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Long-span transmission tower and conductor line systems become important infrastructures in modern societies. The analysis of wind-induced dynamic responses of transmission towers is an essential task in the design of spatial lattice tower structures. Wind effects on the world's tallest transmission tower are presented in this paper. The tower with...
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... Deng et al. [2] studied the dynamic characteristics and wind-induced vibration response of a tower-line system using wind-tunnel tests. Huang et al. [3] performed a numerical simulation and wind tunnel test of a transmission tower and compared the results of the test and simulation using the gust loading factors and gust response factors. The response and failure modes of transmission towers can be effectively predicted using nonlinear finite element analysis [4,5]. ...
To investigate the variation law of the wind-resistant performance of transmission towers during their operation, this paper proposes an evaluation method for the wind resistance of the transmission tower considering corrosion, and a 220-kV transmission tower is analyzed as an example. Considering the uncertainty of the material and geometric parameters, the wind-induced collapse of the transmission tower was analyzed, and the collapse wind speeds were obtained via pushover and incremental dynamic analyses. In addition, the sensitivity of the transmission tower to various parameters was analyzed. Based on the existing meteorological and corrosion data, corrosion prediction models were established using a back-propagation (BP) artificial neural network, and the mean relative error between the predicted and measured values of the test samples was 8.91%. On this basis, the corrosion depth of the tower members in the four regions was predicted, and the fragility of the transmission tower was analyzed considering the effects of corrosion and strong winds. The results show that the collapse wind speed of the transmission tower is most significantly affected by the thickness of the angle steel, followed by the elastic modulus and yield strength, and is less affected by the width of the angle steel. When the exposure time was 25 years, the wind-resistant performance of transmission towers in regions with severe acid rain and coastal industrial regions decreased by 10% to 20%. With an increase in exposure time, the failure mode of the transmission tower tended to be brittle failure.
... Conventionally, the centralized loading mode was adopted to predict the windinduced vibration of transmission tower, [18][19][20][21] which performed well to estimate the overall wind load on the transmission tower but failed to yield accurate simulation results of the wind load distribution along main rods. Furthermore, the additional bending moment caused by distributed wind loads on main rods was ignored in the centralized loading mode. ...
This study aims to investigate refined wind load parameters on main rods and the influence of wind-loading mode on wind-induced responses of the angle-steel transmission tower. The wind load parameters discussed in this study include drag coefficients, wind load distribution factors and skewed wind load factors. To achieve the aim, wind tunnel tests were conducted to explore aerodynamic loads for integrated frame, single frame, and main rod models of cross-arm and tower body. The wind load parameters of the different models were investigated. In addition, a series of wind-induced vibration simulation was applied to examine the wind-induced responses of an ultra-high voltage (UHV) transmission tower with a long cross-arm under concentrated and distributed wind loads. The simulated results under the two types of wind loads were compared. The results show that the longitudinal drag coefficients of the main rods are smaller than the values of the integrated frame, and equivalent on average to the values of the single frame. The experimental shielding factor of the cross-arm is larger than those in different standards due to the joint drag effects of leeward, upper, and lower faces of the cross-arm in the wind tunnel test. The experimented shielding factor of the tower body is in line with those referring to the Chinese and AS/NZS standards, and slightly larger than those based on the British and JEC standards. The skewed wind load factors of the main rod models are quite different from other models for cross-arm and tower body. The wind-induced vibration simulation suggests that, the wind-loading mode has limited impact on the displacements, accelerations, and gust factors of the transmission tower, but significantly influences the maximum normal stresses (MNSs) of the rods’ cross-sections. The MNSs caused by the distributed wind loads are obviously greater than those caused by concentrated wind loads, especially for the rods at the two ends of the cross-arm.
