Improved Tools for Disaster Risk Mitigation in

ITERATE

Deliverable C.1

Report on Available Building Data and Algerian Building Taxonomy

ECHO/SUB/2016/740181/PREV23 – ITERATE – Improved Tools for Disaster Risk Mitigation in Algeria Project co-funded by ECHO – Humanitarian Aid and Civil Protection

Author FEUP Smail Kechidi José Miguel Castro Date 17 October 2017

Review IUSS Pavia Andrés Abarca Ricardo Monteiro Date 31 October 2017

ECHO/SUB/2016/740181/PREV23 – ITERATE – Improved Tools for Disaster Risk Mitigation in Algeria Project co-funded by ECHO – Humanitarian Aid and Civil Protection

Table of Contents

1. Introduction ...... 1 2. Characterisation of the building stock in (local construction practice) ...... 2 2.1. Brief historical perspective ...... 2 2.2. Most common building typologies (local building practice) ...... 2 2.2.1. RC moment resisting frame buildings (with and without soft-storey) ...... 2 2.2.2. Dual RC system: moment resisting frame and shear wall buildings ...... 4 2.2.3. Reinforced concrete shear walls ...... 6 2.2.4. Unreinforced masonry buildings ...... 7 3. Processing of Available Building Data ...... 9 3.1. Available statistical data sources on dwelling and building inventory ...... 9 3.2. Definition of building classes ...... 10 3.3. Number of dwellings and buildings ...... 11 3.4. Occupants per typology ...... 12 3.5. Floor area per typology ...... 12 3.6. Replacement cost ...... 12 4. Exposure model for Blida (Preliminary results) ...... 13 4.1. Inhabitants ...... 13 4.2. Number of buildings ...... 15 4.3. Dwelling fractions ...... 17 4.4. Building fractions ...... 20 4.5. Replacement cost ...... 20 5. Limitations ...... 22 6. Conclusions and Next Steps ...... 23 7. References ...... 24

ECHO/SUB/2016/740181/PREV23 – ITERATE – Improved Tools for Disaster Risk Mitigation in Algeria Project co-funded by ECHO – Humanitarian Aid and Civil Protection

Table of Figures

Figure 1. RC moment resisting frame: a) individual and b) multi-storey building ...... 3 Figure 2. Reinforcement cage for RC: a) ribbed and b) solid slab ...... 3 Figure 3. a) Exterior and b) interior infill walls in RC building...... 4 Figure 4. Columns along with their steel cage and formwork in RC building...... 4 Figure 5. Typical high-rise dual RC system MRF-SWP buildings in Blida ...... 5 Figure 6. Concrete columns and beams in dual RC system MRF-SW building...... 5 Figure 7. a) Solid and b) mixt ribbed-solid RC slabs with dropped beam ...... 6 Figure 8. Typical RC shear wall structure: a) formwork and concrete casting, b) details of structural components ...... 6 Figure 9. a) One and b) three storeys unreinforced masonry building ...... 7 Figure 10. An old unreinforced masonry building...... 8 Figure 11. Vaulted brick floor structure: a) bottom side view and b) schematic representation of the cross section ...... 8 Figure 12. Administrative division levels of Blida, points on map represent a site for risk assessment, in this case the municipalities’ centroids...... 9 Figure 13. Map showing the number of population in Blida for the second administrative level (municipality) according to data updated in 2016...... 14 Figure 14. Map showing the number of dwellings in Blida (2008) for the second administrative level (municipality)...... 16 Figure 15. Map showing the number of buildings in Blida (2008) for the second administrative level (municipality)...... 16 Figure 16. Map showing with pie charts the dwelling fractions in Blida (2008) for the second administrative level (municipality)...... 18 Figure 17. Map showing with pie charts the building fractions in Blida (2017) for the second administrative level (municipality)...... 19 Figure 18. Map for Blida at municipality level showing with pie charts the building fractions (2017)...... 20 Figure 19. Typical architectural plan for a reinforced concrete building...... 25 Figure 20. Typical slab reinforcement for a reinforced concrete building...... 26 Figure 21. Typical ribbed slab cross section...... 27 Figure 22. Details of ribbed slab components ...... 27 Figure 23. Plan for unreinforced masonry building...... 28 Figure 24. Slabs in unreinforced masonry building...... 29

