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RReessttoorraattiioonn PPllaann ooff PPyyaammbbaarr MMoossqquuee iinn BBaamm CCiittaaddeell ((AArrgg ee BBaamm)) Eskandar Mokhtari1, Mahmoud Nejati2 , Naghme Khatuni3, Shirin Shad4

1 Director, Recovery Project of Bam’s Cultural Heritage,

2 Deputy of Research & Technical Consultant, Recovery Project of Bam’s Cultural Heritage,

3 Restoration Expert, Recovery Project of Bam’s Cultural Heritage,

4 Manager of Technical Office, Recovery Project of Bam’s Cultural Heritage

Email: eskandarmokhtari@yahoo.com, nejati@saamco.net, naghmeh2@myway.com, shirin.shad@gmail.com ABSTRACT One of the monuments in Bam Citadel that is collapsed seriously more than 85% during the earthquake on December 2003; is called Pyambar Mosque. This paper is trying to explain the restoration plan for recovery of this monument. The restoration method could present a good example for collaboration between the engineering restoration outcome and traditional restoration knowledge. The achieves, which have been resulted from the pilot projects in Bam Citadel with different national and international colleagues, could be used and upgraded more in the restoration of Pyambar Mosque. In this regards, natural material are using as tensile element and laying horizontal mesh to strength the adobe structures against dynamic loads of the earthquake. It is trying to rebuild the damaged parts according to the original location of the walls to keep the monumental authenticity and to show the architectural values and could generate important experiences for improving stiffness of the adobe buildings. In this paper, the studies and current restoration plan (in process) are addressed.

Figure 1 Pyambar Mosque before and after the earthquake of December 2003

KEYWORDS: Bam, Citadel, Arg e Bam, Pyambar Mosque, Restoration

1. GENERAL VIEWS OF PYAMBAR MOSQUE Pyambar Mosque is located in the western part of the Citadel near Bazaar, sustained a loss more than the other parts through earthquake. The access to the single monument could be possible by the north entrance from Baazar alley on south, east and west. Because of the distance between Baazar and Jaame-Mosque, in the past this small vestry was regularly used to pray by the traders and passengers. However the erratic parts in the process of fabrics design make evolution in the area, this special instance has survived originally during the past years. An altar which was located in the western part may dictate that the building belongs to the Safavid Period. After removal of the debris, the archaeologists started the excavation and found that there are causeway, catch basin and clay pipe in the 80 cm lower than the ground level, which were buried and prevented up to now. According to the archaeological investigations, it might be built under the remains of early construction.

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2. DOCUMENTATION At first, the experts tried to find all the records which had provided before the huge collapse. Only some plans and three reports had been obtained before the earthquake, were the basic data for approaching the team workers to more detail. In the next step, all the plans and sections were drown which conclude to produce the map of demolition percentage and pathology plans, the current situation, the comparative and intervention plans. According to the evidences, the last intervention before earthquake had been happened in 1990.

Figure 2 Pyambar Mosque; picture, northern façade & plan, before earthquake

Even so the primary archaeological theory indicates, this mosque were a part from a big mosque such as the Jaame-Mosque in the south east of the Citadel, more documents and records are needed to approve this theory. On the other hand, the Mosque is placed near the Caravansary and might to be used by the passengers and traders. To approach the precise evolution, some more investigations are needed. 3. STRUCTURAL PATHOLOGY Through the earthquake, all the western part of structure was collapsed and as mentioned before, more than 85% of the structure destroyed (Figure 3). The thick column which suffered fewer amounts of damages transferred the gravity loads to the ground; the domes in Pyambar Mosque collapsed completely and main central column could stand with experiencing of too much cracks in bottom, see Figure 4. The failure pattern in Pyambar Mosque rules as the main key for engineering restoration plan of the monument. The pathology of the building is shown, the typical shear cracks and out of plan failure in main walls and general collapse that caused by bending moments that reached the capacity of the domes.

Figure 3 Demolition percentage of Pyambar Mosque

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4. SEISMIC BEHAVIOR According to the original geometry of the building before earthquake, (it is depicted in 3-D of Pyambar Mosque in Figure 5); this monument has had four dome shape roofs that they were laying on surrounding walls with main load on the central column. The main shock of earthquake acted in direction of west-east and the most part of the structure collapsed heavily. The domes destroyed completely and although the central column stood alone but inclined on the direction to the west, Figure 4.

Figure 4 Pyambar Mosque, after the earthquake, view south-west As it is shown in previous pictures, the Pyambar Mosque was destroyed heavily and the most parts of the structure lost during the earthquake of December 2003, means, the restoration plan should consider many aspects for recovery of this monument.