... Wind-induced interaction between the tower and wires (i.e., the coupling effect) is a tricky issue: the wind load acting on wires is transferred to the tower structure and the vibration of wires makes effects on the tower vibration, which may lead to the tower response amplified remarkably; while the constraints at two ends of the span of wires may change with the tower response, which in turn influences the behavior of wires. Many researchers studied the wind effect on the tower and wires using the approaches of field monitoring (Paluch andCappellari 2007, Takeuchi andMaeda 2010), wind tunnel tests (Liang and Zou 2015, Xie and Cai 2017, Huang and Lou 2012 and analytical-numerical methods (Battista andRodrigues 2003, Wang andChen 2017). ...
The spatiotemporal impact of typhoons moving across transmission networks is increasingly evident, which may result in the failure of the overhead transmission tower-line (TL) system. The structural design and safety assessment to transmission TL systems that subjected to extreme winds are necessary. This paper aims to provide fundamental insights on the wind field caused by typhoons as well as the typhoon-induced dynamic loads and responses of the transmission TL system, by means of the numerical simulation. This paper offers a numerical scheme to simulate the typhoon-induced wind field on a TL system, in which the movement of the typhoon center and the nonstationary fluctuation of the wind are concerned. In the scheme, the near-surface mean wind speed is calculated based on the radial profile and translation of storms; the nonstationary fluctuation component is generated by a time-varying modulation function. By applying the simulated wind field to the finite element model of TL system, we yield the dynamic responses of the TL system as well as the dynamic loads resulting from the interaction between the structure and wind. Utilizing the evolutionary power spectral density (EPSD) function, the fluctuating wind loads and structural responses are addressed both in the time and frequency domains. Further discussion is done on the typhoon-induced loads by constructing the dynamic equivalent factors. The time-varying equivalent factors show the stationary process, which demonstrates the fading out of the non-stationarity for simulated wind loads. The comparison result indicates that the gust response factor of tower recommended by design codes may not be safe enough when the typhoon impact is concerned.
... Wind load is one of the control loads of long-span roof structure due to its light weight and weak stiffness. Wind tunnel test is the reliable tool to determine wind load for wind-induced vibration analysis and wind resistance design of high-rise buildings [1], high-rise structures [2], and longspan roof structures [3]. Based on the time-history data collected from wind tunnel test, the wind-induced vibration can be calculated in the frequency domain [4,5], and some scholars [6][7][8] used the time-domain analysis methods to carry out the wind-induced vibration analysis. ...
A building complex consisting of four identical long-span roof structures are tested in the wind tunnel to determine dynamic wind loads on structures. Based on the time-history data of spatially distributed wind pressure, wind-induced vibration analyses of the structures under varying incident wind attack angles have been carried out in time-domain. Then a novel framework for assessing dynamic wind resistance reliability has been proposed by integrating wind tunnel experiment, Monte Carlo simulation method, and the non-Gaussian wind pressure field simulation technique. The framework takes into account the uncertainties of design wind speed, wind directionality and structural damping ratio, as well as the randomness of Non-Gaussian wind pressure field. It has been demonstrated that the proposed framework is effective and efficient to comprehensively assess the wind-induced dynamic reliability of the long-span roof structure in the rectangular array. The annual failure probability of the long-span roof structure is obtained by considering the first passage reliability of displacement responses.
... Considering the size of the laboratory, the geometric similarity ratio of the transmission tower model was chosen to be = λ 1/15 L . According to the requirements of the Cauchy number similarity ratio, the transmission tower members are regarded as link bars [39], and the tensile stiffness similarity ratio should satisfy = λ λ EA L 3 ; consequently, a metal material with a small elastic modulus was used. To ensure similar aerodynamic shapes and for ease of processing, a thin aluminum sheet was processed into steel angle sections to simulate the tower members. ...
The modal parameters of transmission tower-line systems constitute the basis of their wind and seismic design. However, such structures become complicated spatial systems due to the coupling effects between the towers and lines, making it difficult to evaluate the modal parameters of a transmission tower. To study the tower-line coupling effects on the frequencies and mode shapes of a tower, a stochastic subspace identification (SSI) method for identifying modal parameters is first introduced. Then, a finite element model of a transmission tower-line system is established, and the influences of three transmission line parameters, namely, the total span length, span ratio and height difference angle, on the modal parameters are analyzed. An aeroelastic model of the tower-line system is fabricated, and a percussion experiment is performed. The simulated and experimental results both show that the first-order frequency increases with an increase in the total span length but is only slightly affected by changes in the span ratio and the height difference angle. For the wind and seismic design of transmission towers, to obtain reliable natural vibration characteristics, a complete tower-line system model should be established instead of a single tower model.
