Section-Model Wind Tunnel Test for Flexible Suspended Pedestrian Bridges

2019 ◽  
Author(s):  
Rudolf T. Starossek ◽  
Sejin Kim ◽  
Ho-Kyung Kim
Keyword(s):  
Wind Tunnel ◽  
Dynamic Properties ◽  
Three Dimensional ◽  
Wind Tunnel Test ◽  
Stability Study ◽  
Pedestrian Bridge ◽  
Pedestrian Bridges ◽  
Section Model ◽  
Made In

<p>For most bridge decks certain assumptions and simplifications can be made in order to observe the wind interactions in a “2-D” sectional manner. In case of flexible simple suspended pedestrian bridges, the three- dimensional behavior in a mode is dominant, due to structural and dynamic properties highly different to general cable-supported bridges, therefore special considerations have to be made in section-model tests.</p><p>Typically, the section-model wind tunnel test does focus on the dominant vertical and rotational natural modes of the bridge deck, while the lateral mode is suppressed as non-governing. Since the lateral and rotational modes of the suspended pedestrian bridge occur in a coupled manner in the primary mode shape, they have to be examined as well. Various different methods to include these different behaviors in analysis and tests are discussed and applied on a case study object.</p><p>The paper will propose a modified section-model wind tunnel testing setup for a flexible suspended pedestrian bridge on the case study object of the Sogeum Mountain Suspended Pedestrian Bridge in Korea, where a section-model was made for the conventional wind-stability study in the wind tunnel.</p>

Homogeneous, Isotropic Flow in Grid Generated Turbulence

1999 ◽  
Vol 122 (1) ◽  
pp. 51-56 ◽  
Author(s):  
Riccardo Tresso ◽  
David R. Munoz
Keyword(s):  
Wind Tunnel ◽  
Three Dimensional ◽  
Wind Tunnel Test ◽  
Flow Region ◽  
Hot Wire ◽  
Spatial Homogeneity ◽  
One Dimensional ◽  
Streamwise Location ◽  
Dimensional Measurements ◽  
Approach Zero

Detailed grid generated turbulent analysis has been completed using a three-dimensional hot-wire anemometer and traversing mechanism to identify a homogeneous, isotropic flow region downstream of a square mesh. The three-dimensional fluctuating velocity measurements were recorded along the centerline of a wind tunnel test section and spatially over the entire wind tunnel cross section downstream of the square mesh. Turbulent intensities for various grid sizes and Reynolds numbers ranged from a minimum of 0.2 percent to a maximum of 2.2 percent in each of the three principal velocity directions. Spatial homogeneity and isotropy were determined for several turbulent flow conditions and downstream positions using the method of covariances. Covariances, in theory, should approach zero asymptotically; however, in practice, this was not achievable. A subjective judgment is required to determine downstream location where the variance of the three covariances reaches a value close to zero. The average standard deviation provides an estimate for defining the limit or subjective threshold needed to determine the onset of homogeneous, isotropic flow. Implementing this threshold, a quantitative method was developed for predicting the streamwise location for the onset of the homogeneous, isotropic flow region downstream of a 25.4 mm square grid as a function of Reynolds number. A comparison of skewness, determined from one-dimensional hot wire anemometer measurements, and covariances, determined from three dimensional hot wire anemometer measurements, indicates a need for caution when relying solely on one-dimensional measurements for determination of turbulence isotropy. The comprehensive three-dimensional characterization also provides an improved understanding of spatial distribution of fundamental turbulence quantities generated by the grid within a low-speed wind tunnel. [S0098-2202(00)02501-3]

Carbon Footprint Analysis of Fibre Reinforced Polymer (FRP) Incorporated Pedestrian Bridges: A Case Study

2012 ◽  
Vol 517 ◽  
pp. 724-729
Author(s):  
Jian Guo Dai ◽  
Tamon Ueda
Keyword(s):  
Construction Industry ◽  
Carbon Footprint ◽  
Prestressed Concrete ◽  
Environmental Friendliness ◽  
Pedestrian Bridge ◽  
Reinforced Polymer ◽  
Pedestrian Bridges ◽  
Fibre Reinforced Polymer ◽  
Footprint Analysis

This paper presents a case study on the carbon footprint of a fibre reinforced polymer (FRP)-incorporated pedestrian bridge in comparison with a conventional prestressed concrete (PC) one. The CO2 emission is used as an index and calculated for both the material manufacturing and the construction processes. It is shown that using an FRP-incorporated pedestrian bridge to replace a conventional prestressed concrete (PC) bridge may reduce the CO2 emission by 18% and 70%, respectively, during the material manufacturing and construction periods, leading to a total reduction by about 26%. Such reduction is expected to be more significant if the life-cycle CO2 emission is accounted for, since the former type of bridge is free of corrosion and almost maintenance-free. Therefore, FRP-incorporated bridges may become a more competitive alternative to conventional reinforced concrete (RC) or PC ones with the increasing attention paid on the sustainability and environmental friendliness of construction industry by our society.

