Numerical simulation of the wind action on a long-span bridge deck

Wind-driven rain (WDR) and its interactions with structures is an important research subject in wind engineering. As bridge spans are becoming longer and longer, the effects of WDR on long-span bridges should be well understood. Therefore, this paper presents a comprehensive numerical simulation study of WDR on a full-scale long-span bridge under extreme conditions. A validation study shows that the predictions of WDR on a bridge section model agree with experimental results, validating the applicability of the WDR simulation approach based on the Eulerian multiphase model. Furthermore, a detailed numerical simulation of WDR on a long-span bridge, North Bridge of Xiazhang Cross-sea Bridge is conducted. The simulation results indicate that although the loads induced by raindrops on the bridge surfaces are very small as compared to the wind loads, extreme rain intensity may occur on some windward surfaces of the bridge. The adopted numerical methods and rain loading models are validated to be an effective tool for WDR simulation for bridges and the results presented in this paper provide useful information for the water-erosion proof design of future long-span bridges.

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Deep Learning Based Vehicle Detection and Classification Methodology Using Strain Sensors under Bridge Deck

Sensors ◽

10.3390/s20185051 ◽

2020 ◽

Vol 20 (18) ◽

pp. 5051

Author(s):

Rujin Ma ◽

Zhen Zhang ◽

Yiqing Dong ◽

Yue Pan

Keyword(s):

Neural Network ◽

Bridge Deck ◽

Vehicle Detection ◽

Traffic Monitoring ◽

Transportation Systems ◽

Strain Sensors ◽

Long Span ◽

Long Span Bridge ◽

Pavement Evaluation ◽

Close Range

Vehicle detection and classification have become important tasks for traffic monitoring, transportation management and pavement evaluation. Nowadays there are sensors to detect and classify the vehicles on road. However, on one hand, most sensors rely on direct contact measurement to detect the vehicles, which have to interrupt the traffic. On the other hand, complex road scenes produce much noise to consider when to process the signals. In this paper, a data-driven methodology for the detection and classification of vehicles using strain data is proposed. The sensors are well arranged under the bridge deck without traffic interruption. Next, a cascade pre-processing method is applied for vehicle detection to eliminate in-situ noise. Then, a neural network model is trained to identify the close-range following vehicles and separate them by Non-Maximum Suppression. Finally, a deep convolutional neural network is designed and trained to identify the vehicle types based on the axle group. The methodology was applied in a long-span bridge. Three strain sensors were installed beneath the bridge deck for a week. High robustness and accuracy were obtained by these algorithms. The methodology proposed in this paper is an adaptive and promising method for vehicle detection and classification under complex noise. It would serve as a supplement to current transportation systems and provide reliable data for management and decision-making.

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Numerical Simulation of Characteristics of Wind Field at Bridge Sites in Flat and Gorge Terrains under the Thunderstorm Downburst

Shock and Vibration ◽

10.1155/2021/9962519 ◽

2021 ◽

Vol 2021 ◽

pp. 1-15

Author(s):

Peng Hu ◽

Yilin Chen ◽

Yan Han ◽

Fei Zhang ◽

Yongjian Tang

Keyword(s):

Numerical Simulation ◽

Wind Field ◽

Wind Fields ◽

Monitoring Point ◽

Wind Speeds ◽

Flat Terrain ◽

Long Span ◽

Long Span Bridge ◽

Bridge Girder ◽

Large Wind

To investigate the effects of thunderstorm downburst on the characteristics of wind field at bridge sites in flat and gorge terrains, firstly, numerical simulation of wind fields in the flat terrain under the thunderstorm downburst was conducted through the SST k-ω turbulence model, combined with the impinging jet technology. After verification of the reliability of the numerical model, settings, and methods, the characteristics of wind field over a long-span bridge site in a gorge terrain under the thunderstorm downburst were investigated and the distributions of wind speed and wind attack angle in the flat and gorge terrains were compared. The results show that, under the effects of the thunderstorm downburst, the wind speeds are relatively maximum at the midspan point of the girder in the flat terrain. Besides, the farther away from the midspan point, the smaller the wind speeds, which is opposite to the case in the gorge terrain. The wind speeds at each typical monitoring point are basically the same in the two terrains, before the thunderstorm downburst hits the bridge girder. Later the wind speeds at each point in the gorge terrain are much higher than those in the flat terrain. Most wind attack angles are negative at the monitoring points in the flat terrain, but the farther away they are from the midspan point, the greater the wind attack angles will be. However, the wind attack angles at the monitoring points in the gorge terrain are generally larger than those in the flat terrain, and they gradually turn to be positive farther away from the midspan point. In the flat terrain, both wind speeds and wind attack angles (or their absolute values) at the girder are large within about t = 75∼130 s, indicating that the thunderstorm downburst may exert significant effects on the bridge. However, in the gorge terrain, due to the large wind speeds and wind attack angles (or their absolute values) at the girder after t = 75 s, full attention needs to be paid to the effects of the thunderstorm downburst during this period.