... Moreover, the damping ratios of the three models can be obtained through the transfer functions shown in Fig. 8 by the half power bandwidth method [34]. The identified damping ratios of the reduced scale coupling tower-line system model (4.8% in the X direction and 4.5% in the Y direction) are close to the results obtained from the reduced scale aeroelastic model in [35] and the maximum damping ratio (4%) derived from the dynamic tests on a full-scale UHV transmission mechanical test line [36], which verifies that the damping effect of the wires can be introduced by the different similarity ratio of the conductors. ...
Ultra high voltage (UHV) transmission tower-line coupling system consists of transmission lines (conductors and ground wires) supported by a series of lattice towers. However, in the current seismic design code, the transmission lines are just simplified as additional mass while the effect of nonlinear vibration of transmission lines on the seismic responses of transmission towers is not taken into consideration. To analyze the influence of the ignorance of the coupling effect between towers and transmission lines, two types of model structures, i.e. tower-line coupling system model and single tower model with lumped masses, should be tested for comparison. But normal reduced-scale model design method cannot complete the shaking table test by a uniform geometric similarity ratio for the coupling system in the limit of table size, hence this paper proposed to rescale the geometric similarity ratio for the model design of transmission lines and meanwhile satisfied the requirement in dynamic properties similitude and inertia force similitude separately, which successfully solved the problem that the span of transmission lines in the test was too large to fit within the shaking table. This method may offer reference to experimental studies for other large-span structures and the experimental results show that the nonlinear vibration of transmission lines plays a role as seismic reduction by dissipating some seismic energy to towers under earthquake.
... In terms of tower-line coupled vibration, present research methods are mainly aeroelastic-model wind tunnel tests (Loredo-Souza and Davenport, 2001;Huang et al., 2012;Liang et al., 2015) and numerical simulations (Ghobarah et al., 1996;Battista et al., 2003;Zhang et al., 2013). Adjacent transmission towers are generally far apart and lines are rather thin. ...
This paper reviews the development of forced motion apparatuses (FMAs) and their applications in wind engineering. A kind of FMA has been developed to investigate nonlinear and nonstationary aerodynamic forces considering the coupled effects of multiple degrees of freedom (DOFs). This apparatus can make section models to vibrate in a prescribed displacement defined by a numerical signal in time domain, including stationary and nonstationary movements with time-variant amplitudes and frequencies and even stochastic displacements. A series of validation tests show that the apparatus can re-illustrate various motions with enough precision in 3D coupled states of two linear displacements and one torsional displacement. To meet the requirement of aerodynamic modeling, the flutter derivatives of a box girder section are identified, verifying its accuracy and feasibility by comparing with previously reported results. By simulating the nonstationary vibration with time-variant amplitude, the phenomena of frequency multiplication and memory effects are examined. In addition to studying the aerodynamics of a bluff body under large amplitudes and nonstationary vibrations, some potential applications of the proposed FMA are discussed in vehicle-bridge-wind dynamic analysis, pile-soil interaction, and line-tower coupled vibration aerodynamics in structural engineering.
... Typically, the interference effects of different segments of the transmission tower, towering derrick and communication tower in the height direction are relatively small, meaning that the wind tunnel test can be carried out on different segments to obtain the respective wind coefficients. [25][26][27][28][29] However, the tower crane has a larger extension structure, and the slewing platform, counterweight and cat-head have considerable influence on the nearby structures. If the wind coefficient of each partition is obtained, respectively, it will cause deviations in dynamic responses. ...