Experimental Study of Static Aerodynamic Coefficients of Bridge Section

2011 ◽  
Vol 301-303 ◽  
pp. 780-784
Author(s):  
Liang Gao ◽  
Jian Xin Liu ◽  
Miao Liu
Keyword(s):  
Experimental Study ◽  
Wind Tunnel ◽  
Influencing Factors ◽  
Structural Characteristics ◽  
Wind Tunnel Test ◽  
Vibration Damping ◽  
Wind Loads ◽  
Aerodynamic Coefficients ◽  
Central Trough ◽  
Section Model

With HK-Zhuhai-Macau Bridge as the engineering background, through the section model wind tunnel test, research into the influence of vibration damping measure to the static aerodynamic coefficients of the structure, so as to seek to improve structural characteristics. The influencing factors of static aerodynamic coefficients including the guide plate position, the central trough opening rate, baluster drafty rate, repair car track position, windbreak, and vehicle. The results show that the changes of the static aerodynamic coefficients directly affect the static wind loads, and the influence of changes of these parameters to the static wind load cannot be ignored.

Study on Static Wind Loading Coefficients of Suspension Bridge Based on CFD Simulation and Wind Tunnel Test

2011 ◽  
Vol 66-68 ◽  
pp. 334-339
Author(s):  
Mei Yu ◽  
Hai Li Liao ◽  
Ming Shui Li ◽  
Cun Ming Ma ◽  
Nan Luo ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Cfd Simulation ◽  
Wind Tunnel Test ◽  
Suspension Bridge ◽  
Wind Load ◽  
Dynamics Simulation ◽  
Wind Loading ◽  
Suspension Bridges ◽  
Long Span ◽  
Section Model

Long-span suspension bridges, due to their flexibility and lightness, are much prone to the wind loads, aerodynamics performance has become an important aspect of the design of long-span suspension bridges. In this study, the static wind load acting on the suspension bridge during erection has been investigated through wind tunnel test and numerical analysis. The wind tunnel test was performed using a 1:50 scale section model of the bridge, the static wind load acting on the section model was measured with varying attack angles. Numerical method used here was computational fluid dynamics simulation, a two-dimensional model is adopted in the first stage of the analysis, then the SIMPLE algorithm was employed to solve the governing equations. The analytical results were compared with the wind tunnel test data, it was shown from the study that the results of CFD simulation was good agreement with that of the wind tunnel test.

Efficient stall compliance prediction method for trimmed very light aircraft with high-lift devices

2016 ◽  
Vol 231 (6) ◽  
pp. 1124-1137
Author(s):  
Nhu Van Nguyen ◽  
Daeyeon Lee ◽  
Maxim Tyan ◽  
Jae-Woo Lee ◽  
Sangho Kim
Keyword(s):  
Wind Tunnel ◽  
Stokes Equations ◽  
Transport Model ◽  
Three Dimensional ◽  
Wind Tunnel Test ◽  
Prediction Method ◽  
Aircraft Design ◽  
Design Stage ◽  
High Fidelity ◽  
Configuration Generation

An efficient stall compliance prediction method using quick configuration generation, adapted mesh, high fidelity analysis, and wind tunnel test data for trimmed very light aircraft is proposed. The three-dimensional Navier–Stokes equations are used to determine the characteristics of the flow field around the aircraft, and the [Formula: see text] shear stress transport model is used to interpret the turbulent flow as a solver in the high fidelity analysis. The calibrated mesh and model are developed by comparing the results with the wind tunnel test and adjusting the adapted mesh to match the wind tunnel data. The calibrated mesh and model are applied to conduct the full-scale very light aircraft analysis for the clean and full flap extended flight conditions to comply with the CS-VLA stall regulations. It is recommended that the flap area be increased in the trimmed full flap extended condition. The proposed method demonstrates the feasibility and effectiveness of very light aircraft VLA stall compliance prediction in reducing the development cost and time with small configuration changes at the preliminary very light aircraft design stage.

Experimental Study of the Nonlinear Torsional Flutter of a Long-Span Suspension Bridge with a Double-Deck Truss Girder

2021 ◽  
pp. 2150102
Author(s):  
Ming Li ◽  
Yanguo Sun ◽  
Yongfu Lei ◽  
Haili Liao ◽  
Mingshui Li
Keyword(s):  
Wind Tunnel ◽  
Model Test ◽  
Wind Tunnel Test ◽  
Suspension Bridge ◽  
Suspension Bridges ◽  
Nonlinear Flutter ◽  
Long Span ◽  
Aeroelastic Model ◽  
Flutter Analysis ◽  
Section Model

The purpose of this study is to investigate the nonlinear torsional flutter of a long-span suspension bridge with a double-deck truss girder. First, the characteristics of nonlinear flutter are studied using the section model in the wind tunnel test. Different aerodynamic measures, e.g. upper and lower stabilizers and horizontal flaps, are applied to improve the flutter performance of the double-deck truss girder. Then, the full bridge aeroelastic model is tested in the wind tunnel to further examine the flutter performance of the bridge with the optimal truss girder. Finally, three-dimensional (3D) flutter analysis is performed to study the static wind-induced effects on the nonlinear flutter of the long-span suspension bridge. The results show that single-degree-of-freedom torsional limit cycle oscillations occur at large amplitudes for the double-deck truss section at the attack angles of [Formula: see text] and [Formula: see text]. The upper and lower stabilizers installed on the upper and lower decks, respectively, and the flaps installed near the bottoms of the sidewalks can all effectively alleviate the torsional flutter responses. Meanwhile, it is found that the torsional flutter responses of the truss girder in the aeroelastic model test are much smaller than those in the section model test. The 3D flutter analysis demonstrates that the large discrepancies between the flutter responses of the two model experiments can be attributed to the additional attack angle caused by the static wind-induced displacements. This finding highlights the importance and necessity of considering the static wind-induced effects in the flutter design of long-span suspension bridges.

