• Wind and Structures
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• 제17권2호
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• pp.203-225
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• 2013

An analysis framework for vehicle-bridge dynamic interaction system under turbulent wind is proposed based on the relevant theory of wind engineering and dynamics. Considering the fluctuating properties of wind field, the stochastic wind velocity time history is simulated by the Auto-Regressive method in terms of power spectral density function of wind field. The bridge is represented by three-dimensional finite element model and the vehicle by a multi-rigid-body system connected by springs and dashpots. The detailed calculation formulas of unsteady aerodynamic forces on bridge and vehicle are derived. In addition, the form selection of wind barriers, which are applied as the windbreak measures of newly-built railways in northwest China, is studied based on the suggested evaluation index, and the suitable values about height and porosity rate of wind barriers are studied. By taking a multi-span simply-supported box-girder bridge as a case study, the dynamic response of the bridge and the running safety indices of the train traveling on the bridge with and without wind barriers are calculated. The limit values of train speed with respect to different wind velocities are proposed according to the allowance values in the design code.

• Wind and Structures
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• 제24권4호
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• pp.367-384
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• 2017

The Maanshan Bridge over Yangtze River in China is a new long-span suspension bridge with double main spans of $2{\times}1080m$ and a closed streamline cross-section of single box deck. The flutter and buffeting performances were investigated via wind tunnel tests of a full bridge aeroelastic model at a geometric scale of 1:211. The tests were conducted in both smooth wind and simulated boundary layer wind fields. Emphasis is placed on studying the interference effect of adjacent span via installing a wind deflector and a wind separating board to shelter one span of the bridge model from incoming flow. Issues related to effects of mid-tower stiffness and deck supporting conditions are also discussed. The testing results show that flutter critical wind velocities in smooth flow, with a wind deflector, are remarkably lower than those without. In turbulent wind, torsional and vertical standard deviations for the deck responses at midspan in testing cases without wind deflector are generally less than those at the midspan exposed to wind in testing cases with wind deflector, respectively. When double main spans are exposed to turbulent wind, the existence of either span is a mass damper to the other. Furthermore, both effects of mid-tower stiffness and deck supporting conditions at the middle tower on the flutter and buffeting performances of the Maanshan Bridge are unremarkable.

• 한국안전학회지
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• 제31권5호
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• pp.149-157
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• 2016

This paper presents the traffic speed limit of heavy vehicles at each wind velocity region, which is based on their accident risk analysis under cross-wind. The variables for the accident risk analysis are overall height, overall length, intake weight, and friction coefficient of the road surface. It was confirmed from analysis results that the risk of overturning increased with higher overall height and length, and the risk of sliding decreased with higher intake weight. The risk of sliding was largest at the friction coefficient of 0.1, and the risk of overturning was lagest at friction coefficient more than 0.25. Finally, traffic speed limit was proposed by using the accident risk analysis.

• Wind and Structures
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• 제4권1호
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• pp.45-62
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• 2001

This paper is focused on the torsional effects that are induced on bridge piers by unbalanced wind buffeting on the deck during double cantilever erection stages. The case of decks with variable cross section is considered in particular as this characteristic is typical of most frame bridges that are built by the cantilever method. The procedure outlined in the paper is basically an application of the method that Dyrbye and Hansen (1996) have illustrated for decks with constant cross section. This format was chosen because it is suitable for design purposes and may easily be implemented in structural codes. As a complement, the correspondence with the format that is adopted in the Canadian code (NBCC 1990) for the gust factor is established, which might be useful to bridge designers used to the North-American approach to the gust effects on structures. Only alongwind turbulence and horizontal movements of the deck are considered. The combination of torsional and bending effects is also discussed and it is illustrated with an example of application.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.138-143
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• 2005

In this study, the cross-wind stability of the G7 train and TTX running under the high speed was investigated by using 2-dimensional Reynolds Averaged Navier-Stokes equations. It is very important to analysis the aerodynamic characteristic of bluff body located near a ground at the field of the aeronautical, wind engineering, ground vehicle system. To the point of running stability, it is meaningful to analysis the cross-wind effect to the G7 train and TTX developed by domestic technology. The aerodynamic characteristics of the G7 train equipped by bogie-cover is more superior to the case without bogie-cover. Also 2nd model of TTX has stream-shape body has the more good performance than 1st model of TTX.