ECHO/SUB/2016/740181/PREV23 – ITERATE – Improved Tools for Disaster Risk Mitigation in Algeria Project co-funded by ECHO – Humanitarian Aid and Civil Protection

Table of Tables

Table 1. building classes...... 10 Table 2. Average number of storeys as a function of buildings height and dwellings per story...... 12 Table 3. Inhabitants and surface at municipality level...... 13 Table 4. Number of dwellings and buildings...... 15 Table 5. Disaggregation of the total number of dwelling recorded in 2008...... 17 Table 6. Average built area and replacement coast per building typology...... 21

ECHO/SUB/2016/740181/PREV23 – ITERATE – Improved Tools for Disaster Risk Mitigation in Algeria Project co-funded by ECHO – Humanitarian Aid and Civil Protection

1. INTRODUCTION

Regions with a significant percentage of old and/or non-seismically designed buildings, located in areas with deficient urban planning, are particularly vulnerable to natural hazards such as earthquakes, tsunamis and floods. Algeria has been hit by earthquakes in the northern part of the country e.g., El Asnam in 1980 (Mw 7.1) and Boumerdes in 2003 (Mw 6.8) where significant human and economic losses were endured. Using large-scale seismic risk assessment is becoming a common trend around the world to attempt to reduce potential losses from this type of events. Seismic risk assessment requires the development of three models: seismic hazard, exposure, and vulnerability of the exposed assets. Typically, exposure and vulnerability models for natural hazard risk assessment rely on proxies, such as census data and local experts’ opinion for distribution of population and buildings. Within the scope of the ITERATE project [1], the exposure modelling in Northern Algeria begins by covering a well-identified seismic prone region, the province of Blida, as a first-case study city. The main objective of this report is to develop a dataset featuring the prevailing building typologies and their metrics i.e., number of dwellings and buildings, as well as their spatial distribution and replacement cost, which are fundamental to reliably evaluate physical vulnerability and economic losses due to earthquake hazard. In Section 2, the characterization of the construction practice in Blida, is presented. Subsequently, the procedure implemented to determine representative metrics of the residential building stock is detailed in Section 3. Important results and remarks on the exposure modelling are presented at the end of this report.

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ECHO/SUB/2016/740181/PREV23 – ITERATE – Improved Tools for Disaster Risk Mitigation in Algeria Project co-funded by ECHO – Humanitarian Aid and Civil Protection

2. CHARACTERISATION OF THE BUILDING STOCK IN BLIDA (LOCAL CONSTRUCTION PRACTICE)

2.1. Brief historical perspective Chronologically, the building inventory of the city of Blida begins during the French occupation era (1830 - 1962) in which low rise masonry buildings with steel or wood floor joists were built, as well as some reinforced concrete (RC) buildings which were constructed at the end of this period to develop the first social housing projects which are still operational to this day. Later, following a pause in the first two decades following the independence (i.e., 1962-1980), the construction market burst during the 1980s and 1990s, greatly increasing the urban extension of the city with many new RC buildings with moment frame structural systems. In the last decades, the construction has been highly affected by a programme launched by the Algerian government which started in 1999 and envisages the construction of one million dwellings in the country, which has led to the development of 38 450 units being delivered in Blida alone as to June of 2017. The main arrangement used for these projects has been RC buildings with dual moment frames and shear walls as structural systems.

2.2. Most common building typologies (local building practice) Four main building typologies have been determined to characterize the majority of the as-built building stock in Blida: • RC moment resisting frame buildings (with or without soft-storey) • Dual RC system: moment resisting frame and shear wall buildings • Reinforced concrete shear wall buildings • Unreinforced masonry buildings

2.2.1. RC moment resisting frame buildings (with and without soft-storey) This type of buildings is the most common in Blida, representing about 60% of the residential building population (Figures 1 to 4). A large part of this building typology was built in the 1980s by their owners without any consideration of seismic design provisions (see Figure 1a); and it is rarely found in the old city of Blida, but is rather practiced in its surrounding areas where building terrains were available during that period. Typically, these buildings are from 1 to 3 stories high with structural systems consisting of RC frames with masonry infill walls made of hollow bricks (see Figure 3). The infill walls are provided mainly in the residential part of the building (upper floors) and are usually discontinued at the ground floor level, therefore, this building typology is characterised by soft-storey behaviour during earthquake events. Even though these buildings have most often been built after the development of the 1981 Algerian seismic code (RPA81) [2], most of them have been constructed without consideration of seismic design provisions and historically have been severely affected during past earthquake events (e.g., Boumerdes in 2003, Mw 6.8). However, some RC moment resisting frame buildings, financed by public or private property developers, which are more than 3 storeys high (see Figure 1b) with the

2 ECHO/SUB/2016/740181/PREV23 – ITERATE – Improved Tools for Disaster Risk Mitigation in Algeria Project co-funded by ECHO – Humanitarian Aid and Civil Protection ground floor usually used for parking or for commercial purposes, were built according to the Algerian seismic design provisions.

