Seismic analysis of a system of dam-massed foundation-reservoir under inclined excitation

2021 ◽  
pp. 107754632110005
Author(s):  
Payam Sotoudeh ◽  
Mohsen Ghaemian
Keyword(s):  
Seismic Analysis ◽  
Engineering Practice ◽  
Frequency Content ◽  
Earthquake Excitation ◽  
Concrete Dam ◽  
High Frequencies ◽  
Inhomogeneous Waves ◽  
Earthquake Frequency ◽  
Vertical Propagation ◽  
Massed Foundation

One of the acceptable assumptions in engineering practice is vertical propagation of earthquake waves. When the source of earthquake is located very deep in the ground, this assumption is valid, but for sources located in shallow ground, it loses its viability. In this study, linear seismic analysis of a system of concrete dam-massed foundation-reservoir is performed under inclined earthquake excitation. Both P- and SV-type earthquakes are considered for the purpose of the seismic analysis. To consider the effects of inhomogeneous waves for the case of SV wave propagation, post-critical angles are also considered in the analysis. To investigate the effects of earthquake frequency content on the results, three different records with contents of low, intermediate, and high frequencies are selected. Results indicate that considering vertical propagation underestimates the obtained responses. For the case of SV-type earthquakes, post-critical angles must be looked at. Frequency content of the earthquake also has considerable effects on trend and absolute values of responses.

Estimation Study on Shear Wave Velocity of Seabed Using GRNN

2014 ◽  
Vol 580-583 ◽  
pp. 264-267
Author(s):  
Sheng Jie Di ◽  
Zhi Gang Shan ◽  
Xue Yong Xu
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Seismic Analysis ◽  
Site Response ◽  
Estimation Method ◽  
Response Analysis ◽  
Generalized Regression Neural Network ◽  
Engineering Practice ◽  
Site Classification

Characterization of the shear wave velocity of soils is an integral component of various seismic analysis, including site classification, hazard analysis, site response analysis, and soil-structure interaction. Shear wave velocity at offshore sites of the coastal regions can be measured by the suspension logging method according to the economic applicability. The study presents some methods for estimating the shear wave velocity profiles in the absence of site-specific shear wave velocity data. By applying generalized regression neural network (GRNN) for the estimation of in-situ shear wave velocity, it shows good performances. Therefore, this estimation method is worthy of being recommended in the later engineering practice.

Three-Dimensional Seismic Analysis on Reactor Structure

2010 ◽  
Author(s):  
Naibin Jiang ◽  
Feng-gang Zang ◽  
Li-min Zhang ◽  
Chuan-yong Zhang
Keyword(s):  
Finite Element ◽  
Large Scale ◽  
Seismic Analysis ◽  
Three Dimensional ◽  
Element Model ◽  
Earthquake Excitation ◽  
Finite Element Software ◽  
Reactor Structure ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

The seismic analysis on reactor structure was performed with a new generation of finite element software. The amount of freedom degree of the model was more than twenty millions. The typical responses to operational basis earthquake excitation were given. They are larger than those with two-dimensional simplified finite element method, and the reasons of this phenomenon were analyzed. The feasibility of seismic analysis on large-scale three-dimensional finite element model under existing hardware condition was demonstrated, so some technological reserves for dynamic analysis on complicated equipments or systems in nuclear engineering are provided.

Dynamic response of a concrete dam impounding an ice-covered reservoir: Part II. Parametric and numerical study

2004 ◽  
Vol 31 (6) ◽  
pp. 965-976 ◽  
Author(s):  
Najib Bouaanani ◽  
Patrick Paultre ◽  
Jean Proulx
Keyword(s):  
Dynamic Response ◽  
Frequency Response ◽  
Parametric Study ◽  
Seismic Analysis ◽  
Numerical Study ◽  
Ice Cover ◽  
Concrete Dams ◽  
Response Curves ◽  
Concrete Dam ◽  
Structure Interaction