• 한국항공운항학회지
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• 제17권4호
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• pp.32-41
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• 2009

This paper presents the work being carried out in order to reduce the ground turbulence by the fence in the vicinity of airport runway. In preliminary study, we knows that cross-wind effect in the vicinity of runway is highly dependent on the shape of the buildings and have predicted results confirmed reduction of wind-effect by doing that set up the building with a fence, terraced shape or gap. This study is to figure out effect of ground turbulence by the building with fence, which is changing fence height, in using two-dimensional computational fluid dynamics analysis.

• 한국전산유체공학회지
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• 제1권1호
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• pp.71-80
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• 1996

An iterative time marching procedure for solving incompressible turbulent flow has been applied to the flows around a high speed train including cross-wind effects. This procedure solves three-dimensional unsteady incompressible Reynolds-averaged Navier-Stokes equations on a non-orthogonal curvilinear coordinate system using first-order accurate schemes for the time derivatives and third/second-order accurate schemes for the spatial derivatives. Turbulent flows have been modeled by Baldwin-Lomax turbulent model. To validate present procedure, the flow around a high speed train at zero yaw angle was simulated and compared with experimental data. Generally good agreement with experiments was achieved. The flow fields around the high speed train at 9.2°, 16.7°, and 45° of yaw angle were also simulated.

• Wind and Structures
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• 제24권2호
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• pp.145-169
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• 2017

The auxiliary structures of a high-rise building, such as balconies, ribs, and grids, are usually much smaller than the whole building; therefore, it is difficult to simulate them on a scaled model during wind tunnel tests, and they are often ignored. However, they may have notable effects on the local or overall wind loads of the building. In the present study, a series of wind pressure wind tunnel tests and high-frequency force balance (HFFB) wind tunnel tests were conducted on rigid models of an actual super high-rise building with vertical ribs protruding from its facades. The effects of the depth and spacing of vertical ribs on the mean values, fluctuating values and the most unfavorable values of the local wind pressure coefficients were investigated by analyzing the distribution of wind pressure coefficients on the facades and the variations of the wind pressure coefficients at the cross section at 2/3 of the building height versus wind direction angle. In addition, the effects of the depth and spacing of vertical ribs on the mean values, fluctuating values and power spectra of the overall aerodynamic force coefficients were studied by analyzing the aerodynamic base moment coefficients. The results show that vertical ribs significantly decrease the most unfavorable suction coefficients in the corner recession regions and edge regions of facades and increase the mean and fluctuating along-wind overall aerodynamic forces.

• Wind and Structures
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• 제32권4호
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• pp.293-308
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• 2021

For the past three decades a significant amount of research has been conducted on bridge flutter. Wind tunnel tests for a 2000 m class twin-box suspension bridge have revealed that a twin-box deck carrying 4 m tall 50% open area ratio wind screens at the deck edges achieved higher critical wind speeds for onset of flutter than a similar deck without wind screens. A result at odds with the well-known behavior for the mono-box deck. The wind tunnel tests also revealed that the critical flutter wind speed increased if the bridge deck assumed a nose-up twist relative to horizontal when exposed to high wind speeds - a phenomenon termed the "nose-up" effect. Static wind tunnel tests of this twin-box cross section revealed a positive moment coefficient at 0° angle of attack as well as a positive moment slope, ensuring that the elastically supported deck would always meet the mean wind flow at ever increasing mean angles of attack for increasing wind speeds. The aerodynamic action of the wind screens on the twin-box bridge girder is believed to create the observed nose-up aerodynamic moment at 0° angle of attack. The present paper reviews the findings of the wind tunnel tests with a view to gain physical insight into the "nose-up" effect and to establish a theoretical model based on numerical simulations allowing flutter predictions for the twin-box bridge girder.

• Wind and Structures
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• 제36권4호
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• pp.263-275
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• 2023

As a new kind of construction facility for high rise buildings, the integral steel platform scaffold system (ISPS) consisting of the steel skeleton and suspended scaffold faces high wind during the construction procedure. The lattice structure type and existence of core tubes both make it difficult to estimate the wind load and calculate the wind-induced responses. In this study, an aeroelastic model with a geometry scale ratio of 1:25 based on the ISPS for Shanghai Tower, with the representative square profile, is manufactured and then tested in a wind tunnel. The first mode of the prototype ISPS is a torsional one with a frequency of only 0.68 Hz, and the model survives under extreme wind speed up to 50 m/s. The static wind load and wind vibration factors are derived based on the test result and supplementary finite element analysis, offering a reference for the following ISPS design. The spacer at the bottom of the suspended scaffold is suggested to be long enough to touch the core tube in the initial status to prevent the collision. Besides, aerodynamic wind loads and cross-wind loads are suggested to be included in the structural design of the ISPS.