Aerostatic load on the deck of cable-stayed bridge in erection stage under skew wind

Li, Shaopeng,Li, Mingshui,Zeng, Jiadong,Liao, Haili Techno-Press 2016 Wind and Structures, An International Journal (WAS Vol.22 No.1

In conventional buffeting theory, it is assumed that the aerostatic coefficients along a bridge deck follow the strip assumption. The validity of this assumption is suspect for a cable-stayed bridge in the construction stages, due to the effect of significant aerodynamic interference from the pylon. This situation may be aggravated in skew winds. Therefore, the most adverse buffeting usually occurs when the wind is not normal to bridge axis, which indicates the invalidity of the traditional "cosine rule". In order to refine the studies of static wind load on the deck of cable-stayed bridge under skew wind during its most adverse construction stage, a full bridge 'aero-stiff' model technique was used to identify the aerostatic loads on each deck segment, in smooth oncoming flow, with various yaw angles. The results show that the shelter effect of the pylon may not be ignored, and can amplify the aerostatic loading on the bridge deck under skew winds ($10^{\circ}-30^{\circ}$) with certain wind attack angles, and consequently results in the "cosine rule" becoming invalid for the buffeting estimation of cable-stayed bridge during erection for these wind directions.

Aerostatic load on the deck of cable-stayed bridge in erection stage under skew wind

Shaopeng Li,Mingshui Li,Jiadong Zeng,Haili Liao 한국풍공학회 2016 Wind and Structures, An International Journal (WAS Vol.22 No.1

In conventional buffeting theory, it is assumed that the aerostatic coefficients along a bridge deck follow the strip assumption. The validity of this assumption is suspect for a cable-stayed bridge in the construction stages, due to the effect of significant aerodynamic interference from the pylon. This situation may be aggravated in skew winds. Therefore, the most adverse buffeting usually occurs when the wind is not normal to bridge axis, which indicates the invalidity of the traditional “cosine rule”. In order to refine the studies of static wind load on the deck of cable-stayed bridge under skew wind during its most adverse construction stage, a full bridge ‘aero-stiff’ model technique was used to identify the aerostatic loads on each deck segment, in smooth oncoming flow, with various yaw angles. The results show that the shelter effect of the pylon may not be ignored, and can amplify the aerostatic loading on the bridge deck under skew winds (10º-30º) with certain wind attack angles, and consequently results in the “cosine rule” becoming invalid for the buffeting estimation of cable-stayed bridge during erection for these wind directions.

Vortex-Induced Vibration Optimization of a Wide Streamline Box Girder by Wind Tunnel Test

Ming Li,Yanguo Sun,Hongmiao Jing,Mingshui Li 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.12

Although the streamline box girder exhibits an excellent aerodynamic performance, they are often suffer severe Vortex-Induced Vibrations (VIVs) due to complicated separation and reattachment of air flows. It is necessary to apply control measures on the streamline box girder to suppress VIV. In this study, the VIV optimizations of a super wide streamline box girder were conducted via a series of section model wind tunnel tests. The effects of wind fairings, inspection vehicle rails, guide vanes, traffic barriers and handrails on the heaving VIV performance of the wide streamline box girder were analyzed. The test results show that the inspection vehicle rail and handrail are the main members to induce the heaving VIV of the box girder. A sharper wind fairing without changing the distance of railings is favorable to the heaving VIV performance. However, the countermeasures of changing the position of inspection vehicle rail and installing guide vanes under the girder have slight influences on reducing heaving VIV responses. Inspired by the spanwise sinusoidal perturbation method, the traffic barriers sealed with plates by regular intervals along the bridge deck can suppress the heaving VIV of the box girder successfully. The porosity of handrails has a significant effect on the heaving VIV. By using a sharp wind fairing and circular simplified handrails, the VIV performance of the wide streamline box girder was greatly improved. Their mitigation abilities were verified by a large-scale section model wind tunnel test.

