Person: CÖMERT, MUSTAFA
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Dr. Öğr. Üyesi
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CÖMERT
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MUSTAFA
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Publication Restricted Seismic Retrofit of Substandard RC Columns Using Sprayed Glass Fiber-Reinforced Mortar and Basalt Textile Reinforcement(Taylor & Francis Ltd., 2023) Ateş, Ali Osman; Hajihosseinlou, Saeid; Nasrinpour, Amin; Demir, Cem; CÖMERT, MUSTAFA; Maraşlı, Muhammed; İlki, AlperThis study investigates the seismic retrofit of substandard reinforced concrete (RC) columns through external jacketing of potential plastic hinge zones using sprayed glass fiber-reinforced mortar and basalt textile reinforcement. An innovative spraying method was used to apply the matrix material to the concrete surface. A total number of eight full-scale columns (four reference, four retrofitted) were tested under constant high axial load to capacity ratio and reversed cyclic lateral loading. Columns were constructed using low-strength concrete and transverse reinforcement with various spacing and inadequate hook detailing to mimic the columns in substandard structures. Test results are evaluated in terms of lateral load-drift ratio relationships, displacement ductility, stiffness degradation, energy dissipation, and residual displacements. Evaluation of the test results showed that the proposed technique is effective for seismic retrofit of substandard RC columns, particularly in terms of enhancement of displacement ductility, energy dissipation capacities, and reduction of residual displacements.Publication Restricted Seismic Collapse Performance of a Full-Scale Concrete Building with Lightly Reinforced Columns(Asce-Amer Soc Civil Engineers, 2021) Töre, Erkan; Demir, Cem; CÖMERT, MUSTAFA; İlki, AlperBrittle failure of lightly reinforced concrete columns is one of the primary reasons for partial or total collapse of substandard existing buildings subjected to earthquake loading. This study presents collapse performance of a full-scale building that was performed to gain insight into the seismic behavior and the collapse mechanisms of nonductile buildings with lightly reinforced concrete columns. The three-story building was tested under displacement-controlled quasi-static reversed cyclic loading followed by a lateral pushover loading up to realization of the total collapse. In addition to the poor reinforcement details, columns had high axial load-to-axial capacity ratios as also observed in many existing substandard buildings. During the test, severe structural damage was observed at 0.9% first-story drift ratio in the cyclic part of the lateral loading and the brittle total collapse of the building took place during the pushover loading at 1.45% first-story drift ratio. In this paper, after the introduction of the test campaign, the formation of structural damage and collapse mechanisms are discussed. In addition, an attempt to predict the behavior and performance of the test building is made by using a column model that considers flexural, slip, and shear deformations. Finally, the obtained analytical results are compared with the experimental observations and results.Publication Restricted Structural Characteristics of the Earthquake-Prone Building Stock in Istanbul and Prioritization of Existing Buildings in Terms of Seismic Risk-A Pilot Project Conducted in Istanbul(Taylor and Francis Ltd., 2023) Aydoğdu, Hasan Hüseyin; Demir, Cem; CÖMERT, MUSTAFA; Kahraman, Tayfun; Ilki, AlperEarthquakes have caused catastrophic results in cities since the beginning of settled life, and the cumulative experience of these events has indicated that the lack of seismic resilience brings enormous economic losses and threatens human life. Consequently, the importance of seismic risk mitigation of earthquake-prone structures has arisen to reduce the primary and secondary losses resulting from seismic events in the last decades as developments in the earthquake engineering field occur. The first step for ensuring seismic resilience is the identification of risky buildings, which is a difficult challenge for metropolises like Istanbul since the building stock consists of over a million buildings. Applying code-based detailed assessments to so many buildings is not practical in terms of time and cost. Moreover, the current code-based detailed assessment methodologies such as Provisions for the Seismic Risk Evaluation of Existing Buildings under Urban Renewal Law (2019) and Turkish Building Earthquake Code (2018) provide discrete predictions for existing buildings as either risky or non-risky or satisfying life safety/controlled damage or not. However, a ranking system based on a reliable and realistic risk classification to prioritize the buildings is needed. Therefore, as a pilot project, nearly 23,000 reinforced concrete buildings in 37 different districts of Istanbul have been investigated by Istanbul Metropolitan Municipality (IMM) through PERA2019 performance-based rapid assessment methodology by considering the Design Level and Scenario-Based Earthquake cases. This is the most up-to-date and comprehensive site survey and analysis conducted in Istanbul up to now. In this paper, the characteristics of the building stock in Istanbul based on the conducted site work and the outcomes of the rapid seismic safety assessment efforts are summarized. Then, a discussion on the seismic risk evaluation of the existing residential buildings based on the prioritization of the examined buildings is presented through the results obtained for the Design Level and Scenario-Based Earthquake cases.