This paper presents a numerical and parametric study of the effect of an ice cover on the dynamic response of a concrete dam using the approach proposed in the companion paper in this issue. The method was programmed and implemented in a finite element code specialized for the seismic analysis of concrete dams. The 84-m-high Outardes 3 concrete gravity dam in northeastern Quebec was chosen as a model for this research. Some basic aspects of the numerical model are established in this paper and we show that the ice cover affects the dynamic response of the ice–dam–reservoir system. Main features of this influence are emphasized and discussed in a parametric study through the analysis of: (i) acceleration frequency response curves at the dam crest, (ii) hydrodynamic frequency response curves inside the reservoir, and (iii) the hydrodynamic pressure distribution on the upstream face of the dam. Key words: gravity dams, concrete dams, ice, reservoirs, mathematical models, ice–structure interaction, fluid–structure interaction, forced-vibration testing, finite elements modelling.

scholarly journals Is the Frequency Content of the Calls in North American Treefrogs Limited by Their Larynges?

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Marcos Gridi-Papp
Keyword(s):  
Frequency Modulation ◽  
Sound Intensity ◽  
Frequency Content ◽  
Frequency Range ◽  
Low Frequencies ◽  
High Frequencies ◽  
Mating Calls ◽  
Limited Frequency ◽  
Positive Direct ◽  
High Diversity

A high diversity of mating calls is found among frogs. The calls of most species, however, are simple, in comparison to those of mammals and birds. In order to determine if the mechanics of the larynx could explain the simplicity of treefrog calls, the larynges of euthanized males were activated with airflow. Laryngeal airflow, sound frequency, and sound intensity showed a positive direct relationship with the driving air pressure. While the natural calls of the studied species exhibit minimal frequency modulation, their larynges produced about an octave of frequency modulation in response to varying pulmonary pressure. Natural advertisement calls are produced near the higher extreme of frequency obtained in the laboratory and at a slightly higher intensity (6 dB). Natural calls also exhibit fewer harmonics than artificial ones, because the larynges were activated with the mouth of the animal open. The results revealed that treefrog larynges allow them to produce calls spanning a much greater range of frequencies than observed in nature; therefore, the simplicity of the calls is not due to a limited frequency range of laryngeal output. Low frequencies are produced at low intensities, however, and this could explain why treefrogs concentrate their calling at the high frequencies.

Parametric study of stochastic seismic responses of base-isolated liquid storage tanks under near-fault and far-fault ground motions

2016 ◽  
Vol 24 (24) ◽  
pp. 5747-5764 ◽  
Author(s):  
Sina Safari ◽  
Reza Tarinejad
Keyword(s):  
Base Isolation ◽  
Seismic Analysis ◽  
Ground Motions ◽  
Characteristic Parameter ◽  
Statistical Linearization ◽  
Storage Tanks ◽  
Earthquake Excitation ◽  
Isolation System ◽  
Near Fault ◽  
Liquid Storage

Seismic response of base isolated steel liquid storage tanks is investigated in this study by a stochastic approach in frequency domain. For the purpose of evaluating different frequency contents of seismic events on the responses of fixed and isolated tanks, the earthquake excitation is characterized by power spectral density function. Since earthquake is a random process, stochastic seismic analysis is used and root mean square response predicts behavior of system properly. Two types of isolation system are assumed and nonlinear behavior of base isolation systems are developed by an iterative statistical linearization scheme. The study demonstrates the influence of each characteristic parameter of the storage tanks and isolation system and also excitation features. It is confirmed that near-fault earthquake excitations amplify the overall response of the system. Base isolation is known as an effective technique to reduce responses appropriately. It is demonstrated that the sloshing responses of the tanks is significantly reduced by sliding bearing. Further, excitation parameters, PGV/PGA ratio of records and pulse period in near-fault ground motions, that represent differences in two sets of earthquakes are defined to recognize variation of responses.

scholarly journals Dynamic time-history response of concrete rectangular liquid storage tanks

2021 ◽  
Author(s):  
Amirreza Ghaemmaghami
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Vertical Acceleration ◽  
Surface Boundary ◽  
Frequency Content ◽  
Seismic Behaviour ◽  
Structure Interaction ◽  
Earthquake Frequency ◽  
Wall Flexibility ◽  
Tank System