Investigation on vortex-induced vibration of a suspension bridge using section and full aeroelastic wind tunnel tests

Sun, Yanguo,Li, Mingshui,Liao, Haili Techno-Press 2013 Wind and Structures, An International Journal (WAS Vol.17 No.6

Obvious vortex induced vibration (VIV) was observed during section model wind tunnel tests for a single main cable suspension bridge. An optimized section configuration was found for mitigating excessive amplitude of vibration which is much larger than the one prescribed by Chinese code. In order to verify the maximum amplitude of VIV for optimized girder, a full bridge aeroelastic model wind tunnel test was carried out. The differences between section and full aeroelastic model testing results were discussed. The maximum amplitude derived from section model tests was first interpreted into prototype with a linear VIV approach by considering partial or imperfect correlation of vortex-induced aerodynamic force along span based on Scanlan's semi-empirical linear model. A good consistency between section model and full bridge model was found only by considering the correlation of vortex-induced force along span.

Aerodynamic coefficients of inclined and yawed circular cylinders with different surface configurations

Siyuan Lin,Mingshui Li,Haili Liao 한국풍공학회 2017 Wind and Structures, An International Journal (WAS Vol.25 No.5

nclined and yawed circular cylinder is an essential element in the widespread range of structures. As one of the applications, cables on bridges were reported to have the possibility of suffering a kind of large amplitude vibration called dry galloping. In order to have a detailed understanding of the aerodynamics related to dry galloping, this study carried out a set of wind tunnel tests for the inclined and yawed circular cylinders. The aerodynamic coefficients of circular cylinders with three surface configurations, including smooth, dimpled pattern and helical fillet are tested using the force balance under a wide range of inclination and yaw angles in the wind tunnel. The Reynolds number ranges from 2 X105 to 7X105 during the test. The influence of turbulence intensity on the drag and lift coefficients is corrected. The effects of inclination angle yaw angle and surface configurations on the aerodynamic coefficients are discussed. Adopting the existed the quasi-steady model, the nondimensional aerodynamic damping parameters for the cylinders with three kinds of surface configurations are evaluated. It is found that surface with helical fillet or dimpled pattern have the potential to suppress the dry galloping, while the latter one is more effective.

Fluctuating lift and drag acting on a 5:1 rectangular cylinder in various turbulent flows

Yang Yang,Mingshui Li,Xiongwei Yang 한국풍공학회 2022 Wind and Structures, An International Journal (WAS Vol.34 No.1

In this paper, the fluctuating lift and drag forces on 5:1 rectangular cylinders with two different geometric scales in three turbulent flow-fields are investigated. The study is particularly focused on understanding the influence of the ratio of turbulence integral length scale to structure characteristic dimension (the length scale ratio). The results show that both fluctuating lift and drag forces are influenced by the length scale ratio. For the model with the larger length scale ratio, the corresponding fluctuating force coefficient is larger, while the spanwise correlation is weaker. However, the degree of influence of the length scale ratio on the two fluctuating forces are different. Compared to the fluctuating drag, the fluctuating lift is more sensitive to the variation of the length scale ratio. It is also found through spectral analysis that for the fluctuating lift, the change of length scale ratio mainly leads to the variation in the low frequency part of the loading, while the fluctuating drag generally follows the quasi-steady theory in the low frequency, and the slope of the drag spectrum at high frequencies changes with the length scale ratio. Then based on the experimental data, two empirical formulas considering the influence of length scale ratio are proposed for determining the lift and drag aerodynamic admittances of a 5:1 rectangular cylinder. Furthermore, a simple relationship is established to correlate the turbulence parameter with the fluctuating force coefficient, which could be used to predict the fluctuating force on a 5:1 rectangular cylinder under different parameter conditions.

