Reinforced concrete (RC) structures lose performance over time. One of the most significant environmental factors causing performance degradation is reinforcement corrosion. Corrosion reduces the diameter of the reinforcement and degrades the mechanical properties of both the concrete and the steel. In order to determine the degradation of the structural performance caused by corrosion, it is essential to identify the time periods in which corrosion initiates and propagates, and to thoroughly analyze the parameters that govern these processes. In this study, the corrosion initiation and propagation times were calculated separately for an RC frame exposed to chloride ions. Factors contributing to the further reduction of these processes were identified. Analyses and comparisons were made to determine the structural performance of the calculated RC frame over its service life. The results showed that corrosion reduces the structural performance, especially in regions with high seismic potential, where preventive measures against corrosion are essential. The most important parameter influencing the corrosion mechanism is the corrosion rate, while another important factor is the formation of cracks on the element surface. In cases where cracks are present, the corrosion initiation time is shortened, which means that materials should be selected at the design stage that are suitable for the environment, and the years of maintenance required should be calculated by the design engineers. In addition, the surfaces of RC elements should be monitored, and crack tracking should be carried out.

Heat affects the mechanical properties of steel and the bearing capacity of steel structures, with joints being a crucial factor in determining their behavior. Steel can regain its mechanical properties that are lost owing to heat if the temperature remains below 600 °C, allowing for the possibility of reusing steel after cooling. In such cases, it becomes essential to assess the damage caused by heat exposure to decide whether to demolish the structure or continue using it. However, continuing its usage requires anticipating the potential negative effects of heat. To achieve this, it is necessary to determine the behavior of steel joining tools experimentally or numerically after exposure to heat. This study aims to ascertain the post-fire behavior of various end-plated beam and column connections, providing a cost-effective alternative to expensive fire experiments. Three different end-plated combination models were heated to a specified temperature, and steel frames were constructed after the elements cooled. Six three-point bending tests were conducted, and the experimental data obtained were validated using finite element models. The results indicate that the temperature causes a reduction in the bearing capacity of the joint, and the length of the end plate has a significant effect on the connection behavior. The finite element model validated by experiments is expected to facilitate numerical studies with different characteristics.

Reinforced concrete structures deteriorate over time when exposed to environmental effects throughout their service life, resulting in a loss of structural performance and ultimately a reduction in service life. One of the most critical deterioration mechanisms in this process is the corrosion of the reinforcement steel. The initiation and propagation of corrosion adversely affect the load-bearing capacity, bond strength, and overall structural behavior of reinforced concrete elements, thereby threatening the structural safety. Therefore, understanding the corrosion process and accurately predicting the service life of reinforced concrete structures is critical to ensuring their long-term durability. This study comprehensively examines the effects of chloride-induced rebar corrosion on the service life of reinforced concrete structures. Various mathematical models used to predict corrosion initiation and propagation times are analyzed in detail. These models provide a scientific basis for understanding the effects of environmental conditions and structural properties on the corrosion process and estimating how these effects affect the service life. In particular, the study investigates the effect of parameters such as concrete cover thickness, rebar diameter, crack presence, corrosion rate, and environmental conditions on the corrosion process, all of which also affect structural performance. Cracks in reinforced concrete elements shorten the corrosion initiation period depending on their thickness. Considering that the presence of cracks also changes the structural behavior, it is recommended to use the Kwon model, which takes the presence of cracks into account, in the service life calculations. The presence of cracks is ineffective in the corrosion propagation period, and it is recommended to use the Morinaga model for this period. For reinforced concrete elements exposed to aggressive environments, increasing the thickness of the concrete cover and the diameter of the reinforcement has been shown to increase the service life. Columns with larger diameter reinforcement showed a longer service life than beams with smaller diameter reinforcement. Therefore, evaluating each element separately in service life calculations will ensure that a safer approach is taken. In conclusion, this study serves as a valuable resource for developing design strategies to improve the long-term durability of reinforced concrete structures and to minimize the adverse effects of corrosion on structural performance. It provides design and field engineers with guidance to make more accurate service life assessments and implement effective decisions to improve structural performance.

Bu çalışma, 6 Şubat 2023 Kahramanmaraş depremleri öncesi ve sonrasında Türkiye’nin güney ve güneydoğusundaki on bir ilin (Adana, Adıyaman, Diyarbakır, Elazığ, Gaziantep, Hatay, Kahramanmaraş, Kilis, Malatya, Osmaniye, Şanlıurfa) yapı stoku, zemin özellikleri ve deprem yönetmeliklerindeki değişimleri veriler ve uydu gözlemleriyle bütüncül biçimde değerlendirmektedir. 2002–2024 yılları arasında inşa edilen yapılar; kullanım amacı, taşıyıcı sistem türü, malzeme kalitesi ve yürürlükteki yönetmeliklere göre sınıflandırılmıştır. TÜİK, USGS, CORINE, Google Dynamic World ve OpenLandMap verileri analizlerde kullanılmıştır. Sonuçlar, yapı stokunun %85–95’ini betonarme sistemlerin oluşturduğunu; ancak malzeme ve denetim yetersizliklerinin büyük hasarlara yol açtığını göstermektedir. Deprem sonrası dönemde hızlı inşa süresi ve yüksek dayanım avantajları nedeniyle çelik ve prefabrik sistemlerin oranı artarken, yığma yapılar neredeyse tamamen ortadan kalkmıştır. Uydu analizleri, 1990–2018 arasında yapılaşmanın tüm illerde belirgin biçimde arttığını, 2023 sonrasında ise Kahramanmaraş, Elazığ ve Malatya’da deprem kaynaklı azalmalar yaşandığını göstermektedir. Bu durum, deprem kaynaklı yıkımın ve tahliye edilen bölgelerin mekânsal yansımalarını açıkça gösterirken, zemin analizleri, alüvyon ve suya doygun tabakalarda sıvılaşma ve taşıma gücü kayıplarının hasar şiddetini artırdığını doğrulamıştır. Genel olarak, deprem güvenliğinin yalnızca yönetmeliklerle değil; tasarım, uygulama, zemin etüdü ve denetimin eşgüdümlü iyileştirilmesiyle sağlanabileceği vurgulanmaktadır. Çelik, kompozit ve prefabrik sistemlerin yaygınlaştırılması, yığma yapı stokunun dönüştürülmesi ve uzaktan algılama tabanlı risk haritalarının planlama süreçlerine entegrasyonu, afet sonrası yeniden yapılanma ve kentsel dönüşüm için öncelikli mühendislik adımları olarak önerilmektedir.