Papers by Author: Ahmet Turer

Abstract: Hasankeyf historic settlement area is one the most important sites in southeastern Anatolia which dates back to the 15th century. Zeynelbey Tomb is a distinct cylindrical structure has a height of 9.6 m and with double domes extending to an overall height of 16.5m; however, the outer dome suffers from multiple and large vertical tension cracks threatening the overall structural stability and safety of the structure. A preliminary visual inspection and structural evaluation using analytical modeling was carried out. The tension zones developing at the outer dome was determined using analytical simulations and causes of vertical tension cracks were elaborated. A general remedy of strengthening was developed to surround the dome using vertical ribs and horizontal post tensioning strands that are placed in three vertical layers. The deterministic analytical simulations using the horizontal post-tensioning have allowed finding the necessary amount of tension force in each horizontal strand to diminish the tensile stresses inside the dome and put the structure in a stable compression state. This paper describes the steps carried out for the assessment, evaluation, and retrofit studies, which might set an example to similar historic structures with comparable structural problems in the dome.

Abstract: In Turkey, as well as in Balkan countries, examples of an extant housing tradition namely hımış, which was formed during Ottoman period, can still be observed. In spite of minor local differences according to geographical locations, these Ottoman hımış houses are distinguished with a number of common architectural and technical peculiarities that is worth to preserve. They have similar timber frame construction system with different infill materials. There are numerous reports claiming that the hımış houses are seismically more resistant than other construction types such as reinforced concrete and/or masonry structures. However, nearly all such reports are based on observations made after historical or contemporary earthquakes and lack quantitative engineering approach. For these reasons, within the framework of an ongoing research project, supported by The Scientific and Technological Research Council of Turkey (TUBITAK), coded 106M499, the seismic resistance of traditional timber frame houses in Turkey was investigated. A number of timber frames were tested in the laboratory under cyclic and reverse lateral loading, with and without infill. The results were reproduced with pertinent analytical work. As a result, it was shown that connections that were traditionally made with the sole use of standard nails were always the location of failure. In this paper, the results obtained for one of these frames is presented together with its capacity curve analysis to see whether strengthening is needed or not from seismic design point of view.

Abstract: Conservation studies in developing countries might have additional problems to those that are being experienced by leading developed countries. The problems and difficulties mentioned here do not reflect the common practice in Turkey and mostly list rare cases for information purposes. Countries located in Asia and Middle East have rich structural heritage, in number and significance, which are sometimes even a few millenniums old. On the other hand, often times financial or bureaucratic constraints make the conservation studies more difficult, while technical problems remain to be an issue. It is quite interesting that sometimes having available financial support for conservation studies turns out to be the main source of problem, since quick and not well thought interventions end up damaging hundreds of years old surviving structures, rather than conserving them. Other most common application problems include use of Portland cement in humid environments causing salt contamination (which is now widely being avoided), infilling and freezing cracks that used to work as seasonal water table movement based motion or thermal expansion joints that are cyclic in nature, covering the structure to protect but forming unintentional green house effect – micro climates forming fungus, improper drainage to cause support settlements, removing earth fill or structural members to cause structural movements and cracks, strengthening parts of a flexible structure only to make it more rigid and cause to attract more earthquake forces, disable its energy dissipating mechanisms, applying improper chemicals, using incompatible material or irreversible techniques etc. are just a few to mention. The problem solution strategies in conservation studies should include internationally accepted conservation rules. Multi disciplinary teams are always recommended since combination of various expertise areas are mutually needed in conservation studies; architects, geotechnical and structural engineers, geology and material science specialists, archeologists, art historians are among the most important team members. Analytical modeling and simulations, on-field non destructive testing, instrumented monitoring (SHM), and small scale field treatment tests are recommended to be merged and used in conservation studies, because conventional methods or commercial repair/treatment materials available over-the-counter may not always suitable for a given specific case. Reversibility, minimum intervention, and respect to authenticity should be among the main principles to avoid serious conservation problems.