SEISMIC VULNERABILITY EVALUATION IN THE CITY OF ALGIERS (ALGERIA)

Transcription

1 AURAN PROJECT 4 th World Urban Forum Nanjing (China), 3-6 November 28 SEISMIC VULNERABILITY EVALUATION IN THE CITY OF ALGIERS (ALGERIA) DJILLALI BENOUAR OBJECTIVES OF THE PROJECT EVALUATION OF SEISMIC VULNERABILITY OF THE CITY OF ALGIERS IDENTIFICATION OF VULNERABILTY FACTORS INITIATIVES DEVELOPED WITH LOCAL AUTHORITIES AND OTHERS MEASURES THAT CAN BE IMPLEMENTED TO REDUCE VULNERABILITY 1

2 Risk Definition Risk is defined as: Hazard * Vulnerability Risk = Disaster Management LOCALISATION OF HIGH DENSITY POPULATION AREAS LOCALISATION OF HIGH DENSITY POPULATION AREAS Hammamet Nord El Marsa Beni Messous Dely Brahim El Achour Draria Baie d'alger BordjEl Kiffen Dar El Beida Borgj El Bahri Ain Taya Rouiba 18 Saoula Baraki Les Eucalyptus Rais Hamidou Bouzaréah 4 Bouloghine Bab El Oued Oued Korich Casbah Alger Centre El Biar Ben Aknoun Sidi M'Hammed Hamma Anaser El Madania Hydra El Mouradia Bir Mourad Rais Kouba Birkhadem Djser Kasentina Hussen Dey El Maghania Badjarah Mohammadia Légende <d<1 1<d<2 2<d<3 4<d<5 7<d 23 El Harrach Bourouba Bab Ezzouar Oued Smar 2

3 POPULATION DENSITY IN THE 26 MUNICIPALITIES OF ALGIERS Mohammadia Hydra El Harach Djar Kasentina Bab Ezzouar El Mouradia Bir Mourad Rais Bourouba Badjarah Hamma Anasser Sidi M'Hamed Alger centre Bab El Oued Casbah El Maghania El Madania Bologhine Oued Korich El Biar Kouba Hussen Dey Ben Aknoun Birkhadem Rais Hamidou Bouzareah Oued Smar HOUSING UNITS DENSITY PER HECTARE FOR THE 26 MUNICIPALITIES OF ALGIERS El Harach Mohammadia Djar Kasentina El Biar Bab Ezzouar Oued Korich Bologhine El Madania Casbah Bab El Oued Sidi M'Hamed Alger centre Hamma Anasser El Maghania Bir Mourad Rais Badjarah Bourouba El Mouradia Kouba Ben Aknoun Hydra Birkhadem Rais Hamidou Bouzareah Oued Smar 3

4 AREAS IN HECTARES FOR THE 26 MUNICIPALITIES Rais Hamidou Ben Aknoun Bologhine Oued Korich El Biar Casbah Bouzareah Bab El Oued Alger centre Kouba Bab Ezzouar Sidi M'Hamed Djar Kasentina Badjarah Bourouba Hamma Anasser Birkhadem Bir Mourad Rais El Madania Hussen Dey Mohammadia El Harach Hydra El Mouradia El Maghania Oued Smar DISTRIBUTION OF TYPES OF BUILDINGS IN THE 26 MUNICIPALITIES Hamma Anna Bab El Ou Bologhin El Bia El Harrac Bouroub Oued Sm Hussen De Ben Aknou Djaser kasent Kouba Badjarah Bab Ezzou Hydra Mohammad Alger Cent Sidi M'ham El Madan El Maghan El Mourad Bouzaréah Birkadem Casbah Oued Korich Bir Mourad R immeubles maisons trad maisons ind ateliers/autre précaire total 4

5 EVOLUTION OF THE CONSTRUCTIONS DURING THE THREE MAIN HISTORICAL PERIOD IN ALGERIA 12 % de constructions tous types confondus < DISTRIBUTION OF APPARTMENT BUILDINGS (MASONRY) BY NUMBER OF STORIES R R1 R2 R3 R4 R5 R6 R7 5

