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.

Dynamic response of a concrete dam impounding an ice-covered reservoir: Part I. Mathematical modelling

2004 ◽  
Vol 31 (6) ◽  
pp. 956-964 ◽  
Author(s):  
Najib Bouaanani ◽  
Patrick Paultre ◽  
Jean Proulx
Keyword(s):  
Dynamic Response ◽  
Forced Vibration ◽  
Seismic Analysis ◽  
Ice Cover ◽  
Complex Nature ◽  
Concrete Dams ◽  
Vibration Testing ◽  
Concrete Dam ◽  
Structure Interaction ◽  
Forced Vibration Testing

This paper examines the dynamic response of a concrete dam impounding an ice-covered reservoir and subjected to forced-vibration testing. The analytical research presented is a follow-up to an extensive dynamic testing program carried out on a 84-m high concrete gravity dam located in northeastern Quebec, Canada, under harsh winter conditions, including a 1.0- to 1.5-m-thick ice sheet covering the reservoir. One of the major challenges encountered when analyzing ice-dam-reservoir-foundation interaction is modelling the complex nature of the ice and the boundary conditions governing reservoir motion. The problem is further complicated because there are little or no appropriate experimental data and observational evidence relevant to ice-dam interaction processes. Some of these challenges are addressed herein using a two-dimensional analytical approach, which investigates the effects due to ice cover, water compressibility, and reservoir bottom absorption. A frequency-domain substructure method technique is used and a new boundary condition along the ice-cover-reservoir interface is proposed. The technique developed is implemented in a finite element code specialized in the seismic analysis of concrete dams. Numerical results are discussed in the companion paper in this issue. Key words: gravity dams, concrete dams, ice, reservoirs, mathematical models, ice-structure interaction, fluid-structure interaction, forced-vibration testing, finite elements modelling.

scholarly journals Experimental and Numerical Study on Modal Dynamic Response of Water-Surrounded Slender Bridge Pier with Pile Foundation

2017 ◽  
Vol 2017 ◽  
pp. 1-20 ◽  
Author(s):  
Yulin Deng ◽  
Qingkang Guo ◽  
Lueqin Xu
Keyword(s):  
Dynamic Response ◽  
Water Level ◽  
Pile Foundation ◽  
Numerical Study ◽  
Fluid Structure Interaction ◽  
Bridge Pier ◽  
Experimental Program ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Tip Mass

This paper presents an experimental program performed to study the effect of fluid-structure interaction on the modal dynamic response of water-surrounded slender bridge pier with pile foundation. A reduced scale slender bridge pier specimen is built and tested through forced vibration method. The vibration periods of the first four lateral modes, including the first two modes along x-axis and the first two modes along y-axis, are measured based on the specimen submerged by 16 levels of water and designated with 4 levels of tip mass. Three-dimensional (3D) finite-element models are established for the tested water-pier system and analyzed under various combined cases of water level and tip mass. Percentage increases of vibration periods with respect to dry vibration periods (i.e., vibration periods of the specimen without water) are determined as a function of water level and tip mass to evaluate the effect of fluid-structure interaction. The numerical results are successfully validated against the recorded test data. Based on the validated models, the modal hydrodynamic pressures are calculated to characterize the 3D distribution of hydrodynamic loads on the pier systems. The research provides a better illumination into the effect of fluid-structure interaction on the modal dynamic response of deepwater bridges.

scholarly journals SSI AND SSSI EFFECTS IN SEISMIC ANALYSIS OF TWIN BUILDINGS: DISCRETE MODEL CONCEPT

2012 ◽  
Vol 18 (6) ◽  
pp. 890-898 ◽  
Author(s):  
Sadegh Naserkhaki ◽  
Hassan Pourmohammad
Keyword(s):  
Discrete Model ◽  
Soil Structure ◽  
Seismic Analysis ◽  
Numerical Study ◽  
Elastic Half Space ◽  
Soil Structure Interaction ◽  
Model Concept ◽  
Structure Interaction ◽  
Twin Buildings ◽  
Hard Soils

This paper presents a numerical study of soil-structure interaction (SSI) and structure-soil-structure interaction (SSSI) effects on response of twin buildings during earthquake excitations. The buildings are modeled as shear buildings and the soil is simulated by a discrete model representing a visco-elastic half-space subjected to earthquake acceleration. Equation of motion of twin buildings with different conditions, fixed based (FB), SSI and SSSI, are developed via an analytical procedure and solved numerically. Buildings responses are evaluated for aforementioned three conditions considering various soil types and compared together. One must say that soil causes change in distribution of responses throughout the buildings while ignoring soil interaction may lead to detrimental effects on buildings. Anyway, interaction between twin buildings with SSSI condition slightly mitigates soil unfavorable effects compare to one building with SSI condition. In addition, it is found that influence of soil is very significant for soft to stiff soils whereas negligible for hard soils.