(a) (b) Figure 1. RC moment resisting frame: a) individual and b) multi-storey building

(a) (b) Figure 2. Reinforcement cage for RC: a) ribbed and b) solid slab

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(a) (b) Figure 3. a) Exterior and b) interior infill walls in RC building.

Figure 4. Columns along with their steel cage and formwork in RC building.

2.2.2. Dual RC system: moment resisting frame and shear wall buildings Due to the poor seismic performance of the RC moment resisting frame buildings with masonry infill walls recorded during the earthquake of Boumerdes in 2003, this structural typology was limited to buildings with two storeys maximum in high seismic regions. Consequently, the introduction of shear walls along with moment resisting frames for buildings more than two storeys (over 8 meters) located in high seismic regions (i.e., zone III according to RPA99 V2003 [3]) has become mandatory. Therefore, this dual RC system has become a common building typology in contemporary RC multi- storey buildings in northern Algeria.

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In this building typology (Figures 5 to 7) the lateral load-resisting system is comprised of moment resisting frames and shear walls acting together in the same direction. The RC walls are usually solid (not perforated by openings) and they are usually located at the perimeter of the building and/or around the stairwells and elevator shafts. The shear walls have a positive effect on the performance of the building such as preventing a soft storey collapse. It may be difficult to distinguish a dual system from the shear wall system in a RC building. Additional information on the selection criteria of the lateral-load resisting system type is outlined in Section 3.4 of RPA99 V2003 [3].

(a) (b) Figure 5. Typical high-rise dual RC system MRF-SWP buildings in Blida

Figure 6. Concrete columns and beams in dual RC system MRF-SW building.

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(a) (b) Figure 7. a) Solid and b) mixt ribbed-solid RC slabs with dropped beam

2.2.3. Reinforced concrete shear walls In this building typology, the lateral and gravity load-resisting system consists of RC walls and slabs. Shear walls are the main vertical structural elements with a dual role of resisting both the gravity and lateral loads (see Figure 8). In general, these walls are continuous throughout the building height, however, some walls are discontinued at the street front or basement level to allow for commercial or parking spaces. Usually the wall layout is symmetrical with respect to at least one axis in the plan. Floor slabs are cast-in-situ solid slabs (see Figure 8a). In addition to its earthquake performance, this typology uses a tunnel-form construction method in which the walls and the slab are cast in a single operation using specially designed tunnel formwork, thereby cutting the construction time significantly and making the system highly competitive. In the province of Blida, this type of construction has recently been modestly practiced for medium- to high-rise residential buildings that are usually regular in plan and in elevation.

(a) (b) Figure 8. Typical RC shear wall structure: a) formwork and concrete casting, b) details of structural components

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2.2.4. Unreinforced masonry buildings Masonry buildings are the most common housing constructions in the old city area of Blida (Figures 9 to 11). This building typology, mostly built before 1950 by French contractors, is no longer practiced. Buildings of this type are typically 1 to 3 storeys high (Figure 9), the slabs are wooden structures or shallow arches supported by steel beams (jack arch system as shown in Figure 11). The bearing walls are usually about 400 to 600 mm thick and have adequate gravity load-bearing capacity, however, their lateral load resistance is very low. As a result, the seismic vulnerability of this building typology is considered to be high.

(a) (b) Figure 9. a) One and b) three storeys unreinforced masonry building

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Figure 10. An old unreinforced masonry building.