Experimental Investigation into Aerodynamic Stability of Narrow Steel Truss Girder Suspension Bridge

2011 ◽  
Vol 255-260 ◽  
pp. 938-941
Author(s):  
Hua Bai ◽  
Jia Wu Li
Keyword(s):  
Wind Tunnel ◽  
Geographical Location ◽  
Wind Tunnel Test ◽  
Suspension Bridge ◽  
Mitigation Measures ◽  
Aerodynamic Stability ◽  
Steel Truss ◽  
Section Model ◽  
Wind Climate ◽  
Steel Truss Girder

A narrow steel truss girder suspension bridge was designed for pedestrian and livestock in pasture in Xinjiang Province, China. For the complex wind climate at bridge site, the cautious designers resorted to wind tunnel test to confirm the aerodynamic stability of the bridge. The analysis and results from wind tunnel test conducted in Chang’an Wind Tunnel Laboratory indicated the original scheme must be changed considerably to improve the aerodynamic stability under action of wind. Considering the shape feature of Siudirgol Bridge and its geographical location, section model with such mitigation measures as auxiliary cables and central buckles were re-tested in wind tunnel joint with analysis. The auxiliary cables and central buckles can increase considerably the fundamental frequency of the bridge and hence the critical wind speed of flutter.

Effects of Sensor Shape on Oscillating Pressure Measurements With Wind-Tunnel Test Confirmation

2006 ◽  
Author(s):  
David W. Wu ◽  
Hwang Choe
Keyword(s):  
Wind Tunnel ◽  
Pressure Sensor ◽  
Pressure Wave ◽  
Dynamic Pressure ◽  
Three Dimensional ◽  
Wind Tunnel Test ◽  
Flow Patterns ◽  
External Flow ◽  
Pressure Measurements ◽  
Significant Correction

This paper summarizes the effects of the pressure sensor shape on the dynamic oscillating pressure measurements when the pressure wave modulating along the steam/air flow path is to be characterized. In the study presented in the paper, a three-dimensional CFD model of the external flow around the protruding, dome-shaped sensor was developed to evaluate the effects of the sensor shape on the external flow pattern, and the detailed flow patterns were studied with this protruding, dome-shaped sensors and compared with the flow patterns for the flush mounted sensors. Then, a one-dimensional analysis was done to predict that the dynamic pressures measured with the protruding sensor do not require significant correction, and this was later supported by wind tunnel tests. The amplitude of the dynamic pressure measured on the protruding sensor was determined to be ranging from 0 to 8% higher than measured by a flush mounted pressure sensor. The frequency of the pressure wave is not affected by the presence of the protrusion.

scholarly journals Comparison of Two-Dimensional and Three- Dimensional Responses for Vortex-Induced Vibrations of a Rectangular Prism

2020 ◽  
Vol 10 (22) ◽  
pp. 7996
Author(s):  
Shuai Zhou ◽  
Yunfeng Zou ◽  
Xugang Hua ◽  
Zhipeng Liu
Keyword(s):  
Wind Tunnel ◽  
Scale Effects ◽  
Damping Ratio ◽  
Three Dimensional ◽  
Maximum Amplitude ◽  
Rectangular Prism ◽  
Two Dimensional ◽  
Modal Shape ◽  
Vortex Induced Vibrations ◽  
Section Model

The accurate prediction of the amplitudes of vortex-induced vibrations (VIV) is important in wind-resistant design. Wind tunnel tests of scaled section models have been commonly used. However, the amplitude prediction processes were usually inaccurate because of insufficient evaluations of three-dimensional (3D) effects. This study presents experimental measurements of VIV responses in a prototype rectangular prism and its 1:1 two-dimensional section model in smooth flow. The results show that the section model vibrates with the same Reynolds number, equivalent mass, frequency, and damping ratio as those of the prototype prism without scale effects. The VIV amplitudes can be qualitatively and quantitatively measured and analyzed. The measured VIV lock-ins of these two models agree with each other. However, the prototype prism produces a 20% higher maximum amplitude than the section model. Several classical VIV mathematical models are used to validate the wind tunnel test results. This confirms that the 3D coupling effects of the modal shape and the imperfect correlations of excitation forces positively contribute to the maximum amplitude. Based on the section model outcomes, the amplified factor of 1.2 is found to be appropriate for the amplitude prediction of VIV for the present prism, and it can also provide a reference for other structures.

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