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Papers by Julio Hernandez
13th World Conference on Earthquake …, 2004
Studied are maximum displacements at the edges of the plan of elastic structural systems subjecte... more Studied are maximum displacements at the edges of the plan of elastic structural systems subjected to seismic motions that include accidental inputs: rotational seismic component and variations of center of mass location. The system properties that influence the responses are identified and assessed. Evaluated are the torsional provisions of Venezuelan and Mexican Seismic Codes, International Building Code, and De la Llera and Chopra Procedure; they can be either conservative or unconservative depending on the values of the system properties. A proposal that improves the mentioned procedure leading to a better agreement with the theoretical values, and including limitations concerning torsional stability, is presented.
Progress in Disaster Science, 2019
Revista De La Facultad De Ingenieria Universidad Central De Venezuela, Jun 1, 2011
La ciudad de Caracas con sus 3,2 millones de habitantes (INE, 2002) esta asentada en una cuenca t... more La ciudad de Caracas con sus 3,2 millones de habitantes (INE, 2002) esta asentada en una cuenca tipo semi-graben medio que fue llenado de sedimentos (Singer, 1977) y que es bordeada por relieve montanoso escarpado. Esta singular localizacion de Caracas da cuenta de un conjunto de amenazas socio-naturales a la cual esta expuesta, de las cuales destacan: una amenaza sismica elevada, debido a su cercania al limite entre las placas tectonicas Caribe y Suramerica, con los sistemas de fallas de La Tortuga, San Sebastian, Tacagua-El Avila y La Victoria (de norte a sur; e.g. Audemard et al., 2000), la cual incluye una importante amenaza por deslizamientos en las laderas de variable inclinacion alrededor del valle sedimentario (Hernandez et al., 2008); y una amenaza hidrometeorologica que comprende tanto inundaciones en las cercanias del rio Guaire y sus afluyentes, como deslaves y flujos de escombros provenientes de la Cordillera de la Costa (Cerro El Avila) inmediatamente al norte de la ci...
The method to calculate the critical responses, maximum and minimum, to three translacional seism... more The method to calculate the critical responses, maximum and minimum, to three translacional seismic components that may act with any orientation relative to the structural axes, is presented. Elastic behavior is assumed and the seismic action is specified by means of proportional response spectra for each component. The recent formulation GCQC3 is used to combine the responses to three seismic components, which is a generalization of the method CQC3 and allows that a principal seismic component can depart of the vertical direction. The critical responses to one seismic component are given by the square root of the maximum and minimum eigenvalues of the response matrix R, whose elements are defined by means of the modal responses used in the well-known CQC. The critical responses to three seismic components of arbitrary directions are calculated combining the eigenvalues of R and the intensities of the components. The method can also be applied to the determination of the critical re...
Revista Tecnica De La Facultad De Ingenieria Universidad Del Zulia, 1999
Boletin Tecnico/Technical Bulletin
ABSTRACT
La Comisión Nacional de Gestión de Riesgo ha considerado los estudios de microzonificación sísmic... more La Comisión Nacional de Gestión de Riesgo ha considerado los estudios de microzonificación sísmica como la principal metodología de trabajo para evaluar las condiciones regionales y locales, que ayude a minimizar el riesgo sísmico. Esta herramienta incluye diferentes técnicas multidisciplinarias, mediante las cuales se evalúan la amenaza -las fuentes sísmicas y la propagación de las ondas -y la vulnerabilidad de la infraestructura, social e institucional. Con base en estas consideraciones, FUNVISIS ha elaborado un plan de acción para la ejecución de los proyectos de microzonificación sísmica en las principales ciudades de Venezuela hasta el año 2010, los cuales se realizarán en conjunto entre los profesionales de FUNVISIS y los de las universidades e instituciones locales. Como experiencia piloto puede considerarse el "Proyecto de Microzonificación Sísmica en las Ciudades Caracas y Barquisimeto", a efectuarse en los años 2005 y 2006. Hasta la fecha se han obtenido importan...
Revista de la Facultad de Ingenieria
Revista de la Facultad de Ingenieria
Under the seismic microzoning project of Caracas city, has been done since mid 90s several ambie... more Under the seismic microzoning project of Caracas city, has been done since mid 90s several ambient noise measurements in order to determinate fundamentals periods of soil. In this work we showed a new relationship that includes the effect of the surface sediment layers, considering the values of shear-wave velocities for the first 30 m (Vs30) and the value of Vs to the deepest layer. The results indicate that this relationship generates more accurate estimates of sediment thickness comparing with real values of depth; this relationship was calibrated with information from 4 depth boreholes done in Caracas, obtaining accurate depth values. The main objective for this new relationship is allow for future studies in other cities of country, had a local relationship between period and sediments thickness that considering local information of soils (Vs30 y Vs) to generate accurate sediment thickness maps from environmental noise measurements.