(a) (b) Figure 11. Vaulted brick floor structure: a) bottom side view and b) schematic representation of the cross section

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3. PROCESSING OF AVAILABLE BUILDING DATA

The development of an exposure model capable of providing information about the location, value and vulnerability classification of the exposed assets at a province scale can be a challenging task. The optimal tool for building class and structural attributes identification would be a national cadastre database, containing all the buildings and their relevant structural attributes. However, in Algeria such database does not currently exist. 3.1. Available statistical data sources on dwelling and building inventory Census data along with other datasets to approximate building distribution, such as population datasets, represent a reliable source for the development of an exposure model. Using the official census has three main advantages: first, the census captures both formal and informal construction, which allows for risk assessment in regions with low social development indexes; second, it is performed to the smallest administrative level which allows, to some extent, a detailed risk assessment on a province scale and; third, the census inquiry captures dwelling attributes using a significant number of variables, thus allowing appropriate building class identification.

Figure 12. Administrative division levels of Blida, points on map represent a site for risk assessment, in this case the municipalities’ centroids.

Census surveys have been undertaken in Algeria since 1966 with a 10 year periodicity, but information about the building stock was only included after 1987. The General Census of Population and Building released in 2008 (RGPH 2008 [4]) provided by the National Board of Statistics (ONS) [5], complemented with statistics on constructions built during the period of 1999-2017 provided by

9 ECHO/SUB/2016/740181/PREV23 – ITERATE – Improved Tools for Disaster Risk Mitigation in Algeria Project co-funded by ECHO – Humanitarian Aid and Civil Protection the Direction of Housing (DL) [6] as well as the local experts opinion, are adopted in this research project to develop an exposure model for the province of Blida. 3.2. Definition of building classes The type of construction, the number of units and dispersion of dwellings are among the various attributes considered in the building census survey. However, different attributes have been used herein to define a set of building classes which are the material of construction, type of lateral load resisting system, date of construction (which has a direct relation with the design code level) and number of storeys (height of the building). The first and second attributes are organized in 4 categories: reinforced concrete moment resisting frames (RC MRF); dual reinforced concrete system: moment resisting frames and shear walls (RC MRF-SW); reinforced concrete shear walls (RC SW); and unreinforced masonry (UM). The year of construction plays an important role in classifying the building portfolio according to the level of seismic design. In Algeria, the first design code that contained provisions regarding the consideration of seismic action was released after the earthquake of El Asnam in 1980 (Mw 7.1) entitled RPA81 (1981) [2] which has been revised in 1883 and became RPA81 Rev.83 [7]. In 1988, this code was revised to give RPA88 (1988) [8]. The latest version is RPA99 (1999) [9] which was amended after the earthquake of Boumerdes in 2003 (Mw 6.8) and named RPA99 version 2003 (2003) [3]. Thus, buildings constructed before 1981 are categorized as pre-code (PC), while those built during the period ranging from 1981 to 1999 are termed medium-code (MC). The buildings constructed after 1999 are classified as post-code (PC). Regarding the number of floors, three categories are considered herein: up to three storeys as low-rise (LR), between four and seven storeys as mid-rise (MR) and more than seven storeys as high-rise (HR). Using the previously described categories, a set of classes has been defined to distinguish each building typology according to its seismic vulnerability, as described in Table 1. Table 1. Building classes.

Number of Construction type Design level Vulnerability class storeys *

Medium-code RC MRF LR MC RC moment resisting Low-rise (1-3) Post-code RC MRF LR PC frames Mid-rise (4-7) Pre-code RC MRF MR PC Mid-rise (4-7) Post-code RC SW MR PC RC shear wall High-rise (>7) Post-code RC SW HR PC Low-rise (1-3) Post-code RC MRF-SW LR PC Pre-code RC MRF-SW MR PC

Dual RC system: Mid-rise (4-7) Medium-code RC MRF-SW MR MC moment resisting Post-code RC MRF-SW MR PC frames and shear walls Pre-code RC MRF-SW HR PC High-rise (>7) Medium-code RC MRF-SW HR MC Post-code RC MRF-SW HR PC Unreinforced Masonry Low-rise (1-3) Pre-code UM LR PC (bearing walls) *Design level is according to the construction period: <1981, 1981-1999 and >1999.

