Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

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

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Author: search.filters.author.Demir, U.Publisher: search.filters.publisher.CRC Press

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  • Book Part
    Influence of High Sustained Axial Stresses on the Seismic Behavior of Full-Scale Substandard Reinforced Concrete Columns
    (CRC Press, 2025) Gundogan, S.; Demir, U.; Turan, O.T.; Ilki, A.
    Reinforced concrete (RC) columns are critical structural components that play a decisive role in the seismic performance of buildings. However, the combined effects of long-term sustained axial loads and seismic loading on these columns remain a pressing concern. In particular, design and construction deficiencies, coupled with material deterioration, often result in substandard RC columns experiencing long term axial stresses that far exceed typical service levels. These elevated stress conditions can lead to significant structural vulnerabilities, manifesting as collapses under seismic actions or even under gravity loads alone. Within this context, this study aims to investigate the impact of such high sustained axial stresses on the response of substandard reinforced concrete columns prior to be subjected to reversed cyclic lateral loading simulating seismic actions. For this purpose, two full-scale columns were tested under the combined actions of axial load and reversed cyclic lateral displacements. One of two columns were tested after it was exposed to a sustained axial load of 825 kN, corresponding to 70% of axial load capacity (fbh) for a duration of six months, while the other column was tested as the reference specimen right after it was subjected to same level of axial load. Comprehensive instrumentation during testing and detailed creep analysis under long-term applied axial loads were conducted to evaluate the response of the columns. The findings highlight the significant impact of long-term high axial stress on the seismic performance of substandard RC columns. © 2025 selection and editorial matter, Alphose Zingoni; individual chapters, the contributors. All rights reserved.
  • Book Part
    25 Years of FRP Research at Istanbul Technical University
    (CRC Press, 2025) Ilki, A.; Sari, B.; Goksu, C.; Demir, C.; Demir, U.; Töre, E.
    The application of fiber-reinforced polymer (FRP) composites for structural strengthening and seismic retrofitting has significantly advanced in recent decades. This study presents a com-prehensive review of FRP research conducted at Istanbul Technical University (ITU) in the last 25 years, which has closely aligned with global developments in the field. The research at ITU has focused parti-cularly on addressing the substandard characteristics prevalent in Türkiye's building stock. Investigations have spanned a wide range of specimens, from small-scale concrete prisms to full-scale three-dimensional reinforced concrete (RC) buildings. Key focus areas have included FRP applications for ductility enhancement, flexural strengthening and seismic retrofitting of structural members. Various FRP mate-rials have been examined, including aramid, glass, carbon, basalt and PET fibers. Multiple application techniques have been explored, ranging from externally bonded reinforcement to textile reinforced sprayed mortar. The findings from these extensive studies have consistently demonstrated the efficacy of FRP composites in enhancing the structural performance and seismic resilience of substandard buildings. This body of research has made significant contributions to the development of practical retrofit solutions tailored to the specific challenges posed by Türkiye's existing building stock and has broader implications for seismic risk mitigation in countries with similar construction practices. © 2025 selection and editorial matter, Alphose Zingoni; individual chapters, the contributors. All rights reserved.