Observations of periodic thermally-developed winds beside a bridge region in mountain terrain based on field measurement

et al. 2023

Sustainability

Self Cite

Conformal mapping has achieved many successes in engineering. It can help to solve some complex fluid flow problems. This study proposed a numerical method for conformal mapping of closed box girder bridges and applied it to flutter performance prediction, which is crucial for ensuring the safety and sustainability of bridge structures. The characteristics of conformal mapping coefficients for the closed box were investigated. Thereafter, a numerical method through searching the conformal mapping coefficients was presented. The results show that the proposed numerical method has a smaller error in the existing research. The conformal mapping of six practical bridges agrees well with the closed box girder shapes, indicating the validity of the proposed method. The flutter prediction results by the proposed method are consistent with the wind tunnel test. The conformal mapping and flutter calculations took no more than ten seconds, showing high computing efficiency. This method is easier to understand and implement without complex mathematical derivation, which is helpful for the extensive application of conformal mapping in bridge engineering.

Section: Fundation Solutionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Numerical Method for Conformal Mapping of Closed Box Girder Bridges and Its Application

Zhou

et al. 2023

Sustainability

Self Cite

“…in which z = x + iy, u = ux + iuy; 𝑧̅ and 𝑢 are complex conjugate of z and u, res Then, the imaginary part of Equation ( 8) is equal to Equation (7) without the term, i.e.,…”

Section: Complex Potential In the Fluid Domainmentioning

confidence: 99%

“…The analysis of unsteady aerodynamic forces and vibrations has been a subject of significant interest in the field of engineering [3][4][5], particularly in the design and analysis of streamlined box girder (SBG) bridges. The increasing demand for long-span bridges makes the bridge structure increasingly sensitive to the wind load [6,7], which can result in remarkable structural vibrations [8][9][10] and even the collapse of the bridge [11]. The potential flow theory can provide a useful framework for understanding the basic principles of fluid flow and the resulting forces on structures.…”

Section: Introductionmentioning

confidence: 99%

An Analytical Solution for Unsteady Aerodynamic Forces on Streamlined Box Girders with Coupled Vibration

Jiang

et al. 2023

Sustainability

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This paper is a contribution to analyzing the aerodynamic forces on a streamlined box girder (SBG) with coupled vibration in a potential flow. The key enabling step was to assume that the normal velocity of the airflow at an arbitrary point on the surface of the SBG was equal to the normal velocity of the surface motion. The aerodynamic drag force, lift force, and pitching moment were expressed as functions of the motion state of the SBG and the SBG’s shape-related parameters. To investigate the applicability of this force model, the analytical solution at various angles of attack was compared with a numerical simulation in a viscous flow. The results imply that the amplitude of the analytical lift force and pitching moment agree well with the numerical results under the angles of attack of 0° and ±3°. Furthermore, the analytical drag force effectively predicts the second-order phenomenon resulting from the multiplication of the vertical and torsional vibration velocities. As a consequence, the present analytical solution provides an effective method for analyzing the aerodynamic forces acting on SBGs with coupled vibration.

“…In recent years, measured studies of wind characteristics in complex mountainous areas, such as a large number of field measurements of complex mountain areas in southwest China 7 – 10 , Norway 11 , 12 , etc., have confirmed that intense winds often invade the infrastructures in mountainous areas. In order to ensure the safe driving of vehicles on mountain bridges, attention should be paid to the characteristics of the local wind environment on the bridge deck.…”

Section: Introductionmentioning

confidence: 99%

Field measurement of local wind environment on the approach deck of a suspension bridge in mountain terrain

Jiang

et al. 2022

Sci Rep

Self Cite

The local wind environment above the bridge deck affects the aerodynamic characteristics of vehicles, thus affecting the driving safety of the bridge deck. Influenced by the mountain topography and the bridge deck's ancillary facilities, the local wind environment above the bridge deck is complex and changeable, and its impact on the bridge deck traffic can not be ignored. In order to accurately evaluate the local wind field parameters, a monitoring system of the local wind environment is developed. Utilizing the monitoring system, wind parameters above the approach deck of a long-span suspension bridge in a mountain area are measured. The relationship of wind characteristics between the incoming flow and the wind above the bridge deck is investigated. Results show the significant difference between the local wind environment above the bridge deck and the incoming flow's characteristics; the wind profile above the bridge deck does not follow the exponential distribution; the equivalent height of the wind load on the vehicle is higher than the vehicle's gravity centre. This study is relevant for studying the local wind environment, driving safety, and serviceability of long-span bridges in mountainous areas.