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, UğurHas files: Yes

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  • Article
    Citation - WoS: 10
    Citation - Scopus: 14
    Out-Of Seismic Performance of Bed-Joint Reinforced Autoclaved Aerated Concrete (aac) Infill Walls Damaged Under Cyclic In-Plane Displacement Reversals
    (Elsevier, 2023) Halıcı, Ömer Faruk; Demir, Uğur; Zabbar, Yassin; İlki, Alper
    The infill walls made of Autoclaved Aerated Concrete (AAC), which is a lightweight, fire resistant and energy efficient material, provide effective insulation solutions for building types of structures and becoming more and more popular in earthquake prone regions. Although the number of experimental tests examining the seismic response of clay brick infills is extensive, the amount of prior research on infill walls built of AAC blocks is rather limited. Past research revealed that the use of bed-joint reinforcement is one of the promising solutions to improve the global seismic response of masonry walls by enhancing strength and displacement capacity. In this study, the out-of-plane (OOP) seismic performance of AAC infill walls with flat-truss and innovative cord-type bed-joint reinforcement is experimentally evaluated. Also, consideration is given to the prior in-plane (IP) damage, which was found to degrade the seismic performance of infills in OOP direction. For this purpose, three IP and four OOP, in total, seven experimental tests were performed on four full-scale AAC infill wall specimens. The test parameters were selected in such a way as to make it possible to parametrically compare the OOP performance of AAC infills with flat-truss and cord-type bed-joint reinforcements with unreinforced AAC infill walls, together with the effect of prior IP damage on the OOP response of unreinforced AAC infill walls. It was found that the use of innovative cord-type bed-joint reinforcement improved the OOP strength to a similar extent to what was obtained from the truss-type reinforced specimen. In terms of ultimate displacement and energy dissipation capacity enhancement, the specimen with cord-type reinforcement performed better. In addition, the damages formed due to IP cyclic displacement reversals up to 0.005 drift ratio, which is defined as the drift limit for buildings with brittle infill walls in certain design codes, resulted in a significant reduction in the OOP strength and stiffness properties of AAC infills. The theoretical OOP strength calculations were found to provide unconservative strength values for the IP-damaged specimens.
  • Conference Object
    The Effect of Lap-Splice Configuration on Seismic Performance of Substandard Rc Columns
    (fib. The International Federation for Structural Concrete, 2022) Baltacı, Alihan; Gündoğan, Safiye; Demir, Uğur; İlki, Alper
    A considerable amount of existing reinforced concrete (RC) buildings in developing countries possess vital deficiencies such as incorporating poor quality of concrete and insufficient transverse reinforcement, and use of plain reinforcing bars without proper detailing, such as inadequate configurations of lap-splices at critical plastic hinging zones. While these can affect the strength and ductility of structural members adversely under seismic actions, research on such substandard structural members is scarce. As such, further information is valuable for the assessment of the seismic safety of such substandard columns constructed with inadequate lap-splice configurations of plain round bars. Therefore, this study aims to investigate the effects of different lap-splice configurations of plain bars on the seismic performance of substandard RC columns and contribute to the development of assessment codes for such existing substandard buildings. Towards this aim, three full-scale columns were constructed to represent typical characteristics of substandard RC columns. The columns were subjected to constant axial loading (with an axial load to capacity ratio of 0.3) and reversed cyclic displacement reversals simultaneously representing gravity loads and seismic actions, respectively. The test program included i) one reference column with continuous longitudinal bars (no lap-spliced connection), ii) one lap-spliced column with an overlap length of 20 times the longitudinal bar diameter without any hook and iii) one lap-spliced column with an overlap length of 20 times the longitudinal bar diameter with a 180-degree hook. Test results demonstrated that columns with lap-splices did not reach their flexural strength and experienced more remarkable strength degradation with respect to the column reinforced with continuous longitudinal bars. On the other hand, presence of a 180-degree hook at the ends of spliced bars reduced the negative influence of inadequate lap-splice length in terms of strength and ductility.