Browsing by Author "Gülkan, Polat"

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A Predictive Ground-Motion Model for Turkey and Its Comparison with Recent Local and Global GMPEs
(2011) Cağnan, Zehra; Akkar, Sinan; Gülkan, Polat; 5743
We present a local ground motion prediction equation (GMPE ) for estimating the peak ground-motion values that was derived using the recently compiled Turkish strong motion database . The new GMPE is comparable with the recent global GMPEs in terms of model sophistication and quality of underlying database. Using this equation, we explore the inter-event , inter-station ground motion variability of the recent Turkish strong motion database as well as suitability of some local and global GMPEs for regional seismic hazard assessment analyses. The inter-event error underlines the distinguishing characteristics of few earthquakes, suggesting that the use of local GMPEs can be important especially when specific scenario studies are to be carried out. The inter-station variability allowed us to detect stations with outlier site response and to investigate the goodness of the employed site effect s model. Results also indicate suitability of some global and local GMPEs for use in regional seismic hazard assessments together with the model presented in this study. These should be combined through a logic tree scheme to reduce both aleatory and epistemic uncertainty in local hazard assessments.
Developments in International Bridge Engineering
(2021) Gülkan, Polat; Caner, Alp; Memişoğlu Apaydın, Nurdan
This book reports on current challenges in bridge engineering faced by professionals around the globe, giving a special emphasis to recently developed techniques and methods for bridge design, construction and monitoring. Based on extended and revised papers selected from outstanding presentation at the Istanbul Bridge Conference 2018, held from November 5 – 6, 2018, in Istanbul, Turkey, and by highlighting major bridge studies, spanning from numerical and modeling studies to the applications of new construction techniques and monitoring systems, this book is intended to promote high standards in modern bridge engineering. It offers a timely reference to both academics and professionals in this field.
Displacement Induced Torsion in Structures
(2012) Masoudi, M.; Gülkan, Polat; Dazio, A.; 5743
Satisfying the equations of motion in the deformed configuration leads to actions that inherently contain secondary effects. Similar to the product of vertical loads and lateral displacements which leads to the PΔ effect in structures, lateral displacements may cause significant secondary torsion due to the presence of lateral loads. A simple finite-element formulation is presented in the paper to capture this effect. This formulation is verified by means of the Corotational approach and the updated Lagrangian formulation for acceptable drift limits in structural engineering practice. A simple single-story structure and a 7-story RC and steel structures with no predefined mass eccentricity are subjected to an ensemble of bi-axial ground motions recorded on different soil conditions to demonstrate secondary effects. The paper shows that when the period of the structure is not identical in the two horizontal directions secondary torsion is important and may result in significant torsional amplification.
Examination of code performance limits for shear walls
(2012) Kazaz, İ.; Gülkan, Polat; Yakut, A.; 5743
Recently proposed changes to modeling and acceptance criteria in seismic regulations for both flexure and shear dominated reinforced concrete structural walls suggest that a comprehensive examination is required for improved limit state definitions and their corresponding values. This study utilizes a well calibrated modeling tool to investigate the deformation measures defined in terms of plastic rotations and local concrete and steel strains at the extreme fiber of rectangular structural walls. We compare requirements in ASCE/SEI 41, Eurocode 8 and the Turkish Seismic Code. This way, a critical evaluation of the requirements embedded in these documents becomes possible. It is concluded that the performance limits must be refined by introducing additional parameters. Significant recommendations are provided for Eurocode 8 and the Turkish Seismic Code.
Fragility of Shear Wall Buildings with Torsional Irregularity
(2012) Akansel, Vesile Hatun; Yakut, Ahmet; Gülkan, Polat; 5743
Fragility curves are useful for damage assessment of structures. There are many criteria that affect the reliability of fragility curves such as transitional damage states, plan irregularity and different measures of seismic intensity. Determination of fragility of a shear wall structure is important, especially for installations that have torsional irregularity. In this study fragility curves of a shear wall building with torsional irregularity have been obtained. This building was subjected to synthetic earthquake motions on the AZALEE shaking table under the coordination of CEA (Commissariat à l’Energie Atomique) and Electricité de France (EDF) in Saclay, Paris under the scope of the SMART program. Maximum inter-story drift values have been used as the damage indicator to obtain the fragility curves and different seismic intensity measures such as PGA, PGV, PGD and CAV have been used. Thirty bi-directional horizontal ground motions have been applied for the time history analyses. These synthetic acceleration sets applied to the structure have different amplitudes in the range of 0.1 to 1 g. Micro modeling approach has been used to obtain reasonably accurate and consistent results with experiments. ANSYS finite element software has been used for the response history analyses. Fragility curves of shear wall building have been calculated according to pre-established damage indicators. The limits are light, controlled and extended damage indicators. These curves are compared with those of the HAZUS damage states for correlation.
Grassroots participation vs. dictated partnership: Anatomy of the Turkish risk management reality
(2012) Karancı, Ayşe Nuray; Gülkan, Polat; 5743
Seismic behavior of a four-legged masonry minaret
(2012) Kazaz, İ.; Akansel, V.; Gülkan, Polat; Kazaz, E.; 5743
The four-legged Minaret of Sheikh Mutahhar Mosque has been constructed in the early 16th century during the Aq Qoyunlu Period in Diyarbakır, Turkey, which is located in the second most hazardous zone of the Turkish Seismic Zones Map. This is a special structure, because the minaret body has been placed on four cylindrical stone columns. Therefore, this minaret is seemingly vulnerable though it has survived for five centuries. We use the square cross sectioned minaret as a possible large-scale seismograph to examine the possible limits of ground motion that must have affected it without causing its collapse. In order to investigate the likely seismic performance and strength of the four-legged minaret, a model, which is very close to real structure, was generated with explicit dynamic code LS-DYNA. The developed model takes into account the material nonlinearities and the interface friction and contact behavior between the masonry units. It was displayed that the amplitude of the ground motion in Diyarbakır could not be 0.15g.
The Fatih Project: A Pilot Seismic Assessment of the Architectural Heritage in the Historic Peninsula of Istanbul
(2011) Gülkan, Polat; Sozen, M.A.; Yakut, A.; Celep, Z.; Güler, K.; Kubin, J.; Kubin, D.; Eroğlu, E.; İrfanoğlu, A.; Ahunbay, Z.; 5743
The IAEE at fifty : a brief history of the international association for earthquake engineering.
(International Association for Earthquake Engineering, 2012) Gülkan, Polat; 5743
Vulnerability assessment of two instrumented masonry buildings in Antakya
(2012) Genes, M.C.; Erberik, A.M.; Abrahamczyk, L.; Gülkan, Polat; Bikce, M.; Kacin, S.; Yakut, A.; Schwarz, J.; 5743