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According to RGPH 2008 [4], the building taxonomy in Blida consists of 82% reinforced concrete (RC MRF, RC MRF-SW and RC SW) buildings, 11% of unreinforced masonry (UR) buildings and 7% of other typologies (OT). For what concerns the date of construction, merely 15% of the building stock has been built before the introduction of the 1981 design code (RPA81) [2] and, more specifically regarding the RC buildings, it is considered that most of the RC buildings were constructed while the RPA81 design code was already in force, nevertheless, as discussed in Section 2.2a, the seismic code is not enforced in private construction. Combining the classification from Table 1 with the data from the Building Census survey of 2008, a municipality-based exposure model containing the number of buildings for each vulnerability class was created. For the purposes of computing the seismic hazard for each asset, it will likely be assumed that all the building locations will be located at the centroid of the associated municipality area (see Figure 12), which is a common assumption when performing seismic risk assessment at a large scale (e.g., Bommer et al. (2002) [10], Sousa (2006) [11], Crowley et al. (2008) [12], Campos-Costa et al. (2009) [13]). However, this aggregation of the elements at a single location per municipality can introduce error for larger regions with unbalanced spatial distribution of the building stock and non- uniform seismic hazard, as the ground motion at the area centroid will likely be different from that at the actual location of the assets [14]. In order to investigate this issue, a more accurate exposure model could be created, in which a redistribution of the building stock per municipality will be performed based on the population distribution dataset. This dataset uses an algorithm to allocate population count, based on parameters such as proximity to roads and train lanes, terrain slope, land cover and night-time lights (Dobson et al. (2000) [15]). The buildings will be then distributed proportionally to the amount of population estimated at each location. In this way, the assets within each municipality are shifted to the regions where human activity is more evident [14].

3.3. Number of dwellings and buildings In order to perform an economic loss or damage assessment, it is necessary to quantify the number of buildings, rather than number of dwellings. Since the Algerian national census provides an aggregated number of buildings for each municipality, for the present model, the disaggregation of the number buildings for each type of dwelling was carried out by dividing the number of dwellings by the average number of dwellings per story times the average number of storeys. The dwelling fractions computed in following sections include the range of number of storeys for each building type, and through expert judgment the average number of storeys in each typology and the average number of dwellings per story were defined. The following table presents a summary of the assumed values.

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Table 2. Average number of storeys as a function of buildings height and dwellings per story.

No. of Avg. # of Dwellings Comments on number Comments on number of storeys of dwellings per storeys storeys per storey storeys 60% of 1 storey and 30% of 2 storeys and H: 1-3a 1.25 1 10% of 3 storeys 3-storey buildings 20% of 1 storey and 60% of 2 storeys and represent only 1 H: 1-3b 2 1 20% of 3 storeys dwelling per storey H: 1-3c 2.5 50% of 2 storeys and 50% of 3 storeys 1 Common practice in the country (up to 5 H: 4-7 5 2 Average storeys is not mandatory to have a lift) H: >7 10 Common practice in the country 4 Average

3.4. Occupants per typology The average number of occupants per type of dwellings in each municipality was obtained from census data. Then, the total occupants per typology can be estimated by multiplying this average with the number of dwellings of the exposure model. 3.5. Floor area per typology The average floor area for structures of each typology was estimated based on local experts’ opinion as well as using Google Maps information data for each building class in each municipality, because census data does not provide information on floor areas of dwellings. The assumed values per each building typology can be seen in Table 6. 3.6. Replacement cost Algerian Ministry of Housing Planning and the city (MHUV) [16] defines the costs per unit of area for different quality categories of residential structures ranging from 180 to 630 €/m2, with an average value of 405 €/m2. In the absence of further detailed information, which will be sought within the next tasks of the project, a rough assumption would be that the buildings of all the municipalities in the whole province have the same replacement costs.

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4. EXPOSURE MODEL FOR BLIDA (PRELIMINARY RESULTS)

In 2008, 127 205 residential buildings were reported, housing 149 775 dwellings which has been increased significantly to 205 477 dwellings in June 2017 [6]. In the following sections, the results from census data are presented.