Numerical Study of a New Variable Friction TMD

2011 ◽  
Vol 243-249 ◽  
pp. 5450-5457 ◽  
Author(s):  
Li Qin ◽  
Wei Ming Yan ◽  
Sheng Bo Guo
Keyword(s):  
Frequency Response ◽  
Numerical Study ◽  
Damping Ratio ◽  
Harmonic Balance Method ◽  
Structural Response ◽  
Harmonic Excitation ◽  
Response Curves ◽  
Equivalent Damping ◽  
Response Characteristics ◽  
Variable Friction

The paper proposes a new variable friction system, of which the friction force can increase linearly with the displacement of system. This new system can be used in TMD to avoid the disadvantage of Coulomb friction TMD. Using first order harmonic balance method, the equivalent damping ratio and frequency of SDOF variable friction system is deduced and analyzed. The frequency response characteristics of SDOF variable friction system is discussed. The control effectiveness of variable friction TMD under harmonic excitation is analyzed theoretically. The results demonstrate that the frequency response curves of variable friction TMD and classically damped TMD are similar and both can effectively reduce structural response under harmonic excitation.

Analysis of Nonlinear Dynamic Response of Wind Turbine Blade Under Fluid–Structure Interaction and Turbulence Effect

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Jianping Zhang ◽  
Kaige Zhang ◽  
Aixi Zhou ◽  
Tingjun Zhou ◽  
Danmei Hu ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Turbine Blade ◽  
Nonlinear Dynamic ◽  
Fluid Structure Interaction ◽  
Wind Turbine Blade ◽  
Response Curves ◽  
Nonlinear Dynamic Response ◽  
Structure Interaction ◽  
Turbulence Effect

In this paper, the entity model of a 1.5 MW offshore wind turbine blade was built by Pro/Engineer software. Fluid flow control equations described by arbitrary Lagrange–Euler (ALE) were established, and the theoretical model of geometrically nonlinear vibration characteristics under fluid–structure interaction (FSI) was given. The simulation of offshore turbulent wind speed was achieved by programming in Matlab. The brandish displacement, the Mises stress distribution and nonlinear dynamic response curves were obtained. Furthermore, the influence of turbulence and FSI on blade dynamic characteristics was studied. The results show that the response curves of maximum brandish displacement and maximum Mises stress present the attenuation trends. The region of the maximum displacement and maximum stress and their variations at different blade positions are revealed. It was shown that the contribution of turbulence effect (TE) on displacement and stress is smaller than that of the FSI effect, and its extent of contribution is related to the relative span length. In addition, it was concluded that the simulation considering bidirectional FSI (BFSI) can reflect the vibration characteristics of wind turbine blades more accurately.

Soil-Structure Interaction on the Dynamic Response of Bridge Piers

2016 ◽  
Vol 847 ◽  
pp. 173-180
Author(s):  
Alessandra de Angelis ◽  
Michele Mucciacciaro ◽  
Stefania Sica ◽  
Maria Rosaria Pecce
Keyword(s):  
Dynamic Response ◽  
Soil Structure ◽  
Seismic Analysis ◽  
Ground Level ◽  
Soil Structure Interaction ◽  
Elastic Behaviour ◽  
Structure Interaction ◽  
Linear Elastic ◽  
Linear Elastic Behaviour ◽  
Girder Bridge

The paper analyses the effect of Soil-Structure-Interaction (SSI) on the modal dynamic response of simply-supported span girder bridge with wall piers founded on caissons. A parametric analysis has been carried out in the hypothesis of linear elastic behaviour of all materials (soil and structure) to identify the influence of various design factors, such as the height of the pier, the caisson embedment below the ground level and the soil mechanical properties. The goal of the paper is to highlight SSI effects on the dynamic behaviour of bridges. This is a crucial aspect to be accounted for in order to support monitoring activities on bridges, aimed to structural identification or assessment of structure response under serviceability conditions, or also to have preliminary information for the seismic analysis of the bridge.

Nonlinear Dynamic Response of Hysteretic Wire Ropes: Modeling and Experiments

2018 ◽  
Author(s):  
Andrea Arena ◽  
Biagio Carboni ◽  
Walter Lacarbonara
Keyword(s):  
Dynamic Response ◽  
Frequency Response ◽  
Nonlinear Dynamic ◽  
Wire Rope ◽  
Hysteretic Behavior ◽  
Response Curves ◽  
Nonlinear Dynamic Response ◽  
Wire Ropes ◽  
Tip Mass ◽  
Constitutive Parameters

The nonlinear dynamic response of short cables with a tip mass subject to base excitations and undergoing primary resonance is investigated via experimental tests and by employing an ad hoc nonlinear mechanical model. The considered cables are made of several strands of steel wires twisted into a helix forming composite ropes in a pattern known as ‘laid ropes’. Such short span ropes exhibit a hysteretic behavior due to the inter-wire frictional sliding. A nonlinear one-dimensional (1D) continuum model based on the geometrically exact Euler-Bernoulli beam theory is conveniently adapted to describe the cable dynamic response. The Bouc-Wen law of hysteresis is incorporated in the moment-curvature constitutive relationship to reproduce the hysteretic behavior of short steel wire ropes subject to flexural cycles. The frequency response curves show a pronounced softening nonlinearity induced by hysteresis and inertia nonlinearity as confirmed by the experimental data acquired on a wire rope with a tip mass excited at its base by a shaker. The experimental nonlinear resonance response will be exploited to identify the constitutive parameters of the wire rope that best fit the frequency response curves at various forcing amplitudes.

