Minaret behavior under earthquake loading: The case of historical Istanbul
Article first published online: 1 APR 2011
Copyright © 2011 John Wiley & Sons, Ltd.
Earthquake Engineering & Structural Dynamics
Volume 41, Issue 1, pages 19–39, January 2012
How to Cite
Oliveira, C. S., Çaktı, E., Stengel, D. and Branco, M. (2012), Minaret behavior under earthquake loading: The case of historical Istanbul. Earthquake Engng. Struct. Dyn., 41: 19–39. doi: 10.1002/eqe.1115
- Issue published online: 19 DEC 2011
- Article first published online: 1 APR 2011
- Manuscript Accepted: 26 JAN 2011
- Manuscript Revised: 23 JAN 2011
- Manuscript Received: 5 JUL 2010
- masonry structures;
- seismic performance;
- in situ frequency measurements;
- analytical modeling
Minarets are very slender structures with an old existence. The historical ones are made of cut-stone-block masonry assembled in peripheral cylindrical wall with an interior helicoidal stair supported on a central core and on the wall. They are spread throughout the Islamic world and constitute an important heritage not only of religious value, but also of great cultural interest. Throughout the times, these structures as part of a mosque, have suffered significant damage during the earthquakes. Istanbul presents interesting characteristics to evaluate their dynamic behavior, as they are in great number, in an area where a large event in the next 30 years has been predicted.
In this paper, we performed a series of in situ ambient vibration tests to old minarets of various sizes and compared results of frequencies with numerical modeling of the same structures. For the low-amplitude motion, the frequency values of the first modes can be obtained from an empirical formulae function of the inertia of the cross-section and of the height of the main ‘body.’ Damping ratios for these amplitudes are of the order of 0.5–1.0%.
Dynamic linear analyses of these structures indicate that for most cases very high stresses develop for PGA above 0.5 g, an input with a reasonable chance of occurring in the next 30 years. These high stresses are expected to cause the toppling of the minarets in the form that has been observed in the recent past events. Copyright © 2011 John Wiley & Sons, Ltd.