325 research outputs found

    Case Histories of Foundations on Top of a Rupturing Normal Fault During the Kocaeli 1999 Earthquake

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    Although the Kocaeli (Turkey) earthquake was triggered by reactivation of the North Anatolian strike-slip Fault, normal faulting also occurred within the pull-apart basin of Gölcük. Its effect on overlying structures is summarized in this paper. The normal rupture caused maximum vertical displacements of up to 2.5m. Several structures were crossed by the rupture. As expected, many of them either collapsed or were severely damaged. Surprisingly, several structures survived the dislocation with no damage, while in some cases the rupture deviated, “avoiding” the structures. The foundations of the involved structures comprised a variety of types, ranging from simple separate footings to box foundation and to piled foundation. The paper provides a comprehensive description of the observed fault-foundation interaction patterns, accompanied by the results of soil exploration and geological trenching. Each structure is analyzed through the use of finite element modelling to reveal the main aspects of Fault Rupture––Soil–Foundation–Structure Interaction (FR–SFSI)

    One-loop adjoint masses for branes at non-supersymmetric angles

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    This proceeding is based on arXiv:1105.0591 [hep-th] where we consider breaking of supersymmetry in intersecting D-brane configurations by slight deviation of the angles from their supersymmetric values. We compute the masses generated by radiative corrections for the adjoint scalars on the brane world-volumes. In the open string channel, the string two-point function receives contributions only from the infrared limits of N~4 and N~2 supersymmetric configurations, via messengers and their Kaluza-Klein excitations, and leads at leading order to tachyonic directions.Comment: 15 pages, 5 figures. Contribution to the proceedings of the Corfu Summer Institute 2011 School and Workshops on Elementary Particle Physics and Gravity, September 4-18 2011 Corfu, Greec

    Phenomenological analysis of D-brane Pati-Salam vacua

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    In the present work we perform a phenomenological analysis of the effective low energy models with Pati-Salam (PS) gauge symmetry derived in the context of D-branes. A main issue in these models arises from the fact that the right-handed fermions and the PS-symmetry breaking Higgs field transform identically under the PS symmetry, causing unnatural matter-Higgs mixing effects. We argue that this problem could be solved in particular D-brane setups where these fields arise in different intersections. We further observe that whenever a large Higgs mass term is generated in a particular class of mass spectra, a splitting mechanism -reminiscent of the doublet triplet splitting- may protect the neutral Higgs components from a heavy mass term. We analyze the implications of each individual representation which in principle is available in these models in order to specify the minimal spectrum required to build up a consistent PS model which reconciles the low energy data. A short discussion is devoted on the effects of stringy instanton corrections, particularly those generating missing Yukawa couplings and contributing to the fermion mass textures. We discuss the correlations of the intersecting D-brane spectra with those obtained from Gepner constructions and analyze the superpotential, the resulting mass textures and the low energy implications of some examples of the latter along the lines proposed above.Comment: 50 pages, 3 figures (v2 - Minor corrections

    Scaling laws for shaking table testing of reinforced concrete tunnels accounting for post-cracking lining response

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    This paper proposes a new set of scaling laws for the study of the post-cracking behaviour of lightly reinforced concrete tunnel linings during 1g shaking table testing. The post-cracking behaviour scaling laws are formulated using two non-dimensional parameters: the brittleness number s, which governs the fracturing phenomenon for unreinforced concrete elements and , which plays a primary role for the stability of the process of concrete fracture and steel plastic flow in reinforced concrete elements. The proposed laws allow for the development of an “adequate” experimental model and are validated using numerical analyses of a reinforced tunnel in rock, in both prototype and 1:30 model scale. The adopted experimental set-up is inspired by an existing 1g physical testing campaign on the seismic response of a concrete tunnel in rock and the postulated laws are shown to grant satisfactory similitude between the cracking behaviour of the model and prototype tunnel under two examined earthquake records. The potential of using the proposed laws in 1g tests for Class A predictions of evolving crack patterns in reinforced concrete tunnels is highlighted. The proposed laws are examined under three possible boundary conditions, indicating that both rigid and laminar boxes can still change the behaviour significantly compared to an envisaged free field boundary model. The analysis shows though that for larger soil to lining stiffness ratios, boundary artefacts could be greatly reduced. The present study provides useful recommendations for future 1g tests that did not exist to date, while the proposed scaling laws allow for versatility in the design of novel tunnel lining model test materials

    SU(5) D-brane realizations, Yukawa couplings and proton stability

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    We discuss SU(5) Grand Unified Theories in the context of orientifold compactifications. Specifically, we investigate two and three D-brane stack realizations of the Georgi-Glashow and the flipped SU(5) model and analyze them with respect to their Yukawa couplings. As pointed out in arXiv:0909.0271 the most economical Georgi-Glashow realization based on two stacks generically suffers from a disastrous large proton decay rate. We show that allowing for an additional U(1) D-brane stack this as well as other phenomenological problems can be resolved. We exemplify with globally consistent Georgi-Glashow models based on RCFT that these D-brane quivers can be indeed embedded in a global setting. These globally consistent realizations admit rigid O(1) instantons inducing the perturbatively missing coupling 10105^H. Finally we show that flipped SU(5) D-brane realizations even with multiple U(1) D-brane stacks are plagued by severe phenomenological drawbacks which generically cannot be overcome.Comment: 34 pages v2 minor correction
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