scholarly journals Optimal Design and Application of a Multiple Tuned Mass Damper System for an In-Service Footbridge

2019 ◽  
Vol 11 (10) ◽  
pp. 2801 ◽  
Author(s):  
Chao Wang ◽  
Weixing Shi
Keyword(s):  
Optimal Design ◽  
Vibration Control ◽  
Damping Ratio ◽  
Element Model ◽  
Frequency Bandwidth ◽  
Dynamic Amplification Factor ◽  
Control Effect ◽  
In Situ Test ◽  
Dynamic Amplification

Slender steel footbridges suffer excessive human-induced vibrations due to their low damping nature and their frequency being located in the range of human-induced excitations. Tuned mass dampers (TMDs) are usually used to solve the serviceability problem of footbridges. A multiple TMD (MTMD) system, which consists of several TMDs with different frequencies, has a wide application in the vibration control of footbridges. An MTMD system with well-designed parameters will have a satisfactory effect for vibration control. This study firstly discusses the relationship between the acceleration dynamic amplification factor and important parameters of an MTMD system, i.e., the frequency bandwidth, TMD damping ratio, central frequency ratio, mass ratio and the number of TMDs. Then, the frequency bandwidth and damping ratio optimal formulas are proposed according to the parametric study. At last, an in-service slender footbridge is proposed as a case study. The footbridge is analyzed through a finite element model and an in situ test, and then, an MTMD system is designed based on the proposed optimal design formulas. The vibration control effect of the MTMD system is verified through a series of in situ comparison tests. Results show that under walking, running and jumping excitations with different frequency, the MTMD system always has an excellent vibration control effect. Under a crowd-induced excitation with the resonance frequency, the footbridge with an MTMD system can meet the acceleration limit requirement. It is also found that the analysis result agrees well with the in situ test.

Dynamic Impact Measurements on Crossings, in Free Floating and In-Situ Conditions

2014 ◽  
Author(s):  
M. A. Boogaard ◽  
A. L. Schwab ◽  
Z. Li
Keyword(s):  
Finite Element ◽  
Condition Monitoring ◽  
Impact Loading ◽  
Dynamic Behaviour ◽  
Element Model ◽  
Mode Shapes ◽  
Dynamic Impact ◽  
In Situ Test ◽  
In Situ Conditions

As vibration based condition monitoring requires a good understanding of the dynamic behaviour of the structure, a good model is needed. At the TU Delft a train borne monitoring system is being developed which currently focusses on crossings. Crossings are prone to very fast degradation due to impact loading. In this paper a finite element model of a free floating frog is presented and validated up to a 100 Hz using dynamic impact measurements. The mode shapes of the free floating frog are then also compared to some preliminary results from an in-situ test. This comparison shows that the in-situ frequencies can be up to twice the free floating frequency.

Vibration Control of Offshore Platforms Using a Wideband METMD System

2006 ◽  
Author(s):  
Dong Zhao ◽  
Rujian Ma ◽  
Dongmei Cai
Keyword(s):  
Vibration Control ◽  
Natural Frequency ◽  
Fem Simulation ◽  
Average Frequency ◽  
Offshore Platforms ◽  
Frequency Bandwidth ◽  
Wave Load ◽  
Control Effect ◽  
Exciting Frequency ◽  
Specific Frequency

