الفهرس 
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Abstract
Abstract
Cairo contains a huge number of historical minarets which suffered from deterioration and different levels of damage after past earthquakes. So, minarets became more vulnerable to seismic actions besides other factors such as bad restoration, lack of maintenance, the impact of society, and environmental effects. Therefore, Preserving and protecting historical minarets is very important. In this work, as a first step, the anatomy, evolution, and challenges of historical Cairene minarets are studied in detail. Moreover, their damage patterns after past earthquakes are discussed to better understand their seismic vulnerability and to pick the best methodology that appropriates to their natural and architectural styles.
The adopted methodology of seismic vulnerability in this work is based on a hybrid technique that contains the empirical method; a new assessment method, published in 2018 for slender masonry buildings. Moreover, the experimental method is applied using ambient noise vibration criteria recorded at different levels of each minaret to extract its dynamic characteristics. In order to compile a quite satisfactory sample of minarets, eight minarets of different ages of construction, therefore different construction techniques, typologies architectural styles, and geometry are selected. These minarets are (1) Ahmed ibn Tulun minaret that belongs to the Tulunid era; (2) Two minarets of al-Hakim mosque that belong to the Fatimid era; (3) Two minarets of Sultan Hasan mosque/ madrasa that belong to the Earlier- Mamluk period; (4) The twin minarets of al-Mu’ayyad Shaykh mosque that belong to Later-Mamluk period; (5) the minaret of Yusuf Agha al-Hin mosque.
After applying the methodology, it is found that the natural frequency of each minaret proved that these minarets behave similarly along the different sections. However, this conclusion does not mean that minarets are in ideal condition as, from inspection and the empirical method; we found that most, if not all, of the studied minarets, need rapid intervention and restoration, especially for the non-structural elements. These elements are well interlocking and connected to minarets, but their condition is not good far away. Non-structural elements pose a danger to the minaret itself, as its continued deterioration without proper restoration will weaken the minaret and affect its seismic behaviour later on. In addition, in the current situation, it poses a falling hazard risk even without an earthquake due to its deplorable condition. Moreover, the obtained maximum values of the displacement are the highest near the minaret top meaning that it is displaced more than other parts. In addition, it gives a great possibility of losing the minarets’ tops, especially those belonging to the minarets of al-Hakim mosque and Ibn Tulun mosque with their critical condition.
Keywords: Historical minarets, Seismic vulnerability, Minaret inspection, Seismic vulnerability index, Seismic vulnerability curve, Ambient noise vibration, Natural frequency, Ahmed Ibn Tulun minaret, Al-Hakim minarets, Sultan Hasan, Al-Mu’ayyad Shaykh minarets, Yusuf Agha al-Hin.