Revista de la Facultad de Ingenieria
Based on the results of Caracas Seismic Microzoning Project, carried out in the years 2005 until ... more Based on the results of Caracas Seismic Microzoning Project, carried out in the years 2005 until 2009, in which were identified zones with similar seismic response, the interest of determining how those results could support the urban planning process of the city arises. In order to contribute to the discussion over this issue, the main features of the seismic hazard, as well as other types of hazard, vulnerability aspects and the urban planning regulation frame of Chacao municipality, in which four buildings collapsed during 1967 earthquake, were studied. The study revealed that the hazard levels presented in the seismic microzonation do not rule neither establish conditions to the land use planning nor the urban design, except for economics effects, and it is a necessary improvement to the in force code for seismic-resistant buildings. The seismic microzonation, together with an appropriate urban planning and management process including structural upgrading, urban renovation, gre...
Revista de la Facultad de Ingenieria
Elastic response spectra were developed within the purposes of the Caracas Seismic Microzoning Pr... more Elastic response spectra were developed within the purposes of the Caracas Seismic Microzoning Project, on microzones of the Caracas Metropolitan Area, including detailed site effects to improve the seismic design, overcoming the code spectra. As its core an 1D site response parametric study was performed, as function of shallow ground stiffness and sediment thickness, relying on a local seismic hazard study, the geophysical deposit model and a particular geotechnical model as inputs. The spectra were grouped and validated by means of actual earthquake records, doing small corrections. Basin effects were added from a 2D response study of the area of the valley with larger sediments, undergone to 1967 earthquake, and were extended by means of a 3D study of seismic amplifications in the valley. 2D topographical effects were also estimated. We defined macrozones of diverse seismic hazard and microzones according to shallow ground, deposits and slopes, obtaining expected mean spectra wi...
We developed a ground model in Caracas metropolitan area in Venezuela, to evaluate seismic amplif... more We developed a ground model in Caracas metropolitan area in Venezuela, to evaluate seismic amplification of the site and to develop earthquake scenarios. This is a part of the results obtained from a study on "Disaster Prevention Basic Plan in the Metropolitan District of Caracas in the Bolivarian Republic of Venezuela", executed by Japan International Cooperation Agency. Geotechnical borings database
13th World Conference on Earthquake …, 2004
Studied are maximum displacements at the edges of the plan of elastic structural systems subjecte... more Studied are maximum displacements at the edges of the plan of elastic structural systems subjected to seismic motions that include accidental inputs: rotational seismic component and variations of center of mass location. The system properties that influence the responses are identified and assessed. Evaluated are the torsional provisions of Venezuelan and Mexican Seismic Codes, International Building Code, and De la Llera and Chopra Procedure; they can be either conservative or unconservative depending on the values of the system properties. A proposal that improves the mentioned procedure leading to a better agreement with the theoretical values, and including limitations concerning torsional stability, is presented.
Progress in Disaster Science, 2019
Revista De La Facultad De Ingenieria Universidad Central De Venezuela, Jun 1, 2011
La ciudad de Caracas con sus 3,2 millones de habitantes (INE, 2002) esta asentada en una cuenca t... more La ciudad de Caracas con sus 3,2 millones de habitantes (INE, 2002) esta asentada en una cuenca tipo semi-graben medio que fue llenado de sedimentos (Singer, 1977) y que es bordeada por relieve montanoso escarpado. Esta singular localizacion de Caracas da cuenta de un conjunto de amenazas socio-naturales a la cual esta expuesta, de las cuales destacan: una amenaza sismica elevada, debido a su cercania al limite entre las placas tectonicas Caribe y Suramerica, con los sistemas de fallas de La Tortuga, San Sebastian, Tacagua-El Avila y La Victoria (de norte a sur; e.g. Audemard et al., 2000), la cual incluye una importante amenaza por deslizamientos en las laderas de variable inclinacion alrededor del valle sedimentario (Hernandez et al., 2008); y una amenaza hidrometeorologica que comprende tanto inundaciones en las cercanias del rio Guaire y sus afluyentes, como deslaves y flujos de escombros provenientes de la Cordillera de la Costa (Cerro El Avila) inmediatamente al norte de la ci...
The method to calculate the critical responses, maximum and minimum, to three translacional seism... more The method to calculate the critical responses, maximum and minimum, to three translacional seismic components that may act with any orientation relative to the structural axes, is presented. Elastic behavior is assumed and the seismic action is specified by means of proportional response spectra for each component. The recent formulation GCQC3 is used to combine the responses to three seismic components, which is a generalization of the method CQC3 and allows that a principal seismic component can depart of the vertical direction. The critical responses to one seismic component are given by the square root of the maximum and minimum eigenvalues of the response matrix R, whose elements are defined by means of the modal responses used in the well-known CQC. The critical responses to three seismic components of arbitrary directions are calculated combining the eigenvalues of R and the intensities of the components. The method can also be applied to the determination of the critical re...
