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    Assessment of radiological hazards arising from natural radioactivity in Bayburt stones used in buildings and possible effects on public health
    (Frontiers Media Sa, 2026) Dizman, Serdar; Umar, Muttaka; Hatipoglu, Yavuz Selim
    Background Since ancient times, natural stones have served as essential materials in construction, landscaping, and artistic applications. Bayburt stone is one of the most important stones used in and around Bayburt, in the Eastern Black Sea region of T & uuml;rkiye. It has been frequently used in buildings (castle, house, etc.), street flooring, fountains, and places of worship from ancient times to the present day. Due to their underground origin, natural stones contain natural radioisotopes in various concentrations, making the assessment of their radioactivity levels important for public health.Objective This study aims to determine the natural radioactivity levels of Bayburt stones used in buildings and to assess the potential radiological hazards and possible effects on public health.Methods Natural radioactivity levels (226Ra, 232Th and 40K) were determined in a total of 36 Bayburt stone samples, 30 from five different quarries and 6 from a natural stone factory in Bayburt province. High-purity germanium (HPGe) spectrometry was employed to measure radioactivity concentrations. Additionally, several radiological hazard indices (Raeq, Hin, I gamma, D, AEDE, AGDE, and ELCR) were calculated and compared with reference limits proposed by international organizations.Results The radioactivity concentrations in the Bayburt stone samples ranged from 1.56 to 23.54 Bq/kg for 226Ra, from 0.53 to 23.69 Bq/kg for 232Th, and from 10.31 to 505.35 Bq/kg for 40K. The average activity concentrations were found to be 5.56 +/- 0.90 Bq/kg for 226Ra, 4.62 +/- 0.65 Bq/kg for 232Th, and 179.12 +/- 9.88 Bq/kg for 40K. The average values of Raeq, Hin, I gamma, D, AEDE, AGDE, and ELCR were found to be 18.68 Bq/kg, 0.07, 0.14, 8.91 nGy/h, 43,72 mu Sv/y, 63.06 mu Sv/y, and 17.07 & times; 10-5, respectively. All calculated radiological hazard indices were below the recommended safety limits.Conclusion The findings indicate that the Bayburt stone samples investigated are suitable for construction purposes and do not pose significant radiological hazards to human health when used in building environments.
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    Effective Damping Coefficient of Fluid Viscous Dampers for Dynamic Response Mitigation of Coupled Frames
    (Springer Heidelberg, 2023) Duzgun, Oguz Akin; Hatipoglu, Yavuz Selim
    Purpose In this study, the effective damping coefficient of the fluid viscous dampers (FVDs) used for coupling two adjacent multi-story frames was investigated, considering soil-structure interaction (SSI) effects under seismic excitation. Methods A numerical procedure was employed to obtain the dynamic response of the interconnected frames-soil system. The two-dimensional (2D) finite elements were used for the numerical treatment of the adjacent frames and soil region. Viscous boundary conditions were used as special non-reflecting boundaries on the edges of finite soil region. Five different damping coefficients of FVDs are considered to determine the effective damping coefficient. The effective damping coefficient of FVDs was determined by comparing the results from coupled frames with those of the uncoupled frames. Results The results showed that the most affecting parameter on the system response was found to be soil type. It was also found that the sufficient damping coefficient of the viscous damper is equal to 1 x 10(5) N s/m for minimum response. Conclusion When the effective damping coefficient of the FVDs was provided, the maximum values of the roof displacements, the roof accelerations, and the base shear forces are found to decrease by more than 40%.
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    INVESTIGATION OF THE EFFECTIVENESS OF VISCOUS DAMPERS CONNECTED TO ADJACENT BUILDINGS ON DYNAMIC BEHAVIOR UNDER SOIL-STRUCTURE INTERACTION EFFECTS
    (Yildiz Technical Univ, 2020) Hatipoglu, Yavuz Selim; Duzgun, Oguz Akin
    In this study, the dynamic behavior of two adjacent structures with fluid viscous damper (FVD) was investigated under the influence of earthquake and considering soil-structure interaction (SSI). Adjacent structures with FVD's were analysed for three different soil types. The modelling and analysis were made in two-dimensional (2D) space by using ANSYS package program. Viscous boundary conditions were used on the boundaries of 2D soil model. The analyses results were obtained in terms of displacement, acceleration, and shear force. The effect of FVD was investigated using different connection types. The damping coefficient of FVD's was assumed constant in all analyses. When the results of the analysis are examined, it can be seen that FVD's are effective for seismic response. However, it is necessary to consider the soil-structure interaction. Significant different structural results were obtained between fixed support and three different soil types. For example, in the same model, while the top floor displacement may reduce in Soil Type I, the top floor displacement may increase in Soil Type II. At the end of the study, it was seen that there was no need to connect the FVD to all floors. It was found sufficient to connect a fluid viscous damper only to the top floor (1 FVD) or to the top and middle floor (2 FVD). FVD's have no effect on buildings with the similar dynamic character. In the analysis for seismic control of adjacent buildings, the effect of soil-structure interaction should certainly be taken into account.