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

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.

scholarly journals Wind-Induced Phenomena in Long-Span Cable-Supported Bridges: A Comparative Review of Wind Tunnel Tests and Computational Fluid Dynamics Modelling

2021 ◽  
Vol 11 (4) ◽  
pp. 1642
Author(s):  
Yuxiang Zhang ◽  
Philip Cardiff ◽  
Jennifer Keenahan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
Careful Analysis ◽  
Wind Effects ◽  
Wind Tunnel Tests ◽  
Long Span Bridges ◽  
Long Span ◽  
Comparative Review ◽  
Dynamics Modelling

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.

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

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.

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

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.

scholarly journals Ensuring the aerodynamic stability of the long-span bridges through studies in the wind tunnel

2018 ◽  
Vol 245 ◽  
pp. 02001 ◽  
Author(s):  
Evgenii Khrapunov ◽  
Sergei Solovev
Keyword(s):  
Wind Tunnel ◽  
Design Process ◽  
Aerodynamic Characteristics ◽  
Elastic Instability ◽  
Experimental Facility ◽  
Bridge Design ◽  
Aerodynamic Stability ◽  
Long Span Bridges ◽  
Long Span ◽  
Main Ideas

The main ideas of the aerodynamic studies of large bridges are presented in present paper. Main types of aero-elastic instability for bridges with spans over 100 meters are considered. A two-step modeling approach is presented. At the first stage, the aerodynamic characteristics of the span fragment are considered, at the second.stage the characteristics of the whole bridge. Methods for investigation of bridge oscillations in a special-purpose experimental facility – the Landscape Wind Tunnel – are described. Examples of tests with elastic similar models of bridges are given, and measurements to mitigate dangerous oscillations early in the bridge design process are described.

Cold-Weather Cast-in-Place Segmental Construction for Long-Span Bridges

2000 ◽  
Vol 1712 (1) ◽  
pp. 157-163
Author(s):  
Christopher J. Burgess
Keyword(s):  
Saint Paul ◽  
Cold Weather ◽  
Monitoring Method ◽  
Box Girder ◽  
Long Span Bridges ◽  
Long Span ◽  
Batch Plant ◽  
Reinforced Plastic ◽  
Post Tensioning ◽  
C 50

An innovative heating and monitoring method was developed and used for wintertime casting of the Wabasha Street Bridge in Saint Paul, Minnesota. The bridge’s twin 384-m (1,260-ft) box-girder structures slope 5 percent from atop Saint Paul’s bluffs on the Mississippi River’s north side down to the lower portion of Saint Paul. Each box girder is composed of two 122-m-long (400-ft-long) center spans and two 70-m (230-ft) approach spans. The deck width of 14.54 m (47 ft 8 in.) contains two 3.66-m (12-ft) travel lanes, two shoulders of 0.92 m (3 ft) and 1.83 m (6 ft) with a 3.36-m (11-ft) sidewalk, and 1.11 m (3 ft 8 in.) to account for the barriers. The superstructure consists of 4.88-m (16-ft) typical-length segments that are 6.10 m (20 ft) deep over the piers and 2.44 m (8 ft) deep at midspan and the abutments. The bridge was constructed in balanced cantilever fashion with form travelers. The contractor, the local concrete supplier, the city, and the Minnesota Department of Transportation worked together to develop an innovative mix that would withstand the frigid temperatures and also achieve 24 115 kPa (3,500 lb/in.2) compressive strength in less than 24 h to allow the stressing of the post-tensioning. To insulate and protect the curing concrete, reinforced plastic enclosures surrounding the form travelers housed three 316 761-kJ (300,000-Btu) propane heaters. A layer of plastic and a double layer of insulating blankets covered the top slab. Thermocouples in the segments provided temperature readings, which the contractor used to monitor the effectiveness of the cold-weather procedures. The forms, reinforcing steel, and previous concrete were heated above 10°C (50°F) by using plastic enclosures, propane heaters, and insulating blankets. The concrete arrived from the batch plant at approximately 21°C (70°F) and was still above 13°C (55°F) when it was pumped into the segments. Multiple thermocouples indicated that the top slab cured above 38°C (100°F) for several days, whereas the bottom slab and webs were about 11°C warmer. The contractor ran the propane heaters for 5 days after each pour or until the segments reached a 28-day strength of 41,340 kPa (6,000 lb/in.2). The segments reached the required 24 115 kPa (3,500 lb/in.2) strength for post-tensioning on the day after each pour, including pours made on days as cold as −28°C (−19°F). Only 3 working days were lost because of the cold, and the bridge was completed on time. The method of heating and protection used at the Wabasha Street Bridge proved that the segmental cast-in-place construction method is a viable option in cold-weather climates on major long-span bridges.

