Greece (Bolt, 1995, Coburn and Spence, 1992).
The World Bank loss estimation after the 1977 earthquake (Report No.P-2240-RO, 1978) indicates that from the total loss (2.05 Billion US $) more than 2/3 was in Bucharest, where 32 tall buildings collapsed. Half of the total loss was accumulated from buildings damage. The 1977 direct loss and indirect consequences of loss mark probably the starting point of economical decay of Romania during the next decade. They also explain the present concern of civil engineers and Romanian Government for assessment and reduction of seismic risk in Romania.
The World Map of Natural Hazards prepared by the Münich Re, 1998 indicates for Bucharest: “Large city with Mexico-city effect”. The map focuses the dangerous phenomenon of long (1.6s) predominant period of soil vibration in Bucharest during strong Carpathians Vrancea earthquakes. The Bucharest and Lisbon are the only two European cities falling into Mexico-city category.
International experts and organizations agreed that Bucharest is the capital city in Europe characterised by the highest seismic risk. The paper presents: Part I, Vrancea Seismic Hazard Assessment in Romania, 1.1 Subcrustal Seismicity of the Vrancea Region; 1.2 Codes and standards for design of earthquake resistance of structures
1 National Institute for Building Research, Bucharest, Tel.: 0040.21.255.02.70, Fax: 0040.21.255.00.62, E-mail: lungud@cons.incerc.ro; lungud@incerc2004.ro 2 Technical University of Civil Engineering, Bucharest. Tel.: 0040.21.242.58.04, E-mail: lungud@mail.utcb.ro
(1940 – 2000); 1.3 Seismic hazard assessment in the draft P 100 2003 seismic code of Romania. Part II, Seismic Risk Management, 2.1 The structure of the existing building stock in Bucharest; 2.2 Fragile residential buildings in Bucharest.
Part I: Vrancea seismic hazard assessment in Romania
1.1 Subcrustal seismicity of the Vrancea region of Romania
The Vrancea region, located where the Carpathians Mountains Arch bends, at about 135 ± 35 km epicentral distance from Bucharest, is a source of subcrustal seismic activity, which affects ±35 more than 2/3 of the territory of Romania and an important part of the territories of Republic of Moldova, Bulgaria and Ukraine. The Vrancea source induces the very high seismic risk in the densely built zones of the South-East of Romania. According to the 20th century seismicity, the epicentral Vrancea area is confined to a rectangle of 40x80km2 having the long axis oriented N45E and being centered at about 45.6o Lat.N and 26.6o Long. E.
During the last 60 years, Bucharest was threatened by 4 strong Vrancea events: Nov.10, 1940 (moment magnitude Mw=7.7, focal depth h=150 km), March 4, 1977 (Mw=7.5, h=109 km), Aug 30, 1986 (Mw=7.2, h=133km) and May 30/31, 1990 (Mw=7.0/6.4, h=91/79 km).
The Catalogues of earthquakes occurred on the territory of Romania were compiled by Radu (1974, 1980, 1995) and Constantinescu and Marza (1980, 1995).
The most complete Vrancea historical catalogue is Radu Catalogue, even the majority of significant events are also included in Constantinescu and Marza Catalogue. The Radu Catalogue is about three times larger than the other Catalogue. The magnitude used in the Radu catalogue is the Gutenberg-Richter magnitude, M.
Figure 1. Epicenters of earthquakes in Romania, 984 - 2000
For Vrancea subcrustal source, the conversion of Gutenberg-Richter magnitude into moment magnitude might be approximated by Mw = M + 0.3 for 6.5 < Mw < 7.8 (Lungu et al.1999). From existing catalogues, one may approximately note:
(i) During the time interval 984-1900, one event/century with epicentral intensity I0 ≥ 9.0;
(ii) During the period 1901-2000 the evidence is two events per century of intensity I0 ≥ 9.0 (i.e. Mw ≥ 7.5), Table 1. Table 1. 20th Century catalogue of Vrancea Earthquakes, MGR>6.0
RADU Catalogue, 1994
MARZA Catalogue,
1980
www.infp.roCatalogue,
1998 Date
Time (GMT) h:m:s
Lat. No Long. Eo
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 7.11912 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
The strongest Vrancea earthquake ever occurred is accepted to be the Oct 26, 1802 event (M = 7.5 ….7.7) the most disastrous event is March 4, 1977 earthquake (M=7.2; Mw=7.4 …7.5).
The recurrence-magnitude relationship is determined from Radu’s 20th century Catalogue of subcrustal magnitudes with threshold lower magnitude Mw=6.3. The average number per year of Vrancea subcrustal earthquakes with magnitude equal to and greater than Mw, as resulting also from Figure 2 is (Lungu, Demetriu, 1995):
log n(>Mw) = 3.76 - 0.73 Mw (1a)
The maximum credible magnitude of the source was estimated using Wells and Coppersmith (1994) equations. Even those equations are intended for crustal earthquakes, the experience of recent subcrustal Vrancea events fits approximately the mentioned equations. According to Romanian geologists Sandulescu & Dinu, in Vrancea subduction zone the length of the rupture surface is: SRL ≤ 150÷200 km and the area of the rupture surface is: SRA≤8000 km2. Based on this estimation, one might get from Wells and Coppersmith equations Mw,max= 8.0...8.1 (Lungu et al. 1999).
If the source magnitude is limited by an upper bound magnitude Mw,max, the recurrence relationship (1a)can be modified in order to satisfy the property of a probability distribution (Hwang and Huo 1994). In the case of Vrancea source (Elnashai and Lungu, 1995):
( ) )3.61.8(687.1
)M1.8(687.1M687.1654.8
w e1e1eMn
ww
−−
−−−
−−=≥ (1b)
In Eq.(1), the threshold lower magnitude is Mw0=6.3, the maximum credible magnitude of the source is Mw,max=8.1, and α = 3.76 ln10 = 8.654, β = 0.73 ln10 =1.687.
