Browsing by Autor "Juan C. Reyes"

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Comportamiento sísmico y alternativas de rehabilitación de edificaciones en adobe y tapia pisada con base en modelos a escala reducida ensayados en mesa vibratoria
(Universidad de Los Andes, 2003) Luis E. Yamín; Ángel E. Rodríguez; Luis R. Fonseca; Juan C. Reyes; Camilo A. Phillips
El presente articulo resume los resultados principales de una investigacion tendiente a determinar las principales caracteristicas y propiedades mecanicas de los elementos estructurales que conforman las edificaciones en tierra y a partir de esta informacion plantear alternativas de rehabilitacion sismica acordes con las caracteristicas y entorno de este tipo de construcciones en Colombia. Las medidas de rehabilitacion planteadas que consisten basicamente en reforzamiento con mallas de acero y panetes a base de cal y reforzamiento con elementos de madera confinantes, fueron sometidas a un programa experimental mediante la realizacion de ensayos sobre probetas sometidas a diferentes tipos de solicitaciones, ensayos sobre muros a escala natural sometidos a cargas en el plano y perpendiculares al plano, ensayos de modelos a escala 1:5 sometidos a la accion de mesa vibratoria y ensayos de viviendas a escala 1:1.5 sometidas a carga ciclica horizontal. Los resultados de la investigacion permiten establecer las ventajas y desventajas de cada uno de los sistemas de rehabilitacion analizados. Se encuentra que, a pesar de la alta vulnerabilidad sismica de estos sistemas constructivos, el metodo de rehabilitacion con elementos de madera confinantes representa una alternativa viable y atractiva para la disminucion del riesgo en este tipo de construcciones.
Development of a first 3D crustal velocity model for the region of Bogotá, Colombia
(National University of Colombia, 2017) Andrea C. Riaño; Juan C. Reyes; Luis E. Yamín; Julián Montejo; Jose L. Bustamante; Jacobo Bielak; Nelson Pulido; Carlos Eduardo Rodríguez Molano; Alcides Huguett
Knowledge regarding the characteristics of soils in Bogotá basin has been possible to get through previous microzonation studies. However, there is still insufficient knowledge of the crustal velocity structure of the region. Bogotá is located in a region prone to a significant seismic hazard. Historically, the city has been affected by strong earthquakes, reaching moment magnitudes greater than or equal to 7. Furthermore, the city was built on a lacustrine basin, with soft soils of considerable depth that may strongly amplify the ground motion during an earthquake. In this article, we describe the development of a first crustal structure and material properties model for the region of Bogotá, Colombia, covering an area of about 130 km by 102 km. This effort aims at constructing a realistic 3D seismic velocity model using geological and geotechnical information from several sources. Major geological units have been identified and mapped into the model. The Inverse Distance Weighted (IDW) interpolation was used to create continuous surfaces delimiting the geological units. Seismic-wave properties are assigned to any point in the domain using a location-based approach. We expect this model to be useful for a wide range of applications, including dynamic ground motion simulations and fault system modeling.
Integrating 3D physics-based earthquake simulations to seismic risk assessment: The case of Bogot&#225;, Colombia.
(2023) Andrea C. Riaño; Juan C. Reyes; Jacobo Bielak; Doriam Restrepo; Ricardo Taborda; Luis E. Yamín
The basin beneath the greater metropolitan area of Bogot&#225;, Colombia, consists of soft material deposits with shear wave velocity&#160;Vs&#160;&#8804; 400 m/s that reach depths up to 425 m. Located on a high plateau in the eastern cordillera of the Colombian Andes, this highly populated urban area is subject to significant seismic hazards from local and regional fault systems.&#160;The potential ground motion amplification effects during earthquakes due to the presence of soft soil deposits and the surface and sub-surface topography constitute problems of great importance towards better understanding and estimating the seismic risk of the city. Given the scarcity of seismic data from large magnitude events, and in an effort to advance modern seismic hazard mapping for the region, this study aimed to develop a physics-based framework to generate synthetic ground records that can help to better understand the basin and other amplification effects during strong earthquake shaking in the region, and then to incorporate these effects into the estimation of seismic risk. To this end, a set of simulations were first conducted on Hercules, the wave propagation octree-based finite element simulator developed by the Quake Group at Carnegie Mellon University, to reproduce similar conditions to those observed in Bogot&#225; during past seismic events (e.g., 2008 Quetame Earthquake) and to identify the impacts of hypothetical strong earthquakes scenarios. Then the results from these simulations were then integrated into a new software package for post-processing and assessing the seismic risk in the Bogot&#225; region for different scenarios selected.
Seismic Performance of a 1:4 Scale Two-Story Rammed-Earth Model Reinforced with Steel Strips Tested on a Bi-Axial Shaking Table
(2023) Natalia Barrera; Daniel Ruíz; Juan C. Reyes; Yezid A. Alvarado; Daniela Carrasco-Beltrán
During the 16th and 17th centuries, Latin American cities adopted earthen construction techniques from European colonizers. As a result, rammed earth (RE) buildings now occupy an important place in Latin America&#039;s cultural heritage. However, earthquakes around the world have shown that unreinforced earthen constructions are highly vulnerable. For several years, researchers in northern South America have been proposing a technique that consists of installing confining steel plates (or wooden elements) on both sides of the RE walls forming a grid. This system has shown excellent performance in controlling seismic damage and increasing strength and ductility capacity. Although researchers have tested full-scale one- and two-story earthen walls under pseudo-static loading in the laboratory, and one- and two-story earthen walls at 1:1 and 1:2 scale on uniaxial and biaxial shaking tables, the behavior of a complete reinforced module (one- or two-story) on a shaking table has never been assessed. The present study presents the results of shaking table tests performed on two-story RE modules at 1:4 scale. The experimental data indicate that the retrofit system with confining steel strips was effective in reducing the seismic damage of earthen constructions. In addition, the comparison of the results of the 1:4 scale tests with the 1:2 and 1:1 scale tests previously conducted by the researchers, shows that the acceleration levels of the equivalent prototypes are in the same order of magnitude for the three scales.