Wind-induced Vibration Response Research Articles

Design wind loads for transmission towers with cantilever cross-arms based on the inertial load method

Appropriate design wind loads can effectively avoid damage to transmission towers under strong wind and the wind-induced vibration coefficient β(z) is a critical parameter for determining those loads. Based on the inertial load approach, a step-by-step calculation method for the design wind loads of transmission towers considering the effects of cross-arms and diaphragms was proposed. In order to be consistent with actual transmission towers, the correction coefficient expressions of β(z), such as θb, θl and θη, considering the influence of local shape, mass and windshield area and the spatial correlation of the fluctuating wind, respectively, were derived and investigated. By the introduction of these three coefficients, the design wind loads for transmission towers with cross-arms and diaphragms can be determined. For transmission towers with cantilever cross-arms, design wind load formulae were derived, based on the analyses of 6 tower samples. The example of an actual transmission tower was used to verify the correctness of the derived formulae. The parameter analyses of the design wind loads showed that cross-arms have a great influence on β(z) and the wind-induced vibration response of transmission towers, but diaphragms only have a marginal influence and so may be neglected in the approximate calculation of the design wind loads. The research results provide a calculation method for the wind-resistant design of transmission towers.

Multi-scale Modelling and Wind-induced Vibration Analysis of Transmission Tower Structure

Based on the theory of node displacement compatibility, the multi-point constraint equations of beam-solid elements are derived. The beam element model and multi-scale model are established to analyze the wind-induced vibration response of the transmission tower. The analysis results demonstrate that the dynamic response of the two models is similar in the elastic stage, but the response of the multi-scale model is larger than that of the beam element model in the plastic stage. The main reason is that the multi-scale model can consider the stiffness degradation and cracking of the angle cleat, which will in turn influence the mechanical performance and failure mode of the structure.

Typhoon-induced vibration response and the working mechanism of large wind turbine considering multi-stage effects

The typhoon-induced vibration characteristics of large wind turbines are significantly different in different travelling stages of typhoons due to the structural complexity of typhoons. Influences of multi-stage typhoon-induced effects on structural safety of wind turbines have not been studied yet. The objective of this paper is to investigate the vibration characteristics of wind turbines in different stages of the typhoon as well as the influencing rules of the structural design standards. For this purpose, a framework was established for predicting multi-stage typhoon-induced effects of large wind turbines, which includes a new typhoon-induced multi-stage wind field simulation method and an advanced multi-body model for large wind turbines. On this basis, aerodynamic loads and dynamic response of large wind turbines during different travelling stages of typhoon were analyzed systematically based on the blade element momentum, multi-body dynamic methods, spectral analysis and data statistics. The working mechanisms of multi-stage effects on vibration characteristics of the large wind turbine were revealed. Finally, an evaluation method of vibration amplification effects for large wind turbines with considerations to multi-stage effects was established. Research results demonstrate that the proposed method can predict vibration characteristics of large wind turbines considering the multi-stage effects efficiently. The multi-stage typhoon-induced effects can influence the value of peak factor and the extremum of wind-induced force and vibration responses of large wind turbines significantly. Conversely, the wind vibration coefficient of structural design was affected slightly. Instead of using a uniform structural design standard for large wind turbines, the influence rule of multi-stage effects on anti-typhoon safety performance was summarized in this paper.

Wind-induced Vibration Response Analysis Of FRP Bracket-line Coupling System

According to the basic properties of fluctuating wind, Simiu spectrum and linear autoregressive filter method, a program of Simiu spectrum-time curve has been compiled in the MATLAB. The time history of fluctuating wind velocity for a few points has been simulation based on Simiu spectrum. The results show that the method is feasible. Taking the FRP bracket-line coupling system as an example, the wind-induced vibration response of the structure at different angles of wind and wind speeds is analyzed by using the finite element software ANSYS. The results show that the wind in the 90 degree direction is the most unfavorable wind direction for the whole structure according to the three kinds of angle wind calculated at present and when the 0 degree wind acts on the structure, wires have a certain damping effect in the bracket-line coupling system. By comparing and analyzing the influence of different wind speeds and wind attack angles, it is found that in the bracket-line coupling system, the bracket structure is more sensitive to the increase of wind speed while the conductors are more sensitive to the change of wind attack angle.

