No abstract

Minarets are spread across urban nuclei. Their structural weakness could result in failures with heavy consequences. However, the retrofit solutions are limited due to their simple cantilever scheme. The use of metallic pre-stressed wires/cables is a rather consolidated technique. The use of shape memory alloy (SMA) wires has been recently investigated. In view of such an application, a series of reduced-scale tests was planned and realized. This paper synthesizes the full report on an experimental work performed to study the effect of SMA wires on the dynamic behavior of a single degree of freedom model built in laboratory to represent a 1/16th of a minaret actually built in Cairo, Egypt. The model was tested under free vibration for different values of the axial force, before and after adding SMA wires. The results showed enhancements in the stiffness when the SMA wires were added and when the axial force increased, while a decrease in damping ratios was detected when increasing the applied axial force or after providing SMA wires.

This paper presents the results of a research program sponsored by the European Commission through project WIND-CHIME (Wide Range Non-INtrusive Devices toward Conservation of Historical Monuments in the MEditerranean Area), in which the possibility of using advanced seismic protection technologies to preserve historical monuments in the Mediterranean area is investigated. In the current research, two outstanding Egyptian Mamluk-Style minarets, are investigated. The first is the southern minaret of Al-Sultaniya (1340 A.D, 739 Hijri Date (H.D.)), the second is the minaret of Qusun minaret (1337 A.D, 736 H.D.), both located within the city of Cairo. Based on previous studies on the minarets by the authors, a seismic retrofit technique is proposed. The technique utilizes shape memory alloy (SMA) wires as dampers for the upper, more flexible, parts of the minarets in addition to vertical pre-stressing of the lower parts found to be prone to tensile cracking under ground excitation. The effectiveness of the proposed technique is numerically evaluated via nonlinear transient dynamic analyses. The results indicate the effectiveness of the technique in mitigating the seismic hazard, demonstrated by the effective reduction in stresses and in dynamic response.