Figure 2. Magnitude recurrence relation for the subcrustal Vrancea source (Mw ≥ 6.3)
1.2 Codes and standards for design of earthquake resistance of structures (1940 – 2000)
The codes for earthquake resistance of buildings and structures in Romania during the last 60 years are listed below:
P.I. - 1941 Preliminary instructions (after the 1940 event). Ministry of Public Works and
Communication, Bucharest 1941, 9p.; I - 1945 Instructions for preventing the damage of buildings due to earthquakes. Ministry of Public Works and Communication, Bucharest, 1945, 10p.; P13 - 63 and P13 - 70 Code for (structural) design of buildings in seismic zones. State Committee for Constructions, Architecture and Urban Planning, CSCAS, Bucharest, 1963, 39p. and 1970, 63p.; P100 - 78 and P100 - 81 Code for (structural) design of buildings in seismic zones. Central Institute for Research, Design and Management for Constructions ICCPDC,Bucharest, 1978, 57p. and 1981, 72p.; P100 - 90 and P100 - 92 Code for earthquake-resistant design of civil and industrial buildings. Ministry of Public Works and Land Planning, MLPAT, Bucharest, 1991, 152p. and 1992, 152p (English version 1993, 151p). Chapters 11, 12 were modified in 1996, 50p.
P100 – 2003 - Code for earthquake resistance of buildings and structure (Draft, 2003).
0.001
0.01
0.1
1
6.0 6.4 6.8 7.2 7.6 8.0
Moment magnitude, M w
Cum
ulat
ive
num
ber,
n(>
M)
pery
r
log n (>M w ) = 3.76 - 0.73M w
20 th century Radu's catalogue
M w, max = 8.17.8
6.3 6.7 7.1 7.5 7.9 8.3
( ) )3.61.8(687.1
)1.8(687.1687.1654.8
11
−−
−−−
−
−=≥eeeMn
ww
MM
w
The accompanying standards for seismic zonation of Romania are:
STAS 2923-52 and STAS 2923-63, Macrozonation of the territory of R.S.Romania. State Office for Standardization, Bucharest, 1952 and 1963; Decree No. 66/1977 of the Romanian Government, 1977; STAS 11100/1-77, Macrozonation of the territory of R.S.Romania. Romanian Institute for Standardization, Bucharest, 1978; STAS 11100/1-91 and SR 11100/1-93, Macrozonation of the territory of Romania.Romanian Institute for Standardization, Bucharest, 1991 and 1994.
The contents of the seismic codes and of the standards for seismic zonation of territory of Romania can be classified in four generations of major developments described in Table 2.
Table 2. Classification of codes for design of earthquake resistance of buildings and
standards for seismic zonation of Romania (1940-2003)
Period Code for earthquake resistance of structures
Seismic zonation standard*
Pre-code, before 1963
Prior to the 1940 earthquake and
Prior to the 1963 code
P.I. - 1941 I - 1945
P.I. – 1941 I – 1945 STAS 2923 - 52
Low-code, 1963-1977
Inspired by the Russian seismic practice
P 13 - 63 P 13 - 70 STAS 2923 - 63
Moderate-code, 1977–1990
After the great 1977 earthquake
P 100 - 78 P 100 - 81 STAS 11100/1 - 77
Moderate-code to High-code,
after 1990
After the 1986 and the 1990 earthquakes
P 100 - 90 P 100 - 92
STAS 11100/1 - 91SR 11100/1 - 93
High code, after 2004 Inspired by Eurocode 8 P100 – 2003 (draft) -
*The intensity scale used in Romania is MSK - 64 scale (STAS 3684 - 63, STAS 3684 - 71)
0.0
1.0
2.0
3.0
0 1 2 3 4Period T , s
(T)
0.8/T0.9/T
3/T
0.750.6
7 yr.
12 yr.
6 yr.
6 yr.
after Aug.30, 1986P100-90P100-92
P100-78P100-81
P13-70
after March 4, 1977
ξ = 0.05P13-63
0.6
2.5
0.3 0.4 0.7 1.5
1.0
2.2 2.5
Figure 3. Normalised acceleration elastic response spectra in Romanian seismic codes, from the 1963 to 2002 (Lungu, 1996)
The evolution of normalized acceleration elastic response spectra in design provisions
for earthquake resistance of structures in Bucharest is given in Figure 3 and it is self-explanatory.
The evolution of seismic design coefficient for computing lateral force (shear) at the base of building structure in Bucharest is presented in Figure 4. One should note the gap of the
overall coefficient Cs for flexible buildings and structures built during the period 1963-1978; however, even for rigid structures built during that period, the maximum Cs was about 2/3 of the present Cs due to reduced MSK intensity (VII) recommended for Bucharest by STAS 2923-63 (Table3).
After the 1977 disaster, ductility rules for reinforced concrete structures were imported into Romanian codes from American Concrete Institute (ACI) codes of practice. Those ductility rules were improved in 1990 according to the EUROCODE 8 new requirements. Evolution of seismic zonation maps in Romania during the last 40 years is illustrated by Figure 4 and Table 3.
Figure 4. Evolution of seismic design coefficient in Bucharest during time interval 1940-2000, (Lungu, Demetriu, 1998)
Table 3. MSK seismic intensity in Bucharest Time interval Standard MSK intensity 1952 – 1963 STAS 2923-52 VIII 1963 – 1977 STAS 2923-63 VII 1978 – 1991 STAS 11100/1-77 VIII
1991 - present SR 11100/1-91 and 93 VIII
The present conversion of MSK intensity, adopted by Romanian standard SR 11100/1-93, into peak ground acceleration, ag used by Romanian code for design of earthquake resistance of structures, is given in Table 4.