Experimental and analytical study on design performance of full-scale viscoelastic dampers

Viscoelastic (VE) dampers, with their stiffness and energy dissipation capabilities, have been widely used in civil engineering for mitigating wind-induced vibration and seismic responses of structures, thus enhancing the comfort of residents and serviceability of equipment inside. In past relevant research, most analytical models for characterizing the mechanical behavior of VE dampers were verified by comparing their predictions with performance test results from small-scale specimens, which might not adequately or conservatively represent the actual behavior of full-scale dampers, especially with regard to the ambient temperature, temperature rise, and heat convection effects. Thus, in this study, by using a high-performance testing facility with a temperature control system, full-scale VE dampers were dynamically tested with different displacement amplitudes, excitation frequencies, and ambient temperatures. By comparing the analytical predictions with the experimental results, it is demonstrated that adopting the fractional derivative method together with considering the effects of excitation frequencies, ambient temperatures, temperature rises, softening, and hardening, can reproduce the design performance of full-scale VE dampers very well.

Measurement and Analysis of Wind-induced Vibration Response of the Overhead Working Truck

We obtained the vibration response of the GKZ17 overhead working truck under normal wind load through field measurement made for four operating conditions. In the test, a vibration test system was arranged on the working platform of this overhead working truck. The time-domain and frequency-domain characteristics of displacement and acceleration were obtained from analysis on the measured data. The results show that when the wind direction is perpendicular to the working plane, the downwind response is dominated, but the crosswind response is also large and shall be highly valued; and when the wind direction is parallel with the working plane, the downwind wind-induced vibration response is small and the crosswind response is dominated. The frequency domain analysis indicates that this overhead working truck is more sensitive to low-order frequencies.

Study on the vibration of membrane roof with the influence of added air-mass

For studing the influence regularity of added air-mass on the dynamic characteristics of membrane roof, the three-dimensional membrane roof is taken as the model, we obtained the analytical expression of added air-mass according to the energy conservation and aeroelastic mechanics. Then, futher investigations of the free vibration considering membrane immerse in air is given. Combined with the specific structural parameters, the influence of vibrate mode, membrane’density and the prestress on the additional air quality is discussed, which lays the foundation for further analysis of nonlinear coupling wind induced vibration response of membrane structures.

CFD/FEM Based Analysis Framework for Wind Effects on Tall Buildings in Urban Areas

In this paper, the one-way coupled numerical simulation with computational fluid dynamics (CFD) and finite element method (FEM) is used to evaluate the wind load and wind-induced vibration response of high-rise buildings in urban area. Firstly, this paper presents a complete framework for the numerical simulation of the wind effect of high-rise buildings, which mainly includes the module for the shape coefficient of structural members, the module for fluctuating wind load analysis of structural members and the module for the wind-induced vibration response analysis. Then, based on the proposed numerical simulation analysis framework, this paper selects one typical high-rise building located in the center of the high-density city to carry out the systematic analysis in terms of the shape coefficient, the wind pressure coefficient, the interference factor, the base moment spectrum and structural wind-induced vibration response, and combined with high-rise building structure specifications for its wind-induced vibration of a reasonable assessment. The results show that the proposed framework can effectively assess the wind effect of the high-rise building in the urban area and the accurate evaluation of the wind-induced vibration comfort, and provide a highly efficient and reliable tool for the wind resistance design of the high-rise building.

Computer simulation of reliability algorithm for wind-induced vibration response control of high structures

This paper presents a reliability control algorithm based on computer aided for wind-induced vibration response of high structures. On the basis of modeling parameters and high structure model built by ANSYS, the power spectral density of motion equation and the structure displacement response under random wind load in frequency domain, the relationship between wind velocity and wind pressure and the load of wind effect on the structure are calculated, and the model is analyzed by different variation modes. The reliability of the simulation results is analyzed by the experiment. The computer simulation results show that the simulation results are in good agreement with the actual situation and have strong reliability.

Parameter Analysis on Wind-Induced Vibration of UHV Cross-Rope Suspension Tower-Line

This paper analyzes the influences of important structural design parameters on the wind-induced response of cross-rope suspension tower-line. A finite element model of cross-rope suspension tower-line system is established, and the dynamic time-history analysis with harmonic wave superposition method is conducted. The two important structural design parameters such as initial guy pretension and sag-span ratio of suspension-rope are studied, as well as their influences on the three wind-induced vibration responses such as tensile force on guys, the reaction force on mast supports, and the along-wind displacement of the mast top; the results show that the value of sag-span ratio of suspension-rope should not be less than 1/9 and the value of guy pretension should be less than 30% of its design bearing capacity. On this occasion, the tension in guys and compression in masts would be maintained in smaller values, which can lead to a much more reasonable structure.

