scholarly journals Free Vibration of a Taut Cable with Two Discrete Inertial Mass Dampers

2019 ◽  
Vol 9 (18) ◽  
pp. 3919 ◽  
Author(s):  
Wang ◽  
Yue ◽  
Gao
Keyword(s):  
Numerical Solutions ◽  
String Model ◽  
Inertial Mass ◽  
Transcendental Equation ◽  
Control Performance ◽  
Vibration Mitigation ◽  
Stay Cables ◽  
Modal Damping ◽  
Parametric Studies ◽  
Complex Modal Analysis

Recently, inertial mass dampers (IMDs) have shown superior control performance over traditional viscous dampers (VDs) in vibration control of stay cables. However, a single IMD may be incapable of providing sufficient supplemental modal damping to a super-long cable, especially for the multimode cable vibration mitigation. Inspired by the potential advantages of attaching two discrete VDs at different locations of the cable, arranging two external discrete IMDs, either at the opposite ends or the same end of the cable is proposed to further improve vibration mitigation performance of the cable in this study. Complex modal analysis based on the taut-string model was employed and extended to allow for the existence of two external discrete IMDs, resulting in a transcendental equation for complex wavenumbers. Both asymptotic and numerical solutions for the case of two opposite IMDs or the case of two IMDs at the same end of the cable were obtained. Subsequently, the applicability of asymptotic solutions was then evaluated. Finally, parametric studies were performed to investigate the effects of damper positions and damper properties on the control performance of a cable with two discrete IMDs. Results showed that two opposite IMDs can generally provide superior control performance to the cable over a single IMD or two IMDs at the same end. It was also observed that attaching two IMDs at the same end of the cable had the potential to achieve significant damping improvement when the inertial mass of the IMDs is appropriate, which seems to be more promising than two opposite IMDs for practical application.

scholarly journals Inertial mass damper for vibration control of cable with sag

2018 ◽  
Vol 39 (3) ◽  
pp. 749-760 ◽  
Author(s):  
Zhi-Hao Wang ◽  
Hui Gao ◽  
Bu-qiao Fan ◽  
Zheng-Qing Chen
Keyword(s):  
Inertial Mass ◽  
Damping Coefficient ◽  
Stay Cables ◽  
Modal Damping ◽  
Optimal Damping ◽  
Mass Damper ◽  
Negative Effect ◽  
Supplemental Damping ◽  
Antisymmetric Vibrations ◽  
General Dynamic

It has been theoretically predicted that superior supplemental damping can be generated for a taut cable with an inertial mass damper. This paper extends previous studies to investigate the effect of the cable sag on the efficiency of an inertial mass damper. The general dynamic characteristics of an inclined sag cable with an inertial mass damper installed close to the cable end are theoretically investigated. The parametric analysis of the inertial mass and the damping coefficient of the inertial mass damper are conducted to evaluate the control performance of the cable with different sags. The results show that the inertial mass damper can alleviate the negative effect induced by the cable sag, and the cable sag can even increase modal damping ratios provided by the inertial mass damper. Sags of stay cables used in actual bridges only affect nearly symmetric vibrations of cables, while having little impact on nearly antisymmetric vibrations. The effect of cable sags will reduce the optimal damping coefficient and inertial mass of the inertial mass damper for the first symmetric mode of the cable.

Nonlinear vibrations of CFRP cables excited by periodic motions of supports in cable-stayed bridges

2018 ◽  
Vol 24 (22) ◽  
pp. 5249-5260 ◽  
Author(s):  
Kuihua Mei ◽  
Guoqing Jin ◽  
Shengjiang Sun
Keyword(s):  
Numerical Solutions ◽  
Geometrical Nonlinearity ◽  
Stay Cable ◽  
Periodic Motions ◽  
Nonlinear Dynamic Model ◽  
Steel Cable ◽  
Traffic Loading ◽  
Stay Cables ◽  
Vibration Responses ◽  
Steel Cables

Owing to its excellent non-corrosiveness and fatigue resistance, a carbon fiber-reinforced polymer (CFRP) stay cable is an ideal alternative to overcome corrosion and fatigue problems associated with the traditional steel cable. However, stay cables are prone to various oscillations under wind, rain, and traffic loading. The vibrations of CFRP stay cables excited by periodic motions of the girder and/or pylons were studied and compared with those of steel cables. A nonlinear dynamic model for in-plane and out-of-plane vibrations of stay cables was proposed. Particularly, the geometrical nonlinearity of the cables was considered in this model. On the basis of this model, numerical solutions were obtained for CFRP cables and steel cables with the same conditions. Furthermore, the effects of important parameters on vibrations were discussed. These parameters included cable tensions, excitation amplitudes, and damping ratios. Results demonstrate that small excitation amplitudes may lead to forced vibrations or parametric vibrations with substantial amplitudes when natural frequencies of the cables are approximately half or one time of excitation frequencies. The maximal vibration responses of CFRP cables are weaker than those of steel cables when their lengths are substantial. As static tensions of the cables decrease, the “beating” frequencies and the maximal amplitudes of the vibrations increase.

