A comparative study of the design spectra defined by Eurocode 8, UBC, IBC and Turkish Earthquake Code on R/C sample buildings

Earthquake codes have been revised and updated depending on the improvements in the representation of ground motions, soils and structures. These revisions have been more frequently seen in recent years. One of the key changes in earthquake codes has been performed on the design spectra. In this paper, the design spectra recommended by Turkish Earthquake Code and three other well known codes (Uniform Building Code, Eurocode 8, and International Building Code) are considered for comparison. The main purpose of this study is to investigate the differences caused by the use of different codes in the dynamic analysis and seismic verification of given types of buildings located at code defined different sites. The differences in expressions and some important points for elastic and inelastic spectra defined by the codes are briefly illustrated in tables and figures. Periods, base shears, lateral displacements and interstory drifts for the analyzed buildings located at code defined ground type are comparatively presented.     

Effects of backfill on seismic behavior of rectangular tanks

The reliability and/or stability of the lifeline structures against failure under seismic loads are of critical concern, and must be studied carefully. Therefore, the main objective of this paper is to demonstrate the commonly encountered backfill effects on the dynamic response of rectangular tanks. However, only the exterior wall of the tank which interacts with both the backfill and fluid is tackled, as each part of the structure shows considerable differences in terms of both the load bearing mechanisms and the geometrical and positional differences. Finite element analyses are employed, taking into consideration the fluid-wall-backfill interaction. The analyses are conducted to observe whether or not both backfill and wall behavior can be affected by variation of the internal friction angle. For that purpose, some comparisons are made on vertical displacements of the backfill, roof displacements, stress responses, etc., by means of internal friction angle variations of the backfill from 25° to 40°. Consequently, it is observed that the variations on maximum vertical displacements are affected considerably. In contrast, the maximum stress responses are affected partially. However, the inertial effects of the backfill show that pseudo-static approximations may be insufficient to understand the dynamic behavior of the backfill-wall-fluid system.     

Investigation of dynamic response of masonry minaret structures

Almost all historical minarets in Turkey were constructed using cut stone, masonry blocks or combination of these two materials. The structural and geometrical properties of each masonry minaret, or slender tower structure, depend on many factors including the structural knowledge and applications at the time of construction, experience of the architect or engineer, seismicity of the region, and availability of construction materials in that area. Recent earthquakes in Turkey have shown that most masonry minarets in high seismic regions are vulnerable to structural damage and collapse. In this study, in order to investigate the dynamic behavior of historical unreinforced masonry minarets, three representative minarets with 20, 25, and 30 m height were modeled and analyzed using two ground motions recorded during the 1999 Kocaeli and Duzce, Turkey earthquakes. The modal analyses of the models have shown that the structural periods and the overall structural response are influenced by the minaret height and spectral characteristics of the input motion. The dynamic displacement and axial stress time histories are computed at the critical points on the minarets. During recent earthquakes, most minaret failures occurred above the base of the structure. Consistent with the observed response, the largest stresses were calculated at the same location.     

The effects of season on fatty acid composition and ω3/ω6 ratios of northern pike(Esox lucius L.,1758) muscle lipids

In the present study,the effects of season on fatty acid composition,total lipids,and ω3/ω6ratios of northern pike muscle lipids in Kizilirmak River(Kirikkale,Turkey) were investigated.A total of 35 different fatty acids were determined in gas chromatography.Among these,palmitic,oleic,and palmitoleic acids had the highest proportion.The main polyunsaturated fatty acids(PUFAs) were found to be docosahexaenoic acid,eicosapentaenoic acid,and arachidonic acid.There were more PUFAs than monounsaturated fatty acids(MUFA) in all seasons.Similarly,the percentages of ω3 fatty acids were higher than those of total ω6 fatty acids in the fatty acid composition.ω3/ω6 ratios were calculated as 1.53,1.32,1.97,and 1.71 in spring,summer,autumn and winter,respectively.Overall,we found that the fatty acid composition and ω3/ω6 fatty acid ratio in the muscle of northern pike were significantly influenced by season.     

