Marcelo A. Ceballos - Academia.edu (original) (raw)

Papers by Marcelo A. Ceballos

Nondestructive Testing of Materials and Structures, 2011

This work presents two new wave propagation models for the half-space compatible with the thin la... more This work presents two new wave propagation models for the half-space compatible with the thin layer formulation (TLF). The TLF is based on a polynomial expansion in the wave number κ of the exact matrix of the dynamic stiffness of a layer. The advantage of the TLF with respect to the exact model is that it allows transforming the soil profile response between wave number and spatial domains in analytical form through the decomposition of response in wave propagation modes. The expansion in κ applied to the exact matrix of the half-space does not produce a satisfactory approximation for moderate or large values of κ. Therefore, the TLF in its original form only reproduces with good accuracy the response of soil profiles composed by an assembly of layers over an infinitely stiff half-space. The proposed models eliminate such shortcomings and adequately represent the half-space stiffness in the wave number domain. The techniques used for adjustment of mechanical soil profiles generally represent the half-space through an assembly of strata with increasing thickness in depth. Such approach produces acceptable accuracy in the wave propagation velocity of the fundamental mode for normally dispersive profiles (with increasing stiffness in depth), although it generates spurious modes not related with higher propagation modes. The adjustment of mechanical parameters of inversely dispersive profiles requires an adequate approximation of the half-space dynamic behavior given the significant contribution of the higher propagation modes to the response. The proposed models are suitable for the adjustment of soil profiles with an arbitrary distribution of stiffness in depth and for evaluating the dynamic stiffness of foundations.

ABSTRACT: The Embalse NPP, located in Córdoba, Argentina, is currently being reassessed in order ... more ABSTRACT: The Embalse NPP, located in Córdoba, Argentina, is currently being reassessed in order to pursue a renewal of the operating license, due in 2010. New information pertaining to the seismicity of the region has warranted an updated dynamic analysis in order to verify the adequacy of the reactor building to perform as intended in the original design under the Maximum Credible Earthquake. A dynamic finite element model has been setup, from which a synthetic model representing the first 60 fixed-base modes is extracted and incorporated in the SASSI computer program. The model has been verified and calibrated using actual acceleration records obtained during a minor seismic event (PGA ≈ 1.4 % g) that took place in 2003. This paper presents the modeling procedure followed in order to obtain the synthetic model and the results of the calibration, where it is seen that the model accurately represents the behavior of the structure recorded during the 2003 seismic event both in the f...

is currently being reassessed in order to pursue a renewal of the operating license, due in 2010.... more is currently being reassessed in order to pursue a renewal of the operating license, due in 2010. The original design of the reactor building dates back to the early 80’s, when advanced computer programs for dynamic soil-structure interaction analyses were not of widespread use. In order to reassess the seismic response of the reactor building under the design event, a dynamic finite element model was developed and calibrated using experimental acceleration records from a minor earthquake event in 2003. The current analyses were performed by means of the computer program SASSI, which can accurately model dynamic soil structure interaction and wave propagation phenomena. This paper focuses on the FRS’s obtained by means of the updated structural model using SASSI for the review level earthquake considered at the time the plant started its operations. Results illustrate the reduction of seismic demands when the soil properties used in the model have been verified by actual seismic rec...

La dispersion de fase espacial de ondas superficiales ha sido recientemente utilizada por los aut... more La dispersion de fase espacial de ondas superficiales ha sido recientemente utilizada por los autores como funcion objetivo para la determinacion de velocidades de propagacion de ondas de corte de perfiles mecanicos en terrenos donde se proyectan obras civiles de cierta envergadura. Los perfiles inversamente dispersivos que se caracterizan por la presencia de estratos blandos debajo de estratos duros involucran una marcada participacion de los modos superiores de propagacion en la respuesta superficial del terreno. La dispersion de fase espacial a diferencia de otras funciones objetivo se obtiene considerando la totalidad de los modos de propagacion, de manera que la validez de los resultados no se encuentra condicionada por la distribucion en profundidad de la rigidez del perfil de suelo. Los parametros normalmente incluidos en el proceso de inversion son las velocidades de propagacion de los distintos estratos del terreno que presentan la maxima sensibilidad respecto a esta funcio...

