Browsing by Author "Kaya, Erdem."

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    Influence of shear deformations in plate bending
    (Thesis (Ph.D.)-Bogazici University. Institute for Graduate Studies in Science and Engineering, 2006., 2006.) Kaya, Erdem.; Tezcan, Semih S.,
    The influence of shear deformations in plate bending becomes significant when the ratio of the thickness to span is relatively large. However, the effects of transverse shear strains are neglected normally in classical theory and therefore, Kirchhoff thin plate theory is not adequate for providing accurate deflections, shear and bending moment values in both static and dynamic conditions. In order to include the influence of shear strains, the shear deformation theories, such as the first order shear deformation theory of Mindlin, is used. Normally, for the analyses of relatively thick plates special category of solid finite elements incorporating the shear deformations are used. In this study, however, a new version of Hrennikoff lattice model has been introduced for the analysis of thick plates. The flexural stiffness properties of the individual members of the lattice model have been appropriately modified to take into account the influence of shear deformations. Thus, the complicated expressions and the extensive theoretical derivations involved in following the Mindlin’s thick plate theory, are avoided. Further, the task of computer programming as well as the speed of computations have been simpler and much faster. For purposes of illustration, a number of thick plates of square, rectangular and elliptical shapes and with different support conditions are analysed under the action of UDL and point load for varying thickness to span ratios. The results of analyses corresponding to a) the closed form solutions, b) the 2D and 3D solid finite elements, and c) the lattice model technique have been presented in a comparative fashion. It has been demonstrated that the newly introduced lattice model technique provides relatively very high degree of accuracy for thick plates, by using appropriate shape factors.
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    The Resistance of states system against nonstate violence: International cooperation to preserve state monopoly of force
    (Thesis (M.A.)-Bogazici University. Institute for Graduate Studies in Social Sciences, 2010., 2010.) Kaya, Erdem.; Kut, Gün.
    With the combined impact of the phenomena of state failure and globalization in the post-Cold War period, violent nonstate actors (warlords, militias, terrorist organizations, insurgents, pirates, transnational criminal organizations) in general became transnational players. As the violent nonstate actors threatened the security of more states other than the targeted one(s), governments tended to work together to fight against them. Governments cooperated through diverse methods to re-establish and to preserve state monopoly on the use of violence against the challenge of these actors. Particularly since the late 1990s, states have been forming an international security regime against nonstate violence through mainly multilateral conventions and UN Security Council resolutions. Within the framework of this anti-nonstate violence security regime, cooperation among states is performed via the United Nations and other international, regional and sub-regional intergovernmental organizations. This study contends that the security regime-facilitated international cooperation works to preserve state monopoly of force, which is the main building-block of the existing states system. Therefore, states system has been developing a resistance against nonstate actors’ resurgence to posses the means of large-scale violence.