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Steady-Suction-Based Flow Control of Flutter of Long-Span Bridge

Applied Sciences ◽

10.3390/app10041372 ◽

2020 ◽

Vol 10 (4) ◽

pp. 1372

Author(s):

Jian Zhan ◽

Hongfu Zhang ◽

Zhiwen Liu ◽

Huan Liu ◽

Dabo Xin ◽

...

Keyword(s):

Flow Control ◽

Bridge Deck ◽

Control Method ◽

Control Device ◽

Maximal Increase ◽

Long Span ◽

Suction Control ◽

Long Span Bridge ◽

Bridge Model ◽

Section Model

The present wind tunnel study focuses on the effects of the steady-suction-based flow control method on the flutter performance of a 2DOF bridge deck section model. The suction applied to the bridge model was released from slots located at the girder bottom. The suction rates of all slots along the span were equal and constant. A series of test cases with different combinations of suction slot positions, suction intervals, and suction rates were studied in detail for the bridge deck model. The experimental results showed that the steady-suction-based flow control method could improve the flutter characteristics of the bridge deck with a maximal increase in the critical flutter speed of up to 10.5%. In addition, the flutter derivatives (FDs) of the bridge deck with or without control were compared to investigate the fundamental mechanisms of the steady-suction-based control method. According to the results, installing a suction control device helps to strengthen aerodynamic damping, which is the primary cause for enhanced flutter performance of bridge decks.

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Variation of aerodynamic coefficients with air flow parameters on long span bridge deck

International Journal of Structural Engineering ◽

10.1504/ijstructe.2016.077721 ◽

2016 ◽

Vol 7 (3) ◽

pp. 279

Author(s):

Rohit Kumar Mittal ◽

Vivek Nandan ◽

Pabitra Ranjan Maiti

Keyword(s):

Bridge Deck ◽

Air Flow ◽

Aerodynamic Coefficients ◽

Long Span ◽

Flow Parameters ◽

Long Span Bridge

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Numerical simulation of dynamic response of a long-span bridge to assess its vulnerability to non-synoptic wind

Engineering Structures ◽

10.1016/j.engstruct.2014.11.009 ◽

2015 ◽

Vol 84 ◽

pp. 67-75 ◽

Cited By ~ 6

Author(s):

Bochao Cao ◽

Partha P. Sarkar

Keyword(s):

Numerical Simulation ◽

Dynamic Response ◽

Long Span ◽

Long Span Bridge ◽

Synoptic Wind

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The Icing Distribution Characteristics Research of Tower Cross Beam of Long-Span Bridge by Numerical Simulation

Energies ◽

10.3390/en14175584 ◽

2021 ◽

Vol 14 (17) ◽

pp. 5584

Author(s):

Zhi-Yong Yang ◽

Xiang Zhan ◽

Xin-Long Zhou ◽

Heng-Lin Xiao ◽

Yao-Yao Pei

Keyword(s):

Numerical Simulation ◽

Simulation Method ◽

Distribution Characteristics ◽

Ice Melting ◽

Long Span ◽

Numerical Simulation Method ◽

Long Span Bridge ◽

Ice Accretions ◽

The Cross ◽

Windward Surface

The cross beam of a long-span bridge will freeze in low temperature. When the temperature rises, the ice on the cross beam will thaw and fall off. If the ice is too heavy, it may cause vehicle damage and casualty. In order to reduce the risk of falling ice, a scale model of the cross beam was taken as an example, and a kind of numerical simulation method is presented to study the icing distribution characteristics on surface of the cross beam. This paper simulates the ice accretions process of the cross beam by Fluent module and FENSAP-ICE module of ANSYS and investigates the influence of wind and temperature in the process. This is a new numerical simulation method for studying ice accretions of buildings. The results indicate that water freezes mainly on the windward surface, and the thicker ice is near the top and bottom edge of windward surface. According to the results of numerical simulation, a measure of ice melting based on electric heating method is proposed in this paper, and the feasibility and effectiveness of this method are verified by numerical simulation. The results show that the icing distribution characteristics are accord with the fact and the ice-melting measure is feasible and effective.

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Wind Field Numerical Simulation of Long-Span Bridge

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.361-363.1094 ◽

2013 ◽

Vol 361-363 ◽

pp. 1094-1100

Author(s):

Jian Guo ◽

Wei Chang Gan ◽

Ding Yu Jiang ◽

Bing Nan Sun ◽

Wei Peng

Keyword(s):

Numerical Simulation ◽

Wind Field ◽

Simulation Method ◽

Filter Method ◽

Linear Filter ◽

Wind Field Simulation ◽

Long Span ◽

Long Span Bridge ◽

Target Spectrum ◽

Main Girder

In the research on calculation of interaction of wind and structure, the key to the question is wind field numerical simulation. This paper introduces a practical wind field simulation method of long-span Bridge. The main bridge of Jintang Bridge was analyzed as engineering example, which is a cross-sea cable stayed bridge in Zhoushan of Zhejiang Province , and the linear filter method was applied to calculate along-wind and vertical wind field on main girder, MATLAB program also was adopted to simulate wind field of long-span Bridge. The results show that simulated spectrum is in better agreement with the target spectrum, which verifies validity of the method and correctness of the program.

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