A wideband multiple extended tuned mass dampers (METMD) system has been developed for reducing the multiple resonant responses of the platforms to all kinds of loads, such as earthquake, typhoon, tsunami and big ice load. This system is composed of several subsystems, each of which consists of one set of extended tuned mass damper (ETMD) unit covering a specific frequency bandwidth, and its average frequency is tuned to one of the first resonant frequencies of the platform. The offshore platform is simplified to a single degree-of-freedom (DOF) system to which a METMD subsystem (composed of m ETMDs) is attached and constitutes m+1 DOFs system. The total mass ratio of the METMD subsystem to the platform is 14% and the frequency ratio of the exciting frequency to the platform’s natural frequency varies in [0.5, 1.5]. The theory analysis shows that: 1) the platform has the better vibration control effect when the non-dimensional frequency bandwidth Ω, which is defined as the ratio of the frequency range to the controlled (target) platforms natural frequency, is in [0.35, 0.6]; 2) the damping coefficient ξ of ETMD systems is in [0.05, 0.15] and 3) the number of the ETMDs is 5 when Ω = 0.45 and ξ = 0.1. The FEM simulation shows that the METMD has a better vibration control effect on the mega-platforms’ vibration control under the random ocean wave load.

scholarly journals Damped dynamic response of strengthened beams by composite coats under moving force by FEM

2018 ◽  
Vol 106 (2) ◽  
pp. 206
Author(s):  
Abdennacer Chemami ◽  
Youcef Khadri ◽  
Sabiha Tekili ◽  
El Mostafa Daya ◽  
Ali Daouadji ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Numerical Study ◽  
Moving Load ◽  
Damping Ratio ◽  
Time Integration ◽  
Superposition Method ◽  
Dynamic Amplification Factor ◽  
Aluminum Composite ◽  
Strengthened Beam ◽  
Dynamic Amplification

This paper presents a numerical study of the free and damped forced vibration of simply-supported beams with composite coats subjected to a moving load by use of finite elements method. Three types of beam configurations, aluminum, composite and strengthened beam are investigated. The equation of motion of the beam is solved using the modal superposition method and integrated by applying the Newmark time integration procedure. Good agreements were achieved between the FEM and analytical solutions. The damped dynamic response, critical velocities and the dynamic amplification factor of the beam are calculated for different parameters such as the thickness ratio, the fiber orientation of the coat and damping ratio.

Study on the influence of structural nonlinearity on the performance of multiunit impact damper

2020 ◽  
pp. 107754632092562
Author(s):  
Zheng Lu ◽  
Naiyin Ma ◽  
Hengrui Zhang
Keyword(s):  
Vibration Control ◽  
Damping Ratio ◽  
Mean Square Displacement ◽  
Random Excitation ◽  
Frame Structure ◽  
Control Effect ◽  
Momentum Exchange ◽  
Impact Damper ◽  
Structural Nonlinearity ◽  
Steel Frame Structure

In this article, the vibration control effect of the multiunit impact damper under stationary random excitation and seismic excitation is studied, based on both the elastic and nonlinear benchmark structures. The benchmark structure is a nonlinear steel frame structure, which can calculate the nonlinear response by considering the material nonlinearity at the ends of the beam and column. To analyze the influence of various system parameters on the performance of the multiunit impact damper, such as the number of units, mass ratio, damping ratio, and gap clearance, a great number of parameter studies are carried out. In addition, the control effects of the multiunit impact damper on elastic and nonlinear structures are compared to analyze the influence of structural nonlinearity on the performance of the multiunit impact damper. The results show that a lightweight multiunit impact damper with reasonable parameters can significantly reduce the root mean square displacement response of the benchmark structure. Furthermore, the structural nonlinearity will lead to a decrease in the vibration control performance of the multiunit impact damper. The reasons for this phenomenon are that the effective momentum exchange and energy dissipation of the multiunit impact damper will decrease when the benchmark structure responds in a nonlinear state.

scholarly journals Damping in Dynamic Structure–Foundation Interaction

1975 ◽  
Vol 12 (1) ◽  
pp. 13-22 ◽  
Author(s):  
J. H. Rainer
Keyword(s):  
Damping Ratio ◽  
Dynamic Structure ◽  
Numerical Results ◽  
Material Damping ◽  
Dynamic Amplification Factor ◽  
Foundation Soil ◽  
Modal Damping Ratio ◽  
Modal Damping ◽  
Fixed Base ◽  
Dynamic Amplification