scholarly journals Aerodynamic study of a suspension bridge deck by CFD simulations, wind tunnel tests and full-scale observations

2021 ◽  
Vol 1201 (1) ◽  
pp. 012007
Author(s):  
I. Kusano ◽  
E. Cheynet ◽  
J. B. Jakobsen ◽  
J. Snæbjörnsson
Keyword(s):  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Suspension Bridge ◽  
Aerodynamic Characteristics ◽  
Full Scale ◽  
Navier Stokes ◽  
Cfd Simulations ◽  
Wind Tunnel Tests ◽  
Long Span Bridges ◽  
Wide Range

Abstract Assessing the aerodynamic characteristics of long-span bridges is fundamental for their design. Depending on the terrain complexity and local wind conditions, episodes of large angles of attack (AoA) of 15° may be observed. However, such large AoAs ( above 10°) are often overlooked in the design process. This paper studies the aerodynamics properties of a flow around a single-box girder for a wide range of AoAs, from –20° to 20°, using numerical simulations. The simulations are based on a 2D unsteady Reynolds-averaged Navier–Stokes (URANS) approach using the k − ω SST turbulence model with a Reynolds number of 1.6 × 105. Numerically obtained aerodynamic static coefficients were compared to wind tunnel test data. The CFD results were generally in good agreement with the wind tunnel tests, especially for small AoAs and positive AoAs. More discrepancies were observed for large negative AoA, likely due to the limitation of modelling 3D railings with 2D simulations. The simulated velocity deficit downstream of the deck was consistent with the one measured in full-scale using short-range Doppler wind lidar instruments. Finally, the Strouhal number from the CFD simulations were in agreement with the value obtained from the full-scale data.

scholarly journals An Automated Inspection Method for the Steel Box Girder Bottom of Long-Span Bridges Based on Deep Learning

IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 94010-94023
Author(s):  
Dalei Wang ◽  
Yiquan Zhang ◽  
Yue Pan ◽  
Bo Peng ◽  
Haoran Liu ◽  
...  
Keyword(s):  
Deep Learning ◽  
Automated Inspection ◽  
Box Girder ◽  
Inspection Method ◽  
Long Span Bridges ◽  
Long Span ◽  
Steel Box Girder

The Static Wind Load Research of a Flat Box Girder Based on the Numerical Wind Tunnel

2013 ◽  
Vol 351-352 ◽  
pp. 410-414
Author(s):  
Nan Li ◽  
Ji Xin Yang
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
Wind Field ◽  
Wind Tunnel Test ◽  
Box Girder ◽  
Long Span ◽  
Long Span Bridge ◽  
Tunnel Technique ◽  
Aerodynamic Parameters ◽  
Good Agreement

In this paper, the wind field around the flat box girder of a long-span bridge under 0o attack angle was investigated by the numerical wind tunnel technique, which can not only get the distributions of the pressure, velocity and vortex in the flow field, but also obtain the various aerodynamic parameters of the bridges. The velocity profiles were obtained, and the coefficient of tri-component from the numerical simulations was in good agreement with that from the wind tunnel test, which demonstrated that it was reliable and feasible to utilize the numerical wind tunnel technique to simulate the wind field and certificate the coefficient of tri- component of the bridge.

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