Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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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, AlperA 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.Conference Object Behavior and Modeling of Shear-Critical Rc Beams Under Impact Loading(American Concrete Institute, 2010) Saatçi, Selçuk; Vecchio, Frank J.The lack of a complete understanding of shear behavior under high dynamic conditions hindered the efforts for accurate prediction of impact behavior, since severe shear mechanisms may dominate the behavior of RC structures when subjected to impact loads. This current study involves a well-instrumented experimental program that was undertaken to contribute to our understanding of the effects of shear mechanisms on the behavior of reinforced concrete (RC) structures under impact loads. The test results showed that the shear characteristics of the RC beam specimens played an important role in their overall behavior. All specimens, regardless of their shear capacity, developed severe diagonal shear cracks, forming a shear-plug under the impact point. Furthermore, the application of the Disturbed Stress Field Model (DSFM) as an advanced method of modeling shear behavior under impact conditions is also investigated. A two-dimensional nonlinear finite element reinforced concrete analysis program (VecTor2), developed previously for static loads, was modified to include the consideration of dynamic loads such as impacts. VecTor2 analyses of the test specimens were satisfactory in predicting damage levels, and maximum and residual displacements. The methodology employed by VecTor2, based on the DSFM, proved to be successful in predicting the shear-dominant behavior of the specimens under impact.