Dynamic characteristics and wind-induced vibration coefficients of purlin-sheet roofs

This paper presents the dynamic characteristics analysis of the purlin-sheet roofs by the random vibration theories. Results show that the natural vibration frequency of the purlin-sheet roof is low, while the frequencies and mode distributions are very intensive. The random vibration theory should be used for the dynamic characteristics of the roof structures due to complex vibration response. Among the first 20th vibration modes, the first vibration mode is mainly the deformations of purlins, while the rest modes are the overall deformations of the roof. In the following 30th modes, it mainly performs unilateral local deformations of the roof. The frequency distribution of the first 20th modes varies significantly while those of the following 30th modes are relatively sensitive. For different parts, the contributions of vibration modes on the vibration response are different. For the part far from the roof ridge, only considering the first 5th modes can reflect the wind-induced vibration response. For the part near the ridge, at least the first 12 modes should be considered, due to complex vibration response. The wind vibration coefficients of the upwind side are slightly higher than that of the leeward side. Finally, the corresponding wind vibration coefficient for the purlin-sheet roof is proposed.

Nonlinear analysis of wind-induced vibration of high-speed railway catenary and its influence on pantograph–catenary interaction

ABSTRACTThe wind-induced vibration of the high-speed catenary and the dynamic behaviour of the pantograph–catenary under stochastic wind field are firstly analysed. The catenary model is established based on nonlinear cable and truss elements, which can fully describe the nonlinearity of each wire and the initial configuration. The model of the aerodynamic forces acting on the messenger/contact wire is deduced by considering the effect of the vertical and horizontal fluctuating winds. The vertical and horizontal fluctuating winds are simulated by employing the Davenport and Panofsky spectrums, respectively. The aerodynamic coefficients of the contact/messenger wire are calculated through computational fluid dynamics. The wind-induced vibration response of catenary is analysed with different wind speeds and angles. Its frequency-domain characteristics are discussed using Auto Regression model. Finally, a pantograph model is introduced and the contact force of the pantograph–catenary under stochastic wind is studied. The results show that both the wind speed and the attack angle exert a significant effect on the wind-induced vibration. The existence of the groove on the contact wire cross-section leads to a significant change of the aerodynamic coefficient, which affects largely the aerodynamic forces applied on the catenary wires, as well as the vibration response. The vibration frequency with high spectral power mainly concentrates on the predominant frequency of the fluctuating wind and the natural frequency of catenary. The increase in the wind speed results in a significant deterioration of the current collection. The numerical example shows that a relatively stable current collection can be ensured when the wind flows at the relatively horizontal direction.

Dominant Modals of Wind-Induced Vibration Response for Spherical Kiewitt Cable Dome

Correlation coefficients of mode shape between higher frequency modes and lower frequency modes are given. Then 17 high modes were initially selected as the dominant high modes in the analysis of wind-induced response, and cumulative mode correlation was used to judge the rationality of the method of selecting dominant high modals, so dominant modals of wind-induced response analysis are constructed. Based on these, the wind-induced vibration response of spherical Kiewitt cable dome was analyzed in frequency domain using CQC method. Through analyses of computational results, it is found that the selecting method of dominant modals by using the mode correlation coefficient can be applied in frequency domain analysis for wind-induced vibration response of cable dome structures. If the first 100 modals are considered into the analysis, the computational results obtained will be high precision.

Research on Calculation of Equivalent Damping Ratio of Electrical Transmission Tower-Line System with Viscoelastic Dampers

Installing viscoelastic dampers on electrical transmission tower will significantly reduce the wind-induced vibration response of electrical transmission tower-line system. On the basis of the concept of strain energy method with the combination of related codes and the theories of calculation for equivalent damping,a mothed is presented which is used to estimate the additional damping of electrical transmission tower-line system with viscoelastic dampers.Through a electrical transmission tower with viscoelastic dampers, based on the formula of strain energy in design code,this paper puts forward a calculation method of equivalent damping ratio based on the concept story of transmission tower,and through finite element model the responses of transmission tower with viscoelastic dampers model and the one with additional damping ratio model were compared.The simulation results show that the calculation method of equivalent damping ratio has high precision,and the errors are less than 5% in multi engineering conditions.

Wind response of high-rise building in diversified inlets to construct wind turbine system on roof

Many skyscrapers have installed wind turbine systems to use new renewable energy. In particular, building an integrated wind power generation system by installing a wind power generator inside a building is an attractive method to secure safe energy. However, most studies have dealt with the efficiency of wind turbines and the response effects of wind induced vibration; space preparation for wind turbine installations has not been sufficiently considered. This work reviewed the shapes of openings where wind turbines can be installed in skyscrapers, and the characteristics of wind induced vibration responses occurring in the building with changes in cross sectional area. Nine wind power models were constructed to carry out the experiment. According to the experimental results, wind speed varies with shape of opening in the order of C-type>S-type>R-type. Moreover, wind speed increases as the area is reduced.