4.1. Inhabitants

Table 3. Inhabitants and surface at municipality level. Inhabitants Districts Municipalities Surface (km2) (2016)

Blida 181 393 72.1 Blida

Bouarfa 41 418 67.16

Boufarik 82 406 50.97

Boufarik Soumaa 43 207 27.75 23 308 18.01

Bougara 59 523 86.12

Bougara 7 696 151.9 Ouled Slama 48 112 71.18

Bouinian 37 269 73.2 Bouinian

Chebli 38 445 61.46

El Affroun 46 717 55.87

Oued Djer 76 64 61.14

Larbaa 109 520 85.25 Larbaa

Souhane 561 64.5

Meftah 77 331 55.12

Djebabra 4 447 28.48

Mouzaia 59 672 83.9

Mouzaia Ain Romana 15 503 101.4

Chiffa 42 079 48.11

Oued El Alleug 47 323 55.53 Beni Tamou 55 214 27.67

Ben Khellil 36 716 43.63

Ouled Yaich 125 815 14.02 Ouled Yaich Beni Mered 51 897 15.72

Chrea 1 221 80.29 Total 1 244 457 1500.48

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Figure 13. Map showing the number of population in Blida for the second administrative level (municipality) according to data updated in 2016.

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4.2. Number of buildings

Table 4. Number of dwellings and buildings.

Dwellings (2008) Buildings (2008) Municipalities # % # %

Blida 26963 18% 21388 17%

Bouarfa 5451 4% 5299 4%

Boufarik 10834 7% 7303 6%

Soumaa 5220 3% 4906 4% Guerrouaou 2383 2% 2659 2%

Bougara 7242 5% 5379 4%

Hammam Melouane 902 1% 1150 1% Ouled Slama 3969 3% 5859 5%

Bouinian 4186 3% 4379 3%

Chebli 4151 3% 4110 3%

El Affroun 6479 4% 5503 4%

Oued Djer 1051 1% 1204 1%

Larbaa 12236 8% 9865 8%

Souhane 62 0% 232 0%

Meftah 8908 6% 7725 6%

Djebabra 428 0% 615 0%

Mouzaia 7731 5% 6491 5%

Ain Romana 1734 1% 2205 2%

Chiffa 4819 3% 4464 4%

Oued El Alleug 5572 4% 5258 4%

Beni Tamou 5215 3% 5819 5%

Ben Khellil 3782 3% 4076 3%

Ouled Yaich 14534 10% 6105 5%

Beni Mered 5756 4% 4408 3%

Chrea 167 0% 803 1% Total 149775 100% 127205 100%

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Figure 14. Map showing the number of dwellings in Blida (2008) for the second administrative level (municipality).

Figure 15. Map showing the number of buildings in Blida (2008) for the second administrative level (municipality).

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4.3. Dwelling fractions The following table shows the number of dwellings (2008) in each municipality per building classes which are different than the ones defined in Section 3.2. Table 5. Disaggregation of the total number of dwelling recorded in 2008. Type of the building RC multi-storey RC individual Other building Precarious Municipalities Masonry buildings Unknown subtotal building buildings types buildings # % # % # % # % # % # % # %

Blida 8758 32% 13356 50% 2585 10% 176 1% 1331 5% 757 3% 26963 100%

Bouarfa 281 5% 3583 66% 1148 21% 28 1% 335 6% 76 1% 5451 100%

Boufarik 3920 36% 5079 47% 1093 10% 70 1% 224 2% 448 4% 10834 100%

Soumaa 922 18% 3046 58% 1103 21% 5 0% 54 1% 90 2% 5220 100% Guerrouaou 120 5% 2037 85% 94 4% 1 0% 81 3% 50 2% 2383 100%

Bougara 1935 27% 4272 59% 804 11% 29 0% 68 1% 134 2% 7242 100%

Hammam Melouane 44 5% 417 46% 20 2% 6 1% 409 45% 6 1% 902 100% Ouled Slama 40 1% 3479 88% 339 9% 2 0% 38 1% 71 2% 3969 100%

