RECONSTRUCTION OF HOUSING DESTROYED IN THE 2003 BAM-IRAN EARTHQUAKE

RECONSTRUCTION OF HOUSING DESTROYED IN THE 2003 BAM-IRAN EARTHQUAKE

A. Astaneh-Asl1, M. Saeedikia2, M.H. Havaii3, M. Fat’hi4, S.M. Fatemi-Aghda5, S. R. Mir Ghaderi6 and G. Heidarinejad7

ABSTRACT

On December 26, 2003, a magnitude 6.3 earthquake devastated the cities of Bam and Baravat and the surrounding villages in Islamic Republic of Iran. More than 26,000 people perished and thousands were injured while the quake destroyed more than 53,000 houses and other buildings. After the quake, the Housing Foundation of Islamic Revolution of Iran, HFIR, (Bonyad Maskan Enghelab Islami Iran) was put in charge of the reconstruction of Bam including housing, commercial units and infrastructures. Within four weeks after the earthquake, about 30,000 survivors were placed in tents and other emergency shelters while removal of debris and construction of temporary housing continued and within 8 months, about 30,000 temporary houses, each with an area of about 20m2 (180ft2) were built and replaced the emergency shelters. In the meantime the master plans for urban development of the cities of Bam and Baravat and 260 villages were outlined. The Housing Foundation formulated a “4-element” plan for reconstruction of the permanent homes. In the plan, the new homes would replace the destroyed homes following the traditional 3-element team of owner-architect-contractor, with the owner in full charge. In the process, the Housing Foundation would act as the fourth element helping the owner with finances, architectural/engineering services, construction materials and the contractors. At this writing (January 12, 2006) more than 22,000 permanent homes have been completed and more than 15,000 are in various stages of construction. All 25,000 rural homes are to be completed by March 21, 2006.

Introduction

On December 26, 2003 (5 Dei, 1382 Hejree Shamsee on Iranian Calendar) at 1:56:57

1Professor, Dept. of Civil and Env. Engineering, University of California, Berkeley, CA, 94720-1710, USA 2Head of Bam Reconstruction Project and Minister of Housing and Urban Development, Islamic Republic of Iran. 3Project Manager, Bam Reconstruction Project, Bonyad Maskan Engheleb Islami, Islamic Republic of Iran. 5 Director General of Public Relations, Bonyad Maskan Engheleb Islami, Islamic Republic of Iran. 4Assocate Professor, Tarbiat Moallem Univ. of Tehran and Gen. Director of Res. Inst. of Natural Disaster of Iran. 6Assistant Professor, Department of Civil Engineering, University of Tehran, Islamic Republic of Iran 7Associate Professor, Tarbiat Moddares Univ. and President of Building and Housing Research Center, I. R. Iran

Greenwich Mean Time (5:26:57AM local time) a magnitude Mw=6.3 earthquake devastated the historical cities of Bam and Baravat and more than 260 villages in Kerman Province of the Islamic Republic of Iran. About 200,000 people were living in the areas of severe shaking. The death toll from the quake was estimated at 32,000 (26,271 official death certificates were issued) and more than 25,000 were injured (BMEI, 2004). The quake destroyed more than 53,000 residential and other buildings, caused damage to infrastructure and lifelines and damaged the historical Bam Citadel (Arg-e-Bam). In the following, after a brief summary of the seismological aspects and the damage, we will focus on the reconstruction of homes destroyed by the quake followed by lessons learned and recommendations. Table 1 shows a select statistical data on population, agricultural and industrial aspects of the greater Bam area affected by the 2003 quake collected by the Iran Statistical Center (Markaz-e-Aamaar-e- Iran) in 1996 census (ISC, 2003.)

Table 1. Statistical dataa on the Bam Greater Cityb prior to earthquake (ISC, 2003) Item Data

Total Population 223,000 Number of industrial workshops (number of active ones) 1266(837) Number of residential buildings (number occupied in 2002) 34531(31222) Buildings with engineered steel or reinforced concrete structures 31 Number of adobe (khesht-o-gel) residential units 17524 Number of brick-and-steel or stone-and-steel residential units 13364 Number of residential units with cement block, brick , or stone 1180

a Data is estimated based on the 1996 census (ISC, 2003). b Bam Greater City consists of cities of Bam and Baravat and 260 villages.