Fil: Stuardi, Jose Enrique. Universidad Nacional de Cordoba. Facultad de Ciencias Exactas Fisicas... more Fil: Stuardi, Jose Enrique. Universidad Nacional de Cordoba. Facultad de Ciencias Exactas Fisicas y Naturales. Departamento de Estructuras; Argentina;

Este trabajo presenta dos modelos de propagacion de ondas para el semi-espacio que se asume como ... more Este trabajo presenta dos modelos de propagacion de ondas para el semi-espacio que se asume como el estrato mas profundo de un perfil de suelo. Estos modelos resultan compatibles con la formulacion de capas delgadas utilizada para el ajuste de perfiles mecanicos de suelos a traves de tecnicas de analisis espectral de ondas superficiales. La respuesta en la superficie del perfil de suelo se calcula habitualmente en el dominio numero de onda k convirtiendose luego al dominio espacial a traves de la transformada de Hankel. La version analitica de esta transformada no resulta aplicable en casos practicos, por lo que suele recurrirse a implementaciones numericas que arrastran imprecisiones e implican un alto costo computacional. La ventaja mas relevante de la formulacion de capas delgadas es que permite pasar la respuesta del perfil entre ambos dominios en forma analitica a traves de la descomposicion modal de esta respuesta en diferentes patrones de onda. Esto se consigue a traves de un...

Las vibraciones inducidas por el viento, asociadas al fenomeno de desprendimiento de vortices, ti... more Las vibraciones inducidas por el viento, asociadas al fenomeno de desprendimiento de vortices, tienen un fuerte impacto en la vida util de conductores electricos en lineas de alta tension debido a la ocurrencia de potencialmente elevadas tensiones de fatiga. Una forma habitual de evitar fallas por fatiga en los conductores electricos es colocar amortiguadores del tipo “Stockbridge” en cercania de los extremos de los vanos, lo que consigue reducir las tensiones de fatiga por debajo de los niveles considerados inseguros. El objetivo de este trabajo es presentar y comparar diferentes modelos analiticos y numericos que pueden utilizarse para definir el tipo, la posicion y la cantidad de amortiguadores necesarios. Las comparaciones de los resultados se asocian a modelos con diferentes grados de detalle. El problema planteado se torna marcadamente complejo debido a las incertidumbres originadas por el caracter aleatorio de la fuente de excitacion y al comportamiento no-lineal de los amort...

Las tecnicas experimentales para la determinacion de las caracteristicas dinamicas de perfiles de... more Las tecnicas experimentales para la determinacion de las caracteristicas dinamicas de perfiles de suelo en el sitio de emplazamiento de grandes obras poseen amplia difusion en la actualidad. El analisis espectral de ondas superficiales (SASW, siglas en ingles) se destaca entre estas tecnicas debido al limitado equipamiento requerido y a que no resulta necesario realizar perforaciones. Sin embargo, la tecnica SASW presenta algunas limitaciones asociadas a las hipotesis que se adoptan para la construccion de la curva de dispersion. Esta tecnica solo permite una determinacion exacta del perfil de ondas de corte en casos donde la rigidez del suelo aumenta o se mantiene constante con la profundidad, dado que pierde resolucion cuando existen estratos blandos debajo de estratos mas duros. La curva de dispersion experimental resulta en rigor dependiente de la separacion entre los transductores utilizados para el registro de las ondas superficiales; la falta de unicidad de esta curva se rela...

La realizacion de conciertos de musica rock en estadios con un numero importante de personas en e... more La realizacion de conciertos de musica rock en estadios con un numero importante de personas en el campo de juego saltando al ritmo de la musica ha motivado quejas y denuncias por parte de vecinos que viven en edificios de departamentos en las zonas residenciales aledanas por encontrarse sometidos a molestas vibraciones durante estos eventos. Las ondas superficiales generadas por el salto de los espectadores coordinado por el tempo de las distintas canciones se propagan a gran distancia pudiendo producir la resonancia de los edificios cuya frecuencia fundamental se encuentra en un rango entre aproximadamente 1.8 y 2.5 Hz. En este trabajo se analizan resultados de modelos numericos de edificios que involucran efectos de interaccion suelo-estructura para reproducir las vibraciones registradas durante recitales en la terraza de edificios proximos al estadio del Club Atletico River Plate. Los modelos calibrados permiten realizar predicciones de las vibraciones en los edificios en base a...

