The main cause of many physical and chemical events in the world is shown as high temperature. When concrete used as a building material is exposed to high temperatures, its physical and mechanical properties change. The aim of this study is to investigate the change in compressive strength of normal strength concrete exposed to different temperatures for different periods of time when subjected to cyclic loading. For this purpose, 13 reinforced concrete frame specimens and 39 standard cylinder specimens were produced and exposed to 200, 400, 600 and 800 °C high temperatures for 60, 120 and 180 min. Then, the frame test members were allowed to cool on their own and when they reached room temperature, they were removed from the oven and tested under cyclic load. At the end of the cyclic loading tests, 26 concrete core samples were taken from the frame test members and compressive strengths were determined. As a result of the study, it was determined that thermal cracks in normal concrete caused by heat treatment lead to physical and mechanical changes, and these changes are effective in the decrease in strength. In the study, it was found that the decrease in compressive strength was more than 78% in concretes exposed to cyclic lateral loads after high-temperature effect. A comparison of the experimental strength loss curves of concrete with the design curves in the literature was also made.

Betonarme perde elemanlarının kayma merkezlerinin belirlenmesi uygulanan kuvvetin kesitte burulma oluşturmadan sadece eğilme meydana getirmesi bakımından önemlidir. Deprem bölgelerinde gerek yapının güvenliğini sağlamak gerekse yer değiştirmeleri sınırlandırarak yapısal olmayan elemanlarda meydana gelecek hasarları azaltmak için perde elemanlara etkiyen yatay yüklerin perdenin kayma merkezlerinden uygulanması burulma etkisini ortadan kaldırması bakımından önemlidir. Bu çalışmada U kesitli betonarme perdenin, farklı yatay yük etkileri altında doğrusal olmayan analizleri yapılarak, kayma merkezlerinin nonlineer değişimi araştırılmıştır.

The high performance of reinforced concrete structural elements under the effects of lateral loads such as earthquakes is of great importance in terms of minimizing the loss of life and property that may occur due to earthquakes. One of the parameters affecting the earthquake behavior of a reinforced concrete structure is the corrosion effect. The aim of this study is to investigate the behavior of reinforced concrete columns exposed to different corrosion levels for different durations within the damage limits. In this direction, it is aimed to perform linear and nonlinear analysis of reinforced concrete columns in 5 different corrosion scenarios. In the study, nonlinear analyzes of the column were made using ANSYS software, the data obtained were determined for different damage limit levels and compared with the section analysis. Because of the study, moment-curvature relations, lateral load-horizontal displacement relations, bending ductility and plastic rotation capacity of the reinforced concrete column were determined for each corrosion scenario.

In recent years, many experimental and numerical studies have carried out to design structures resistant to high temperature effects caused by events such as fire. Reinforced concrete structures exposed to high temperature effects due to events such as fire, etc., also exposed to cyclic loading effects such as earthquakes during their lifetime. This study numerically investigates the behaviour of reinforced concrete frame members under cyclic lateral loading after exposure to high temperature effects In this context, 13 reinforced concrete frame members were modelled with the ABAQUS program and analysed under cyclic lateral loading after being exposed to 200, 400, 600 and 800 °C for 60, 120 and 180 minutes. Because of the thermo-mechanical analysis, the lateral load - horizontal displacement relationship and stiffness - horizontal displacement relationship of the reinforced concrete frames compared with the reference element that not exposed to high temperature effect. The results obtained confirm that the lateral load and stiffness capacities obtained from thermo-mechanical analysis with the CDP material model in ABAQUS are in good agreement with the experimental results. The use of the degree of high temperature and the duration of exposure as two variable parameters at the same time constitutes the main innovation that distinguishes the study from the literature. Because of the study, it recommended that reinforced concrete frames exposed to temperatures of 600 °C and above for 60, 120 and 180 minutes should not be use without strengthening. It thought that these suggestions would be useful to the reader in the rapid evaluation of fire-exposed reinforced concrete structural elements.

Temperature causes many physical and chemical changes and has a negative impact on reinforced concrete (RC) structures. Long-term exposure to high temperatures reduces the strength and durability of RC elements and alters their seismic behavior. This study investigates the post-fire response of an RC column exposed to 600, 800, and 1000 °C following the ISO 834 standard fire curve. After natural cooling, the column behavior under cyclic lateral loading was analyzed. A finite element model was developed in ABAQUS to perform thermal analyses, followed by cyclic structural analyses. The effects of high temperature were evaluated in terms of changes in lateral load-carrying capacity and stiffness under different axial load levels. The results show that increasing temperature leads to a continuous reduction in both lateral load-carrying capacity and stiffness. At 1000 °C, these reductions reach approximately 53% and 85%, respectively. Based on these findings, RC columns exposed to temperatures of 600 °C and above 180 minutes should not be reused without strengthening. This study provides practical support for the post-fire evaluation of reinforced concrete structural elements.