This study investigates the causes of soft-storey and weak-storey formations in low- and mid-rise RC (Reinforced Concrete) buildings in Türkiye. In the first phase of the study, 96 model buildings were designated for the examination of soft-storey irregularity when the ground floors are used for commercial purposes and the upper floors for residential use. The ground floor heights that would cause soft-storey irregularity in each of the selected buildings were determined according to the formulas given in the Türkiye Building Earthquake Code (TBEC) and the American Society of Civil Engineers Standard (ASCE). It was found that the ground floor heights obtained according to ASCE are usable in practice, whereas those obtained according to the TBEC, particularly for buildings over three storeys, are excessively high for practical use. This indicates that, even if the buildings in Türkiye are designed with very high ground floor heights, they do not have soft-storey irregularities, according to the TBEC, but soft-storey formation may occur in these buildings due to the high ground floor height as a result of the effects of earthquakes. Instead of the soft-storey irregularity coefficient limit value (n_ki > 2) found in the TBEC, this study proposes a new limit value to prevent the design of buildings with very high ground floors. In the second phase of the study, for the purpose of examining weak-storey irregularity, 105 model buildings differing in their infill wall layout, number of spans, span length, and number of storeys were selected. The weak-storey irregularity coefficients of each of these models were determined according to the TBEC. The results of the study revealed that buildings with no infill walls in one direction or with infill walls in only one of the exterior axes in one direction have a high risk of having weak storeys.

Many factors affect the earthquake vulnerability of reinforced concrete (RC) structures, constituting a large part of the existing building stock. Short column in RC structures is one of the reasons for earthquake damage. Significant damages may occur due to brittle fractures in structural elements when the shear resistances are exceeded under the effect of high shear stress in short columns formed due to architectural and topographic reasons. This study created structural models for three situations: the hill slope effect, band-type window and mezzanine floor, which may cause short column formation. The structural analyses by SAP2000 were compared with the reference building model with no short columns. Structural analyses were performed separately according to strength-based and deformation-based design approaches in the updated Türkiye Building Earthquake Code (TBEC-2018). Short column formation; the effects on soft-storey irregularity, the relative storey drifts, column shear force, plastic rotation in columns, roof displacement, base shear force and column damage levels were investigated. As a result of the analysis, it was determined that the relative drifts from the first floor of the building decreased significantly due to the band-type window and slope effect, which caused the second storey to fall into the soft-storey status. In addition, short-column formation caused a significant increase in both plastic rotation demand and shear force in short columns.

On 6 February 2023, the Kahramanmaraş earthquakes clearly showed that the elastic spectrum curves in TBEC-2018 are insufficient to represent earthquake behavior. In this study, the effect of using a site-specific spectrum curve instead of the elastic spectrum given in TBEC-2018 on the earthquake safety of a building is investigated. For this purpose, the provinces in southwest Anatolia, Türkiye, which is one of the most tectonically complex regions with frequent seismic events, were selected. In the first stage of the study, spectrum curves were obtained for earthquakes with return periods of 2475, 475, and 72 years for each of the provinces in this region. These spectrum curves were obtained using probabilistic seismic hazard studies that take into account the active faults of the provinces and earthquake activity in both historical and instrumental periods. In the second stage of the study, analytical models of a selected model RC building were created according to each province, and static pushover analyses of these building models were performed both according to the elastic spectrum given in TBEC-2018 and according to the spectrum curve created specifically for the province. The results of the analyses show that the change in the spectrum changes the target displacement level of the buildings, and as a result, the cross-sectional damage zone of the structural elements under the earthquake effect is changed. So much so that using the site-specific instead of the elastic spectrum given in TBEC-2018 changed the damage zone of 43% of the beams and 26.4% of the columns in the İzmir model. The change in the section damage zones changed the performance level of some floors of the models and the performance level of the building. The study revealed the importance of using the most realistic elastic spectrum curves in order to determine the earthquake performance of buildings that is as close as possible to their behavior in a possible earthquake.

It is known fact that the earthquake occurred in two decades have been caused serious pecuniary loss and spiritual damages in Turkey. Massive earthquakes revealed that the existing building stocks in urban regions are significantly vulnerable to seismic hazard. It is very important that earthquake safety of existing buildings should be determined as soon as possible and that unsafe ones should be strengthened. Investigations on the damaged buildings show that material strengths are very important parameters on the building performance. This paper aimed to determine the seismic safety of the buildings in risky regions in terms of earthquake and to evaluate general situation. Therefore,120 existing RC residential buildings are chosen from different cities to predict the general trend on the seismicity of buildings. The available material qualities are taken into account in the analyzes of the buildings. Analyzes were carried out by increasing the material strengths and the effect of the material strength on the earthquake performance was examined. Structural Analyzes Program (SAP 2000) was used in modelling of buildings and to obtain seismic performance of residential buildings. Nonlinear elastic procedures given in Turkish Earthquake Code 2007 (TEC) were applied in the analyses of structural systems.

Bu çalışmada, tasarımı TBDY (2018)’e göre yapılan ve yapımı devam eden betonarme bir binanın incelenmek üzere proje verileri elde edilmiştir. Binanın doğrusal elastik olmayan değerlendirme yöntemlerinden tek modlu statik itme analizi ile performans düzeyi belirlenmiştir. Elde edilen performans analizinin sonucu TBDY 2018’de verilen hedef performans seviyesi ile kıyaslanmıştır. Bina daha yapım aşamasında olduğundan yeni yapılacak bir bina gibi değerlendirilip performans analizi bu kapsamda yapılmıştır. Kesitlerin moment eğrilik analizleri ile plastik mafsal özelliklerinin belirlenmesi için SAP 2000’in Section Desinger arayüzünde faydalanılmıştır. Yapılan statik itme analizi sonucu kolon ve betonarme perdelerde herhangi bir hasar meydana gelmemiş, kirişlerin ise bazıları belirgin hasar bölgesinde kalmıştır. Düşey taşıyıcı elemanlarda hasar oluşmadığı için bina performans seviyesi kiriş hasarlarına bakılarak karar verilmiştir. Binanın yönetmelikte verilen hedef performans seviyesini sağladığı belirlenmiştir.