The dynamic performance of a highway bridge with precast pre-stressed concrete deck and stays mad... more The dynamic performance of a highway bridge with precast pre-stressed concrete deck and stays made of solid section 47 mm diameter steel bars in lieu of typical strand cable systems is addressed by comparing design predictions with actual dynamic load tests performed at the end of construction. The design was based on the Spanish design code IAP-11 of 2011. Due to the particular selection of solid steel bars to serve as stays in a highway bridge, the dynamic performance of the bridge and their fatigue life prediction suggested at design stage the need to perform a series of tests of an existing smaller bridge with similar structural concept and materials, and upon completion of construction of the new bridge, to carry out dynamic tests. The tests consisted on recording vertical component of accelerations at the mid-span section of one of the main spans when the control vehicle prescribed in the IAP-11 Code rolled on at the allowed speed limit. In contrast to the case of the previous...

The mechanical characterization of soil profiles by means of the Spectral Analysis of Surface Wav... more The mechanical characterization of soil profiles by means of the Spectral Analysis of Surface Waves (SASW) has become a widely accepted practice in recent years. This technique presents some limitations inherent to the hypotheses adopted in establishing the analytical dispersion curve used for the adjustment of the soil profile model. It relies on the adjustment of the fundamental propagation mode and thus lacks capacity to identify the presence of soft layers located under stiffer strata, where higher surface wave modes are generally excited. The experimental dispersion curve is affected by the variation of the "effective" velocity of the profile, which depends on the propagation modes involved and on the location of the transducers. This work presents a multiple transducers experimental technique based on a target function with two independent variables: the input frequency of the source and the propagation velocity of the surface waves. This function, herein referred to...

El ajuste de la flexibilidad dinamica exacta de un semi-espacio homogeneo a traves de tecnicas de... more El ajuste de la flexibilidad dinamica exacta de un semi-espacio homogeneo a traves de tecnicas de analisis modal experimental ha permitido la definicion de matrices de rigidez que pueden ensamblarse directamente con las matrices de estratos ubicados por encima del semi-espacio para formar matrices globales de rigidez de perfiles estratificados de suelo. Las matrices de los estratos que se utilizan se derivan de la formulacion de capas delgadas, cuya version original precisamente carece de capacidad para representar el comportamiento dinamico del semi-espacio que se ubica como ultimo estrato del perfil de suelos. La resolucion de un problema generalizado de autovalores del perfil completo permite expresar su respuesta dinamica a traves de una combinacion de modos de propagacion de ondas con importantes ventajas numericas respecto a la utilizacion directa de las matrices exactas. Este trabajo presenta como aplicacion del modelo modal propuesto la determinacion de la rigidez dinamica d...

La instalacion de equipos sensibles a las vibraciones en plantas industriales requiere a menudo d... more La instalacion de equipos sensibles a las vibraciones en plantas industriales requiere a menudo del diseno de un sistema de aislamiento de la inmision, que permita cumplir con las especificaciones de los fabricantes en cuanto al nivel de vibraciones maximo tolerado. Los disenos cubren una amplia gama que va desde los bloques inerciales rigidos, apoyados sobre medios elasticos, a las losas flotantes que abarcan superficies de gran tamano. Cuando la cantidad de equipos a aislar es grande se opta generalmente por una sala provista de un piso sobre fundacion elastica o losa flotante. A la mayor flexibilidad de layout que provee esta alternativa, se suman las ventajas tecnicas de construir una losa de grandes dimensiones y masa, lo que beneficia la estabilidad del sistema. El medio elastico consiste generalmente en una manta continua de elastomero o bloques discretos de menor tamano, construidos del mismo material, o mediante resortes y amortiguadores viscosos. Con frecuencia son utiliza...

The Reactor Building of the Embalse Nuclear Power Plant, located in Córdoba, Argentina, consists ... more The Reactor Building of the Embalse Nuclear Power Plant, located in Córdoba, Argentina, consists of a prestressed concrete outer shell and dome, an internal building formed by several concrete slabs and shear walls, founded on a 1.7-m thick concrete mat bearing on soils. The mass of the entire structure is 64,000 metric tons and the outside diameter of the shell is 43.7 m. The plant became operational in the early 1980s and its license is due for renewal in 2010, for which efforts are being carried out in order to reassess the adequacy of the structure in light of updated design requirements. As a part of this effort, the University of Córdoba was retained in order to setup a numerical model capable of reproducing the dynamic behavior of the soil-structure system in order to perform updated analyses. A finite element model was setup using available information from original design drawings and reports, whereas the soil stiffness profile at the site was derived by means of the Spectr...