Experimental Study on Multi-Mode Vibration Control of a Stay Cable with a Passive Magnetorheological Damper

2013 ◽  
Vol 361-363 ◽  
pp. 1402-1405
Author(s):  
Zhi Hao Wang
Keyword(s):  
Vibration Control ◽  
Mr Damper ◽  
Magnetorheological Damper ◽  
Test Results ◽  
Stay Cable ◽  
Mr Dampers ◽  
Stay Cables ◽  
Modal Damping ◽  
Mode Vibration ◽  
Multi Mode

Effective vibration control technology for stay cables is extremely critical to safe operations of cable-stayed bridges. For super-long cables, passive linear damper cannot provide sufficient damping since it can be only optimum for a given mode of cable, while a long cable may vibrate with several modes. This paper focuses on multi-mode vibration control of stay cables with passive magnetorheological (MR) dampers. Firstly, a 21.6m-long model cable was designed and established in the laboratory.Then, control performance of the cable with a passive MR damper was tested. The test results show that modal damping ratios of the cable in the first four modes can be improved significantly with the MR damper. It is further demonstrated that optimal tuned passively operated MR damper can outperform the passive viscous damper.

Experimental Study of Vibration Mitigation of Bridge Stay Cables

1999 ◽  
Vol 125 (9) ◽  
pp. 977-986 ◽  
Author(s):  
Y. L. Xu ◽  
S. Zhan ◽  
J. M. Ko ◽  
Z. Yu
Keyword(s):  
Experimental Study ◽  
Vibration Mitigation ◽  
Stay Cables

Eigenvalue Solution of Thermoelastic Damping in Beam Resonators Using a Finite Element Analysis

2007 ◽  
Vol 129 (4) ◽  
pp. 478-483 ◽  
Author(s):  
Yun-Bo Yi ◽  
Mohammad A. Matin
Keyword(s):  
Finite Element ◽  
Numerical Solutions ◽  
Finite Element Formulation ◽  
Element Formulation ◽  
Thermoelastic Damping ◽  
Element Analysis ◽  
Beam Resonator ◽  
Various Boundary Conditions ◽  
Parametric Studies ◽  
Analytical Approaches

A finite element formulation is developed for solving the problem related to thermoelastic damping in beam resonator systems. The perturbation analysis on the governing equations of heat conduction, thermoleasticity, and dynamic motion leads to a linear eigenvalue equation for the exponential growth rate of temperature, displacement, and velocity. The numerical solutions for a simply supported beam have been obtained and shown in agreement with the analytical solutions found in the literature. Parametric studies on a variety of geometrical and material properties demonstrate their effects on the frequency and the quality factor of resonance. The finite element formulation presented in this work has advantages over the existing analytical approaches in that the method can be easily extended to general geometries without extensive computations associated with the numerical iterations and the analytical expressions of the solution under various boundary conditions.

Calculation on Modal Damping Ratio of Stay Cable Using Nonlinear Friction Damper

2012 ◽  
Vol 538-541 ◽  
pp. 1800-1803
Author(s):  
Hui Ping Wang
Keyword(s):  
Damping Ratio ◽  
Free Vibrations ◽  
Nonlinear Friction ◽  
Friction Damper ◽  
Stay Cable ◽  
Lumped Mass ◽  
Mass Model ◽  
Modal Damping Ratio ◽  
Stay Cables ◽  
Modal Damping

Stay cables of long span cable-stayed bridges are easy to vibrate under wind or wind/rain loads owning to their very low inherent damping. To install cable dampers near to the anchorages of cable has become a common practice for cable vibration control of cable-stayed bridge structures. In this study, the behaviors of a nonlinear frictional type of damper were investigated. The equations of motion of a cable with a friction damper were derived by using a lumped mass model. Then by introducing modal transformation, the analytical solution for the motion equations was obtained. The results show that the friction damper evokes linearly decaying of free vibrations of the cable as long as the damper does not lock the cable. The modal damping ratio of cable with the friction damper is strongly amplitude dependent. Calculation of modal damping ratio can be simplified using control parameter and the maximum modal damping ratio can be obtained. A universal estimation curve is proposed that is similar to linear viscous damper. These studies could provide design basis for the vibration mitigation of stay cables using nonlinear friction.

Convective Heat Transfer in Microchannels of Noncircular Cross Sections: An Analytical Approach

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
S. Shahsavari ◽  
A. Tamayol ◽  
E. Kjeang ◽  
M. Bahrami
Keyword(s):  
Heat Flux ◽  
Cross Sections ◽  
Numerical Solutions ◽  
Thermal Characteristics ◽  
Temperature Fields ◽  
Constant Property ◽  
Nusselt Numbers ◽  
Parametric Studies ◽  
Predicted Values ◽  
Newtonian Constant

Analytical solutions are presented for velocity and temperature distributions of laminar fully developed flow of Newtonian, constant property fluids in micro/minichannels of hyperelliptical and regular polygonal cross sections. The considered geometries cover several common shapes such as ellipse, rectangle, rectangle with round corners, rhombus, star-shape, and all regular polygons. The analysis is carried out under the conditions of constant axial wall heat flux with uniform peripheral heat flux at a given cross section. A linear least squares point matching technique is used to minimize the residual between the actual and the predicted values on the boundary of the channel. Hydrodynamic and thermal characteristics of the flow are derived; these include pressure drop and local and average Nusselt numbers. The proposed results are successfully verified with existing analytical and numerical solutions from the literature for a variety of cross sections. The present study provides analytical-based compact solutions for velocity and temperature fields that are essential for basic designs, parametric studies, and optimization analyses required for many thermofluidic applications.

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