Smart Civil Structures

Xu, You Lin; He, Jia

doi:10.1201/9781315368917

Cited by 27 publications

(24 citation statements)

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“…Hence, the development of vibration reduction methods is of considerable significance. The approach that focuses on improving the dynamic resistance of structures (by applying active, semiactive, or passive dampers to those structures) has been dominant in the protection of structures from dynamic impacts [31][32][33]. However, at present, vibration mitigation techniques based on the transmission paths of waves are being intensively developed [13,[15][16][17][18].…”

Section: Discussionmentioning

confidence: 99%

Vibration mitigation efficiency of an inclined, curved, open trench

Herbut

2020

PLoS ONE

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The vibration screening efficiency of a curved, inclined, open trench is investigated in this paper. An elastic, transversely isotropic half-space with hysteretic damping, acted upon by a harmonic vertical excitation, is assumed. Equations of motion with absorbing boundary conditions are presented and numerically integrated using FlexPDE software, based on the finite element method. The barrier efficiency is analysed in terms of the reduction of the vertical and horizontal components of the ground surface vibration. The results are presented for trenches with different geometric features based on the non-dimensional amplitude reduction factor. The trench inclination angle, the shape of the trench surface and the distance between the source of vibration and an obstacle are investigated as factors that can improve the trench reduction ability. It is demonstrated that a better attenuation of vibration is achieved with the proposed inclined trench than with its vertical counterpart. Moreover, the vibration mitigation effect is more significant in the case of a more horizontally located trench than for its vertical counterpart (even up to 5 times smaller displacement amplitudes for the vertical displacement component). Additionally, assuming the same trench depth, the vibration reduction effect is better in the case of a smaller number of rings used. The vibration attenuation efficiency is more visible if the trench is located closer to the vibration source.

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Section: Discussionmentioning

confidence: 99%

Vibration mitigation efficiency of an inclined, curved, open trench

Herbut

2020

PLoS ONE

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“…A CFD model, becoming more commonplace today, is capable of generating a full (velocity, pressure, etc) approximation of field variables. Though computing power has increased dramatically in recent history, CFD analysis of VAWTs is still very computationally expensive [40], especially in three dimensions which is often required for adequately addressing turbulence. For example, Badshah et al [41] performed a 3D FSI simulation of a horizontal tidal current turbine (TCT) using an 18-core Intel Xeon Processor (2.3 GHz) that required over 11 days to accurately predict performance for a single set of conditions.…”

Section: Methodsmentioning

confidence: 99%

Double-Multiple Streamtube Analysis of a Flexible Vertical Axis Wind Turbine

Roy

Kincaid

Mahmud

et al. 2021

Fluids

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Vertical-axis wind turbines (VAWTs) have drawn increased attention for off-grid and off-shore power generation due to inherent advantages over the more popular horizontal-axis wind turbines (HAWTs). Among these advantages are generator locale, omni-directionality and simplistic design. However, one major disadvantage is lower efficiency, which can be alleviated through blade pitching. Since each blade must transit both up- and down-stream each revolution, VAWT blade pitching techniques are not yet commonplace due to increased complexity and cost. Utilizing passively-morphing flexible blades can offer similar results as active pitching, requiring no sensors or actuators, and has shown promise in increasing VAWT performance in select cases. In this study, wind tunnel tests have been conducted with flexible and rigid-bladed NACA 0012 airfoils, in order to provide necessary input data for a Double-Multiple Stream-Tube (DMST) model. The results from this study indicate that a passively-morphing VAWT can achieve a maximum power coefficient (Cp) far exceeding that for a rigid-bladed VAWT CP (18.9% vs. 10%) with reduced normal force fluctuations as much as 6.9%. Operational range of tip-speed ratio also is observed to increase by a maximum of 40.3%.

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“…Civil engineering structures are prone to deterioration or damage due to certain factors, such as strong dynamic loadings, material fatigue accumulation and environmental corrosion. To date, a variety of vibration-based damage detection and system identification methods have been developed [1,2]. Most of them are applicable when the structure of interest is linear.…”

Section: Introductionmentioning

confidence: 99%

Model-Free Identification of Nonlinear Restoring Force with Modified Observation Equation

Zhang

et al. 2019

Applied Sciences

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Nonlinearity exists widely in civil engineering structures; for example, the initiation and growth of damage under dynamic loadings is a typical nonlinear process. To date, for the purpose of structural evaluation and a better understanding nonlinear characteristics of complicated structures, a number of parametric and nonparametric methods have been developed for the identification of nonlinear restoring force (NRF). However, due to the highly individualistic nature of nonlinear systems, it would be inefficient to attempt to express the structural NRF in a general parametric form. For many nonparametric techniques, their nonparametric models or approximations may result in undesirable results or oscillations around unsmooth points. In this paper, on the basis of extended Kalman filter (EKF), a model-free NRF identification approach is proposed to circumvent the limitations mentioned above. The NRF to be identified was treated as ‘unknown fictitious input’, and thus, no prior assumptions or approximations for the NRF model were required. With the aid of a projection matrix, a modified version of observation equation was obtained. Based on the principle of EKF, the recursive solution of the proposed approach was analytically derived. The NRFs provided by the nonlinear components were identified by means of least squares estimation (LSE) at each time step. Numerical examples, including building structures equipped with magnetorheological (MR) damper and shape memory alloy (SMA) damper, demonstrated that the proposed approach is capable of satisfactorily identifying NRF without knowledge or intuitive assumptions of any nonlinear model class in advance.

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Smart Civil Structures

Cited by 27 publications

References 0 publications

Vibration mitigation efficiency of an inclined, curved, open trench

Vibration mitigation efficiency of an inclined, curved, open trench

Double-Multiple Streamtube Analysis of a Flexible Vertical Axis Wind Turbine

Model-Free Identification of Nonlinear Restoring Force with Modified Observation Equation

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