La evaluacion numerica del oleaje inducido en embalses por el efecto de sismos constituye un aspe... more La evaluacion numerica del oleaje inducido en embalses por el efecto de sismos constituye un aspecto potencialmente relevante en el diseno de aprovechamientos hidroelectricos en zonas sismicas, particularmente en aquellas regiones afectadas por sismos originados por mecanismos de subduccion. El interes por la modelacion numerica del oleaje inducido por sismos surge como consecuencia de la necesidad de usar sus resultados para complementar y contrastar la informacion que surge de observaciones empiricas, teniendo en cuenta que normalmente las estructuras son sensibles a frecuencias en el rango de 0 a 25 Hz, mientras que la altura del oleaje es solo sensible a frecuencias inferiores a 0.1 Hz. En particular, el efecto del oleaje cuya maxima amplitud ocurre en bajas frecuencias produce tensiones y deformaciones casi estaticas en las estructuras cuya valoracion no presenta dificultades particulares, sino que es necesario verificar que la ola no supere el nivel de las estructuras como cri...

Journal of Vibration and Control, 2020

This paper begins with a brief compilation of analytical models typically used to calculate the d... more This paper begins with a brief compilation of analytical models typically used to calculate the dynamic response of a conductor span belonging to an overhead transmission line, with a Stockbridge-type damper located near one of its ends. In most of analyses found in the literature, the calculation of the response is done through the superposition of waves that propagate in both longitudinal directions impinging and reflecting at the span ends and at the damper attachment points. The approach proposed in this paper allows obtaining the response as the steady-state solution of the governing differential equations providing suitable analytical expressions for conductors with bending stiffness, which are dispersive media for propagating waves. Using these analytical solutions, the influence of bending stiffness on the efficiency and on the optimal mechanical impedance of the damper, which are of great importance in damper design, can be described explicitly. At the same time, the propos...

Journal of Computational and Applied Mathematics, 2017

Abstract This paper presents numerical techniques for evaluating integrals of the form ∫ 0 ∞ J β ... more Abstract This paper presents numerical techniques for evaluating integrals of the form ∫ 0 ∞ J β ( k ρ ) J γ ( k R ) k α ( k − s ) d k . These integrals arise during the application of the Hankel transform to pass the displacements of a layered soil profile from the wave number domain to the spatial domain in three-dimensional problems of elastodynamics. The objective here is to obtain solutions with an adequate accuracy from the engineering point of view to the integrals that arise in a first order formulation of a wave propagation model widely used for layered soils.

Procedia Structural Integrity, 2017

Abstract Assessment of the performance of a road bridge for pedestrian comfort at design stage is... more Abstract Assessment of the performance of a road bridge for pedestrian comfort at design stage is often carried out following simplified rules defined by design codes of practice. The purpose of this paper is to assess the effectiveness of one such simplified procedure by means of actual dynamic load tests carried out on an unconventional cable-stayed bridge with precast pre-stressed deck and solid section 47 mm diameter steel bars acting as tension members in lieu of specific traditional strand cable systems. The rule given by the Spanish Design Code (IAP-11, “Instruccion sobre las acciones a considerar en el proyecto de puentes de carretera”, 2011) is taken as the basic design requirement to be assessed by a series of time records of the vertical acceleration caused by passage of the control vehicle. The tests consisted on recording vertical component of accelerations at the mid-span section where the stays converge just outside of the pedestrian sidewalk. The control or reference vehicle used for the tests conforms to the requirements described in the Spanish IAP-11 Code. The focus of the paper is to establish a direct comparison between the code-prescribed analyses of the structure under the reference vehicle to evaluate pedestrian comfort according to IAP-11. Computed maximum accelerations at the mid-span section are found to be approximately one half of the measured values, fact that is at least partially attributed to ignoring the inertial mass and mechanical characteristics of the reference truck that does not allow for vehicle-structure interaction.

