Sürdürülebilir Kalkınma Amaçları

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• MakaleAçık Erişim2018/r/gumushane/15075
  Sensitivity-Based Model Updating of Building Frames using Modal Test Data

  Altunişik, Ahmet Can; Karahasan, Olguhan Şevket; Genç, Ali Fuat; Okur, Fatih Yesevi; Günaydin, Murat; Adanur, Süleyman

  Model updating is of significant importance in the actual analyses of real structures. The differences between experimental and numerical dynamic characteristics can be minimized by means of this procedure. This procedure can be carried out using two approaches, namely, the manual model updating and the global or local automated model updating. The local model updating is a convenient tool for all kind of structures capable of minimizing the differences mentioned previously nearly to zero and also of identifying the damage locations and monitoring structural integrity. In this way, current realistic behavior of structures can be represented by updated finite element models. This paper describes a Reinforced Concrete (RC) frame model, its ambient vibration testing, finite element modeling and sensitivity-based automated model updating. The RC frame is of ½ geometric scale with two floors and two bays in the longitudinal direction. It was built and then subjected to ambient vibration tests to determine experimentally their dynamic characteristics. Additionally, the finite element computer program ANSYS was used to determine its initial numerical dynamic characteristics. The experimental and numerical results were compared resulting in maximum differences of 38.38% between them. To minimize these differences, the finite element model was updated using the global and local automated approach using a sensitivity-based analyses with some uncertain parameters. The differences were finally reduced to 4.4% and 0.21% by the global and the local automated model updatings, respectively. It is concluded that sensitivity-based automated updating is a very effective procedure to obtain the updated finite element model which can reflect the current behavior of a structure.

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  İncele
• MakaleAçık Erişim2015/r/gumushane/15779
  Time dependent changing of dynamic characteristics of laboratory arch dam model

  Altunişik, Ahmet Can; Sevİm, Barış; Bayraktar, Alemdar; Adanur, Süleyman; Günaydin, Murat

  This paper investigates the time dependent changing of dynamic characteristics of laboratory arch dam models using ambient vibration test. For this aim, a prototype arch dam-reservoir-foundation model is constructed in laboratory conditions. The first experimental measurement tests are performed after the poured concrete aged for 10 months for some damage scenarios such as undamaged, minor-damaged and severely damaged of dam body in November 2009. To extract the experimental dynamic characteristics such as natural frequencies, mode shapes and damping ratios, a small impact effect is used as a source of ambient vibrations. Experimental measurements tests are repeated using same excitations considering severely damaged conditions with and without reservoir water in February 2014, and the dynamic characteristics are obtained, experimentally. Enhanced Frequency Domain Decomposition Method in the frequency domain is used to extract the experimental dynamic characteristics. At the end of the study, experimentally identified dynamic characteristics are compared with each other and time effects are investigated in detail. Maximum differences between the natural frequencies obtained as 15.36% and 14.38% in the third mode for empty and full reservoir conditions, respectively. It is thought that the increase of the natural frequencies is resulted from gaining of rigidity of the concrete, ageing, temperature and different environmental effects.

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