Spatial Distribution of Gusty Loads on a Rectangular Prism in Boundary Layer Flows

Jiadong Zeng,Mingshui Li,Shaopeng Li,Ruwei Ma 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.8

The pressure fluctuations acting on a stationary rectangular prism with cross configuration (2:1/1:2) are investigated by windtunnel testing. The synchronous surface pressures on the rigid model were measured in simulated atmospheric boundary layer flowand the unsteady forces were calculated by numerical integral of surface pressures. The effects of the wind fields and the model’s sideratio on the aerodynamic coefficients, spectral characteristics and spatial correlation of aerodynamic loading were investigated. Themain purpose of this study is to further analyze the spatial structure of the fluctuating wind loads acting on a rectangular prism as wellas to use the cross correlation coefficient and coherence function to explore their distribution trends. The results show that the alongwindgust loading is consistent with the longitudinal turbulence and the across-wind aerodynamic force is mainly induced by thevortex-shedding, recirculation and reattachment of separation shear layers on the lateral sides. In practical applications, the Strouhalnumber is approximately constant along the height. Extended empirical coherence models of the fluctuating along-wind and acrosswindloads are proposed with consideration to the effects of wind fields, the structure characteristics and dimensions of the prism andlength scale.

Aerodynamic coefficients of inclined and yawed circular cylinders with different surface configurations

Lin, Siyuan,Li, Mingshui,Liao, Haili Techno-Press 2017 Wind and Structures, An International Journal (WAS Vol.25 No.5

Inclined and yawed circular cylinder is an essential element in the widespread range of structures. As one of the applications, cables on bridges were reported to have the possibility of suffering a kind of large amplitude vibration called dry galloping. In order to have a detailed understanding of the aerodynamics related to dry galloping, this study carried out a set of wind tunnel tests for the inclined and yawed circular cylinders. The aerodynamic coefficients of circular cylinders with three surface configurations, including smooth, dimpled pattern and helical fillet are tested using the force balance under a wide range of inclination and yaw angles in the wind tunnel. The Reynolds number ranges from $2{\times}10^5$ to $7{\times}10^5$ during the test. The influence of turbulence intensity on the drag and lift coefficients is corrected. The effects of inclination angle yaw angle and surface configurations on the aerodynamic coefficients are discussed. Adopting the existed the quasi-steady model, the nondimensional aerodynamic damping parameters for the cylinders with three kinds of surface configurations are evaluated. It is found that surface with helical fillet or dimpled pattern have the potential to suppress the dry galloping, while the latter one is more effective.

Investigation on vortex-induced vibration of a suspension bridge using section and full aeroelastic wind tunnel tests

Yanguo Sun,Mingshui Li,Haili Liao 한국풍공학회 2013 Wind and Structures, An International Journal (WAS Vol.17 No.6

Obvious vortex induced vibration (VIV) was observed during section model wind tunnel tests for a single main cable suspension bridge. An optimized section configuration was found for mitigating excessive amplitude of vibration which is much larger than the one prescribed by Chinese code. In order to verify the maximum amplitude of VIV for optimized girder, a full bridge aeroelastic model wind tunnel test was carried out. The differences between section and full aeroelastic model testing results were discussed. The maximum amplitude derived from section model tests was first interpreted into prototype with a linear VIV approach by considering partial or imperfect correlation of vortex-induced aerodynamic force along span based on Scanlan’s semi-empirical linear model. A good consistency between section model and full bridge model was found only by considering the correlation of vortex-induced force along span.

Flutter suppression of long-span suspension bridge with truss girder

Kai Wang,Haili Liao,Mingshui Li 한국풍공학회 2016 Wind and Structures, An International Journal (WAS Vol.23 No.5

Section model wind tunnel test is currently the main technique to investigate the flutter performance of long-span bridges. Further study about applying the wind tunnel test results to the aerodynamic optimization is still needed. Systematical parameters and test principle of the bridge section model are determined by using three long-span steel truss suspension bridges. The flutter critical wind at different attack angles is obtained through section model flutter test. Under the most unfavorable working condition, tests to investigate the effects that upper central stabilized plate, lower central stabilized plate and horizontal stabilized plate have on the flutter performance of the main beam were conducted. According to the test results, the optimal aerodynamic measure was chosen to meet the requirements of the bridge wind resistance in consideration of safety, economy and aesthetics. At last the credibility of the results is confirmed by full bridge aerodynamic elastic model test. That the flutter reduced wind speed of long-span steel truss suspension bridges stays approximately between 4 to 5 is concluded as a reference for the investigation of the flutter performance of future similar steel truss girder suspension bridges.