Examinando por Autor "Vergara, Juan"
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Ítem Analytic approximation to the scattering of antiplane shear waves by free surfaces of arbitrary shape via superposition of incident, reflected and diffracted rays(OXFORD UNIV PRESS, 2013-03-01) Jaramillo, Juan; Gomez, Juan; Externo - Escuela - Ciencias; Vergara, Juan; Mecánica AplicadaThe scattering induced by surface topographies of arbitrary shapes, submitted to horizontally polarized shear waves (SH) is studied analytically. In particular, we propose an analysis technique based on a representation of the scattered field like the superposition of incident, reflected and diffracted rays. The diffraction contribution is the result of the interaction of the incident and reflectedwaves, with the geometric singularities present in the surface topography. This splitting of the solution into different terms, makes the difference between our method and alternative numerical/analytical approaches, where the complete field is described by a single term. The contribution from the incident and reflected fields is considered using standard techniques, while the diffracted field is obtained using the idea of a ray as was introduced by the geometrical theory of diffraction. Our final solution however, is an approximation in the sense that, surface-diffracted rays are neglected while we retain the contribution from corner-diffracted rays and its further diffraction. These surface rays are only present when the problem has smooth boundaries combined with shadow zones, which is far from being the typical scenario in far-field earthquake engineering. The proposed technique was tested in the study of a combined hill-canyon topography and the results were compared with those of a boundary element algorithm. After considering only secondary sources of diffraction, a difference of 0.09 per cent (with respect to the incident field amplitude) was observed. The proposed analysis technique can be used in the interpretation of numerical and experimental results and in the preliminary prediction of the response in complex topographies. © The Authors 2012. Published by Oxford University Press on behalf of The Royal Astronomical Society.Ítem Construction of rational models for topographic effects and size-conditioned-response-spectra(Elsevier Ltd, 2021-01-01) Vergara, Juan; Sierra C.; Mario Saenz; Jaramillo, Juan; Gomez, Juan; Mecánica AplicadaWe used the decay-with-distance effect of diffracted waves generated from the interaction of a plane wave with a geometric singularity, to establish the connection between the spectral response of a topographic profile and the minimum required sizeÍtem A Superposition Based Diffraction Technique to Study Site Effects in Earthquake Engineering(Hindawi Publishing Corporation, 2016-01-01) Gomez, Juan; Jaramillo, Juan; Mario Saenz; Vergara, Juan; Mecánica AplicadaA method to study the response of surface topographies submitted to incident SH waves is presented. The method is based on the superposition of diffracted sources described in Jaramillo et al. (2013). Since the technique proceeds in the frequency domain in terms of the superposition of incident, reflected, and diffracted waves, it has been termed like a superposition based diffraction approach. The final solution resulting from the superposition approach takes the form of a series of infinite terms, where each term corresponds to diffractions of increasing order and of decreasing amplitude generated by the interactions between the geometric singularities of the scatterer. A detailed, step-by-step algorithm to apply the method is presented with regard to the simple problem of scattering by a V-shaped canyon. In order to show the accuracy of the method we compare our time and frequency domain results with those obtained from a direct Green's function approach. We show that fast solutions with an error of the order of 6.0% are obtained.