Revista Iberoamericana De Ingenieria Mecanica, 2013

Nondestructive Testing of Materials and Structures, 2011

This work presents two new wave propagation models for the half-space compatible with the thin la... more This work presents two new wave propagation models for the half-space compatible with the thin layer formulation (TLF). The TLF is based on a polynomial expansion in the wave number κ of the exact matrix of the dynamic stiffness of a layer. The advantage of the TLF with respect to the exact model is that it allows transforming the soil profile response between wave number and spatial domains in analytical form through the decomposition of response in wave propagation modes. The expansion in κ applied to the exact matrix of the half-space does not produce a satisfactory approximation for moderate or large values of κ. Therefore, the TLF in its original form only reproduces with good accuracy the response of soil profiles composed by an assembly of layers over an infinitely stiff half-space. The proposed models eliminate such shortcomings and adequately represent the half-space stiffness in the wave number domain. The techniques used for adjustment of mechanical soil profiles generally represent the half-space through an assembly of strata with increasing thickness in depth. Such approach produces acceptable accuracy in the wave propagation velocity of the fundamental mode for normally dispersive profiles (with increasing stiffness in depth), although it generates spurious modes not related with higher propagation modes. The adjustment of mechanical parameters of inversely dispersive profiles requires an adequate approximation of the half-space dynamic behavior given the significant contribution of the higher propagation modes to the response. The proposed models are suitable for the adjustment of soil profiles with an arbitrary distribution of stiffness in depth and for evaluating the dynamic stiffness of foundations.

ABSTRACT: The Embalse NPP, located in Córdoba, Argentina, is currently being reassessed in order ... more ABSTRACT: The Embalse NPP, located in Córdoba, Argentina, is currently being reassessed in order to pursue a renewal of the operating license, due in 2010. New information pertaining to the seismicity of the region has warranted an updated dynamic analysis in order to verify the adequacy of the reactor building to perform as intended in the original design under the Maximum Credible Earthquake. A dynamic finite element model has been setup, from which a synthetic model representing the first 60 fixed-base modes is extracted and incorporated in the SASSI computer program. The model has been verified and calibrated using actual acceleration records obtained during a minor seismic event (PGA ≈ 1.4 % g) that took place in 2003. This paper presents the modeling procedure followed in order to obtain the synthetic model and the results of the calibration, where it is seen that the model accurately represents the behavior of the structure recorded during the 2003 seismic event both in the f...

is currently being reassessed in order to pursue a renewal of the operating license, due in 2010.... more is currently being reassessed in order to pursue a renewal of the operating license, due in 2010. The original design of the reactor building dates back to the early 80’s, when advanced computer programs for dynamic soil-structure interaction analyses were not of widespread use. In order to reassess the seismic response of the reactor building under the design event, a dynamic finite element model was developed and calibrated using experimental acceleration records from a minor earthquake event in 2003. The current analyses were performed by means of the computer program SASSI, which can accurately model dynamic soil structure interaction and wave propagation phenomena. This paper focuses on the FRS’s obtained by means of the updated structural model using SASSI for the review level earthquake considered at the time the plant started its operations. Results illustrate the reduction of seismic demands when the soil properties used in the model have been verified by actual seismic rec...

La dispersion de fase espacial de ondas superficiales ha sido recientemente utilizada por los aut... more La dispersion de fase espacial de ondas superficiales ha sido recientemente utilizada por los autores como funcion objetivo para la determinacion de velocidades de propagacion de ondas de corte de perfiles mecanicos en terrenos donde se proyectan obras civiles de cierta envergadura. Los perfiles inversamente dispersivos que se caracterizan por la presencia de estratos blandos debajo de estratos duros involucran una marcada participacion de los modos superiores de propagacion en la respuesta superficial del terreno. La dispersion de fase espacial a diferencia de otras funciones objetivo se obtiene considerando la totalidad de los modos de propagacion, de manera que la validez de los resultados no se encuentra condicionada por la distribucion en profundidad de la rigidez del perfil de suelo. Los parametros normalmente incluidos en el proceso de inversion son las velocidades de propagacion de los distintos estratos del terreno que presentan la maxima sensibilidad respecto a esta funcio...