The Bam-2003 Earthquake On Friday, December 26, 2003 (5 Dei, 1382 Hejree Shamsee) at 1:56:57 Greenwich Mean Time (5:26:57AM local time) a magnitude Mw=6.3 earthquake shook the southeastern Iran, Fig. 1(a). The depth of hypocenter was estimated at 7 km. Fig. 1(b) shows three components of the acceleration records obtained by the Building and Housing Research Center (BHC, 2004a) of Iran from an instrument located at the governor’s building in downtown Bam. (From: Building and Housing Research Center, Iran, ( www.bhrc.ac.ir))

(b) Source:www.geosource.ac.uk

Bam

Persian Gulf

Caspian Sea

(a)

Vertical

Longitudinal

Transverse

Acc. (mm/s2)

Acc. (mm/s2)

Acc. (mm/s2)

Damage to Built Structures

The earthquake destroyed 80% of the buildings in the affected areas and damaged more than 17% of the buildings beyond repair (Havaii and Hoseini, 2004). More than 50,000 houses were destroyed with about half of them in the cities of Bam and Baravat and the remaining half in the surrounding villages. The quake also caused significant damage to the historical Bam Citadel (Arg-e-Bam), Figure 2.

In the cities of Bam and Baravat, many of the houses that collapsed were non-engineered buildings with brick bearing walls and jack-arch (tagheh-zarbi) roofs, Fig. 3(a). The jack-arch (tagheh-zarbi) roof system consists of approximately 5cm (2-inch) thick relatively flat brick arches, with rise of about 5cm-10cm (2-4 inches) placed between the two adjacent steel beams with I-shaped cross section. The distance between the I-beams is usually about one-meter (3 feet). To balance the horizontal push-out force of the arch on the I-beams, rebars are used to connect the bottom flanges of the I-beams at close intervals. The system, quite common throughout Iran, is covered by the Iranian seismic code and if designed and constructed per code requirements, is expected to fulfill the “life safety” objective of the code. However, many buildings with jack-arch (tagheh-zarbi) floors, especially in one and two-story buildings in small towns and rural areas are constructed lacking engineering requirements and sufficient inspections. The result is often the tragic collapse of these relatively heavy, weak and non-ductile masonry buildings during even a moderate earthquake.

Figure 2. The historical Bam Citadel (Arg-e-Bam): (a) before and; (b) after the earthquake

Photo: Janice Holve (b)(a)

Figure 3. (a) A collapsed house with jack-arch roof in Bam and (b) a partially collapsed adobe house in a village near Bam

(b)(a)

Figure 1. (a) Location of Bam and; (b) Strong Motion Record obtained by BHRC Station in Bam.

In the affected villages, the main damage was the collapse of houses and shops, the majority of which were adobe one story buildings with mud brick arch roofs and relatively thick mud brick and mud mortar walls, Fig. 3(b). The damage to the infrastructure and non-building facilities was also substantial though not as devastating as the one to non-engineered buildings. In contrast most of the 31 engineered buildings in greater Bam area (see Table 1) survived the quake without significant structural damage, Figure 4(a). One exception was the concentrically braced 4-story residential building, Fig. 4(b), which developed soft ground floor and collapsed during the quake. The damage to kanats, the main source of water for the region, was extensive and it was determined that if kanats were not repaired rapidly, the resulting draught would cause the loss of most of the date and citrus trees, the main local agriculture. Therefore, one of the first renewal efforts of the government was to restore the damaged kanats to their pre-quake water production level. Kanat, a thousands years old Iranian invention, is a system of vast underground tunnels, often many kilometers long with gentle slopes, which collect subsurface waters and brings the water to the cities and farms.