Two methods of calculating the damping ratio for structures on compliant foundations are presented. One method employs the calculation of the system damping ratio from the dynamic amplification factor, the other the modal damping ratio from energy considerations. The numerical results for both methods are compared and interpreted. Three sources of damping are considered: inter-storey damping, radiation damping, and foundation material damping. The numerical results demonstrate that with the introduction of compliant foundations the damping ratio of the system can be larger or smaller than that of the corresponding fixed-base structure. Material damping in the foundation soil has been shown to contribute significantly to the over-all damping ratio.

scholarly journals Exact Solutions for a Novel H2 Optimal Design of Electromagnetic Tuned Mass Damper

2021 ◽  
Author(s):  
Ge Li ◽  
Qibo Mao ◽  
Yifan Luo ◽  
Yong Wang ◽  
Lei Liu
Keyword(s):  
Vibration Control ◽  
Optimization Design ◽  
Damping Ratio ◽  
Tuned Mass Damper ◽  
Parameters Optimization ◽  
Structural Vibration ◽  
Control Effect ◽  
Mass Damper ◽  
Two Parameters ◽  
H2 Optimization

To realize structural vibration control,a two parameters H2 optimization design was proposed to optimize the tuning ratio and damping ratio for electromagnetic tuned mass damper (EMTMD). The control effect of this two parameters optimization design is better than that of classical tuned mass damper (TMD).For this two parameters optimization,the most important thing is that the inductance of the coil can be set very small and the external load resistance can be positive ,which can avoid the use of complex negative impedance circuit. If Ref.[6] were designed according to the H2 optimization of two parameters, the EMTMD can be used for multi-modal vibration control of structures without connecting negative inductance and negative resistance spontaneously.

scholarly journals Evaluation of the Increased Dynamic Effects on the Highway Bridge Superstructure

2018 ◽  
Vol 13 (3) ◽  
Author(s):  
Ilze Paeglite ◽  
Juris Smirnovs ◽  
Ainars Paeglitis
Keyword(s):  
Amplification Factor ◽  
Dynamic Properties ◽  
Concrete Slab ◽  
Damping Ratio ◽  
Dynamic Amplification Factor ◽  
Reinforced Concrete Slab ◽  
Girder Bridges ◽  
Bridge Superstructure ◽  
High Dynamic ◽  
Dynamic Amplification

Dynamic properties of the bridge superstructure vary depending on many characteristics of the bridge and the loading conditions. In this paper, maximum Dynamic Amplification Factor was calculated for six different types of typical pre-stressed concrete beam bridges. It showed that each type of bridge with similar loading has a different range of Dynamic Amplification Factor. At the same time, every recently built bridge has different geometry and design load. Hence, it is difficult to determine a characteristic value of Dynamic Amplification Factor for the similar type of structures. By using fullscale dynamic and static bridge tests, it is possible to determine the necessary characteristics which show possibly high Dynamic Amplification Factor. This factor indicates if it is necessary to make a full-scale bridge dynamic analysis. It was found that those characteristics are natural frequency (first mode), damping ratio, relative deflection, and span and depth ratio. Obtained results from tests show a range of values for each of the characteristic. These ranges were analysed for reinforced concrete slab and pre-stressed concrete slab, and girder bridges.

scholarly journals Optimization of VEDs for Vibration Control of Transmission Line Tower

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Guoping Huang ◽  
Jianhua Hu ◽  
Yuzhu He ◽  
Haibo Liu ◽  
Xiugui Sun
Keyword(s):  
Transmission Line ◽  
Vibration Control ◽  
Damping Ratio ◽  
Element Model ◽  
Control Performance ◽  
Bending Vibration ◽  
Viscoelastic Dampers ◽  
Modal Damping Ratio ◽  
Modal Damping ◽  
The Finite Element Model