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
Rigid buildings
Flexible buildings
Table 4 MSK-64 intensity in SR 11100/1-93 9 8 7 6 5ag /g in P100-92 code 0.32 0.25 and 0.20 (2 zones) 0.16 0.12 0.08
Figure 5. Evolution of seismic zonation of Romania (from 1963 to 1993 and 2002)
It is emphasized that the present seismic code of Romania, P100-92 defines the earthquake hazard by 50 yr. mean recurrence interval event (MRI=50yr i.e. 63% exceedance probability in 50 yr). However, since the American loading code ASCE 7-95, 2000 and EUROCODE 8 for earthquake resistance of structures define the design earthquake by 475 yr.
mean recurrence interval (MRI=475yr i.e. 10% exceedance probability in 50 years) event, the level of seismic hazard in present seismic code is now under revision. A comparison of the max. peak ground acceleration for design (MRI = 50yr. and MgRI = 475 yr.) in Bucharest, Skopje and other 8 cities around the world is presented in Figure 6.
Figure 6. Seismic hazard around the world – U.N. RADIUS Project,1999
The recorded maximum peak ground acceleration in Romania during in 1977, 1980 and 1990 Vrancea earthquakes in given in Figure 7.
Figure 9
Figure Figure 7.
Figure 7
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Peak
Gro
und
Acc
eler
atio
nPG
A,g
Rome Bucharest Sofia Skopje Algiers Tehran Katmandu Salvador Santiago Bogota
Europe Africa Asia America
0.06
0.10
0.20
0.40
0.28
0.12 0.13
0.32
0.40
0.13
0.18
0.330.36
0.14
0.38
0.75
0.82
0.30 0.31
0.20
T = 50 yr
Mean recurrence intervalT = 475 yr
#·
#·
#·
#·
#
%
%
%
$
#
%
# ##
#
#
#
#
&
#
$$
%
#
#
&
&
%
#&
#
#
#
%
##
&
&
&
#
&
#
#
#
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
#
#
#
#
#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
79.1
97.2
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
1.3 Draft P 100 2003 seismic code of Romania. Seismic hazard assessment
The present joint map of Vrancea seismic hazard of Romania, Bulgaria and Moldavia. Figure 8 and Tabel 5 still suggests a need for map improvement by joint regional efforts.
Figure 8. Seismic zonation maps for countries affected by Vrancea earthquakes
Table 5 for the map in Figure 8.
PGA/g
MSK Intensity ROMANIA P100-92&
SR 11100/1-93
Rep. of MOLDOVA, UKRAINE
SNIP II-7-81
BULGARIA 1987 code
IX 0.32 0.40 0.27
VIII 0.25 0.20 0.20 0.15
VII 0.16 0.10 0.10
V 0.12 0.08 - 0.05
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 8 presents the proposed hazard map for the new code for design of earthquake resistant buildings in Romania, P100-2003. The map give the design peak ground acceleration, ag for the MRI=100 yr seismic event.
Zaicenco, Lungu, 1999
Figure 9. Peak ground acceleration for design, ag for MRI=100 y., P100-2003 code proposal
The response spectra in Figure 9 is recommended for Romania and Bucharest 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.
Tξ
0.7s<Tc ≤ 1.0sξ =0.05
1.0s<ξ= 0
0
0.5
1
1.5
2
2.5
3
3.5
0 0.5 1 1.5 2 2.5 3Perioada T , s
T B =0.07 T D =3
1.925/T
β 0 =2.75
T C =0.7s
2
2.5
3
3.5
2.75/T
β 0 =2.75
0
0.5
1
1.5
2
2.5
3
3.5
0 0.5 1 1.5 2 2.5 3Perioada T , s
TD =2
8
4.4/Tβ 0 =2.75
TB =0.16 T C=1.6s
Period T,s
Period T,s
c ≤ 0.7s =0.05
Tc ≤ 1.6s .05
3.5 4
5.775/T 2
0
0.5
1
1.5
0 0.5 1 1.5 2 2.5 3 3.5 4Perioada T , s
T C=1.0sTB =0.1 T D=3
8.25/T 2
3.5 4
.8/T 2
Period T,s
Figure 10. Normalised acceleration design spectra for various soil condition in Romania, P100-2003 code proposal
There is an instrumental evidence, from both the 1977 earthquake and 1986 earthquake that soil condition in Bucharest is 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 Figure10. A tentative macrozonation of Tc in Romania teritory is given in Figure 11.
Figure 8. Romania . Control period of response spectra, P100 - 2003
Figure 11. INCERC seismic station in Eastern Bucharest. Normalised power spectral density for the NS comp. of the Mar 4, 1977 and Aug 30, 1986 earthquakes
Figure 12. Romania. Control period of response spectra, P100-2003
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0 10 20 30 40Pulsatia ω, rad/s
Den
sita
tea
spec
trala
norm
aliz
ata 4 Martie 1977, M=7.2, comp.NS
30 Aug. 1986, M=7.0, comp. NS
ωp =2 π/T p
INCERC Bucuresti
PSD
Part II. Seismic Risk Management
2.1 The structure of the existing building stock in Bucharest
The structure of the existing building stock in Bucharest is given in Figure 12 and Table 6. The Bucharest population is about 2 million inhabitants. It is almost constant during the last 10 years.
Table 6. Inventory of existing housing units in Bucharest according to the periods of validity of various Romanian seismic codes.
