A smart model of a long-span suspended bridge for wind tunnel tests

Engineers, architects, planners and designers must carefully consider the effects of wind in their work. Due to their slender and flexible nature, long-span bridges can often experience vibrations due to the wind, and so the careful analysis of wind effects is paramount. Traditionally, wind tunnel tests have been the preferred method of conducting bridge wind analysis. In recent times, owing to improved computational power, computational fluid dynamics simulations are coming to the fore as viable means of analysing wind effects on bridges. The focus of this paper is on long-span cable-supported bridges. Wind issues in long-span cable-supported bridges can include flutter, vortex-induced vibrations and rain–wind-induced vibrations. This paper presents a state-of-the-art review of research on the use of wind tunnel tests and computational fluid dynamics modelling of these wind issues on long-span bridges.

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Flutter mitigation of a superlong-span suspension bridge with a double-deck truss girder through wind tunnel tests

Journal of Vibration and Control ◽

10.1177/1077546320946150 ◽

2020 ◽

pp. 107754632094615

Author(s):

Yanguo Sun ◽

Yongfu Lei ◽

Ming Li ◽

Haili Liao ◽

Mingshui Li

Keyword(s):

Wind Tunnel ◽

Damping Ratio ◽

Suspension Bridge ◽

Wind Tunnel Tests ◽

Long Span Bridges ◽

Long Span ◽

Upper Deck ◽

Torsional Damping ◽

And Control ◽

Wind Induced Vibration

As flutter is a very dangerous wind-induced vibration phenomenon, the mitigation and control of flutter are crucial for the design of long-span bridges. In the present study, via a large number of section model wind tunnel tests, the flutter performance of a superlong-span suspension bridge with a double-deck truss girder was studied, and a series of aerodynamic and structural measures were used to mitigate and control its flutter instability. The results show that soft flutter characterized by a lack of an evident divergent point occurred for the double-deck truss girder. Upper central stabilizers on the upper deck, lower stabilizers below the lower deck, and horizontal flaps installed beside the bottoms of the sidewalks are all effective in suppressing flutter for this kind of truss girder. By combining the structural design with aerodynamic optimizations, a redesigned truss girder with widened upper carriers and sidewalks, and double lower stabilizers combined with the inspection vehicle rails is identified as the optimal flutter mitigation scheme. It was also found that the critical flutter wind speed increases with the torsional damping ratio, indicating that the dampers may be efficient in controlling soft flutter characterized by single-degree-of-freedom torsional vibration. This study aims to provide a useful reference and guidance for the flutter design optimization of long-span bridges with double-deck truss girders.

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Research on Snow Load Characteristics on a Complex Long-Span Roof Based on Snow–Wind Tunnel Tests

Applied Sciences ◽

10.3390/app9204369 ◽

2019 ◽

Vol 9 (20) ◽

pp. 4369 ◽

Cited By ~ 2

Author(s):

Guolong Zhang ◽

Qingwen Zhang ◽

Feng Fan ◽

Shizhao Shen

Keyword(s):

Wind Tunnel ◽

Basic Characteristic ◽

Wind Tunnel Test ◽

Experimental System ◽

Similarity Criteria ◽

Wind Tunnel Tests ◽

Snow Load ◽

Long Span ◽

Characteristic Modes ◽

Snow Distribution

A considerable number of studies have been carried out for predicting snowdrifts on roofs over the years. However, few studies have focused on snowdrifts on complex long-span roofs, as the complex shape and fine structure pose significant challenges. In this study, to simplify the calculation requirements of snow load on such roofs, work was conducted to decompose the snowdrift on a complex roof into snowdrifts on several simple roofs. First, the snow–wind tunnel test similarity criteria were investigated based on a combined air–snow–wind experimental system. Thereafter, with reference to the validated experimental similarity criteria, a series of snow–wind tunnel tests were performed for snowdrifts on a complex long-span structure under the conditions of different inflow directions. Finally, based on empirical orthogonal function (EOF) analysis, the snowdrifts on the complex roof were decomposed into basic characteristic distribution modes, including snowdrifts caused by the local and overall roof forms. The snow distribution under a specific inflow direction could be derived from the weighted combination of the basic characteristic modes, based on the wind direction coefficients. Therefore, it is possible for the snow load on a complex roof to be estimated preliminarily based on the snow distributions on several simple roofs.

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A predictive critical flutter wind speed modeling for long-span bridges

Advances in Structural Engineering ◽

10.1177/1369433219900977 ◽

2020 ◽

Vol 23 (9) ◽

pp. 1823-1837

Author(s):

Kun Lin ◽

Minghai Wei ◽

Hongjun Liu ◽

Huafeng Wang

Keyword(s):

Wind Speed ◽

Wind Tunnel ◽

Dimensional Space ◽

Three Dimensional ◽

Wind Tunnel Tests ◽

Long Span Bridges ◽

Wind Speeds ◽

Long Span ◽

Aerodynamic Model ◽

Proposed Model

In this article, a two-dimensional Lighthill aerodynamic model is first extended to three-dimensional space, and then combined with the larger Von Karman plate deformation theory, a model for predicting the critical flutter wind speeds of long-span bridges in the primary design is proposed. The predictions of the presented model are compared to the results of wind tunnel tests for five long-span bridges with different main girder section forms. After that, based on the proposed model, the effects of width to span ratio and thickness to span ratio on the critical flutter wind speeds of long-span bridges are investigated. The results show that the differences between the proposed model and wind tunnel tests are only 7%–14%. Therefore, the presented model can assess the flutter wind speed in preliminary design stages of a bridge. The results also reveal that width to span ratios between 1/30 and 1/10 and thickness to span ratios between 1/300 and 1/100 are optimal for long-span bridges.

