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    The Impact of Scaling Methods and Strong Ground Motion Segments on the Seismic Behaviour of a Low-Rise Tunnel-Form System Building
    (Springer Science and Business Media Deutschland GmbH, 2024) Tozlu, I.; Borekci, M.
    Tunnel-Form System (TFS) has become widely preferred, both for their ability to meet the increased housing demand due to the speed of construction and their high seismic performance. This underscores the importance of understanding TFS buildings’ behaviour during earthquakes. To obtain realistic responses under earthquake effects, Nonlinear Time History Analysis (NLTHA) is an effective method and, accordingly selection of appropriate Ground Motion (GM) and their scaling to a target design spectrum is one of the important steps of NLTHA. In this study, the seismic behavior of a TFS building was analyzed using three pairs of GMs scaled with Amplitude Scaling Method (ASM) and Spectrum Matching Method (SMM). Due to the considerably large stiffness matrices of the TFS buildings, NLTHA for that structure may require a significant amount of time and substantial data storage. To address this, the study investigates the potential for reducing analysis duration and data storage by shortening the records to their Significant Ground Motion (SGM) segment and comparing the results with those obtained with the original records. The analysis results indicate that the responses obtained with ASM exhibit greater variability compared to those obtained with SMM. Also, ASM yields greater responses than those for SMM and it is noteworthy that using GMs scaled with ASM is more conservative. Additionally, a comparison of results from the entire record and SGM segment has shown that using the SGM segment can significantly reduce analysis duration (60%) and the amount of data storage (70%) without substantially altering the responses. © The Author(s), under exclusive licence to Shiraz University 2024.
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    Residual stress measurement in rails by destructive and non destructive method
    (TANGER Ltd., 2015) Turan, M.E.; Ozcelik, S.; Zengin, H.; Ahlatci, H.; Turen, Y.; Tozlu, I.; Sun, Y.
    Residual stress is an elastic stress in remaining part after the various stages of production. If residual stress values in rails are known, mechanical properties of rails and their effects in railway can be predicted. For this purpose, residual stresses of rails which had same casting number were measured by cutting and X-ray diffraction method in this study. Five rails were used for measurement. Firstly, according to the EN 13674-1 which is railway rails standard, strain gauge that is an electrical apparatus were used and one meter long rails were cut. After cutting, Hooke law was applied and residual stress values of rails were found. The residual stress values were around between 115 MPa and 180 MPa. In addition to standard residual stress measurement, X-ray diffraction method was used to compare between destructive and nondestructive techniques. Five specimens were taken from five rails in the appropriate size for X-ray device. In this method stress values were around between 200 and 400 MPa. After residual stress measurement, Brinell's hardness test was applied to three samples and microstructure of rail which has biggest residual stress value was examined by SEM. The results show that, residual stress values in cutting method were different from X-ray diffraction method and residual stress could affect the rails hardness.