Seismic code inter- benchmark periods
Housing units built during inter-benchmark periods
% housing units built during inter-benchmark periods
before 1941 168,556 21.95 ~22% 1941-1963 69,702 9.08 1963-1970 110,669 14.42 1970-1978 119,625 15.57 ~39% 1978-1992 292,594 38.09 1992-1995 6,844 0.89 ~ 39% Total 768,000 100%
0
500
1000
1500
2000
2500
Period of constructionN
umbe
rofb
uild
ings
Mid-rise buildings(3-7 storeys)
1900 1929 1945 1963 1970 1977 1990
Figure 13. Distribution of Bucharest buildings with period of construction
0
500
1000
1500
2000
2500
3000
Period of construction
Num
bero
fbui
ldin
gs
High-rise buildings(≥8 storeys)
1900 1929 1945 1963 1970 1977
0
5000
10000
15000
20000
25000
30000
35000
Period of construction
Num
bero
fbui
ldin
gs
Low-rise buildings(1-2 storeys)
1900 1929 1945 1963 1970 1977 1990
2.2 Fragile residential buildings in Bucharest
The List of the vulnerable buildings built in the center of Bucharest before 1940 and identified as having highest risk of collapse in the case of strong earthquake (comparable to 1977 event) contains 115 fragile mid-rise and high-rise buildings (March 2001/ Jan. 2003).
All those tall buildings listed as very vulnerable were located on the city map using the Geographic Information System (GIS) infrastructure, Figure 13 and Table 5.
In so called “Test area of central Bucharest” the GIS map (1:500) contains the location and detailed information on the more than 1700 buildings. All those buildings represented on map were digitised at Karlsruhe University within the technical cooperation between Technical University of Civil Engineering Bucharest (UTCB) and Karlsruhe University in the frame of German Science Foundation Project 461 devoted to Vrancea earthquakes.
The Test area in central Bucharest was selected by UTCB in 1997 based on location of the collapsed buildings during the 1977 earthquake in Bucharest.
Presently, the central Bucharest test area was extended to about 24000 buildings within European RISK-UE Project at University of Civil Engineering Bucharest, (UTCB) for including majority of the building listed as seismically vulnerable in Bucharest.
#
#
#
#
#
##
#
#
#
###
#
#
#
#
# ##
#
#
##
#
##
#
##
#
#
#
#
###
#
##
##
#
#
#
#
#
# #
##
##
#
#
#
#
#
#
#
#
#
#
##
#
##
#
#
#
#
#
#
# #
#
#
##
#
#
#
#
#
#
##
##
##
#
#
#
#
DACIA
MOSIL
O
VICTORIEI
BASARAB MATEI
LABIRINT
ICOANEI
H.BOTEV
KOGALNICEANU MIHAIL
BATISTEI
BRAT IANU
I.C.
POPA SOARE
SEL
A RI
ARDELENI
LEMNEA
SILVESTR
U
PLANTELOR
SMIRDAN
NATIUNILOR
CORBENI
AMMAN
DOAMNEI
OLARI
PREOT-VASILE-LUCACI
ARME
NEAS
CA
NEGUSTORI
PERI
LATI NA
ARGHEZITUDOR
ROSETTI C.A.
SCHITUMAG
UREANU
PALEOLOGU
STU
PINE
I
COLTEI
LASC
ARVA
SILE
(FO
S TA
GA L
A TI )
ACAD
EMIEI
UMOASA
EFORIEI
SPAT
ARUL
UI
LUPUD IO NI SI E
VASELO
ARHI TECTU RI I DI AN EI
PITAR
MOS
VISA
RIO
N
ITALI ANA
RASURI
DRA
GOS
VODA
BISERICA AMZEI
SLAN
IC
POPA PETREP
AUR
ORA
ARGE S
POPA RUSU
COVACI
PRECUPETII VECHI
REM
US
LEONIDA
VENEREI
MAGHE RU
GHEO
RGHE
-Gen.
ROM
ULU S
DUMBRAVA ROSIE
SFI
NTU
LS T
E FA N
ILFO
V
CAIMATEI
BARA
ZZAVILL ANLUIGI
IAN
CU
C
LICURG
SPERA
NTEI
SALCIMILOR
ONC
IUL
DIM
ITR I
E
ZBORULUI
PIATA-AMZEIM
INTU
LEAS
A
ARC
UL U
I
LUTE
RAN
A
ZECE MESE
ROBESCU F.C.BLANARI
RADU- Episc
opul
MOXA MIHAIL
BROSTENI
ENESCU GEORGE
ROSETTI MARIA
ARM
ONIE I
OLTARULUI
ZEFIRULUI
RAM
ULUS
GABROVENI
GRIGORESCU
BANULUI
LUN
I I
AD EREA
BA STI LIE I
MECHELET
SAHIAA LE X.(CALDERON
JEANL.)
LIPSCANI
FI LI PESCU
NICOLAE
STELEA SPATARUL
MEN
D ELEE V
D. I.
DRO
BET A
SFINTILOR
POST
EI
RACOVITA DIMITRIE
MIHAI VODA
RUSSO ALECU
GOLES CU
N IC OLA E
IULIU
CO
N TA
VAS I
LE
POL IT IE
MIH
AIL E
ANU
STEF
AN
IGORE -Prof.
LOG.STRO
ICI
BURGHEL EA
- Do cto r
IERNII
DOBRESCU ION
URALI
RADU-IL IE
SP IRUHARET
ROMANO - Pic tor
DOMNITA ANASTASIA
VERII
CERCUL
UI
CAVAFIIVECH
I
SF. MI NA
BOT
EANU
VALORII
LUMINEI
MILLE CONSTANTIN
FRANZELARILOR
CARAGIALE ION LUCA
FETITELOR
SAGET
II
ACELARI
MALNAS
OCOLULUIDA
STAVROPOLEOS
VIGILENTEI
PESTERI I
CR IS TIA N
TE LL-General
SUVENIR
BAC
ANI
GHICA ION
EPISCOPIEI
ORBESCU DIMITRIE
SAPIENTEI
BREZOIANUION
M INTULESA
DR.
V.SI
MIO
N
MO V
IL AI O
N
ENERGIEI
UDRISTE LOGOFAT
GUTEMBERG
MANDINESTI
FILIPIDE ALEXANDRU
FRANKLINBENJANIM
DON IC I ALE XANDRU
URSUION-Prof.