Fil: Stuardi, Jose Enrique. Universidad Nacional de Cordoba. Facultad de Ciencias Exactas Fisicas... more Fil: Stuardi, Jose Enrique. Universidad Nacional de Cordoba. Facultad de Ciencias Exactas Fisicas y Naturales. Departamento de Estructuras; Argentina;

Este trabajo presenta dos modelos de propagacion de ondas para el semi-espacio que se asume como ... more Este trabajo presenta dos modelos de propagacion de ondas para el semi-espacio que se asume como el estrato mas profundo de un perfil de suelo. Estos modelos resultan compatibles con la formulacion de capas delgadas utilizada para el ajuste de perfiles mecanicos de suelos a traves de tecnicas de analisis espectral de ondas superficiales. La respuesta en la superficie del perfil de suelo se calcula habitualmente en el dominio numero de onda k convirtiendose luego al dominio espacial a traves de la transformada de Hankel. La version analitica de esta transformada no resulta aplicable en casos practicos, por lo que suele recurrirse a implementaciones numericas que arrastran imprecisiones e implican un alto costo computacional. La ventaja mas relevante de la formulacion de capas delgadas es que permite pasar la respuesta del perfil entre ambos dominios en forma analitica a traves de la descomposicion modal de esta respuesta en diferentes patrones de onda. Esto se consigue a traves de un...

Las vibraciones inducidas por el viento, asociadas al fenomeno de desprendimiento de vortices, ti... more Las vibraciones inducidas por el viento, asociadas al fenomeno de desprendimiento de vortices, tienen un fuerte impacto en la vida util de conductores electricos en lineas de alta tension debido a la ocurrencia de potencialmente elevadas tensiones de fatiga. Una forma habitual de evitar fallas por fatiga en los conductores electricos es colocar amortiguadores del tipo “Stockbridge” en cercania de los extremos de los vanos, lo que consigue reducir las tensiones de fatiga por debajo de los niveles considerados inseguros. El objetivo de este trabajo es presentar y comparar diferentes modelos analiticos y numericos que pueden utilizarse para definir el tipo, la posicion y la cantidad de amortiguadores necesarios. Las comparaciones de los resultados se asocian a modelos con diferentes grados de detalle. El problema planteado se torna marcadamente complejo debido a las incertidumbres originadas por el caracter aleatorio de la fuente de excitacion y al comportamiento no-lineal de los amort...

Las tecnicas experimentales para la determinacion de las caracteristicas dinamicas de perfiles de... more Las tecnicas experimentales para la determinacion de las caracteristicas dinamicas de perfiles de suelo en el sitio de emplazamiento de grandes obras poseen amplia difusion en la actualidad. El analisis espectral de ondas superficiales (SASW, siglas en ingles) se destaca entre estas tecnicas debido al limitado equipamiento requerido y a que no resulta necesario realizar perforaciones. Sin embargo, la tecnica SASW presenta algunas limitaciones asociadas a las hipotesis que se adoptan para la construccion de la curva de dispersion. Esta tecnica solo permite una determinacion exacta del perfil de ondas de corte en casos donde la rigidez del suelo aumenta o se mantiene constante con la profundidad, dado que pierde resolucion cuando existen estratos blandos debajo de estratos mas duros. La curva de dispersion experimental resulta en rigor dependiente de la separacion entre los transductores utilizados para el registro de las ondas superficiales; la falta de unicidad de esta curva se rela...

La realizacion de conciertos de musica rock en estadios con un numero importante de personas en e... more La realizacion de conciertos de musica rock en estadios con un numero importante de personas en el campo de juego saltando al ritmo de la musica ha motivado quejas y denuncias por parte de vecinos que viven en edificios de departamentos en las zonas residenciales aledanas por encontrarse sometidos a molestas vibraciones durante estos eventos. Las ondas superficiales generadas por el salto de los espectadores coordinado por el tempo de las distintas canciones se propagan a gran distancia pudiendo producir la resonancia de los edificios cuya frecuencia fundamental se encuentra en un rango entre aproximadamente 1.8 y 2.5 Hz. En este trabajo se analizan resultados de modelos numericos de edificios que involucran efectos de interaccion suelo-estructura para reproducir las vibraciones registradas durante recitales en la terraza de edificios proximos al estadio del Club Atletico River Plate. Los modelos calibrados permiten realizar predicciones de las vibraciones en los edificios en base a...