Comparison of the QBO and F10.7 Solar Flux Effects on Total Mass Density

Geomagnetism and Aeronomy - The comparison of the Quasi Biennial Oscillation (QBO) and F10.7 solar flux effects on Total Mass Density (TMD) obtained from NRLMSIS-00 model for 90 km altitude of...     

The Relationship between Dst,IMF-Bz and Collision Parameters for O+ + N2 → NO+ + N Reactive Scattering in the Ionosphere

Geomagnetism and Aeronomy - The kinetic theory is particularly suitable and convenient to calculate the collision parameters in the ionospheric medium. In this study, the mean free path (λ)...     

Pseudo dynamic test of a deficient reinforced concrete frame upgraded with internal steel frames

Two‐story, three‐bay reinforced concrete (RC) frames with and without internal steel frame (ISF) retrofits were tested using continuous pseudo dynamic test method. The ISFs were installed to the middle bay of the RC frame. Test results indicated that ISF retrofit was beneficial in resisting deformation demands without significant damage under simulated ground motions. The ISF shifted the failure mode of the system from a brittle to a ductile mode. The test results were compared with the results of the nonlinear time history analysis. The analysis results were capable of tracing the overall behavior of global response parameters; however, estimations of local demand parameters were less accurate. Copyright © 2012 John Wiley & Sons, Ltd.     

A precise gravimetric geoid model in a mountainous area with scarce gravity data: a case study in central Turkey

In mountainous regions with scarce gravity data, gravimetric geoid determination is a difficult task that needs special attention to obtain reliable results satisfying the demands, e.g., of engineering applications. The present study investigates a procedure for combining a suitable global geopotential model and available terrestrial data in order to obtain a precise regional geoid model for Konya Closed Basin (KCB). The KCB is located in the central part of Turkey, where a very limited amount of terrestrial gravity data is available. Various data sources, such as the Turkish digital elevation model with 3 ?? × 3?? resolution, a recently published satellite-only global geopotential model from the Gravity Recovery and Climate Experiment satellite (GRACE) and the ground gravity observations, are combined in the least-squares sense by the modified Stokes?? formula. The new gravimetric geoid model is compared with Global Positioning System (GPS)/levelling at the control points, resulting in the Root Mean Square Error (RMS) differences of ±6.4 cm and 1.7 ppm in the absolute and relative senses, respectively. This regional geoid model appears to be more accurate than the Earth Gravitational Model 2008, which is the best global model over the target area, with the RMS differences of ±8.6 cm and 1.8 ppm in the absolute and relative senses, respectively. These results show that the accuracy of a regional gravimetric model can be augmented by the combination of a global geopotential model and local terrestrial data in mountainous areas even though the quality and resolution of the primary terrestrial data are not satisfactory to the geoid modelling procedure.     

Comparison of GPS TEC with modelled values from IRI 2016 and IRI-PLAS over Istanbul,Turkey

The Total Electron Content (TEC) prediction performances of the empirical IRI model and IRI-PLAS model were investigated by comparing the GPS-based TEC values provided by the IONOLAB group. TEC values were obtained on equinox (March 21 and September 23) and solstice (June 21, and December 21) days in low (2009), medium (2012) and high (2015) solar activity periods at Istanbul, Turkey. The prediction performances of the models were statistically analyzed based on the differences between the GPS-TEC and the empirical models, considering the maximum and minimum deviations, the correlation analysis and the root mean square error (RMSE). As a result of the investigation, it is seen that the empirical models have similar predictive performances when the plasmaspheric effects are neglected, and the IRI-PLAS estimations are generally a little closer to the observed GPS-TEC values than all options of IRI-2016 model. Also, it can be said that “IRI2001”, one of the IRI-2016’s “topside” options, can make better predictions than other options and “IG” solar proxy option of IRI-PLAS model is a more appropriate option than the others in TEC calculations over Istanbul, Turkey.