SERGHIESCU MARIN
PATRASCU VODA
COMANITA
XEN OP
OLA
LEXA
NDRU
PREPELITEI
PASULUI
DON
AN I
C OL A
E-G
ener
al
CULM
EAVECH
E
PUTIUL -C U-PLOPI
CAVNIC
IORGA NICOLAE
SALIGN
YA
NGHE
L- Inginer
CA R
A DA
EUGE
N IU
COLUMBELOR
LUCHIANSTEFAN- Pic tor
G-R AL-G
H.MAG
HER U
CA L
OTES
TI
BA LCE SCU
N ICOLA E
SCH
ITU
DAR
VAR
ITIBANA
SLAVESTI
FILITTI C. IO
BIJUTERIEI
SFI
NTU
LSP
IRI D
ON
BLANDUZIEI
BAIA
DE FIER
MAVROGHENI NICOLAE
BANIEI
BRUTUSM
I
XANDRA
MON UME NTULUI
ION-Erou
QUINET EDGAR
BOBE ICAPRISTOLU
LUI
VIROAGEI
ZALOMIT ION
COBILITEI
C-TIN-EXARCU
DOMNESTI
ARON FLORIAN
General
VRAC
AGEO
RGE
TOPL
ICEN
I
GRADIN
A CUCAI
RUMEOARA
BOTEZCORNELIU
SECUREI
SEVCENCOTARAS
CON
S TAN
T INES CU
MI TRITA
-Pro f.
COMEDIA
BALABANEM IL
- Ing iner
IPAT ESCUGR
IGO
RE- G
en e ra l
VICTORIA
PACIUREA DIMITRIE
SIPOTUL FINTINILOR
L UCA STROICI - L ogofat
MAJESTIC
PICTOR-VERONASFI NTU LSAV A
PROGRESULUI
ION
NIS
T OR
RIUREANU - Doctor
IANCU
CA V
VERMO
NT- Pi ctor
CRE
T ULES CU
NICO
L AE
URSEANU VASILE - Ami ral
GIURESCU DIMITRIE - Maior
BACALO
GUEM
ANO
IL -d o ct o r
UNI
VERS
ITAT
I I
MARCOVICI ALEXANDRU - Doctor
BELDIMAN
A LEXAND
RU
SSIMA - Profeso
r
TOMESCU TOMA - Doctor
IOANIDGHE.-pictor
NIC
OLAE- IORG
A
SCOALEI
POLO
N A
MIHAI BRAVU
DONICI ALEXANDRU
30DECE
ORIZONTUL
13-DECEMBRIE
PAL EOLOGU
ITALIANA
SAH
I AAL
EX. (C
ALD
ERO
NJE
ANL.
)
TREI SCAUNE
EMINESCU MIHAI
TRAIA N
ROSETTI C.A .
DO
ROBANT I
TOAM
NEI
IORGA NICOLAE
CERNICA
MIHAI-VODA
INDEPENDENTEI
REPUBLICII
REPUBLICII
BREZOIANUION
IONESCU CRISTEA
AVRA
MIANC
U
ROSETTI C.A.
ROSETTI MARIA
LIPSCANI
BI SER ICA
AMZE I
SF. VINER
MATEI MILLO
ARM
ENEA
SCA
LIPSCANI
LIPSCANI
CALARASI
VIITORU
LUI
ICO
A NEI
3
5
4
1
6
8
9 2
7
12
91
92
16
20
30
959461
11
19
13
1417
15
1865
63
3133
28
73
40
54
4748
49
43
35
68
7269
51
36
52
96
97 98
42
56
71
25 32
55
24
23
60
39
70
3446
38
87
64
50
80
78
90
88
99 57
76
59
6753
8345
74
5893
7579
4422
10
86
62
85
26
104100
105
109110
107
103
108
106
101
102
0.5 0 0.5 1 Kilometers
N
EW
S
ArcView GIS 3.2 - ESRI CaliforniaLungu & Arion, 2000
Figure 14. Central Bucharest area with buildings built prior to 1945 and identified as having high risk of collapse in case of a strong earthquake (Mw≥7.5)
Table 7. Buildings with more than 5 stories built before 1940 located on the two most important boulevards of central Bucharest and identified as having highest risk of collapse in
case of strong (comparable to 1977) earthquake8
* Classification of damage in 1977 follows vulnerability classes of HAZUS methodology, 1998, (see Lungu, D., et al., 2000. Advanced Structural Analysis, Conspress, UTCB, 177p.);
No Address
Year of building
construction
Commercial occupancy of groundfloor
Storeys No. of Apt.
Total area sqm.
