Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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  • Article
    Damage Assessment of Structures Following the February 6, 2023 Kahramanmaraş Earthquakes: A Dataset-Based Case Study in Gaziantep, Türkiye
    (Springer Heidelberg, 2025) Atasever, Kurtulus; Aydogdu, Hasan Huseyin; Narlitepe, Furkan; Goksu, Caglar; Demir, Ugur; Demir, Cem; Ilki, Alper
    Following the 2023 Kahramanmara & scedil; Earthquakes (Mw 7.7 and 7.6) that struck T & uuml;rkiye on February 6, 2023, the Ministry of Environment, Urbanization, and Climate Change (MoEUCC) initiated a large-scale post-earthquake damage assessment campaign, targeting more than 2,3 million structures within the affected region. A comprehensive field survey was carried out in and around Gaziantep, one of the most severely affected cities. The authors assessed more than 1700 structures representing a wide range of occupancy types, including residential, educational, healthcare, religious, administrative, industrial, and lodging structures. In this paper, the methodological process of post-earthquake data collection in and around Gaziantep is presented, together with the data on the distribution of damage with respect to construction period, number of stories, and building occupancy type, to ensure a complete understanding of the extent and characteristics of structural damage. The damage assessment employed two data sources: (i) the data gathered through the authors' newly developed, novel damage-assessment software, presented here for the first time, and (ii) the official post-earthquake damage database of the MoEUCC. A further novelty of this study is the presentation of the largest dataset to date for the investigated earthquake doublet, encompassing approximately 1700 buildings. Additionally, the relationship between damage states, peak ground accelerations, and fault distances is thoroughly investigated. The detailed earthquake-hit site investigations revealed that the examined structures displayed structural inadequacies akin to those witnessed in previous seismic events, with a notable focus on the arrangement of the structural system, the quality of construction materials and reinforcement detailing.
  • Article
    Citation - WoS: 3
    Citation - Scopus: 3
    Seismic Testing and Modeling of Full-Scale Substandard Rc Columns Retrofitted With Sprayed Gfrm With and Without Basalt Mesh Under High Axial Compression and Shear Demand
    (Asce-Amer Soc Civil Engineers, 2025) Kian, Nima; Demir, Ugur; Ates, Ali Osman; Celik, Oguz C.; Ilki, Alper
    This study presents the experimental and analytical hysteretic behaviors of eight full-scale RC square and rectangular columns. The columns were designed to have different shear spans that represent: (1) a column that complies with the Turkish Government Ministry of Reconstruction and Resettlement's ( 1975) seismic design code, Turkish Seismic Design Code (TSDC); (2) a substandard column; and (3) two sprayed glass fiber-reinforced mortar (GFRM)-retrofitted counterparts of the substandard column with and without basalt mesh. The substandard columns were designed to be subjected to relatively high shear ratios (i.e., the ratio of the shear force that corresponds to the moment capacity to shear strength of the cross section) up to 0.85 and with a high axial load-to-capacity ratio of 0.75. All columns were tested under constant axial load and reversed cyclic lateral displacement excursions. The results revealed that the columns that complied with the TSDC showed satisfactory behavior for seismic performance, and the performance of the substandard columns was extremely poor. However, the hysteretic performance of the substandard columns that were subjected to high axial stress and shear significantly improved after the proposed retrofitting. Finally, a numerical model was developed in OpenSees to reproduce the hysteresis curves of the specimens. The slip of the longitudinal bars at the column-foundation interface, strain penetration into the foundation, and buckling of the longitudinal bars in compression were accounted for in the modeling. The results are in good agreement with the experimental hysteresis curves. The performance levels of the columns are further specified, and the predictions of the current seismic codes were analyzed: (1) the European Committee for Standardization's 2005 code, Eurocode 8: Design of structures for earthquake resistance; Parts 1-3: Strengthening and repair of buildings (EC8-3); and (2) the Turkish Government Ministry of Interior Disaster and Emergency Management Authority's 2018 code, Turkish Building Earthquake Code (TBEC). The TBEC provided more accurate estimates of plastic rotation capacities for substandard specimens. In contrast, EC8-3 overestimated the plastic rotation capacity when shear stresses were relatively high due to lower shear span-to-depth ratios (a/d).
