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Yayın Precursors of instability in a natural slope due to rainfall: a full-scale experiment(Springer Heidelberg, 2018-09) Askarinejad, Amin; Akça, Mehmet Devrim; Springman, Sarah MarcellaA full-scale landslide-triggering experiment was conducted on a natural sandy slope subjected to an artificial rainfall event, which resulted in mobilisation of 130m(3) of soil mass. Novel slope deformation sensors (SDSs) were applied to monitor the subsurface pre-failure movements and the precursors of the artificially triggered landslide. These fully automated sensors are more flexible than the conventional inclinometers by several orders of magnitude and therefore are able to detect fine movements (<1mm) of the soil mass reliably. Data from high-frequency measurements of the external bending work, indicating the transmitted energy from the surrounding soil to these sensors, pore water pressure at various depths, horizontal soil pressure and advanced surface monitoring techniques, contributed to an integrated analysis of the processes that led to triggering of the landslide. Precursors of movements were detected before the failure using the horizontal earth pressure measurements, as well as surface and subsurface movement records. The measurements showed accelerating increases of the horizontal earth pressure in the compression zone of the unstable area and external bending work applied to the slope deformation sensors. These data are compared to the pore water pressure and volumetric water content changes leading to failure.Yayın Uni-axial behavior of energy dissipative steel cushions(Techno Press, 2018-06-25) Özkaynak, Hasan; Khajehdehi, Arastoo; Güllü, Ahmet; Azizisales, Faraz; Yüksel, Ercan; Karadoğan, Hüseyin FarukSeismic excitations may impart a significant amount of energy into structures. Modern structural design attitudes tend to absorb some part of this energy through special dissipaters instead of heavy plastic deformations on the structural members. Different types of dissipater have been generated and utilized in various types of structures in last few decades. The expected earthquake damage is mainly concentrated on these devices and they may be replaced after earthquakes. In this study, a low-cost device called energy dissipative steel cushion (EDSC) made of flat mild steel was developed and tested in the Structural and Earthquake Engineering Laboratory (STEELab) of Istanbul Technical University (ITU). The monotonic and cyclic tests of EDSC were performed in transversal and longitudinal directions discretely. Very large deformation capability and stable hysteretic behavior are some response properties observed from the tests. Load vs. displacement relations, hysteretic energy dissipation properties as well as the closed form equations to predict the behavior parameters are presented in this paper.Yayın On the existence of some evolution equations in fluid-filled elastic tubes and their progressive wave solutions(Pergamon-Elsevier Science Ltd., 2004-09) Demiray, HilmiIn the present work, by employing the nonlinear equations of motion of an incompressible, isotropic and prestressed thin elastic tube and the approximate equations of an incompressible inviscid fluid, we studied the existence of some possible evolution equations in the longwave approximation and their progressive wave solutions. It is shown that, depending on the set of values of the initial deformation, it might be possible to obtain the conventional Korteweg-deVries (KdV) and the modified KdV equations of various forms. Finally, a set of progressive wave solutions is presented for such evolution equations.Yayın Weakly nonlinear waves in a viscous fluid contained in a viscoelastic tube with variable cross-section(Gauthier-Villars/Editions Elsevier, 2005-03) Demiray, HilmiIn the present work, treating the arteries as a thin walled prestressed viscoelastic tube with variable cross-section, and using the longwave approximation, we have studied the propagation of weakly nonlinear waves in such a fluid-filled viscoelastic tube by employing the reductive perturbation method. By considering the blood as an incompressible viscous fluid, depending on the order of various physical entities, various evolution equations with variable coefficients are obtained and progressive wave solutions to these evolution equations are given whenever possible. It is shown that this type of equations admit solitary wave type of solutions with variable wave speeds.Yayın Spatial slip behavior of large strike-slip fault belts: Implications for the Holocene slip rates of the eastern termination of the North Anatolian Fault, Turkey(Blackwell Publishing Ltd, 2015-12) Zabcı, Cengiz; Sançar, Taylan; Akyüz, Hüsnü Serdar; Güneç Kıyak, NafiyeWe present new data on Holocene slip rates for the eastern end of the North Anatolian Fault (NAF) by using the optically stimulated luminescence ages of the offset terrace deposits at two sites, where a total of four displaced landforms was studied. Each offset feature was analyzed independently, and three different assumptions were made for all the offsets, depending on whether the age of the upper tread (upper tread reconstruction), the lower tread (lower tread reconstruction), or all bounding surfaces (intermediate solution) were used in dating of the terrace risers. The deflected geometry of the risers strongly suggests the use of either the intermediate solution or the upper tread reconstruction. The joint slip rate distributions for the upper tread reconstructions and the intermediate solutions were modeled as 13.0 + 1.8 / -1.4 and 14.3 + 5.8 / -2.4 mm/yr (2?), respectively. Although the intermediate solution covers the full range of ages for the measured displacements, the curved geometry of the terrace risers suggests that the initiations of the riser offsets are most probably close to the abandonment ages of the upper terrace treads. Therefore, we accepted the joint slip rate of the intermediate solution but suggested that the average rate for the main displacement zone of the eastern NAF should be close to its lower limits. This slower rate with respect to previous estimates suggests that the total deformation is not only accommodated on the main displacement zone but is also distributed along the secondary faults to the south of the easternmost segments of the NAF.