Damages after the 1977 earthquake in structural
elements
Repairing work after the 1977 earthquake
Gulkan Damage
score
1 Balcescu 24 (Pherekide) 1928 Yes 13 61 12197
Columns: Beams : Masonry:
Extreme Extreme Extreme
Jacketing of columns and beams
Masonry Repairs Epoxy resins injections
Mortar injections Finishes
100
4Calea Victoriei
101A-B
1937 Yes 11 61 6111Columns: Beams : Masonry:
Extreme Extreme
-
Jacketing of columns Masonry Repairs
Epoxy resins injections 86
6 Magheru 20 1935 Yes 10 52 5484Columns: Beams : Masonry:
-Light Light
Masonry Repairs Epoxy resins injections
Mortar injections 11
11 Magheru 27 1935 Yes 9.5 36 6405 Columns: Beams : Masonry:
Light --
Jacketing of columns 14
12 Calea Victoriei 2-4 1928 Yes 9 76 12994
Columns: Beams : Masonry:
Light Medium
-
Masonry Repairs 29
16 Calea Victoriei 128A 1935 Yes 9 22 6675
Columns: Beams : Masonry:
Extreme Extreme Extreme
Jacketing of columns and beams
Masonry Repairs 100
20 Calea Victoriei 112 1939 Yes 9 27 5210
Columns: Beams : Masonry:
Extreme Extreme Extreme
Jacketing of 4 columns Masonry Repairs
Epoxy resins injections
100
27 Calea Victoriei 208 1940 Yes 8.5 44 5200
Columns: Beams : Masonry:
Extreme Medium Extreme
Jacketing of beams Masonry Repairs
Epoxy resins injections 86
30 Calea Victoriei 139 1934 Yes 8 30 1290
Columns: Beams : Masonry:
Light Light
Medium
Masonry Repairs 29
61 Balcescu 25 (Wilson) 1928 Yes 12 93 12287
Columns: Beams : Masonry:
Extreme Extreme Extreme
Jacketing of columns and beams
Masonry Repairs Epoxy resins injections
Mortar injections Finishes
*partially collapsed in 1977
105
65 Calea Victoriei 124 1900 Yes 6.5 28 3045
Columns: Beams : Masonry:
--
Light/ Medium
Masonry Repairs 37
91 Calea Victoriei 25 1936 Yes 13 49 6078
Columns: Beams : Masonry:
Extreme Extreme Extreme
Jacketing of 6 columns Epoxy resins injections
100
92 Calea Victoriei 95 1938 Yes 10.5 51 4010
Columns: Beams : Masonry:
Extreme Extreme Extreme
Jacketing of columns and beams
100
94 Balcescu 32-34 1935 Yes 10 41 6996
Columns:
Beams :
Masonry:
Light/ Medium Light/
Medium -
Masonry Repairs 42.5
95 Balcescu 30 1936 Yes 9.5 25 2756
Columns: Beams : Masonry:
Extreme -
Medium
Masonry Repairs Epoxy resins injections
Finishes 64
100 Balcescu 7 1933 Yes 7 15 2730
Columns: Beams : Masonry:
Light Light
Extreme
Masonry Repairs Epoxy resins injections
36
104 Calea Victoriei 33-35 1930 Yes 6.5 39 4800
Columns: Beams : Masonry:
Medium Medium Medium
Jacketing of columns Masonry Repairs
50
Balcescu 24(Pherekide) Calea Victoriei 101 A-B Magheru 20
Magheru 27 Calea Victoriei 2-4 Calea Victoriei 128A
Calea Victoriei 112 Calea Victorie 208 Calea Victoriei 139
Balcescu 25 (Wilson) Calea Victoriei 124 Calea Victoriei 25
Calea Victoriei 95 Balcescu 32-34 Balcescu 30
Balcescu 7 Calea Victoriei 33-35
Figure 15 Seismic vulnerability class 1
buildings on the most important two boulevards in
central Bucharest
The damage score for the fragile building structures from the list of 115 buildings in Bucharest was computed with a simplified version of the damage methodology proposed by Gulkan (1994), Middle East Technical University, Ankara, Turkey.
The calculation of damage score, SD for a building is based on the level of damage of the structural members at the most severely damaged story of the buildings (usually the groundfloor). The damage level of structural member is classified as follows:
No damage MD score = 0 Moderate damage MD score = 2 Light damage MD score = 1 Extreme damage MD score = 4.
The importance factor for structural elements, ω is selected as follows (Gulkan, 1994): Columns ω=2; Beams ω=1; Infill masonry ω=0.5.
The building structure damage score, SD can be computed as follows:
( ) ( ) ( )( ) ( ) ( )[ ] 100
4MDMDMD
SDillsinfbeamscolumns
illsinfbeamscolumns ⋅++
⋅+⋅+⋅=
ωωωωωω
SD varies from 0 to 100. The vulnerability classes can be selected based on SD score.
The simple criteria might confirm the hierarchy of actual vulnerability of the fragile buildings in Bucharest in the case of a strong earthquake:
(i) Presence of visible damage after the 1977 earthquake as well as the presence of visible local repairing made after that earthquake;
(ii) Presence of the soft ground floor due to commercial use of that floor (no infilled masonry walls);
(iii) Number of storeys of building (taller the building, higher the risk); (iv) Lack of vertical and horizontal symmetry of the building (setbacks,
asymmetrical architecture of the corner buildings) as well as unintended local structural damage due to occupancy changes and activities, corrosion of the reinforcement, low strength concrete (mean compressive strength 100-200 daN/cm2). etc. Table 5 and Figure 14 give the characteristics and the photos of 17 buildings seismic vulnerability class 1 located on the two most important boulevards of Bucharest. All of them were built before WWII (1940). Seismic "risk class” in present Romanian seismic code (P100-92) is actually seismic vulnerability class! That is why the seismic risk matrix presented in Table 8 should be used for the classification of actual seismic risk of vulnerable buildings in Romania.
Table 8. Seismic risk classes
Importance and exposure class Seismic Vulnerability/or
fragility class
IEssential facilities
II Hazardous buildings
III General buildings
IV Minor buildings
1 1 1 1&2 32 1&2 2 3 33 3
Recently (Dec 2002/Jan 2003), 42 pre-1977 buildings built during the time interval 1945- 1977 were included into the most dangerous seismic vulnerability class 1 buildings in Bucharest, Table 9 and Figure 16. They are tall RC buildings characterised by soft groundfloor located on soft soil condition of Bucharest city. Table 9. Fragile tall RC buildings having flexible groundfloor, built prior to 1977 earthquake in Bucharest
No. Name of street No. of buildings No. of stories Address of buildings
1
Calea Grivitei
18
B*+GF+ (7......12)S No. 3-5, 134, 139, 148, 156, 158, 163, 164, 169, 196, 198, 200, 206, 236, 238, 395, 398, 399
2 Stefan cel Mare 11 B+GF+ (6...8)S No. 5, 15. 17, 27, 28, 31, 33, 40, 42, 128, 188
3 Bd. Mihalache (1 Mai) 4 B+GF+(8...10)S No. 170, 172, 174, 399 4 Gara de Nord 3 B+GF+8S No. 2-4, 6-8, no.2 Piata 5 Dinicu Golescu Bd., 1 B+GF+9S No. 23-25 6 Piata Chibrit –C 1 B+GF+8S 7 Piata Amzei 1 B+GF+7S No. 12-22 8 Bd. N. Balcescu 1 B+GF+9S No. 33
9 Dorobanti/Stefan cel Mare corner 1 B+GF+12S Blocul Perla
10 Sos. Mihai Bravu, 1 B+GF+8S No. 107-119 * B – basement. GF – groundfloors, S - stories
Figure 16. Fragile tall RC buildings having flexible groundfloor, built prior to 1977 earthquake in Bucharest
Table10. List of cities with hospital buildings requiring strengthening work
Number of hospitals buildingsCitySeverely damaged.