This paper investigates the optimization of viscoelastic dampers (VEDs) for vibration control of a transmission line tower. Considering the stiffness of the steel brace connected to a VED, the mechanical model of the VED-brace system was established. Subsequently, the additional modal damping ratio of the transmission line tower attached with VEDs was obtained analytically. Furthermore, the finite element model of a two-circuit transmission line tower with VEDs was built in ANSYS software, and the influences of installation positions and parameters of VEDs on the additional modal damping ratio were clarified. In addition, the control performance of VEDs on the transmission line tower subjected to wind excitations was emphatically illustrated. The results show that the stiffness of the steel brace connected to a VED has a significant effect on the maximum additional modal damping ratio of the VED-brace system provided for the transmission line tower and the optimal parameters of the VED. Meanwhile, the installation positions of VEDs dramatically influence the additional modal damping ratio. Moreover, the increase of the brace stiffness and the loss factor is beneficial to improve the control performance of VEDs. Besides that, the VEDs present superior control performance on the top displacement of the transmission line tower as well as the transverse bending vibration energy.

Determination of dynamic amplification factors for heavy haul railways

2016 ◽  
Vol 232 (2) ◽  
pp. 514-528 ◽  
Author(s):  
Xin Zhao ◽  
Jizhong Yang ◽  
Boyang An ◽  
Chao Liu ◽  
Yabo Cao ◽  
...  
Keyword(s):  
High Frequency ◽  
Element Model ◽  
Rolling Contact ◽  
Dynamic Amplification Factor ◽  
Explicit Finite Element ◽  
Amplification Factors ◽  
Rail Corrugation ◽  
Heavy Haul ◽  
Dynamic Amplification ◽  
Heavy Haul Railway

A new approach has been developed to determine the dynamic amplification factors of railways. This approach employs a traditional multi-body dynamic model of vehicle–track interaction and a 3D explicit finite element model of wheel–rail rolling contact to treat the low- and high-frequency dynamics, respectively. Excitations are considered by contact surface unevenness and more specifically, by the power spectrum density of track irregularity for the low-frequency analysis and by the critical wheel flat, weld, and rail corrugation for the high frequency. For the 40-tonne axle load heavy haul railway simulated in this work, it has been found that the optimum fastening stiffness should be 150–200 MN/m; the dynamic amplification factors of the wheel–rail contact, fastening, and ballast forces are 1.94, 2.0, and 1.67, respectively, if the fastening stiffness of 200 MN/m is applied. Finally, new dynamic amplification factor formulae that include key parameters such as the fastening stiffness, speed, and axle load are proposed for the heavy haul railway design.

scholarly journals Dynamic Response of Long Rectangular Floors Subjected to Periodic Force Excitation

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1417 ◽  
Author(s):  
Zsuzsa B. Pap ◽  
László P. Kollár
Keyword(s):  
Dynamic Response ◽  
Amplification Factor ◽  
Damping Ratio ◽  
Effective Width ◽  
Rectangular Plates ◽  
Dynamic Amplification Factor ◽  
Periodic Force ◽  
Static Loads ◽  
Dynamic Amplification ◽  
Force Excitation

Since damping in lightweight floors is usually low, dynamic amplification can be rather high. Long rectangular plates subjected to concentrated loads are often investigated by a replacement beam with a so called “effective width”. Although this approach is a reliable tool for static loads, the steady-state dynamic response of beams and long plates subjected to periodic loads are significantly different. The maximum displacements and accelerations of beams (and of not-long rectangular plates) are obtained by using a dynamic amplification factor, which in the case of resonance is equal to 1 / 2 ξ , where ξ is the damping ratio. For long plates (and for not-long orthotropic rib-stiffened plates), as discussed in the paper, the response and the amplification factor are substantially different from those of beams. Hence, design based on effective width may lead to 2–4 times higher acceleration than the real values. In an economic design, to avoid unnecessary damping enhancement, this effect must be taken into account.

Sign in / Sign up

Export Citation Format

Share Document