The dynamic performance of a highway bridge with precast pre-stressed concrete deck and stays mad... more The dynamic performance of a highway bridge with precast pre-stressed concrete deck and stays made of solid section 47 mm diameter steel bars in lieu of typical strand cable systems is addressed by comparing design predictions with actual dynamic load tests performed at the end of construction. The design was based on the Spanish design code IAP-11 of 2011. Due to the particular selection of solid steel bars to serve as stays in a highway bridge, the dynamic performance of the bridge and their fatigue life prediction suggested at design stage the need to perform a series of tests of an existing smaller bridge with similar structural concept and materials, and upon completion of construction of the new bridge, to carry out dynamic tests. The tests consisted on recording vertical component of accelerations at the mid-span section of one of the main spans when the control vehicle prescribed in the IAP-11 Code rolled on at the allowed speed limit. In contrast to the case of the previous...

The mechanical characterization of soil profiles by means of the Spectral Analysis of Surface Wav... more The mechanical characterization of soil profiles by means of the Spectral Analysis of Surface Waves (SASW) has become a widely accepted practice in recent years. This technique presents some limitations inherent to the hypotheses adopted in establishing the analytical dispersion curve used for the adjustment of the soil profile model. It relies on the adjustment of the fundamental propagation mode and thus lacks capacity to identify the presence of soft layers located under stiffer strata, where higher surface wave modes are generally excited. The experimental dispersion curve is affected by the variation of the "effective" velocity of the profile, which depends on the propagation modes involved and on the location of the transducers. This work presents a multiple transducers experimental technique based on a target function with two independent variables: the input frequency of the source and the propagation velocity of the surface waves. This function, herein referred to...

El ajuste de la flexibilidad dinamica exacta de un semi-espacio homogeneo a traves de tecnicas de... more El ajuste de la flexibilidad dinamica exacta de un semi-espacio homogeneo a traves de tecnicas de analisis modal experimental ha permitido la definicion de matrices de rigidez que pueden ensamblarse directamente con las matrices de estratos ubicados por encima del semi-espacio para formar matrices globales de rigidez de perfiles estratificados de suelo. Las matrices de los estratos que se utilizan se derivan de la formulacion de capas delgadas, cuya version original precisamente carece de capacidad para representar el comportamiento dinamico del semi-espacio que se ubica como ultimo estrato del perfil de suelos. La resolucion de un problema generalizado de autovalores del perfil completo permite expresar su respuesta dinamica a traves de una combinacion de modos de propagacion de ondas con importantes ventajas numericas respecto a la utilizacion directa de las matrices exactas. Este trabajo presenta como aplicacion del modelo modal propuesto la determinacion de la rigidez dinamica d...

La instalacion de equipos sensibles a las vibraciones en plantas industriales requiere a menudo d... more La instalacion de equipos sensibles a las vibraciones en plantas industriales requiere a menudo del diseno de un sistema de aislamiento de la inmision, que permita cumplir con las especificaciones de los fabricantes en cuanto al nivel de vibraciones maximo tolerado. Los disenos cubren una amplia gama que va desde los bloques inerciales rigidos, apoyados sobre medios elasticos, a las losas flotantes que abarcan superficies de gran tamano. Cuando la cantidad de equipos a aislar es grande se opta generalmente por una sala provista de un piso sobre fundacion elastica o losa flotante. A la mayor flexibilidad de layout que provee esta alternativa, se suman las ventajas tecnicas de construir una losa de grandes dimensiones y masa, lo que beneficia la estabilidad del sistema. El medio elastico consiste generalmente en una manta continua de elastomero o bloques discretos de menor tamano, construidos del mismo material, o mediante resortes y amortiguadores viscosos. Con frecuencia son utiliza...

The Reactor Building of the Embalse Nuclear Power Plant, located in Córdoba, Argentina, consists ... more The Reactor Building of the Embalse Nuclear Power Plant, located in Córdoba, Argentina, consists of a prestressed concrete outer shell and dome, an internal building formed by several concrete slabs and shear walls, founded on a 1.7-m thick concrete mat bearing on soils. The mass of the entire structure is 64,000 metric tons and the outside diameter of the shell is 43.7 m. The plant became operational in the early 1980s and its license is due for renewal in 2010, for which efforts are being carried out in order to reassess the adequacy of the structure in light of updated design requirements. As a part of this effort, the University of Córdoba was retained in order to setup a numerical model capable of reproducing the dynamic behavior of the soil-structure system in order to perform updated analyses. A finite element model was setup using available information from original design drawings and reports, whereas the soil stiffness profile at the site was derived by means of the Spectr...

