• Title, Summary, Keyword: wind loads

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Investigation of 3-D dynamic wind loads on lattice towers

  • Zou, Lianghao;Liang, Shuguo;Li, Q.S.;Zhao, Lin;Ge, Yaojun
    • Wind and Structures
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    • v.11 no.4
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    • pp.323-340
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    • 2008
  • In this paper, the along-wind, across-wind as well as torsional dynamic wind loads on three kinds of lattice tower models are investigated using the base balance technique in a boundary layer wind tunnel. The models were specially designed, and their fundamental frequencies in the directions of the three principal axes are still in the frequency range of the spectra of wind loads on lattice towers. In order to clear contaminations to the spectra of wind loads induced by model resonance, the generalized force spectra of the first mode of the models in along-wind, across-wind and torsional directions were derived based on measured base moments of the models. The RMS generalized force coefficients are also obtained by removing the contributions of model resonance. Finally, the characteristics of the 3-D dynamic wind loads, especially those of the across-wind dynamic loads, on the three kinds of lattice towers are presented and discussed.

Across-wind dynamic loads on L-shaped tall buildings

  • Li, Yi;Li, Qiu-Sheng
    • Wind and Structures
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    • v.23 no.5
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    • pp.385-403
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    • 2016
  • The across-wind dynamic loads on L-shaped tall buildings with various geometric dimensions were investigated through a series of wind tunnel testing. The lift coefficients, power spectral densities and vertical correlation coefficients of the across-wind loads were analyzed and discussed in details. Taking the side ratio and terrain category as key variables, empirical formulas for estimating the across-wind dynamic loads on L-shaped tall buildings were proposed on the basis of the wind tunnel testing results. Comparisons between the predictions by the empirical formulas and the wind tunnel test results were made to verify the accuracy and applicability of the proposed formulas. Moreover, a simplified procedure to evaluate the across-wind dynamic loads on L-shaped tall buildings was derived from the proposed formulas. This study aims to provide a simple and reliable way for the estimation of across-wind dynamic loads on L-shaped tall buildings.

Equivalent static wind loads for stability design of large span roof structures

  • Gu, Ming;Huang, Youqin
    • Wind and Structures
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    • v.20 no.1
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    • pp.95-115
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    • 2015
  • Wind effects on roofs are usually considered by equivalent static wind loads based on the equivalence of displacement or internal force for structural design. However, for large-span spatial structures that are prone to dynamic instability under strong winds, such equivalent static wind loads may be inapplicable. The dynamic stability of spatial structures under unsteady wind forces is therefore studied in this paper. A new concept and its corresponding method for dynamic instability-aimed equivalent static wind loads are proposed for structural engineers. The method is applied in the dynamic stability design of an actual double-layer cylindrical reticulated shell under wind actions. An experimental-numerical method is adopted to study the dynamic stability of the shell and the dynamic instability originating from critical wind velocity. The dynamic instability-aimed equivalent static wind loads of the shell are obtained.

Wind load effects and equivalent static wind loads of three-tower connected tall buildings based on wind tunnel tests

  • Ke, Shitang;Wang, Hao;Ge, Yaojun
    • Structural Engineering and Mechanics
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    • v.58 no.6
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    • pp.967-988
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    • 2016
  • Due to the significant aerodynamic interference from sub-towers and surrounding tall buildings, the wind loads and dynamic responses on main tower of three-tower connected tall building typically change especially compared with those on the isolated single tall building. This paper addresses the wind load effects and equivalent static wind loads (ESWLs) of three-tower connected tall building based on measured synchronous surface pressures in a wind tunnel. The variations of the global shape coefficients and extremum wind loads of main tower structure with or without interference effect under different wind directions are studied, pointing out the deficiency of the traditional wind loads based on the load codes for the three-tower connected tall building. The ESWLs calculation method based on elastic restoring forces is proposed, which completely contains the quasi-static item, inertia item and the coupled effect between them. Then the wind-induced displacement and acceleration responses for main tower of three-tower connected tall building in the horizontal and torsional directions are investigated, subsequently the structural basal and floor ESWLs under different return periods, wind directions and damping ratios are studied. Finally, the action mechanism of interference effect on structural wind effects is investigated. Main conclusions can provide a sientific basis for the wind-resistant design of such three-tower connected tall building.

Wind-induced response and loads for the Confederation Bridge -Part II: derivation of wind loads

  • Bakht, Bilal;King, J. Peter C.;Bartlett, F.M.
    • Wind and Structures
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    • v.16 no.4
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    • pp.393-409
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    • 2013
  • This paper uses ten years of on-site monitoring data for the Confederation Bridge to derive wind loads and investigate whether the bridge has experienced its design wind force effects since its completion in 1997. The load effects derived using loads from the on-site monitoring data are compared to the load effects derived using loads from the 1994 and 2009 wind tunnel aerodynamic model tests. The research shows, for the first time, that the aerodynamic model-based methodology originally developed in 1994 is a very accurate method for deriving wind loads for structural design. The research also confirms that the bridge has not experienced its specified (i.e., unfactored) wind force effects since it was opened to traffic in 1997, even during the most severe event that has occurred during this period.