Revista Tecnica De La Facultad De Ingenieria Universidad Del Zulia, 1999
Boletin Tecnico/Technical Bulletin
ABSTRACT
La Comisión Nacional de Gestión de Riesgo ha considerado los estudios de microzonificación sísmic... more La Comisión Nacional de Gestión de Riesgo ha considerado los estudios de microzonificación sísmica como la principal metodología de trabajo para evaluar las condiciones regionales y locales, que ayude a minimizar el riesgo sísmico. Esta herramienta incluye diferentes técnicas multidisciplinarias, mediante las cuales se evalúan la amenaza -las fuentes sísmicas y la propagación de las ondas -y la vulnerabilidad de la infraestructura, social e institucional. Con base en estas consideraciones, FUNVISIS ha elaborado un plan de acción para la ejecución de los proyectos de microzonificación sísmica en las principales ciudades de Venezuela hasta el año 2010, los cuales se realizarán en conjunto entre los profesionales de FUNVISIS y los de las universidades e instituciones locales. Como experiencia piloto puede considerarse el "Proyecto de Microzonificación Sísmica en las Ciudades Caracas y Barquisimeto", a efectuarse en los años 2005 y 2006. Hasta la fecha se han obtenido importan...
Revista de la Facultad de Ingenieria
Revista de la Facultad de Ingenieria
Under the seismic microzoning project of Caracas city, has been done since mid 90s several ambie... more Under the seismic microzoning project of Caracas city, has been done since mid 90s several ambient noise measurements in order to determinate fundamentals periods of soil. In this work we showed a new relationship that includes the effect of the surface sediment layers, considering the values of shear-wave velocities for the first 30 m (Vs30) and the value of Vs to the deepest layer. The results indicate that this relationship generates more accurate estimates of sediment thickness comparing with real values of depth; this relationship was calibrated with information from 4 depth boreholes done in Caracas, obtaining accurate depth values. The main objective for this new relationship is allow for future studies in other cities of country, had a local relationship between period and sediments thickness that considering local information of soils (Vs30 y Vs) to generate accurate sediment thickness maps from environmental noise measurements.
Revista de la Facultad de Ingenieria
Based on the results of Caracas Seismic Microzoning Project, carried out in the years 2005 until ... more Based on the results of Caracas Seismic Microzoning Project, carried out in the years 2005 until 2009, in which were identified zones with similar seismic response, the interest of determining how those results could support the urban planning process of the city arises. In order to contribute to the discussion over this issue, the main features of the seismic hazard, as well as other types of hazard, vulnerability aspects and the urban planning regulation frame of Chacao municipality, in which four buildings collapsed during 1967 earthquake, were studied. The study revealed that the hazard levels presented in the seismic microzonation do not rule neither establish conditions to the land use planning nor the urban design, except for economics effects, and it is a necessary improvement to the in force code for seismic-resistant buildings. The seismic microzonation, together with an appropriate urban planning and management process including structural upgrading, urban renovation, gre...
Revista de la Facultad de Ingenieria
Elastic response spectra were developed within the purposes of the Caracas Seismic Microzoning Pr... more Elastic response spectra were developed within the purposes of the Caracas Seismic Microzoning Project, on microzones of the Caracas Metropolitan Area, including detailed site effects to improve the seismic design, overcoming the code spectra. As its core an 1D site response parametric study was performed, as function of shallow ground stiffness and sediment thickness, relying on a local seismic hazard study, the geophysical deposit model and a particular geotechnical model as inputs. The spectra were grouped and validated by means of actual earthquake records, doing small corrections. Basin effects were added from a 2D response study of the area of the valley with larger sediments, undergone to 1967 earthquake, and were extended by means of a 3D study of seismic amplifications in the valley. 2D topographical effects were also estimated. We defined macrozones of diverse seismic hazard and microzones according to shallow ground, deposits and slopes, obtaining expected mean spectra wi...
We developed a ground model in Caracas metropolitan area in Venezuela, to evaluate seismic amplif... more We developed a ground model in Caracas metropolitan area in Venezuela, to evaluate seismic amplification of the site and to develop earthquake scenarios. This is a part of the results obtained from a study on "Disaster Prevention Basic Plan in the Metropolitan District of Caracas in the Bolivarian Republic of Venezuela", executed by Japan International Cooperation Agency. Geotechnical borings database