Bouinian 682 16% 2426 58% 955 23% 7 0% 30 1% 86 2% 4186 100%

Chebli 475 11% 2116 51% 766 18% 49 1% 648 16% 97 2% 4151 100%

El Affroun 1545 24% 3747 58% 794 12% 7 0% 252 4% 134 2% 6479 100%

Oued Djer 80 8% 822 78% 22 2% 37 4% 82 8% 8 1% 1051 100%

Larbaa 2030 17% 7739 63% 1346 11% 40 0% 774 6% 307 3% 12236 100%

Souhane 18 29% 24 39% 20 32% 0 0% 0 0% 0 0% 62 100%

Meftah 1508 17% 6197 70% 547 6% 51 1% 362 4% 243 3% 8908 100%

Djebabra 1 0% 392 92% 30 7% 0 0% 3 1% 2 0% 428 100%

Mouzaia 1644 21% 4271 55% 1304 17% 70 1% 285 4% 157 2% 7731 100%

Ain Romana 13 1% 1240 72% 369 21% 14 1% 58 3% 40 2% 1734 100%

Chiffa 895 19% 3233 67% 329 7% 6 0% 254 5% 102 2% 4819 100%

Oued El Alleug 665 12% 2870 52% 1689 30% 13 0% 271 5% 64 1% 5572 100%

Beni Tamou 525 10% 3882 74% 438 8% 7 0% 293 6% 70 1% 5215 100%

Ben Khellil 116 3% 2955 78% 579 15% 15 0% 43 1% 74 2% 3782 100%

Ouled Yaich 9298 64% 4035 28% 252 2% 51 0% 427 3% 471 3% 14534 100%

Beni Mered 2672 46% 2574 45% 178 3% 40 1% 112 2% 180 3% 5756 100%

Chrea 38 23% 98 59% 16 10% 13 8% 0 0% 2 1% 167 100% Total 38225 26% 83890 56% 16820 11% 737 0% 6434 4% 3669 2% 149775 100%

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Figure 16. Map showing with pie charts the dwelling fractions in Blida (2008) for the second administrative level (municipality).

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Figure 17. Map showing with pie charts the building fractions in Blida (2017) for the second administrative level (municipality).

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4.4. Building fractions The following map shows a proposal of the building fractions for 2017 in each municipality per each of the building typologies defined in Section 3.2. This was derived based on official census data (the total number of dwellings recorded in 2017) together with the disaggregation proposed on Table 2 which is based on previous research and by local experts. It is important to note that this disaggregation was derived rather than taken from official data, given that the official census information from 2017 only contained the total number of dwellings and the previous census information presented on Table 5 does not provide a breakdown in the same typology which will be used in the current project, defined in Table 1.

Figure 18. Map for Blida at municipality level showing with pie charts the building fractions (2017).

4.5. Replacement cost The final step is the estimation of the replacement cost per building type, which differs from the exposed value. In this context, the replacement cost refers to the value of replacing a building in accordance with the latest building standards applicable for the country, and it includes the cost of the lateral load resisting system and the non-structural components (the cost of the terrain lot is not included).

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The following table presents the average area per dwelling and the average replacement cost per built area utilised in the model, which were estimated based on local research and dictated by the Algerian Ministry of Housing Planning and the city (MHUV) [16]. It can be observed that a range of replacement cost is stated and that no specific value is set for each typology. This is because, within the province of Blida, the replacement cost varies considerably from urban to rural areas, but it was decided to maintain this range for all typologies until additional research becomes available, to accurately define a replacement cost for each.

Table 6. Average built area and replacement coast per building typology. Average Replacem Number of built Construction type Design level Vulnerability class ent coast floors area (€/m2) (m2) Medium-code RC MRF LR MC RC moment Low-rise (1-3) 90 Post-code RC MRF LR PC resisting frames Mid-rise (4-7) Pre-code RC MRF MR PC 170 Mid-rise (4-7) Post-code RC SW MR PC RC shear wall high-rise (>7) Post-code RC SW HR PC 340 Low-rise (1-3) Post-code RC MRF-SW LR PC 90 Pre-code RC MRF-SW MR PC Dual RC system: Mid-rise (4-7) Medium-code RC MRF-SW MR MC 170 180 - 630 moment resisting Post-code RC MRF-SW MR PC frames and shear Pre-code RC MRF-SW HR PC walls High-rise (>7) Medium-code RC MRF-SW HR MC 340 Post-code RC MRF-SW HR PC Unreinforced Masonry (bearing Low-rise (1-3) Pre-code UM LR PC 90 walls)

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5. LIMITATIONS

A great amount of information was reviewed in order to define each building class. For the most common typologies, reinforced concrete buildings, a substantial amount of data was successfully gathered from different private and governmental institutions in order define attributes like the number of dwellings, date of construction and building height. However, in terms of the number of buildings per each building typology, little information has been gathered in order to reliably disaggregate the number of buildings in each municipality per building classes defined in Table 1. This parameter was derived for this report considering official data (the total number of dwellings and their fractions as well as the total number of buildings recorded in 2008, in addition to the number of dwellings recorded in 2017) together with assumptions recommended in previous research and by local experts’ rather than actual data. Furthermore, disaggregation of the number of buildings in each municipality per building classes will be cross-checked after the feedback from the in-situ data collection that will be carried out using a smartphone/tablet App which is being developed within the scope of the ITERATE project.