Passive control of along-wind response of tall building

Most of modern tall buildings using lighter construction materials with high strength and less stiffness are more flexible, which occurs excessive wind-induced vibration, resulting in occupant discomfort and structural unsafety. It is necessary to predict wind-induced vibration response and find out a method to mitigate such an excessive wind-induced vibration at the preliminary design stage. Recently, many studies have been conducted in using actuator control force based on the linear quadratic optimum control algorithm. It was accepted as a common knowledge that the performance of passive tuned mass damper (TMD) could increase by incorporating a feedback active control force in the design of TMD, which is called active tuned mass damper (ATMD). However, the fact that ATMD is superior to TMD to reduce wind-induced vibration of a tall building is still a question. The effectiveness of TMD for mitigating the along-wind vibration of a tall building was investigated. Optimum parameters of tuning frequency and damping ratio for TMD under a random load which has a white noise spectra were used. Fluctuating along-wind load acting on a tall building treated as a stationary Gaussian random process was simulated numerically using the along-wind load spectra. And using this simulated along-wind load, along-wind responses of a tall building with and without TMD were calculated and the effectiveness of TMD in mitigating the along-wind response of a tall building was found out.

Investigations on the Wind Vibration Coefficient of Single Layer Lattice Barrel Vault Structures

Wind actions on the structures consist of two parts, the average action and the fluctuation action. The fluctuation action will cause the structures vibrating and enlarge the wind action of the structures. This paper investigates the wind vibration coefficient for the single layer lattice barrel vault structures. In the analysis, the simulation velocity-time curve of wind is developed and the finite element methods are used to analyze the wind-induced vibration responses of the lattice barrel vault structures. The influence of the rise to span ratio, the length to width ratio of the structure, and the different average velocity of the wind are investigated. Based on the numerical analysis results, the formula of the wind vibration coefficient for the single layer lattice barrel vault structure is suggested for the wind resistance design of the structures.

The Wind-Induced Vibration Response for Tower Crane Based on Virtual Excitation Method

The dynamics of Tower Crane is complicated by wind excitation which complicates the wind-induced vibration response analysis. The random wind-induced response analysis of tower crane is presented based on finite element method and virtual excitation method. The pulsating wind loads change into multiple-point correlation stationary excitation. This paper uses Davenport’s wind speed spectrum which does not change with height, and considers multiplepoint correlation of wind-induction. The tower crane was employed as a numerical example; the response spectra and Mean Square Root (RMS) of the tower crane were obtained by wind-induced vibration. The results indicate that the vibration of the tower crane showed a greater response in low frequency with the One-third Octave acceleration RMS being lower. Finally, the influences of the wind-induced vibration on comfort were analyzed.

Analysis of Wind-Induced Vibration Response for a Long-Span Double-Arch-Support Steel Structure

As a new long-span double-arch-support steel structure system is applied to a stadium, it is necessary to study the wind-induced vibration response of the roof structure to meet the need of design. The modal analysis and the response analyses which include static wind response and wind-induced vibration response are calculated by ANSYS. The results show that the natural vibration frequency of structure is intensive (0.93 Hz~4.2 Hz). The most unfavorable wind direction angle of 135o is selected to study the wind-induced vibration response. And the wind-induced vibration coefficient calculated is satisfactory when compared with the wind tunnel test. It can be seen that it is feasible to use the stochastic simulation analysis method of wind-induced vibration response to get the wind-induced vibration coefficient.

Wind-Induced Vibration Analysis of Overhead Working Truck

As to the complicated characteristics of overhead working truck under effects of random dynamic wind, the traditional method is difficult to reflect its dynamic response in real time, in the study; it proposes the random wind induced vibration response analysis method based on the finite element method and pseudo-excitation method. An it regards the vibration of the fluctuating wind load as coherent random vibration under stationary random excitation, and it uses Davenport wind velocity spectrum which does not change with height, the correlation of the wind excitation are considered. It takes the folding type arm overhead working truck as example, the random wind vibration analysis are performed, and it gets the acceleration response spectrum and root mean square the of aerial work platform. The analysis results show that the low-order frequency will cause great vibration of the work platform, and the vertical one third of the root-mean-square of acceleration is below international standards, it has no uncomforted effect on operation workers.