Dynamic response and transfer characteristics of joint neurons in somatosensory thalamus of the cat

1976 ◽  
Vol 39 (3) ◽  
pp. 582-600 ◽  
Author(s):  
T. C. Yin ◽  
W. J. Williams
Keyword(s):  
Time Delay ◽  
Transfer Function ◽  
Knee Joint ◽  
Dynamic Response ◽  
Frequency Response ◽  
Corner Frequency ◽  
Response Curves ◽  
Pass Filter ◽  
Somatosensory Thalamus ◽  
Joint Receptors

1. The dynamic response of neurons sensitive to knee joint rotation in the cat somatosensory thalamus was studied during sinusoidal variation of joint angle. The input sine waves were applied with a precise voltage-controlled, electromechanical actuator. The average rate of discharge of a single cell was considered as the output parameter. Describing functions of the sensory system were extracted by correlation and spectral analysis techniques. The effects of anesthetic, bias angle, and excursion angle were investigated. Discrete and swept sinusoidal waveforms between 0.1 and 7.0 Hz were used as inputs.2. The majority of joint cells in the thalamus were rapidly adapting and had frequency-response curves that were characterized as highpass filters. Although the major features of the response curves for individual cells were very similar, they could not all be fit with a single transfer function. The describing function of all the rapidly adapting cells averaged together was well fit by a transfer function that could be termed velocity sensitive in the bandwidth between 0.1 and 6.5 Hz. Most of these phasic cells showed a phase-locking tendency, particularly at high frequencies.3. The dynamics of the response for the rapidly adapting cells was relatively independent of anesthetic, bias angle, and excursion angle. Threshold and saturation effects were exhibited by some cells for very small (less than 1 degree) and large (greater than 10 degrees) input amplitudes, respectively. In addition a few (17%) showed a bidirectional response, i.e., responded at both flexion and extension of the limb. The anesthetic had a strong effect in depressing the spontaneous discharge of the cells and seemed to change the character of the tonic response by introducing a bursting component.4. The transfer characteristic of the thalamic cells was found to be a single-pole low-pass filter plus a time delay. The optimized value for the filter was found to have a corner frequency of 6.0 Hz with a time delay of 6 ms.5. Of the knee joint sensitive cells, 17% were slowly adapting or tonic, and more tonic cells were found in the unanesthetized animals. Only one tonic cell was studied in detail, and its dynamic characteristics were similar to that of the slowly adapting joint receptors at low frequencies. In this respect the rapidly adapting and slowly adapting joint cells in the thalamus have strikingly different frequency-response curves, the former curves have a much steeper slope in the magnitude.6. The functional implications of these results and of other recent findings in relation to the probable role of joint receptors in mediating proprioception are discussed.

Parametric Study of the Dynamic Response a Cable-Stayed Bridge

2001 ◽  
Vol 84 (7) ◽  
pp. 99-106
Author(s):  
Sven Mayer ◽  
Steven L. McCabe
Keyword(s):  
Dynamic Response ◽  
Parametric Study ◽  
Cable Stayed Bridge

Effects of nonlinear interactions of flexural modes on the performance of a beam autoparametric vibration absorber

2019 ◽  
Vol 26 (7-8) ◽  
pp. 459-474
Author(s):  
Saeed Mahmoudkhani ◽  
Hodjat Soleymani Meymand
Keyword(s):  
Frequency Response ◽  
Internal Resonance ◽  
Continuation Method ◽  
Harmonic Balance Method ◽  
Vibration Absorber ◽  
Primary System ◽  
Lumped Mass ◽  
Response Curves ◽  
Internal Resonances ◽  
The One

The performance of the cantilever beam autoparametric vibration absorber with a lumped mass attached at an arbitrary point on the beam span is investigated. The absorber would have a distinct feature that in addition to the two-to-one internal resonance, the one-to-three and one-to-five internal resonances would also occur between flexural modes of the beam by tuning the mass and position of the lumped mass. Special attention is paid on studying the effect of these resonances on increasing the effectiveness and extending the range of excitation amplitudes at which the autoparametric vibration absorber remains effective. The problem is formulated based on the third-order nonlinear Euler–Bernoulli beam theory, where the assumed-mode method is used for deriving the discretized equations of motion. The numerical continuation method is then applied to obtain the frequency response curves and detect the bifurcation points. The harmonic balance method is also employed for detecting the type of internal resonances between flexural modes by inspecting the frequency response curves corresponding to different harmonics of the response. Parametric studies on the performance of the absorber are conducted by varying the position and mass of the lumped mass, while the frequency ratio of the primary system to the first mode of the beam is kept equal to two. Results indicated that the one-to-five internal resonance is especially responsible for the considerable enhancement of the performance.

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