6 APPLICATION TO THE DISTRICT OF BAB EL OUED GEOGRAPHICAL SITUATION POPULATION DENSITY LARGE HOMOGENEITY ARCHITECTURAL OF CONSTRUCTIONS MOST REPRESENTATIVE DISTRICT OF THE OLD CITY OF ALGIERS. DATA AVAILABLE. ZONE UNDER INVESTIGATION OF THE DISTRICT OF BAB EL OUED C im e t i è r e E l K e tta r P oint n 7 R+M(16m) P oint n 6 R(4m) P oint n 1 R (11m) P oint n 4 Arg+L(4m) M o h a m e d T a z a i t R u e Boulevard Taleb Abderahmane R u e d e s R u e A h m e d A v e n u e F r è r e s A c h a c h e B o u k h e z a r C o l o n n e l Rue des Frères Déraoui L o t f i T o u a t i A ve n u e P o in t E l K e tta n i C o m m a n d a n t M e r Point n 2 R+Arg (3-4m ) A b d e ra h m a n e P oint n 3 R+S ( m ) M ira B o u l e v a r d S a i d P oint n 5 R+Arg (5-1 3m ) H ô p i t a l M a illo t S ta d e F e rhani N o r d 6

7 DISTRIBUTION OF BEARING WALL BUILDINGS BY TYPE OF FLOOR (BAB EL OUED) 7 7 nombre de batiments R+ R+1 R+2 R+3 R+4 R+5 R+6 >R+6 voutains bois mixte dalle nombre de bâtiments DISTRIBUTION OF REINFORCED CONCRETE BUILDINGS BY TYPE OF FLOOR R+ R+1 R+2 R+3 R+4 R+5 >R+6 voutains bois mixte dalle 8 7

8 nombre de constructions DISTRIBUTION OF MIXTE BUILDINGS BY TYPE OF FLOOR R+ R+1 R+2 R+3 R+4 R+5 R+6 >R+7 voutains bois mixte dalle DISTRIBUTION OF BUILDINGS BY NUMBER AND AGE commune de Bab -El -Oued Immeubles Maisons Ind Maisons Trad Ateliers Précaire <

9 DISTRIBUTION OF % BUILDINGS BY NUMBER OF STORIES 3 25 % de constructions R R1 R2 R3 R4 R5 R6 >R7 nombre de niveaux CRITERIA TO SELECT A REPRESENTATIVE BUILDING ACCORDING TO THE STATISTICS OF THE BUILDING STOCK IN THE MUNICIPALITY OF BAB EL OUED, THE CRITERIA ARE: 1 - SIX STORY BUILDING (R+5) 2 BEARING WALL STRUCTURE IN STONE MASONRY 3 FLOORS IN VOUTAINS 9

10 CURRENT FLOOR «BUILDING 12 AVENUE DE LA BOUZARÉAH», APRIL 194 Horizontal Dimensions: 16.5 m x 19.3 m Height above the ground: 23 m Walls thickness vary from 5 to 8 cm. Continuous foundations of 7 to 1cm wide CROSS-SECTION «BUILDING 12 AVENUE DE LA BOUZARÉAH», APRIL 194 1

11 CURRENT FLOOR OF AN ANGLE BUILDING(1926) fig. n 15 : plan d étage courant d un bâtiment d angle ( 1926 ) 12 1 CONSTRUCTION OF VULNERABILITY FUNCTIONS CONSTRUCTION OF VULNERABILITY FUNCTIONS dommage ,5 6,5 7,5 accélération ( %g ) 8,5 9,5 1, ,5 16,8 E / G = 2,5 E / G = 6 11

