Gaziantep Kurtuluş camisinin deprem davranışının incelenmesi

Abstract

Kültürel mirasımızın önemli parçasını oluşturan tarihi yapılar, potansiyel bir deprem tehlikesine sahip olan ülkemizde sürekli deprem etkisine maruz kalmakta ve depremler sebebiyle hasarlara uğramaktadırlar. Bu yüzden, tarihi yapıların deprem altındaki davranışlarının incelenerek, geleceğe güvenli bir şekilde aktarılması oldukça önem arz etmektedir. Bu çalışmada, 125 yıllık tarihi yığma bir yapı olan Gaziantep Kurtuluş camisinin depreme karşı davranışı incelenmiş ve muhtemel hasar potansiyeli değerlendirilmiştir. Bu kapsamda, katı elemanlar kullanılarak sonlu elemanlar yöntemi ile yapının üç boyutlu sayısal modeli oluşturulmuştur. Deprem etkisi, zaman-tanım (time-history) alanında tanıtılan özel olarak seçilmiş 10 adet senaryo deprem kayıtları kullanılarak incelenmiştir. Yapıdaki davranışlar deprem hareketinin nonlineer etkisine göre hesaplanmıştır. Dinamik etkiler, alternatif olarak önerilen hızlı nonlineer analiz (FNA) yöntemi ile belirlenmiştir. Deprem hareketi X ve Y olmak üzere iki ayrı yönde uygulanmıştır. Analizler sonucunda deprem etkisi altında camide oluşan yer değiştirme, ivme, gerilme (çekme ve basınç), taban kesme kuvveti, doğal titreşim periyodu ve titreşim modları hesaplanmıştır. Analiz bulguları, camide bazı bölgelerde yer değiştirme ve çekme gerilmelerinin müsaade edilebilir sınır değerleri aştığını göstermiş olup hasar riski oluşturmuştur. Ayrıca, caminin hesaplanan doğal titreşim periyodunun (0.5s), depremin hakim periyoduna (0.35s) yakın seyrettiği belirlenmiştir. Bu durum deprem etkisi altında camide rezonans meydana gelebileceğine işaret etmiştir. Elde edilen bulguların camide yapılacak restorasyon çalışmalarına katkı sağlayacağı düşünülmektedir.

Keywords

• Tarihi yığma yapılı cami, deprem, sonlu elemanlar, doğal titreşim periyodu, hasar

Investigation of earthquake response of Gaziantep Kurtuluş mosque

Abstract

The seismic assessment of historical structures is a fundamental issue nowadays for protecting the cultural heritage. In many countries, masonry structures still play a central role for representation of country’s history and its development. Most of these structures have a historical and architectural value in both, thus they are permanently needed to ensure their reliable seismic safety with accurate analysis tools. Accordingly, nowadays, the most advanced computer based methods employing numerical package softwares available for structural assessment have been used to analyze the behavior of historical masonry structures, resulting in different levels of complexity and cost in the viewpoint of computational effort. Damage risk of the most vulnerable masonry historical structures should be minimized to avoid significant social and economical losses. These requirements are particularly evident in historical masonry mosques, since their assessment is strongly needed for restoration by administrative authorities frequently. Several procedures have been employed in last decades in order to predict the behavior of masonry structures. The difficulty in representing the behavior of the material and the structural resistance requires the use of effective structural model. Nonlinear analysis is the most comprehensive procedures to study the complex behavior of masonry structures during an earthquake, since more reliable solution can be obtained as compared to conventional linear approaches such as collapse mechanisms, ductility, forces redistribution, damage, etc. In principle, nonlinear time-history analysis is the most suitable seismic assessment tool, but it needs fast algorithms to obtain the solutions more practice. Moreover, dynamic nonlinear analysis is strongly dependent on the input excitation and has a high computational time and effort, which must be seriously considered when complex structures are analyzed. Historical buildings that become an important part of our cultural heritage in Anatolia are mostly subjected to earthquake effects in our country. Therefore, they have a dangerous earthquake potential, which results in significant damage. Thus, it is quite important to transfer the historical structures to next generations through the investigation of their responses under earthquake. In this study, the behavior of a 125-years old historical masonry structure, Gaziantep Kurtulus mosque, was studied against earthquake effect, with an evaluation of possible damage potential. For this purpose, three-dimensional numerical model of Kurtuluş mosque was built with finite element method. Solid elements were used for the building of the numerical model due to finite element. The dynamic effects due to earthquake motions for the dynamic responses of structure are estimated in a time-history domain employing some possible records of scenario earthquakes. The scenario earthquakes included 10 strong ground motions that were selected to represent the earthquake effect to Gaziantep city in the viewpoint of peak ground acceleration as a preliminary assessment in this study. The earthquake motions have been exerted to the numerical model of structure under consideration of nonlinear stress-strain behavior of dynamic excitation. Fast nonlinear analysis (FNA) method was used for the nonlinear behavior of earthquake motion. The FNA methodology has also been applied to provide less time and computational effort in the study. Under the earthquake excitation, the structural behavior has been calculated and evaluated in the responses of displacement, stress, acceleration, predominant period and mode of vibration. The computations have been carried out using SAP2000 package software. As a consequence of the analysis, the findings obtained show that displacements and tensile strengths in some part of the mosque exceed their allowable limits. This indicates that the mosque has a potential damage hazard under a possible earthquake. In addition, natural vibration period of mosque (T=0.5s) is found to close to predominat period of earthquake (T=0.35s). This could result in the mosque and earthquake vibration to be in resonance that could also cause a potential damage. The study with the findings could be considered to be beneficial for the local authorities during the restoration of Kurtuluş mosque.

Keywords

• Historical masonry structure, earthquake, finite element, natural vibration period, damage