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Öğe Condition and characterization analysis of a twentieth century cultural heritage through non?destructive testing (NDT) methods: the case of the Sivas industry school ironworking atelier in Turkey(Heritage Science, 2023) Pehlivan Fahriye GamzeBefore the conservation and restoration of many types of cultural heritage, it is necessary to perform careful examination. This study aimed to determine the original building state and deterioration by applying non-destructive testing (NDT) methods in the case of a heritage building. Another goal was to determine, via NDT methods, whether the limestones observed in this study of different forms, colours, and textures were truly different. The Sivas Industry School Ironworking Atelier, which constitutes the research object, is one of the important public buildings in the city of Sivas, Turkey. Within the scope of the study, non-destructive infrared thermography (IRT), Schmidt hammer rebound (SHR) tests, and X-ray fluorescence (XRF) spectroscopy were applied. Accordingly, through IRT, deteriorations, anomalies, and material differences were investigated, and via SHR testing, uniaxial compressive strength (UCS) estimates, strength levels and hardness classes of stones were obtained. Moreover, via XRF spectroscopy, characterization analysis of stones was conducted. The data obtained could provide information to establish a basis for subsequent conservation. The innovation of this study is that although the infrared thermography technique is typically used in the investigation of materials, it was revealed that another technique such as XRF analysis is needed to better determine whether stones that seem different based on IRT are actually different. With IRT technique, anomaly and material detorioration can be determined. In addition to these two techniques, SHR tests that are non-destructive methods are needed to think about mechanical features of the material. Therefore, when determining the conditions and for characterization analysis of a cultural heritage before restoration, different techniques should be jointly used to complement each other.Öğe Risk-targeted design of seismically isolated buildings(Nisan 2022) Güneş, NecmettinSeismic isolation has been used to improve the seismic performance of buildings for the last decades. However, it has been shown that the code-based displacement capacity of isolation members does not provide adequate collapse probabilities for different Risk Categories of ASCE 7–16. Seismic design codes stipulate to determine maximum isolator displacement at the Risk-Targeted Maximum Considered Earthquake (MCER) level. Although the code-based isolator displacement capacity is checked with the mean displacement of the MCER level nonlinear time history analysis results, extreme event effects and incorporating uncertainties into fragility curves create additional displacement demands. Therefore, there is a need to amplify the code-based displacement capacity of isolators to obtain sufficient collapse performance. A previous study, assumed elastic behavior and rigid mass model for the superstructure, proposes an iterative probabilistic approach. In the present study, seven different seismically isolated buildings are modeled, and the nonlinear behavior of isolators and superstructures is considered in the incremental dynamic analyses achieved for all models to obtain fragility curves. Although the seismic isolation considerably decreases the spectral accelerations of the superstructure, it is shown that the R-μ-T relations for diaphragm level accelerations, transferred accelerations from base to superstructure, become more sensitive to nonlinear behavior at the superstructure mode periods. The fragility curves of five case study buildings are obtained using the FEMA P695 procedure, and it is figured out that the collapse probability of isolation units is highly correlated with the required isolator displacement to code-based maximum isolator displacement (D/DM) ratio. Then, two simple equations with high correlation coefficients are acquired to estimate the required displacement capacity for prescribed risk-target levels. Further, the obtained equations are verified for two different isolated building models, and their results are compared with the Incremental Dynamic Analysis (IDA) results. The verification results show that the given equations can be used in the preliminary design phase of seismically isolated mid-rise reinforced concrete buildings.Öğe Effects of near-fault pulse-like ground motions on seismically isolated buildings(2022) Güneş, NecmettinForward-directivity effects create distinct velocity pulse in the fault-normal direction of near-fault ground motions. It has been shown that this pulse period governs the structural response of fixed base buildings. The present study examines the effects of the near-fault pulse-like ground motions on seismically isolated buildings, considering different effective isolation period to pulse period ratios. Three sets for near-fault ground motions with varying pulse periods are employed to determine the effects of pulse-like ground motions on isolator displacements, superstructure drift ratios, and superstructure load distributions. These effects are categorized as spectral shape and amplification. It is seen that the pulse period forms the spectral shape of records. Spectral acceleration relatively decreases in the short periods and increases in the long periods by enhancing the pulse period. This phenomenon reduces isolator displacement demand for near-fault ground motions with the large and medium pulse periods considering ASCE 7–16 scaling range. An intensity measure parameter is modified to indicate the spectral shape effect of pulse-like records on the isolated buildings. Also, the amplification ratio for the isolator displacement caused by the pulse period is obtained, excluding the spectral shape effect and considering the pulse period to effective isolation period ratio. Further, the R-μ-T relation of the first-floor acceleration, transferred acceleration to the superstructure, is acquired to determine the pulse period effect on superstructures. The results show that the superstructure ductility demand is very sensitive to the pulse period, and the effectiveness of the isolation system considerably decreases by enhancing the pulse period. Also, it is demonstrated that the pulse period governs the lateral load distribution for the superstructure.
