Ramazan Livaoglu

Traditional Turkish Masonry Monumental Structures and their Earthquake Response

Many historical and new masonry minarets were damaged or collapsed during the 1999 earthquakes in Kocaeli and Duzce, Turkey. These and other recent earthquakes not only caused loss of property but also loss of many lives. The structural failures and resulting casualties have led to discussion and investigation of potential reasons for poor seismic performance of masonry minarets. The primary goal of this study is to review the construction practices for historical and new masonry minarets in Turkey and to discuss the seismic damage observed in those structures. The architectural and structural properties of contemporary and historical Ottoman minarets and their components are presented. For example, a very old special technique for reinforcing and linking adjacent stone blocks with iron pieces in the vertical and horizontal directions is discussed. The structural damage examples are used to better understand the reasons for the observed failure mechanisms. It is concluded that the transition region between the square minaret boot and cylindrical body was most vulnerable to damage, and the iron clamps used in historical minarets effectively prevented structural damage.

THE NUMERICAL AND EMPIRICAL EVALUATION OF STRUCTURAL PERFORMANCE OF ELEVATED TANKS CONSIDERING SOIL–STRUCTURE INTERACTION EFFECTS

Water tanks are an essential lifeline whose continuing availability and serviceability immediately after earthquake events are crucial for providing undisrupted emergency services. Their seismic performance is, therefore, of paramount importance. The seismic response of an elevated liquid tank situated on a soft soil deposit was studied by means of field vibration tests and numerical simulations. The ambient and forced vibration tests were conducted to identify the soil–structure interaction (SSI) effects on the small strain dynamic behavior of the structure. A series of time domain numerical analyses were performed to evaluate the seismic performance of these structures from a performance based design point of view. The results showed that consideration of SSI increased the displacement demand significantly. Thus, the calculated maximum displacement demand for supporting frame components of the tank may be underestimated significantly when the SSI effects are neglected. In addition, the seismic induced shear forces considering SSI effects were much smaller than the seismic shear forces for the fixed based case. For some soil types, the effect of this reduction on the overall response may become more prominent than the structural ductility mechanism. This resulted in the failure mechanism being initiated by a coupled compression — bending moment effect, rather than shear failure. Finally, the sloshing response is significantly increased due to the SSI.