The Bam airport building survived the quake and was operational immediately after the quake being used extensively for transport of the injured out and bringing in the first responders and emergency rescue and recovery equipments. Most of the local government buildings, religious and cultural institutions, health care facilities, schools and two universities in Bam were destroyed or damaged beyond repair and had to be demolished. At this writing (January 12, 2006) almost all of the demolished government buildings, hospitals and clinics, schools, two universities, two jails, a stadium and a complex of sports facilities are under construction and on the average about 70% complete. In addition to the government, the Iranian and international non-government organizations (NGOs) are also helping the reconstruction primarily building cultural, health and educational facilities which are expected to be completed by December 2006, the third anniversary of the 2003 Bam earthquake.

Emergency Response and Recovery

After the earthquake, the Iranian and international first-responders rushed to the affected areas with the aim of tending to the injured and rescuing the victims trapped under the rubble.

Figure 4. (a) The Main Mosque (Masjed Jame’a) under construction in Bam sustained no visible structural damage and (b) collapsed building with steel concentrically braced frame

(b)(a)Photo: Housing Foundation, Iran

Unfortunately, due to the heavy damage and timing of the earthquake, occurring in the early morning hours, more people were killed in this earthquake (estimated at 32,000) than injured (estimated at 25,000). Since the Bam airport, was still functional, the national and international emergency response teams as well as the supplies could reach the victims relatively fast and the injured were transported to the hospitals outside the affected areas shortly after the quake. The Islamic tradition requires a rapid burial of the dead. Therefore, in the aftermath of the quake, the bodies of the dead had to be recovered and buried as fast as possible. A large team was dispatched from Tehran’s main cemetery to undertake the task of recovery and religious burial. Despite all the efforts, the quake brought to light the importance of the coordination or the lack of it, among the responding agencies. To deal with national disasters in the future, the need to develop a “decision-tree” for the decision makers to manage a catastrophe and to put in place a plan of management for the responding organizations and their command and control personnel became paramount. Such plan would make the emergency response during the first vital days more effective.

Iran’s Innovative Approach to Reconstruction of Collapsed Houses

About a month after the earthquake, the president of Islamic Republic of Iran charged the Housing Foundation of Iran with rebuilding the two cities of Bam and Baravat and the 260 villages damaged by the quake. The second author, M. Saeedikia, who was then the Director General of the Housing Foundation, was appointed as the Director of the Bam Reconstruction Project. The government also formed a cabinet level Steering Staff Headquarters (Setaad Rahbordy), for reconstruction of Bam which was charged with steering all the efforts related to response, recovery, reconstruction and renewal of the affected areas. An act of Iranian Parliament (Majlis Shorayeh Islami) gave the authorities and responsibilities of the President of Iran to the Steering Staff Headquarters (Setaad Rahbordy) for items under its charge regarding renewal of the greater Bam area. The Steering Staff Headquarters has the following membership: three members appointed by the President, the Ministers of Housing and Urban Development, Interior, Justice, Economy and Treasury, Culture and Islamic Guidance, the Head of the Management and Planning Organization, the Head of the Iran Red Crescent Organization, the Head of the Bam Reconstruction Organization (the second author), and the Governor of the Kerman Province where Bam is located. The first action taken by the Steering Staff Headquarters was to establish reconstruction policies, identifying the responsibilities of all agencies and sectors involved in the reconstruction as well as approving the funding for various segments of the reconstruction. One of the first actions of the Steering Staff Headquarters (Setaad Rahbordy) was to assign the task of debris removal and reconstruction of urban and rural housing to Housing Foundation of the Islamic Revolution (HFIR). Utilizing its past experience in reconstruction of the rural areas, the Housing Foundation implemented a model for reconstruction of the affected areas, which was a refined version of its methods, used in recent years, and submitted the plan to the Steering Staff Headquarters (Setaad Rahbordy) for its approval. According to this model, called herein the “Bam-Iran Model” the affected areas are reconstructed fulfilling three basic expectations: (a) participation by the people involved, (b) preserving the historical and Islamic character of Bam and (c) designing and constructing seismically safe buildings.