Requiring immediatetechnical assessment
Having atechnical
report
Approvedproject forretrofitting
Retrofitting inwork
Bacau 3Bucharest 13 16 6 10Buzau 9Constanta 7Craiova 4Focsani 2Galati 6 2 1Giurgiu 1Iasi 21 17 2 5Pitesti 2 7Ploiesti 2Sibiu 1Targu-Mures
2
Vaslui 4 1Barlad 2
Churches damaged by major historical earthquakes in Bucharest Table 11
Level of damage No. Name Address 1802
event 1838 event
1940 event
1977 event
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
Hospitals requiring technical assessment and retrofitting works (design, construction, financing) in various Romanian counties are listed in Figure 17 and Table 10. Various orthodox churches damaged by major historical earthquake in Bucharest are listed in Table 11 and in Figure18.
Figure 17
Figure 18
There is a certitude that, for about 50 years recurrence interval Vrancea earthquake, several dozens of pre-WWII tall RC buildings in Bucharest will collapse (there are about 60-100 pers/bldg). More than half of those buildings and several pre - 1977, framed RC structures in are already identified by licensed experts as “seismic risk class 1” buildings. The governmental action of identification of dangerous buildings in Romania started in 1994. In 2001, a new Government Order stated that the Government will 100% advance the necessary payment, for strengthening of the buildings, to the private owners of apartments in “seismic risk class 1” buildings (more than 95%of housing units are private in Romania!). If the owner salary is less then national average, he have to pay back(to the state) nothing. If it is not, he has to pay the money back in 25 years, with 5% interest. Anyway, the owner has to agree on the strengthening of its apartment, in case he has to leave the housing unit during the construction work. Of course, the owners do not like leaving and the necessity buildings for temporary housing during strengthening are not yet implemented. Moreover, if one apartment owner does not like/agree on strengthening of its apartment, the strengthening of the whole building can not be done!!! There is a promise of the Ministry of Public Works, during a May, 2003 Seminar, for promoting a new official act which will make compulsory the strengthening of the building structure if the majority of private owners will accept the strengthening(in spite of several owners who would not like to allow strengthening of their apartments). Distribution per counties of residential buildings, hospital buildings and school buildings, requiring strengthening/retrofitting works in Romania is presented in Figure 19. Present stage of construction work of the first 8 buildings under retrofitting/strengthening in Bucharest is given in Table 12. Table 12.
Building 1 2 3 4 5 6 7 8
Total area (sqm) 6050 1831 1615 1750 12313 2013 3706 2271
Height B+GF+8S B+GF+6S B+GF+6S B+GF+6S B+GF+11S B+GF+5S B+GF+8S B+GF+5S
1 ) Present stage of retrofitting work, 20÷70%; 2) Cost of structure strengthening 50 - 150€/ sqm, 3) Duration of construction, 8÷12 month
Figure 19
Seismic instrumentation of Romania and Bucharest
Based on deep recognizance of the extraordinary importance of seismic records for understanding of the strong motion characteristics, Romania installed in the last 2 years about 50 digital K2 and ETNA, Kinemetrics instruments.
The present seismic instrumentation of Romania is summarized in Table 13 and in the maps in Figure 20.
Table 13. Seismic networks of Romania, 2003 Name of network Bucharest Romania
(including Bucharest) INCERC & ISC, State Inspectorate for Construction
7 ETNA 31 ETNA
New digital networks, installed in 2003 CNRRS & JICA, Japan
International Cooperation Agency Project1
11 K2 16 instruments: -11 K2; - 5 ETNA
INCERC
21 instruments: -10 SMA-1 (analog) -9 ADS (digital) -2 digital stations for continuous monitoring
70 instruments: -58 SMA-1(analog) -9 ADS (digital) 3 digital station for continuous monitoring Existing seismic
networks, in 2002 INFP/SFB 461 German Science Foundation Project at University of Karlsruhe
15 K2 41 K2
TOTAL 54 digital instruments 158 instruments 100 digital 1) UTCB & INCERC are partner institutions with CNRRS.
Figure 20
The table indicates 100 Kinemetrics digital instruments in Romania, 54 in Bucharest, as well as more than 100 instruments in INCERC seismic network, (45 digital) and 41 Kinemetrics digital instruments in the joint seismic network of SFB 461- Project on Vrancea earthquakes at Karlsruhe University, and INFP, National Institute for Earth Physics, Bucharest.
The Japan-Romanian Project on Seismic Risk Reduction in Romania, implemented by JICA & CNRRS in partnership with UTCB & INCERC, installed in 2003 16 instruments in Romania i.e.:
(i) 7 K2 stations at 7 locations in Bucharest, each with 3 sensors: 1 free field and 2 in deep boreholes (-30.0 m ÷ -180.0 m);
(ii) 5 ETNA accelerometers outside Bucharest; (iii) 4 K2 station in four significant buildings in Bucharest. In addition to the Romanian-Japanese and Romanian-German seismic cooperation
projects, State Inspectorate for Construction of Romania provided 31 ETNA Kinemetrics digital instruments, which are operated by INCERC in partnership with ISC (10 instruments, still to be installed).
