• Wind and Structures
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• v.29 no.3
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• pp.149-161
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• 2019

When a railway vehicle runs in crosswinds, the unsteady aerodynamic forces acting on the train induced by the vehicle speed, crosswind velocity and local landforms are a common problem. To investigate the dynamic performance of a railway vehicle due to the influence of unsteady aerodynamic forces caused by local landforms, a vehicle aerodynamic model and vehicle dynamic model were established. Then, a wind-loaded vehicle system model was presented and validated. Based on the wind-loaded vehicle system model, the dynamic response performance of the vehicle, including safety indexes and vibration characteristics, was examined in detail. Finally, the effects of the crosswind velocity and vehicle speed on the dynamic response performance of the vehicle system were analyzed and compared.

• Wind and Structures
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• v.6 no.1
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• pp.1-22
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• 2003

Nowadays balanced cantilever construction plays an essential role as a sophisticated erection technique of bridges due to its economical and ecological advantages. Experience teaches that wind has a great importance with regard to this construction technique, but methods proposed by codes to take wind effects into account are still rather crude and, in most cases, completely lacking. Also research in this field is quite limited and aimed at studying only the longitudinal shear and the torque at the pier base, caused by the mean wind velocity and by the longitudinal turbulence actions over the deck. This paper advances the present solutions by developing a new procedure that takes into account all wind effects both on the deck and on the pier. The proposed model assumes the mean wind velocity as orthogonal to the bridge plane and considers the effects produced by all the three turbulence components and by the vortex shedding. The applications point out the role of each loading component on different bridge configurations and show that disregarding the presence of some effects may imply oversimplified results and relevant underestimations.

• Wind and Structures
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• v.8 no.4
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• pp.251-268
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• 2005

This paper describes the work of the International Association for Wind Engineering Working Group E -Dynamic Response, one of the International Codification Working Groups set up at the Tenth International Conference on Wind Engineering in Copenhagen. Comparisons of gust loading factors and wind-induced responses of major codes and standards are first reviewed, and recent new proposals on 3-D gust loading factor techniques are introduced. Then, the combined effects of along-wind, crosswind and torsional wind load components are discussed, as well as the dynamic characteristics of buildings. Finally, the mathematical forms of along-wind velocity spectra for along-wind response calculation and codification of acceleration criteria are discussed.

• Wind and Structures
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• v.38 no.5
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• pp.367-379
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• 2024

Compared with traditional transmission towers, T-shaped angle towers have long cross-arms and are specially used for ultrahigh-voltage direct-current (UHVDC) transmission. Nevertheless, the wind loads of T-shaped towers have not received much attention in previous studies. Consequently, a series of wind tunnel tests on the T-shaped towers featuring cross-arms of varying lengths were conducted using the high-frequency force balance (HFFB) technique. The test results reveal that the T-shaped tower's drag coefficients nearly remain constant at different testing velocities, demonstrating that Reynolds number effects are negligible in the test range of 1.26 × 10⁴-2.30 × 10⁴. The maximum values of the longitudinal base shear and torsion of the T-shaped tower are reached at 15° and 25° of wind incidence, respectively. In the yaw angle, the crosswind coefficients of the tower body are quite small, whereas those of the cross-arms are significant, and as a result, the assumption in some load codes (such as ASCE 74-2020, IEC 60826-2017 and EN 50341-1:2012) that the resultant force direction is the same as the wind direction may be inappropriate for the cross-arm situation. The fitting formulas for the wind load-distribution factors of the tower body and cross-arms are developed, respectively, which would greatly facilitate the determination of the wind loads on T-shaped angle towers.

• Wind and Structures
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• v.38 no.6
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• pp.411-425
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• 2024

To investigate the optimal aerodynamic parameters of wind barriers for the T-beam of high-speed railway (HSR) bridge and the wind field of the wind barrier-train-bridge system, the three-component forces of the system and the wind pressure on the vehicle surface were tested and analyzed through the sectional model wind test. The effects of wind velocity, with/without wind barrier, the height of wind barrier, and the air permeability of the wind barrier on the aerodynamic characteristics of the train-bridge system are discussed. Additionally, a CFD numerical model is constructed to evaluate the wind environment of the bridge surface with/without the wind barrier, and the impact of wind barrier on the running safety of vehicles are analyzed. Comprehensively considering the running safety of the train and the wind-resistant stability of the bridge, it is more appropriate to set the wind barrier height H as 3.5 m and the porosity 𝛽 as 30% respectively.

• Wind and Structures
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• v.37 no.5
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• pp.331-346
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• 2023

This work investigates the effects of transverse inclination on an aeroelastic prism through forced-vibration wind tunnel experiments. The aerodynamic characteristics are tri-parametrically evaluated under different wind speeds, inclination angles, and oscillation amplitudes. Results show that transverse inclination fundamentally changes the wake phenomenology by impinging the fix-end horseshoe vortex and breaking the separation symmetry. The aftermath is a bi-polar, one-and-for-all change in the aerodynamics near the prism base. The suppression of the horseshoe vortex unleashes the Kármán vortex, which significantly increases the unsteady crosswind force. After the initial morphology switch, the aerodynamics become independent of inclination angle and oscillation amplitude and depend solely on wind speed. The structure's upper portion does not feel the effect, so this phenomenon is called Base Intensification. The phenomenon only projects notable impacts on the low-speed and VIV regime and is indifferent in the high-speed. In practice, Base Intensification will disrupt the pedestrian-level wind environment from the unleashed Bérnard-Kármán vortex shedding. Moreover, it increases the aerodynamic load at a structure base by as much as 4.3 times. Since fix-end stiffness prevents elastic dissipation, the load translates to massive stress, making detection trickier and failures, if they are to occur, extreme, and without any warnings.

• Wind and Structures
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• v.37 no.5
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• pp.361-373
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• 2023

Suspended monorail trains (SMTs) are sensitive to crosswinds, and instantaneous aerodynamic characteristics of two SMTs passing each other under crosswinds are particularly complicated. In this study, a pressure measurement test is carried out on stationary train-bridge models arranged in several critical positions. In addition, a validated moving CFD model is developed with the dynamic and sliding mesh method to explore the realistic train movement effects. The time-varying aerodynamic forces and surface pressure distribution on, as well as the flow field around running trains and bridges during trains passing each other, are computed in detail to illustrate the shielding effect of the upstream train. The results reveal that when two trains begin to pass each other, the side force coefficient of the downstream train reduces significantly to negative values due to the wind shielding effect of the upstream train. The moving model successfully captures that airflow is separated on the middle line of the head car for the suspended monorail train, and the surrounding bluff double-beams can significantly affect the flow structures around the train. The wind shielding effect of the upstream train on the downstream train will weaken as the relative yaw angle decreases.