The essence of the plan to rebuild the areas destroyed by a disaster was to engage participation of the survivors in reconstruction. Throughout the project, the homeowners, who had lost their homes during the disaster, were treated as “clients” of the government who needed to build their homes, rather than victims who needed housing built for them by the government in a “big-brotherly” approach as was the case in the past in Iran and many other countries where the central government plays a major role in reconstruction. The Bam reconstruction plan was divided into three segments: (1) the reconstruction of rural homes with first priority, (2) the reconstruction of homes in the cities of Bam and Baravat, and (3) the reconstruction and restoration of various components of the infrastructures such as the kanats (to provide water supplies), power lines, water pipelines, sewer system, communication lines and transportation lines and facilities. In the following a brief summary of the reconstruction of homes in rural and urban areas, Items (1) and (2) in above list, is provided.

Rural Housing

Reconstruction of rural houses, due to their less complex nature compared to urban housing, started first. Figure 5 shows the architectural plan and a cross section of the rural permanent homes. The standard rural homes had 60 m2 (650 ft2 ) area and were one story single family detached buildings with a living room, two bedrooms, a kitchen, and a separate shower and restroom in accordance with most homeowners’ religious preferences. If a homeowner opted for a larger home, the standard plan could easily be expanded to 90 m2 (970 ft2 ) to include a third bedroom and a larger living room as shown in dashed lines in Figure 5.

Although the plans were standard, the homeowners had a broad choice of interior finishes and fixtures. At this writing (January 12, 2006) more than 19,000 rural homes have been completed and occupied and the remaining 6000 rural homes are under construction scheduled to be completed and occupied by March 21, 2006. Figure 6 shows two rural homes under

Section A-A

1. Living Room 2. Kitchen 3. Bedroom 4. Bath 5. Toilet 6. Terrace

Plan

Figure 5. Architectural details of Bam rural houses (Havaii and Hosseini, 2004)

construction in villages near Bam. Mr. Roshan, a date farmer in the foreground on the left photo in Figure 6 is the owner and was helping to build his house.

Figure 7 shows the structural details of the rural homes being constructed in damaged

villages. The steel structures of the houses consist of shop-welded and field-bolted “inverted-V” concentrically braced frame in both directions. The foundations are reinforced concrete isolated

footings tied to each other by reinforced concrete tie beams. The sizes of footings are set by the site soil condition established by the soil mechanics laboratories set-up by the Housing

Figure 6. Two rural homes under construction in villages near Bam

Framing Plan

Roof System

Foundation Plans

Steel Frame

Figure 7. Structural details of rural housing (Havaii and Hosseini, 2004)

Foundation in the area. The roof system used in the structures is shown in Figure 7, which

consists of pre-cast reinforced concrete joists, spaced at 50cm (20 inches) intervals and the space between the joists is filled with hollow clay blocks. The system, used extensively in Iran in engineered buildings, performs well under gravity and seismic loads and because of the hollow blocks, acts as temperature insulation suited for the harsh cold and hot weather conditions of Bam. The structural design of rural homes (as well as the homes in the cities discussed later) satisfies the Iranian Seismic Code-2800 (BHRC, 2003). Figure 8 shows the response spectra of the code. Using the spectra, the design base shear for Bam structures was established as follows:

Base acceleration (percentage of g), A=0.35 Importance Factor, I=1.0, Response Modification Factor, R=6.0

Spectral acceleration, B= 2.5(To/T) 2/3 ≤ 2.5 (Conservatively, a value of 2.5 is used) Weight of one unit for seismic design, W= 65 metric tons (143 kilo-pounds) Base shear used in seismic design, V= (ABI/R) W = (0.35×1.0×2.5/6) (65 tons) = 9.5 tons.