ACKNOWLEDGEMENT
We would like acknowledge our deep gratitude to:
- ISC, State Inspectorate for Construction, Romania;- JICA, Japan International Cooperation Agency and - UTCB, Technical University for Civil Engineering Bucharest and CNRRS,
National Centre for Seismic Risk Reduction joint instrumentation team, - INCERC seismic network laboratory, - SFB 461- Project on Vrancea Earthquake at Karlsruhe University
for their sustained efforts during years to complete the present stage of digital seismic instrumentation of Romania and Bucharest.
REFERENCES
ASCE 7-98, 2000. ASCE Standard: Minimum design loads for buildings and other structures. American Society of Civil Engineers, New-York, ASCE, SEI
Bolt B., (1995), Earthquakes, W.H. Freeman and Company, New York, 331 p. Coburn, A., Spence, R., (1992), Earthquake protection, John Wiley & Sons., New York, 355p. Constantinescu, L, Marza, V., (1980), A computer-compiled and computer-oriented catalogue of Romania’s
earthquakes during a millenium (984-1979), Géophysique, Tome 24, No2, Bucharest, p.193-206. Elnashai A., Lungu D., 1995. Zonation as a tool for retrofit and design of new facilities. Report of the Session
A.1.2. 5th International Conference on Seismic Zonation, Nice, France, Oct. 16-19, Proceedings Vol.3, Ouest Editions, Preses Academiques, p.2057-2082.
Eurocode 8 - Design provisions for earthquake resistance of structures, 1994. Part 1-1: General rules - Seismic actions and general requirements for structures. CEN, European Committee for Standardization, Oct.
Hwang H.H.M., Huo J.R., 1994. Generation of hazard-consistent fragility curves for seismic loss estimation studies. Technical Report NCEER-94-0015. National Center for Earthquake Engineering Research, State University of New York at Buffalo, Aug.
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., Vacareanu, R., Aldea, A., Arion, C., 2000. Advanced Structural Analysis, Conspress, UTCB, 177p. Lungu, D., Arion, C., Baur, M., Aldea, A., 2000. Vulnerability of existing building stock in Bucharest, 6ICSZ Sixth
International Conference on Seismic Zonation, Palm Springs, California, USA, Nov.12-15, p.837-846 Lungu, D., Aldea, A., Arion, C., 2000. "Engineering, state & insurance efforts for reduction of seismic risk in
Romania" In: Proceedings of the 12th World Conference on Earthquake Engineering, Auckland, New Zealand, Jan/Feb.
Lungu D., 1999. Seismic hazard and countermeasures in Bucharest-Romania, Bulletin of the International Institute of Seismology and Earthquake Engineering IISEE, Tsukuba, Japan, Vol.33, p.341- 373.
Lungu, D. & Aldea, A., 1999. Understanding Urban Risk Around the World. United Nations RADIUS Project at Geohazards Int., Ca., USA. Document City of Bucharest Seismic Profile, 29p.+25p.+8p.
Lungu, D., Arion, C., Aldea, A., Demetriu, S., 1999, “Assessment of seismic hazard in Romania based on 25 years of strong ground motion instrumentation”, NATO ARW Conference on strong motion instrumentation for civil engineering structures, Istanbul, Turkey, June 2-5, 1999.
Lungu, D., Aldea, A., Arion, C., Cornea, T., 1998. "Seismic hazard zonation in Eastern Europe", Second International Conference on Earthquake Hazard and Seismic Risk Reduction, September 15-21, Yerevan, Armenia , Kluwer Academic Publisher, 2000, p281-289.
Lungu, D., Demetriu, S., Arion, C. 1998. Seismic vulnerability of buildings exposed to Vrancea earthquakes in Romania. In Vrancea Earthquakes. Tectonics, Hazard and Risk Mitigation, Kluwer Academic Publishers, Wenzel F., Lungu D., editors, Proc. of First International Workshop on Vrancea Earthquakes, p.215-224.
Lungu D., Cornea T., Nedelcu C., 1998. Probabilistic hazard assessment and site-dependent response for Vrancea earthquakes. In Vrancea Earthquakes. Tectonics, Hazard and Risk Mitigation, Kluwer Academic publishers b.v., Wenzel F., Lungu D., editors, p.251-268
Marza, V.I., Kijko, A., Mäntyniemi, P., (1991), Estimate of earthquake hazard in the Vrancea (Romania) region,Pageoph, Vol.136, No.1, Birkhäuser Verlag, Basel, p.143-154.
Munich Re, 1998. World Map of Natural Hazards Radu C. manuscripts, 1994. Catalogues of earthquakes occurred on Romanian territory during the periods 984-
1990 and 1901-1994. Zanfir A., 2000. Assessment of damage buildings (Master thesis, in Romanian), UTCB, 75p. Wells D.L., Coppersmith K.J., 1994. New empirical relations among magnitude, rupture length, rupture width,
rupture area, and surface displacement. Bulletin of the Seismological Society of America, Vol.84, No 4,p. 974-1002.
Cornea T., Vacareanu R. and Lungu D., 2000 Technical Report for Collaborative Research Center (CRC) 461 of SFB, Germany: “Strong Earthquakes: A Challenge for Geosciences and Civil Engineering”, Karlsruhe University, 64 p.
HAZUS – Technical Manual 1997. Earthquake Loss Estimation Methodology, 3 Vol. Newmark, N. M., and Hall, W. J. (1982). Earthquake Spectra and Design. Berkeley, Calif. Earthquake
Engineering Research Inst. Văcăreanu R., Cornea T., Lungu D. Evaluation of seismic fragility of buildings, Earthquake Hazard and
Countermeasures for Existing Fragile Buildings, Editors: Lungu D. & Saito T., Independent Film, Bucharest Romania.