  • Article
    Impact of High Axial Stress on Seismic Behavior of Substandard Reinforced Concrete Columns
    (Elsevier Science inc, 2025) Gundogan, Safiye; Demir, Ugur; Turan, O. Tugrul; Ilki, Alper
    The seismic performance of reinforced concrete (RC) buildings, particularly those constructed without adequate seismic detailing, remains a critical concern in earthquake-prone regions worldwide. Many of these buildings, often referred to as substandard RC structures, were built before modern seismic codes were established and are characterized by poor material quality and inadequate construction practices. The Southern T & uuml;rkiye earthquakes on 6 February 2023 underscored the urgent need to better understand the seismic behavior of these substandard structures, which frequently fail to meet modern design standards and are prone to damage or collapse. Substandard RC columns, characterized by low concrete strength and inadequate transverse reinforcement, are susceptible to severe seismic damage, increasing the risk of collapse and life loss. While numerous studies have experimentally examined the seismic behavior of RC columns under low to moderate axial load to capacity ratios (typically below 0.30), these conditions do not accurately reflect the reality of many existing substandard columns that are frequently subjected to higher axial compression stresses. This study addresses this critical gap by presenting the first experimental data on the seismic behavior of full-scale, substandard RC columns under high axial load ratios (0.30-0.80). The analysis focused on lateral load-displacement relationships, ductility, plastic hinge length, stiffness, energy dissipation capacity, and residual displacements. Increases in axial load led to more brittle failure modes, reduced displacement ductility and an extended plastic hinging zone. High axial loads also caused accelerated stiffness degradation, reduced cumulative energy dissipation, and progressive residual deformations. Analytical models overestimated deformation capacity, making them unreliable for substandard RC columns under high axial stress. Additionally, predictions using plastic hinge length formulas underestimated the values at high axial loads. The study also evaluated the performance of widely used concrete confinement models in predicting the moment-curvature responses and corresponding ductility for substandard RC columns with low compressive strength and subjected to high axial stress. These findings underscore the critical need for refined modelling approaches and assessment methodologies to improve the seismic evaluation of substandard existing buildings.
  • Conference Object
    Citation - Scopus: 1
    Observed Performance of a RC Wall-Frame Building During the February 2023 Turkey Earthquake and Performance Improvement Using FRPs
    (International Institute for FRP in Construction (IIFC), 2023) Tura, C.; Sahinkaya, Y.; Güllü, M.F.; Demir, U.; Orakcal, K.; Ilki, A.
    In this study, results of nonlinear response history analysis are presented for an existing RC wall-frame building, which has suffered collapse-level damage during the devastating February 2023 Kahramanmaras earthquakes. Performance analysis results for two building configurations are compared; first for the existing building configuration generated upon on-site observations, and second, for a hypothetical configuration in which the structural walls and columns are retroffited using externally-bonded FRP sheets. Analysis results reveal that in its existing configuration, mostly due to detailing deficiencies, a collapse-level performance was not unexpected; whereas FRP strengthening of the building would have resulted in collapse-prevention performance. © CICE 2023 - 11th International Conference on FRP Composites in Civil Engineering. All rights reserved.
  • Conference Object
    Citation - WoS: 1
    Citation - Scopus: 3
    Structural Performance of R/C Buildings in 2023 Kahramanmaraş Earthquakes Under the Lens of Hassan Index
    (Springer Science and Business Media Deutschland GmbH, 2024) Yildirim, Meltem Eryilmaz; Yesilyurt, Cennet; Gozun, Uveys; Ozturk, Baki; Donmez, Cemalettin
    Starting with the 1999 Kocaeli Earthquake, seismic damage indices have been developed to quantify damage potential. The late Professor Mete Sozen played a significant role in this endeavor by introducing the Hassan Index, which is an indirect measure of the robustness of structures. Its calculation is straightforward, given the vertical structural element dimensions at ground level. Various earthquakes worldwide, from Taiwan to Chile, have provided opportunities to assess its effectiveness across diverse building practices and earthquake characteristics. Following the February 2023 Kahramanmaras Earthquakes, a reconnaissance team was dispatched to gather field data to observe the damages through the lens of the Hassan Index. The study extended to cover all major city and town centers, studying around 250 reinforced concrete buildings with 2-16 stories. These buildings were all constructed after the 2000s. Hence, the data set sheds light on the performance of Turkish construction practices after the commencement of the 1998 Turkish Building code and the following earthquake regulations. By evaluating the newly gathered data alongside the existing dataset, a basis is established to consider the Hassan Index as a preliminary design index rather than solely as a seismic damage index.
  • Conference Object
    Citation - WoS: 2
    Citation - Scopus: 6
    Discussion on the Causes of the Observed Damages in the 2023 Kahramanmaraş Earthquakes
    (Springer Science and Business Media Deutschland GmbH, 2024) Gultepe, Ekin; Comlekoglu, Hakki Gurhan; Ozturk, Baki; Donmez, Cemalettin
    The devastating earthquakes in February 2023 in south-east Turkiye demonstrated that the Turkish built environment does not meet the needed performance. The frequency of earthquakes in Turkiye calls for urgent organization to upgrade the existing structures and avoid the repetition of deficient applications. Hence, it is necessary to identify the causes of the damage. The presented study concentrated on a subset of the existing inventory built under the governance of 1998 and later Turkish Earthquake Codes. Following the earthquakes in Kahramanmaras, Turkiye, a reconnaissance study was conducted to understand the causes of the damage incurred. The extensive study covered all the major city and town centers, specifically concentrating on the 2- to 16-story reinforced concrete buildings. The first impression of the data gathered indicates significant detailing imperfections. Poor drift control, inferior layout preferences, and non-structural detailing issues are the other suspects. The observed damage and the current seismic regulation requirements will be critically discussed to form a basis for possible future improvements to the seismic code.