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6. CONCLUSIONS AND NEXT STEPS

An extensive review of available data on the Algerian building taxonomy and identification of deficiencies, was carried out as a preliminary step for exposure modelling. This step enabled a better understanding of the current exposure characterisation of Northern Algeria in-built, adopting the province of Blida as a first-case study city. Explored sources consisted of: census data, national agencies, municipality archives, scientific studies and reports, as well as online tools. A full survey on replacement costs for buildings (to be used for estimates of economic losses) has also been conducted. This initial collection of available information will be complemented with field surveys. Given that the reviewed data from census and additional sources are usually insufficient, additional data will be collected via different stakeholders, particularly university students and practitioners. This will be achieved by using data collection form that is reproduced electronically to rapidly and efficiently reach large numbers of people in large areas. The different fields of building information to collect are assembled in a user-friendly smartphone/tablet App that will be distributed across the above-mentioned stakeholders during the workshop that will take place at the University of Blida on the 13th of November 2017. The use of the App will speed up the process, with respect to paper forms, will minimize errors and will transfer exact information such as geographic location or photos. Also, the App will connect directly to a Web-Based Platform so that information can be uploaded and checked in real time. Otherwise, the App will also enable the information to be stored in the device (smartphone or tablet) until upload is carried out.

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7. REFERENCES

[1] http://www.iterate-eu.org/ [2] RPA81 Algerian seismic Regulation, Ministry of Housing and Urban-Planning, January 1982. [3] RPA99 Rev. 2003 Algerian seismic Regulation, Ministry of Housing and Urban-Planning, January 2004 [4] Recensement General de la Population et de l’Habitat RGPH (2008), Direction de la Planification et de l’Aménagement du Territoire (DPAT), Blida, Algeria. [5] Office national de la statistique (ONS), http://www.ons.dz/ [6] http://www.wilayadeblida.dz/ [7] RPA81 Rev. 83 Algerian seismic Regulation, Ministry of Housing and Urban-Planning, January 1984. [8] RPA88 Algerian seismic Regulation, Ministry of Housing and Urban-Planning, January 1989. [9] RPA99 Algerian seismic Regulation, Ministry of Housing and Urban-Planning, January 2000. [10] Bommer, J. J., Spence, R., Erdik, M., Tabuchi, S., Aydinoglu, N., Booth, E., Re, D. D., Pterken, D. (2002). “Development of an Earthquake Loss Model for Turkish Catastrophe Insurance”. Journal of Seismology, 6:431-446 [11] Sousa, M. L. (2006). Seismic risk in the mainland of Portugal (PhD thesis), Instituto Superior Técnico, Portugal (in Portuguese). [12] Crowley, H., Borzi, B., Pinho, R., Colombi, M., Onida, M. (2008). “Comparison of two mechanics-based methods for simplified structural analysis in vulnerability assessment”. Advances in Civil Engineering, 2008:19. [13] Campos-Costa, A., Sousa, M. L., Carvalho, A., Coelho, E. (2009). “Evaluation of seismic risk and mitigation strategies for the existing building stock: application of LNECloss to the metropolitan area of Lisbon”. Bulletin of Earthquake Engineering, 8:119-134. [14] Silva, V. (2013). Development of open models and tools for seismic risk assessment: application to Portugal (PhD thesis), University of Aveiro, Portugal. [15] Dobson, J., Bright, E., Coleman, P., Durfee, R., Worley, B. (2000). “LandScan: a global population database for estimating populations at risk”. Photogrammetric Engineering and Remote Sensing, 66:849-857. [16] Algerian Ministry of Housing Planning and the city, http://www.mhuv.gov.dz/Pages/IndexFr.aspx

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ANNEX 1 CONSTRUCTION DETAILS

Figure 19. Typical architectural plan for a reinforced concrete building.

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Figure 20. Typical slab reinforcement for a reinforced concrete building.

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Figure 21. Typical ribbed slab cross section.

(a) (b) Figure 22. Details of ribbed slab components

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Figure 23. Plan for unreinforced masonry building.

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Figure 24. Slabs in unreinforced masonry building.

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