Examinando por Autor "Gómez, J."
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Ítem Effects of realistic topography on the ground motion of the Colombian Andes - A case study at the Aburra Valley, Antioquia(OXFORD UNIV PRESS, 2016-03-01) Restrepo, D.; Bielak, J.; Serrano, R.; Gómez, J.; Jaramillo, J.; Mecánica AplicadaThis paper presents a set of deterministic 3-D ground motion simulations for the greater metropolitan area of Medellin in the Aburra Valley, an earthquake-prone region of the Colombian Andes that exhibits moderate-to-strong topographic irregularities. We created the velocity model of the Aburra Valley region (version 1) using the geological structures as a basis for determining the shear wave velocity. The irregular surficial topography is considered by means of a fictitious domain strategy. The simulations cover a 50 x 50 x 25 km(3) volume, and four M-w = 5 rupture scenarios along a segment of the Romeral fault, a significant source of seismic activity in Colombia. In order to examine the sensitivity of ground motion to the irregular topography and the 3-D effects of the valley, each earthquake scenario was simulated with three different models: (i) realistic 3-D velocity structure plus realistic topography, (ii) realistic 3-D velocity structure without topography, and (iii) homogeneous half-space with realistic topography. Our results show how surface topography affects the ground response. In particular, our findings highlight the importance of the combined interaction between source-effects, source-directivity, focusing, soft-soil conditions, and 3-D topography. We provide quantitative evidence of this interaction and show that topographic amplification factors can be as high as 500 per cent at some locations. In other areas within the valley, the topographic effects result in relative reductions, but these lie in the 0-150 per cent range.Ítem Seismic response of three-dimensional rockfill dams using the Indirect Boundary Element Method(IOP PUBLISHING LTD, 2014-01-01) Sánchez-Sesma, F.J.; Arellano-Guzmán, M.; Pérez-Gavilán, J.J.; Suarez, M.; Marengo-Mogollón, H.; Chaillat, S.; Jaramillo, J.D.; Gómez, J.; Iturrarán-Viveros, U.; Rodríguez-Castellanos, A.; Sánchez-Sesma, F.J.; Arellano-Guzmán, M.; Pérez-Gavilán, J.J.; Suarez, M.; Marengo-Mogollón, H.; Chaillat, S.; Jaramillo, J.D.; Gómez, J.; Iturrarán-Viveros, U.; Rodríguez-Castellanos, A.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecánica AplicadaThe Indirect Boundary Element Method (IBEM) is used to compute the seismic response of a three-dimensional rockfill dam model. The IBEM is based on a single layer integral representation of elastic fields in terms of the full-space Green function, or fundamental solution of the equations of dynamic elasticity, and the associated force densities along the boundaries. The method has been applied to simulate the ground motion in several configurations of surface geology. Moreover, the IBEM has been used as benchmark to test other procedures. We compute the seismic response of a three-dimensional rockfill dam model placed within a canyon that constitutes an irregularity on the surface of an elastic half-space. The rockfill is also assumed elastic with hysteretic damping to account for energy dissipation. Various types of incident waves are considered to analyze the physical characteristics of the response: symmetries, amplifications, impulse response and the like. Computations are performed in the frequency domain and lead to time response using Fourier analysis. In the present implementation a symmetrical model is used to test symmetries. The boundaries of each region are discretized into boundary elements whose size depends on the shortest wavelength, typically, six boundary segments per wavelength. Usually, the seismic response of rockfill dams is simulated using either finite elements (FEM) or finite differences (FDM). In most applications, commercial tools that combine features of these methods are used to assess the seismic response of the system for a given motion at the base of model. However, in order to consider realistic excitation of seismic waves with different incidence angles and azimuth we explore the IBEM. © 2010 IOP Publishing Ltd.