5. RESTORATION PLAN Since the earthquake of December-2003, the main focus on restoration plan of Pyambar Mosque has started using the last experiences in various restoration pilot projects in Bam Citadel, with special noting to the tradition methods that based on the previous experiences in Bam Citadel and with concerning the earthquake load as a destructive lateral load on the structure. The authenticity is considered in accepted level, although the level of destructions in monument was high, the fourth reference. The restoration plan of Pyambar Mosque is including to the four main parts (for more detail see the third reference); documentation, pathology, restoration, rehabilitation. This part is trying to describe all the parameters in concern with the applied structural appliance in the restoration plan:

5.1 Structural Appliances The main key in restoration plan of Pyambar Mosque is based on strategies that make the monument strong against the further earthquakes. Then the main idea for restoration; is to use the natural materials as introducing tensile elements to the building. The introduced tensile element is called “Siess” which are planned to insert in two months in walls and domes of the Pyambar Mosque. Siess is made of the skin of palm trees, this material is very cheap and available in huge amounts of the area. For anti – termite processing some recommendations are planned and relevant to provide a shear effect on the elements, some specific production will be applied. Up to any presenting restoration plan in Recovery Project of Bam’s Cultural Heritage (RPBCH);

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5.2. Lateral Load Lateral load made by earthquake, caused major failures in the domes and surrounding walls. On the other hand, the continuity in connection between walls and domes has been lost and made the big failure in the whole structure. The study on failure criteria with provided 3-D map (Figure 5) of the structure, could lead the main keys for providing the location of the vertical and horizontal tensile elements that are described in next session.

Figure 5 3D of Pyambar Mosque, after the earthquake, view north-east 5.3. “Siess” Introduced To The Monument As A Strengthening Materials For Earthquake Load Definitely the crashed area of the monument, needs restoration / reconstruction and as it is mentioned above, introducing tensile elements for avoiding such experience in December 2003, are needed (with consideration of authenticity). Siess will be introduced to the structure vertically and horizontally in different forms. The vertical elements will provide any required bending resistance and horizontal elements will act as the elements that provide shear resistance. Implementation of these two elements is different and more detail will be published in next annual report of RPBCH. The following picture shows shortly the details. Figure 6 shows the drilling procedure for inserting vertical elements that will be installed with grout injection, as in this figure is cleared, the vertical elements follows each other in center line of the main walls and the maximum distance is around 1.1 m that is reduced to 0.6 m in the compulsory points. The horizontal elements that are provided for shear resistance will be inserted as a mesh form with thin thickness and there are in production line by local producers right now. In Figure 7, the sample of horizontal mesh with thick element (available on time in the site) is shown; some simple tool is produced for installation process.

Figure 6 Drilling procedures for inserting vertical Siess elements in main walls of Pyambar Mosque

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The most advantages of the Siess elements can be listed as following: • being cheap, • available on Bam in every season, • the craftsmen could work with the Siess easily, • flexible materials, • anti-termite (some reports shows its resistance against the termite is around 300 years), • compatible with adobe and whole structure (color and mechanical properties), • keeps the authenticity in advanced level, • provides ductility for the structure, • formability for any kind of usage and insertion.

Figure 7 Horizontal Siess, simulation process with available thick elements in site just for learning the implementation adjustment

(the main useable Siess will be strongly thinner) 6. CONCLUSION The restoration of Pyambar Mosque as the first engineering restoration in RPBCH in Bam Citadel that is leading completely from the local experts; is worth too much. Because is based on gathered experiences with different national and international colleagues due to execution of their pilot projects. It means the proposed restoration plan and its implementation process just based on local availability and could lead the project to the economic and cost effective solutions for the further restoration. The Siess elements are available too much in the area and in case of acceptance of this methodology as the main method for strengthening the adobe buildings in Bam Citadel, then the Siess element will be used in huge amounts of restoration process in Citadel. This method has potential to use in other parts of the country and in the world. Simple type of implementation process in one hand and the provided ductility on the other hand, and many other advantages of this material that keeps the authenticity of the monuments are the main factors of Siess that should be prevailed to the other introduced tensile elements in restoration pilot projects in RPBCH. For final confirmation to use the Siess elements in huge scale in restoration plans in Bam Citadel; the full dynamic tests on shaking table are advised and specific static tests for study on bonding effect are considered. Definitely the final confirmation of this material is based on the decision were made by Steering Committee of RPBCH and World Heritage Committee.

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7. REFERENCES Eskandar Mokhtari Taleghani, Mahmoud Nejati, Shirin Shad, Oct. 12-17, 2008, Lessons learned from Recovery Project of Bam’s Cultural Heritage, 14th World Conference on Earthquake Engineering, Beijing China,

Eskandar Mokhtari Taleghani, Mahmoud Nejati, Farshid Khademi, Shirin Shad, Oct. 12-17, 2008, Restoration Plan of Second Gate in Bam Citadel (Arg e Bam), 14th World Conference on Earthquake Engineering, , Beijing China,

Mahmoud Nejati, 2008, Annual Report, Central Archive, Recovery Project of Bam’s Cultural Heritage,

Mehdi Keramatfar, 2007, Demolition percentage of Bam Citadel, Central Archive, Recovery Project of Bam’s cultural Heritage (RPBCH), Tehran-Iran,

Architect Mahsa Nicknam, 2007, 3-D of Pyambar Mosque, Central Archive, Recovery Project of Bam’s Cultural Heritage,

Mahshid Jaafari, 1990, Documentation and Pathology of Pyambar Mosque, Recovery Project of Bam’s Cultural Heritage.