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Article Citation - WoS: 6Citation - Scopus: 7Finite Element Analysis of Frames With Reinforced Concrete Encased Steel Composite Columns(Mdpi, 2022) Tunc, Gokhan; Othman, Mohammed Moatasem; Mertol, Halit CenanStructural frame systems that consists of concrete-encased-steel-embedded composite columns and reinforced concrete beams are typically used in mid-rise to tall buildings. In order to understand their overall structural behavior, a total of 12 frame models with high and low ductility features were constructed and analyzed using LS-DYNA software. Two of these models were validated using the results of previously tested frames. The remaining 10 models were studied to predict the behavior of frames with varying concrete strengths, reinforcement configurations, and structural steel sections under vertical and lateral loads. The results were investigated in terms of cracks and failure patterns, load-deflection relationships, energy dissipation, and stiffness degradation. The analytical results indicated that the high ductile frame models showed slightly better lateral load carrying performances compared to low ductility frame models. Moreover, the analytical studies demonstrated that the existence of structural steel in a column, regardless of its cross-sectional shape, was the most important parameter in improving the lateral load carrying capacity of a frame.Article Citation - WoS: 54Citation - Scopus: 58Investigation of Rc Buildings After 6 February 2023, Kahramanmaras, Turkiye Earthquakes(Mdpi, 2023) Mertol, Halit Cenan; Tunc, Gokhan; Akis, Tolga; Kantekin, Yunus; Aydin, Ishak CanTwo major earthquakes struck Pazarcik and Elbistan, towns in Kahramanmaras, Turkiye, on 6 February 2023, approximately 9 h apart. The first earthquake, recorded at 04:17 local time, had a M-w = 7.7, with a focal depth of 8.6 km. At 13:24 local time, a second earthquake occurred with M-w = 7.6 at a focal depth of 7 km, approximately 90 km north of the first one. A total of 11 provinces were severely affected by these earthquakes. As of 15 April 2023, they caused close to 51,000 deaths and almost 215,000 completely destroyed/severely damaged buildings. At some locations, the largest horizontal peak ground acceleration (PGA) values of the first and second earthquakes exceeded the code-generated PGAs by almost 3 and 1.75 times, respectively. A technical team visited these areas within 15 h of the first earthquake. The purpose of this article is to present their observations, findings, and the characteristics of the two earthquakes, with comprehensive site survey results supported by photographs. This study concludes that most of the collapsed and severely/moderately damaged buildings in the region were built between 1975 and 2000, when site inspections were rare or non-existent. In addition to the high PGAs recorded in these earthquakes, it was verified that the design and construction of these buildings did not fully comply with the earthquake codes valid at the time. The collapsed buildings and their damage patterns confirm inadequate development length, violation of bending stirrup ends at 135 & DEG;, deficiencies in construction materials and reinforcement configuration, noncompliance with confinement zones, violation of the strong beam-stronger column analogy, and issues related to building inspection. Based on the extent of the damage, it is strongly recommended that the structural performance inspection of all other buildings located near major fault lines, specifically those constructed between 1975 and 2000, should be completed. Since these earthquakes generated much higher PGAs, which is believed to be one of the main reasons for the extensive damage, a re-evaluation of all other PGAs along major fault lines is also recommended.