La evaluacion numerica del oleaje inducido en embalses por el efecto de sismos constituye un aspe... more La evaluacion numerica del oleaje inducido en embalses por el efecto de sismos constituye un aspecto potencialmente relevante en el diseno de aprovechamientos hidroelectricos en zonas sismicas, particularmente en aquellas regiones afectadas por sismos originados por mecanismos de subduccion. El interes por la modelacion numerica del oleaje inducido por sismos surge como consecuencia de la necesidad de usar sus resultados para complementar y contrastar la informacion que surge de observaciones empiricas, teniendo en cuenta que normalmente las estructuras son sensibles a frecuencias en el rango de 0 a 25 Hz, mientras que la altura del oleaje es solo sensible a frecuencias inferiores a 0.1 Hz. En particular, el efecto del oleaje cuya maxima amplitud ocurre en bajas frecuencias produce tensiones y deformaciones casi estaticas en las estructuras cuya valoracion no presenta dificultades particulares, sino que es necesario verificar que la ola no supere el nivel de las estructuras como cri...

Journal of Vibration and Control, 2020

This paper begins with a brief compilation of analytical models typically used to calculate the d... more This paper begins with a brief compilation of analytical models typically used to calculate the dynamic response of a conductor span belonging to an overhead transmission line, with a Stockbridge-type damper located near one of its ends. In most of analyses found in the literature, the calculation of the response is done through the superposition of waves that propagate in both longitudinal directions impinging and reflecting at the span ends and at the damper attachment points. The approach proposed in this paper allows obtaining the response as the steady-state solution of the governing differential equations providing suitable analytical expressions for conductors with bending stiffness, which are dispersive media for propagating waves. Using these analytical solutions, the influence of bending stiffness on the efficiency and on the optimal mechanical impedance of the damper, which are of great importance in damper design, can be described explicitly. At the same time, the propos...

Journal of Computational and Applied Mathematics, 2017

Abstract This paper presents numerical techniques for evaluating integrals of the form ∫ 0 ∞ J β ... more Abstract This paper presents numerical techniques for evaluating integrals of the form ∫ 0 ∞ J β ( k ρ ) J γ ( k R ) k α ( k − s ) d k . These integrals arise during the application of the Hankel transform to pass the displacements of a layered soil profile from the wave number domain to the spatial domain in three-dimensional problems of elastodynamics. The objective here is to obtain solutions with an adequate accuracy from the engineering point of view to the integrals that arise in a first order formulation of a wave propagation model widely used for layered soils.

Procedia Structural Integrity, 2017

Abstract Assessment of the performance of a road bridge for pedestrian comfort at design stage is... more Abstract Assessment of the performance of a road bridge for pedestrian comfort at design stage is often carried out following simplified rules defined by design codes of practice. The purpose of this paper is to assess the effectiveness of one such simplified procedure by means of actual dynamic load tests carried out on an unconventional cable-stayed bridge with precast pre-stressed deck and solid section 47 mm diameter steel bars acting as tension members in lieu of specific traditional strand cable systems. The rule given by the Spanish Design Code (IAP-11, “Instruccion sobre las acciones a considerar en el proyecto de puentes de carretera”, 2011) is taken as the basic design requirement to be assessed by a series of time records of the vertical acceleration caused by passage of the control vehicle. The tests consisted on recording vertical component of accelerations at the mid-span section where the stays converge just outside of the pedestrian sidewalk. The control or reference vehicle used for the tests conforms to the requirements described in the Spanish IAP-11 Code. The focus of the paper is to establish a direct comparison between the code-prescribed analyses of the structure under the reference vehicle to evaluate pedestrian comfort according to IAP-11. Computed maximum accelerations at the mid-span section are found to be approximately one half of the measured values, fact that is at least partially attributed to ignoring the inertial mass and mechanical characteristics of the reference truck that does not allow for vehicle-structure interaction.

Revista Iberoamericana De Ingenieria Mecanica, 2013