Hagia Sophia, which was converted into a mosque with the conquest and served as a mosque for 481 years, was closed to the public with the start of restoration works in the 1930s. It was then converted into a museum with a Council of Ministers decision dated 24 November 1934. The Council of State cancelled the decision of the Council of Ministers on 10 July 2020. Immediately afterwards, Hagia Sophia was reopened to worship with the Presidential Decree No. 2729 issued with the signature of President Recep Tayyip Erdoğan.
Hagia Sophia Kebir Mosque is one of the oldest surviving buildings in the world for 1486 years. During this time, it has been exposed to many disasters, especially earthquakes, partial collapse-collapse and fires. In the 570 years since the conquest of Istanbul by Mehmed the Conqueror, extensive fortifications, repairs and restorations have been carried out to keep Hagia Sophia alive, and it has turned into a complex with structures such as imaret, madrasah and tombs added around it in time. Today, Hagia Sophia is carefully protected and kept alive. In this context, under the supervision of the General Directorate of Foundations, the Istanbul Directorate of Survey and Monuments and the Governorship of Istanbul, the restoration of the Mausoleums, the SıbyanSchool and the Muvakkithâne has started with holistic project works.
Objectives:
The works carried out within the scope of the preparation of holistic projects are as follows:
It is known that many institutions have carried out various studies, projects and restorations related to the Hagia Sophia Kebir Mosque complex over time. It is obvious that information-document management is of great importance for future studies, applications, researches and scientific publications. For a holistic approach, it is necessary to bring together all the works carried out from the past to the present and to archive and classify them digitally using technological means. Individual archives, archives of foreign universities, academic literature, etc. are also scanned and studies, documents and visuals related to Hagia Sophia are transferred to the digital environment.
A holistic, high resolution, detailed point cloud data defined in the national coordinate system was created, covering all the buildings within the complex, the garden walls surrounding the parcel and the immediate surroundings of the complex. From this point cloud data, high resolution orthophotos were produced for surveys.
Within the scope of this study, state-of-the-art equipment and software were used and geomatics engineers experienced in three-dimensional surveying and evaluation were employed. Although three-dimensional laser scanning measurements were planned to be carried out, direction-edge measurements, satellite-based position determination and photogrammetric measurements were also needed in areas where necessary in order to establish a geodetic infrastructure and to control the measurements. In this respect, photogrammetry method, high resolution DSLR cameras and lenses were also used where necessary. Due to the size of the structure, photogrammetric completion was carried out using drones. The accuracy of the measurement was increased by creating ground control points for photogrammetric measurements.
It is aimed to have an up-to-date digital twin of the building by continuously updating this point cloud, which is high resolution and reflects the real geometry and architectural features of the building, in future studies.
Considering that the structure of the Hagia Sophia Kebir Mosque is approximately 1500 years old, structural radar studies, which is a non-destructive method, were carried out with academician geophysical engineers experienced in antiquities in order to investigate whether there are significant damages such as mortar discharges, subsequent cavities, cracks, crevices, dampness, etc. in the structural elements and whether there are structural elements (such as beams, tensioners) that cannot be seen from the outside.
Survey and identification studies consisting of two-dimensional drawings documenting the current condition of the building are ongoing.
14 plans and (at least 8) sections and a sufficient number of detail projects are prepared.
Analytical survey studies are ongoing and material analysis and damage-disturbance analysis sheets are being prepared in this context.
In its 1486 years of life, Hagia Sophia has suffered many earthquakes, large and small. It is known that the main dome was partially destroyed in the 6th, 10th and 14th centuries and that the destroyed parts were rebuilt, and that it underwent continuous repairs both in the Eastern Roman, Ottoman Empire and Republican periods. It is aimed to determine these repairs as much as possible through period analyses.
The studies to determine the earthquake safety of Hagia Sophia and its minarets are being carried out under the supervision of Prof. Dr. Alper İlki, Faculty of Construction, Istanbul Technical University, and his team and the Scientific Committee.
A digital model of the structure is made using current point cloud data. Structural performance and earthquake behaviour analyses will be performed to determine possible damage and collapse modes. In analyses and investigations, the Guide for the Management of Earthquake Risks for Historic Buildings (2017) is used. Retrofitting proposals are developed, simulated and analysed on the model.
After the survey, analytical survey, structural performance analyses and determination of earthquake safety, restoration projects will be started to be prepared.
Currently approved restoration projects prepared by different authors are as follows:
Located in the complex;