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Wind Tunnel Tests and Numerical Simulations of Wind-Induced Snow Drift in an Open Stadium and Gymnasium

Advances in Civil Engineering ◽

10.1155/2020/8840759 ◽

2020 ◽

Vol 2020 ◽

pp. 1-15

Author(s):

Xintong Jiang ◽

Zhixiang Yin ◽

Hanbo Cui

Keyword(s):

Wind Tunnel ◽

Numerical Simulations ◽

Wind Direction ◽

Interference Effect ◽

Mutual Interference ◽

Wind Tunnel Tests ◽

Direction Angle ◽

Long Span ◽

Snow Drift ◽

Snow Distribution

A long-span sports centre generally comprises multiple stadiums and gymnasiums, for which mutual interference effects of wind-induced snow motion are not explicitly included in the specifications of various countries. This problem is addressed herein by performing wind tunnel tests and numerical simulations to investigate the snow distribution and mutual interference effect on the roofs of long-span stadiums and gymnasiums. The wind tunnel tests were used to analyse the influences of the opening direction (0°, 90°, 180°, and 270°) and spacing (0.3 L, 0.5 L, 1 L, 1.5 L, 2 L, and 2.5 L, where L is the gymnasium span) of the stadium and gymnasium. The wind tunnel tests and numerical simulations were used to analyse the influence of the wind direction angle (from 0° to 315°, there are a total of eight groups in 45° intervals). The following results were obtained. The stadium opening had a significant effect on the snow distribution on the surface of the two structures. An even snow distribution was obtained when the stadium opened directly facing the gymnasium, which corresponded to the safest condition for the structures’ surfaces. As the spacing between the buildings increased, the interference effect between the two structures was reduced. The interference was negligible for a spacing of 2 L. The stadium had the most significant amplification interference effect on the gymnasium for a wind direction angle of 45°, which was extremely unfavourable to the safety of the structure. The most favourable wind direction angle was 270°, where there were both amplification interference and blockage interference.

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A Quick Assessment and Optimization Method for a Flutter Aerodynamic Measure of a Typical Flat Box Girder

Shock and Vibration ◽

10.1155/2020/8823921 ◽

2020 ◽

Vol 2020 ◽

pp. 1-11

Author(s):

Feng Wang ◽

Chuan Xiong ◽

Zijian Wang ◽

Congmin Guo ◽

Hua Bai ◽

...

Keyword(s):

Numerical Analysis ◽

Wind Tunnel ◽

Energy Input ◽

Test Procedure ◽

Optimization Method ◽

Box Girder ◽

Wind Tunnel Tests ◽

Long Span Bridges ◽

Long Span ◽

Quick Assessment

Flutter is one of the most serious wind-induced vibration phenomena for long-span bridges and may cause the collapse of a bridge (e.g., the Old Tacoma Bridge, 1940). The selection and optimization of flutter aerodynamic measures are difficult in wind tunnel tests. It usually takes a long time and consumes more experimental materials. This paper presents a quick assessment and design optimization method for the flutter stability of a typical flat box girder of the long-span bridges. Numerical analysis could provide a reference for wind tunnel tests and improve the efficiency of the test process. Based on the modal energy exchange in the flutter microvibration process, the global energy input and local energy input are analyzed to investigate the vibration suppression mechanism of a flat steel box girder with an upper central stabilizer. Based on the comparison between the experimental and numerical data, a quick assessment method for the optimization work is proposed. It is practical to predict the effects of flutter suppression measures by numerical analysis. Thus, a wind tunnel test procedure for flutter aerodynamic measures is proposed which could save time and experimental materials.

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Experimental Study on Suppression of Vortex-Induced Vibration of Central-Slotted Box Girder by Aerodynamic Countermeasures

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.638-640.1067 ◽

2014 ◽

Vol 638-640 ◽

pp. 1067-1078

Author(s):

Ting Yang ◽

Zhi Yong Zhou

Keyword(s):

Wind Tunnel ◽

Large Scale ◽

Vibration Measurement ◽

Test Results ◽

Box Girders ◽

Vortex Induced Vibration ◽

Wind Tunnel Tests ◽

Long Span ◽

Bridge Model ◽

Sectional Model

To study the mechanism on the vortex resonance characteristics of the central-slotted box girders, the large-scale sectional model vibration measurement and pressure measurement are employed. This paper takes a long-span cable-stayed bridge over the Yangtze River as an example to conduct the wind tunnel tests of large-scale sectional model. The test results indicate that it is the inside maintenance rails located in the aerodynamic susceptible sites that cause the vortex-induced vibration (VIV) of bridge model. Accordingly, the inside maintenance rails are proposed to be moved towards the central axis by a certain distance. The static pressure test results show that when shifting the inside maintenance rails, the negative mean pressure at the soffit plate knuckle line will not change dramatically, the fluctuating pressures on the upwind and downwind inclined panels can be reduced, and the fluctuating energy will be dispersed without a consistent predominant frequency. Wind tunnel tests of modified section are conducted and the results show that the VIV of bridge model can be suppressed completely due to the shift of inside rails.

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