12 CONSTRUCTION OF VULNERABILITY FUNCTIONS CONSTRUCTION OF VULNERABILITY FUNCTIONS dommage VULNERABILITY CURVES FOR E/G = 6 accélération ( %g ) type M type S REF (89) CONSTRUCTION OF VULNERABILITY FUNCTIONS SEISMIC VULNERABILITY EVALUATION USING DAMAGE STATISTICS: MASONRY BUILDINGS IN ALGIERS 12

13 INTRODUCTION This study is based on the damage statistics caused by the October 29th October 1989 in Tipaza. Ms 6. Io VIII (MSK) Depth 1 km 35 dead, 7 injured, 5 homeless Damaged75 housing units, 5 public buildings Historical seismicity of the region Cherchell (1735), Hadjout (1756), Kolea (182) and Cherchell (1847) Douera (1924), Boumedfaa (1959), Oued Djer (1988), Ain Benian (1996), Boumerdes (23) 13

14 Damage Observed During this earthquake, the influence of some structural and non-structural elements on the behavior of the structures was observed; A sample of 2.3 buildings is considered Each building was screened by structural engineers and damage was reported on a questionnaire Damage Each questionnaire contains more than 6 information relative to type of damage, structural and non-structural components, identification, use and brief description of the structure Inventory of damage was: 11,938 buildings were expertised in which 6,142 did not suffer any damage, thus 5,79 were damaged 14

15 15

16 Damage Statistics Only 2,3 buildings were used in this study distributed as: 1,766 buildings with bearing walls (87%) 228 Buildings in Reinforced Concrete (11%) 3 Buildings with mixed structures (bearing wall structures and RC) (1.5%) CLASSIFICATION OF BUILDINGS ACCORDING TO DAMAGE Among the 1,766 damaged buildings: 46 did not suffer any damage (green 1) or slight damage (green 2) 1,165 suffered damaged to be expertised in details (Orange 3 and 4) 141 considerably damaged (to be demolished) (Red 5) 16

17 Classification by pathology criteria Quality of bracing (Qc) Non structural elements (Es) Materials degradation (Vm) Wall linkage (Cm) Elevation irregularity (Ie) Plan asymmetry (As) File redundancy (Rf) Soil condition (So) Classification of structures 1,36 STRUCTURES HAVE SUFFERED DAMAGE IN WHICH 1,89 HAVE AN ADVANCED DEGRADATION OF MATERIAL 914 HAVE BAD QUALITY OF BRACING 719 HAVE SECONDARY ELEMENTS SERIOUSLY DAMAGED 67 HAVE NO LINKAGE IN THE WALLS 146 HAVE IRREGULAR ELEVATION 17

18 Classification of structures 14 have no symmetry in plan 119 have irregular redundancy in span 4 built on bad soil conditions Weighting coefficients Pathology Criteria % Damage Weighting coefficient Normalized Weighting coefficient Vm Qc Es Cm Ie As Rf So

19 Estimation of damage by building Damage None Slight Moderate Important Collapse Value Color Green Green Orange Orange Red Percent of damage % 25% 5% 75% 1% Evaluation of the vulnerability index Sum of pathology weighting coefficients V= 1.Vm+.84Qc+.66Es+.55Cm+.13AS+.12Rf+.2So Correlation of Damage and Vulnerability Linear Function D = av + b Quadratic Function D = av 2 + bv + c 19

20 Correlation Damage-Vulnerability Linear Function D = 8V (Figure 1) Quadratic Function D =.21V V (Figure 2) 2

21 CONCLUSIONS AND RECOMMENDATIONS THE EVALUATION OF THE VULNERABILITY COMBINED WITH SEISMIC HAZARD IN ALGIERS WILL ALLOW THE ASSESSMENT OF THE SEISMIC RISK FOR GIVEN CHARACTERISTICS OF AN EARTHQUAKE. THE AIM OF THIS PROJECT IS TO GUIDE ALL LEVELS OF GOVERNMENT TO REDUCE THE RISK BY IMPLEMENTING ADEQUATE PREVENTIVE MEASURES TO REDUCE THE VULNERABILITY OF A GIVEN STRUCTURE 21