Response of fiber reinforced plastic chimneys to wind loads

  • Awad, A.S.;El Damatty, A.A.;Vickery, B.J.
    • Wind and Structures
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    • v.3 no.2
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    • pp.83-96
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    • 2000
  • Due to their high corrosion and chemical resistance, fiber reinforced plastics (FRP) are becoming widely used as the main structural material for industrial chimneys. However, no national code currently exists for the design of such type of chimneys. The purpose of this study is to investigate analytically the response of FRP chimneys to wind loads. The classical lamination theory is used to substitute the angle-ply laminate of a FRP chimney with an equivalent orthotropic material that provides the same stiffness. Dynamic wind loads are applied to the equivalent chimney to evaluate its response to both along and across wind loads. A parametric study is then conducted to identify the material and geometric parameters affecting the response of FRP chimneys to wind loads. Unlike the across-wind response, the along-wind tip deflection is found to be highly dependent on the angle of orientation of the fibers. In general, the analysis shows that FRP chimneys are very vulnerable to across-wind oscillations resulting from the vortex shedding phenomenon.

Wind Loads of 5 MW Horizontal-Axis Wind Turbine Rotor in Parked Condition (운전정지 조건에서 5 MW 수평축 풍력터빈 로터의 풍하중 해석)

  • Ryu, Ki-Wahn;Seo, Yun-Ho
    • Journal of the wind engineering institute of Korea
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    • v.22 no.4
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    • pp.163-169
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    • 2018
  • In this study, wind loads exerted on the offshore wind turbine rotor in parked condition were predicted with variations of wind speeds, yaw angles, azimuth angle, pitch angles, and power of the atmospheric boundary layer profile. The calculated wind loads using blade element theorem were compared with those of estimated aerodynamic loads for the simplified blade shape. Wind loads for an NREL's 5 MW scaled offshore wind turbine rotor were also compared with those of NREL's FAST results for more verification. All of the 6-component wind loads including forces and moments along the three axis were represented on a non-rotating coordinate system fixed at the apex of rotor hub. The calculated wind loads are applicable for the dynamic analysis of the wind turbine system, or obtaining the over-turning moment at the foundation of support structure for wind turbine system.

Case study of random vibration analysis of train-bridge systems subjected to wind loads

  • Zhu, Siyu;Li, Yongle;Togbenou, Koffi;Yu, Chuanjin;Xiang, Tianyu
    • Wind and Structures
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    • v.27 no.6
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    • pp.399-416
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    • 2018
  • In order to reveal the independent relationship between track irregularity and wind loads, the stochastic characteristics of train-bridge coupling systems subjected to wind loads were investigated by the multi-sample calculation. The vehicle was selected as 23 degrees of freedom dynamical model, and the bridge was described by three-dimensional finite element model. It was assumed that the wind loads were random processes with strong spatial correlation, while the track irregularities were stationary random ones. As a case study, a high-speed train running on a cable-stayed bridge subjected to wind loads was studied. The effect of rail irregularities was deemed to be independent of the effect of wind excitations on the coupling system in the same wind circumstance for the same project, leading to the conclusion that the effect of wind loads and moving vehicle could be calculated separately. The variance results of the stochastic responses of vehicle-bridge coupling system under the action of wind loads and rail irregularities together were equivalent to the sum of the variance of the responses induced by each excitation. Therefore, when one of the input excitations is different, only the effect of changed loads needs to be assessed. Moreover, the new calculated results were combined with the effect of unchanged loads to present the stochastic response of coupling system subjected to the different excitations, reducing the cost of computations. The stochastic characteristics, the CFD (cumulative distribution function) of the coupling system with different wind velocities, vehicle speed, and vehicle marshalling were studied likewise.

Aerodynamic loading of a typical low-rise building for an experimental stationary and non-Gaussian impinging jet

  • Jubayer, Chowdhury;Romanic, Djordje;Hangan, Horia
    • Wind and Structures
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    • v.28 no.5
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    • pp.315-329
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    • 2019
  • Non-synoptic winds have distinctive statistical properties compared to synoptic winds and can produce different wind loads on buildings and structures. The current study uses the new capabilities of the WindEEE Dome at Western University to replicate a stationary non-Gaussian wind event recorded at the Port of La Spezia in Italy. These stationary non-Gaussian wind events are also known as intermediate wind events as they differ from non-stationary non-Gaussian events (e.g., downbursts) as well as stationary Gaussian events (e.g., atmospheric boundary layer (ABL) flows). In the present study, the wind loads on a typical low-rise building are investigated for an intermediate wind event reproduced using a continuous radial impinging jet (IJ) at the WindEEE Dome. For the same building model, differences in wind loads between ABL and IJ are also examined. Wind loads on different surface zones on the building, as defined in the ASCE code for design loads, are also calculated and compared with the code.

Calculation of Wind Loads on the Cladding of Apartment Building according to Panel Size (패널 크기에 따른 아파트 건축물 외장재의 풍하중 산정)

  • Cho, Kang-Pyo;Jeong, Seung-Hwan;Kim, Won-Sool
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.739-744
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    • 2007
  • Wind loads for cladding can be estimated using the maximum wind pressure including gust effects from wind-tunnel tests. However, when estimating the maximum wind pressure with gust effects, wind pressure coefficients for cladding would be different according to the averaging time of wind pressures, In the paper, for wind pressures obtained from wind-tunnel tests for apartment buildings, whose window panes were damaged by actual strong wind, it was investigated how pressure coefficients varied according to the size of cladding and averaging time using TVL method of Lawson. In result, it was found that the lesser the size of cladding and averaging time were, the larger pressure coefficients became. Accordingly, to estimate wind loads for cladding of apartment buildings and design it, the averaging time of wind pressures should be considered properly.

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