Prior to construction, the structure of Bam homes was tested under simulated seismic

0.4 0.5 0.7 1.0 Soil Type IV Soil Type

Soil Type I Soil Type II

0.0 1.0 2.0 3.0 4.0

2.5

2.0

1.0

0.0

Figure 9. Horizontal Force- displacement curve and a bracing connection (BHRC, 2004b)

Figure 8. Design response spectra in Iranian seismic code (BHRC, 2003)

Photo: BHRC, Iran

loads at the laboratories of the Building and Housing Research Center of Iran (BHRC, 2004b). Figure 9 shows cyclic loading versus horizontal displacement of the roof for one of the specimens. The objective was to study inelastic cyclic behavior of the system in order to verify the applicability of Response Modification Factor equal to 6 used in seismic design as well as to improve the ductility of the system by modifying the connection details as well as the members. Also, the tests were performed to establish stiffness, failure modes, damageability and energy dissipation characteristics of the system. After completion of the tests pre-fabrication of the steel structures en-mass began in Bam in five newly established steel fabrication sites. The sites were under strict quality control especially with regard to the quality of welds, which were done by certified welders. Each fabricator had a specified color for painting the steel so the fabricator of all steel pieces could be identified. The fabrication of steel structure as well as its erection at the site was under strict quality control by the engineers certified by the Professional Engineers Board of Registration (Nezaam Mohandesi) of Iran. Each structure bore the stamp of the inspector on it which ensured a diligent inspection of the job by the inspector.

Reconstruction of Destroyed Homes in the City of Bam

The first step in providing shelter to victims, who were living in emergency shelters (tents), was to build temporary housing until permanent homes could be built. Within 8 months after the earthquake, about 30,000 temporary houses, each with an area of about 20 m2 (215 ft2) were built on the location of the destroyed homes or were installed as prefabricated units. For permanent housing the Housing Foundation developed an innovative “4-element” approach. In this approach, the destroyed homes were replaced by the new homes built by the traditional 3-element team of owner-architect-contractor. The role of the Housing Foundation was to act as a fourth element to help the surviving owners of the quake with finances, architectural and engineering services, construction materials and the contractors. At this writing (January 12, 2006) more than 4,000 permanent homes have been completed and occupied by the owners in the cities of bam and Baravat and more than 19,000 are in various stages of completion. Unlike the rural housing, the plans for homes in the City of Bam were not similar and varied in architectural aspects. The owners of the destroyed homes were still the most important element of the 4-elemnt (owner-architect-contractor-government) model. The Housing Foundation during the first 3-months after the quake built a Technical and Engineering Services Headquarters in Bam, which included a building to house more than 41 architectural design offices, a building to exhibit various materials and fixtures such as bath tubs, tiles, etc., and several sites to build the model homes for the residents of Bam to visit and select from. After the issuance of permit and selection of the contractor, the construction of the home under the supervision of the owner and the government inspectors would start. Figure 10 shows the examples of the exterior and the interior of the homes built in Bam since the earthquake.

Figure 10. Examples of exterior and interior of home rebuilt in Bam

Lessons Learned and Recommendations

1. The experience of the response to the Bam earthquake indicated the paramount need for a comprehensive plan of efficient emergency response to disasters in Iran which would include a “decision-tree” and disaster management plans.

2. The “4-element” model of the reconstruction of rural and urban housing, implemented by Housing Foundations, has been a successful undertaking resulting in the replacement of more than 58,000 houses destroyed in the earthquake within three years after the earthquake.

3. There is a need for more efficient plans for reconstruction of private commercial buildings in Bam which currently are not reconstructed with the same speed as the houses.

Acknowledgments This paper is a result of a self-supported research project undertaken by the first author; Abolhassan Astaneh-Asl, to investigate and document the reconstruction of Bam. The remaining authors are all leaders in certain aspects of the reconstruction. The first and second authors have been friends since college days; though have not worked together on any project since 1970’s. The authors would like to express their special thanks to Mr. Engr. Rashtian of the Housing Foundation of Iran for his untiring efforts in reconstruction of Bam as well as his contributions to this paper. The opinions expressed here are those of the authors and not necessarily the opinions of the individuals and agencies whose names appear in this paper. All photographs are by Abolhassan Astaneh-Asl unless otherwise noted. The Middle-east Earthquake Hazard Reduction (MEHR) Initiative and its Iran Directorate, led by Professor Fatemi-Aghda, provided logistical and transportation support for the first author during his four research trips to Bam and other earthquake affected areas in Iran. The support is sincerely appreciated.

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