The maximum wind load direction of tower crane is considered to be perpendicular to its jib. The interference effects of its different segments and across-wind loads are ignored in traditional crane safety evaluation. This study proposes a general scheme for the safety evaluation of tower cranes under fluctuating wind loads. The wind coefficients of a full-scale model of a tower crane were calculated by computational fluid dynamics, and then the time history of wind loads, simulated through the autoregressive method, were applied to the finite element model of a tower crane. The results reveal that the maximum along-wind load direction deflected 30°–60°, and the mean ratio of the absolute value of the across-wind coefficient to the along-wind coefficient of the tower crane was 8.56%, which indicated that the across-wind loads should be taken into account in wind-resistant design. Comparing the wind-induced responses of four typical wind directions, the maximum displacement, the bending stress and the axial stress of the tower crane occurred in the positive direction. Furthermore, the maximum acceleration of the cat-head was 0.028 m/s², which met the comfort requirements of the operator. Although the tower crane met the strength and static stiffness requirements of design rules, the maximum bending stress at the junctions between the jib and the slewing platform, the counterweight and the counter-jib, exceeded the allowable stress, and the first modal of the tower crane was excited. These results warrant considering the effect of fluctuating wind loads in the safety evaluation of a tower crane.
... Due to the complex geometry of a steel lattice tower, full-scale measurements and wind tunnel tests on an aero-elastic model are more reliable than computational fluid dynamics and various regional design codes (Savory, Parke, Disney, & Toy, 2008;Ducloux & Figueroa, 2016;Allegrini et al., 2018). Many researchers have carried out wind tunnel tests on aeroelastic models of transmission tower-line systems to investigate their dynamic behaviour under different wind speeds in a boundary layer wind tunnel ( Huang et al., 2012; Liang, Zou, Wang, & Cao, 2015;Xie, Cai, & Xue, 2017;Hamada, King, El Damatty, Bitsuamlak, & Hamada, 2017). Elawady et al. (2017) assessed the dynamic response of a multi-span transmission tower-line system under a scaled downburst wind field at the famous WindEEE dome facility. ...
This article reports on a detailed study of the wind characteristics and dynamic behaviour of a transmission
tower, based on field monitoring during the passage of Typhoon Haima. It was found that the
wind direction at the eye of the storm has an approximately 180� turn, and the mean wind speed
shows an apparent M-shaped variation during the passage of the typhoon. The turbulence intensity
and gust factor show significant decreasing trends with the mean wind speed. The turbulence integral
scale increases with the mean wind speed at the landfall phase, while the tendency at the after-landfall
phase is somewhat opposite. Compared with the empirical spectrum, the proposed normalised
power spectrum agrees well with the measured wind spectrum. The identified fundamental frequency
of the transmission tower decreases with the mean wind speed while the damping ratio increases due
to the aerodynamic damping contribution, and their percentages could be very considerable at high
wind speed. The structural damping ratio of the investigated transmission tower is close to the recommended
amount of 1 percent in regional structural codes.
... Lou et al. (2000) evaluated the aerodynamic responses of a tall lattice transmission tower using a 1/100 full aeroelastic model in the wind tunnel. Meanwhile, the aerodynamic force coefficients, acceleration responses and wind load factors at various wind velocities and wind attack angles were discussed (Huang et al. 2012). Li et al. (2011) analyzed the wind induced vibration response of the aeroelastic model based on the single-tower and tower-line system of the large-span TTLS under the uniform as well as turbulent flow field. ...
As a regenerated turbulent wind field process, wind tunnel test has proven to be a promising approach for investigating the transmission tower-line system (TTLS) performance in view of experimental scaled models design, simulation techniques of wind field, and wind induced responses subjected to typhoon. However, the challenges still remain in using various wind tunnels to regenerate turbulent wind field with considerable progress having been made in recent years. This review paper provides an overview of the state-of-the-art of the wind tunnel based on active or passive controlled simulation techniques. Specific attention and critical assessment have been given to: (a) the design of experimental scaled models, (b) the simulation techniques of wind field, and (c) the responses of TTLS subjected to typhoon in wind tunnel. This review concludes with the research challenges and recommendations for future research direction.
