Abstract
Cracks have major effects on both static and dynamic behaviour of masonry structures. Cracking stalls at the weakest region and propagates through the whole structure as load is increased. Hence, investigation of the crack propagation gives an idea about the possible collapse mechanisms of any masonry structure. A worldwide known 1500 years old masonry building is Hagia Sophia with its unique structural system of its roof and size, covering a column free 2000 sqm. large space. Hagia Sophia will stands and resists earthquakes, although it has a lot of cracks. Cracking of a structure strongly depends on the form and the rigidity of its elements. For this reason, in this paper, two alternative structural models of Hagia Sophia are investigated from dynamic point of view considering the crack propagation. The original model represents the structure as built, whereas a fictitious second one is obtained by modifying the east and west arches of the first. In the second model, the size of the weak east and west arches is increased to be equal to that of the strong north and south arches. Results of the analyses are given in terms of diagrams for the principal stress distributions. It turns out that the model with strong arches in both directions provides a higher resistance to earthquake, even after cracking.