In this study, the finite element method is used to investigate the seismic behaviour of concrete, open top rectangular liquid tanks in two and three-dimensional spaces. This method is capable of considering both impulsive and convective responses of liquid-tank system. The sloshing behaviour is simulated using linear free surface boundary conditions. Two different finite element models corresponding with shallow and tall tank configurations are studied under the effects of all components of earthquake record. The effect of earthquake frequency content on the seismic behaviour of fluid-rectangular tank system is investigated using four different seismic motions including Northridge, El-Centro, San-Fernando and San-Francisco earthquake records. These records are scaled in such a way that all horizontal peak ground accelerations are similar. Fluid-structure interaction effects on the dynamic response of fluid containers are taken into account incorporating wall flexibility. A simple model with viscous boundary is used to include deformable foundation effects as a linear medium. Six different soil types are considered. In addition the application of slat screens and baffles in reducing the sloshing height of liquid tank is investigated by carrying out a parametric study. The results show that the wall flexibility, fluid damping properties, earthquake frequency content and soil-structure interaction have a major effect on seismic behaviour of liquid tanks and should be considered in design criteria of tanks. The effect of vertical acceleration on the dynamic response of the liquid tanks is found to be less significant when horizontal and vertical ground motions are considered together. The results in this study are verified and compared with those obtained by numerical methods and other available methods in the literature.

scholarly journals Dynamic time-history response of concrete rectangular liquid storage tanks

2021 ◽  
Author(s):  
Amirreza Ghaemmaghami
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Vertical Acceleration ◽  
Surface Boundary ◽  
Frequency Content ◽  
Seismic Behaviour ◽  
Structure Interaction ◽  
Earthquake Frequency ◽  
Wall Flexibility ◽  
Tank System

In this study, the finite element method is used to investigate the seismic behaviour of concrete, open top rectangular liquid tanks in two and three-dimensional spaces. This method is capable of considering both impulsive and convective responses of liquid-tank system. The sloshing behaviour is simulated using linear free surface boundary conditions. Two different finite element models corresponding with shallow and tall tank configurations are studied under the effects of all components of earthquake record. The effect of earthquake frequency content on the seismic behaviour of fluid-rectangular tank system is investigated using four different seismic motions including Northridge, El-Centro, San-Fernando and San-Francisco earthquake records. These records are scaled in such a way that all horizontal peak ground accelerations are similar. Fluid-structure interaction effects on the dynamic response of fluid containers are taken into account incorporating wall flexibility. A simple model with viscous boundary is used to include deformable foundation effects as a linear medium. Six different soil types are considered. In addition the application of slat screens and baffles in reducing the sloshing height of liquid tank is investigated by carrying out a parametric study. The results show that the wall flexibility, fluid damping properties, earthquake frequency content and soil-structure interaction have a major effect on seismic behaviour of liquid tanks and should be considered in design criteria of tanks. The effect of vertical acceleration on the dynamic response of the liquid tanks is found to be less significant when horizontal and vertical ground motions are considered together. The results in this study are verified and compared with those obtained by numerical methods and other available methods in the literature.

Sensitivity of the Effective Seismic Support Damping in a Class I Piping System to Analysis Parameters

2009 ◽  
Author(s):  
Nima Zobeiry
Keyword(s):  
Seismic Analysis ◽  
Response Spectrum ◽  
Time History ◽  
Class I ◽  
Piping System ◽  
Frequency Content ◽  
Response Spectrum Analysis ◽  
History Analysis ◽  
The Coefficient Of Friction ◽  
Seismic Damping

It is understood that the level of seismic damping in a piping system is strongly influenced by the supports. Put differently, the supports contribute to an effective damping that can be considered in the seismic analysis of the piping system. This paper investigates the issue for the feeder pipes of a CANDU™ reactor. Feeders are numerous class I pipes in parallel, which are separated by frictional spacer elements. The results of a time history analysis, taking into account different damping mechanisms, are compared to those from a response spectrum analysis to deduce the effective damping in the system. The sensitivity of the effective damping to different parameters, such as the coefficient of friction and the input frequency content, is investigated.

Sign in / Sign up

Export Citation Format

Share Document