Flutter and galloping of cable-supported bridges with porous wind barriers

https://doi.org/10.1016/j.jweia.2017.10.012Get rights and content

Highlights

  • Porous wind barriers alter aerodynamic loads on cable-supported bridges.

  • Drag force increases as wind-barrier porosity decreases, and as wind-barrier height increases.

  • Wind barriers negligibly influence bridge susceptibility to galloping.

  • Critical wind velocity for flutter decreases as wind barriers become less porous.

  • Effects of increasing wind-barrier height on flutter are simultaneously influenced by aerodynamic shape of bridge decks.

Abstract

Wind-tunnel experiments are carried out to analyze the influence of wind-barrier porosity and height on aerodynamic and aeroelastic characteristics of wide long-span cable-supported bridges. The experiments are carried out on sectional models of the Golden Gate Bridge (USA), Kao-Pin Hsi Bridge (Taiwan), and Great Belt Bridge (Denmark). The bridge-deck section models are equipped with the wind-barrier models at the windward (leading) edge of the studied sections. The experimental results indicate that the effects of wind barriers on galloping sensitivity of studied bridge decks are rather negligible, while bridge decks become quite prone to flutter for wind barriers placed at their windward edge. These trends are more exhibited for more-solid wind barriers. The effects of increasing wind-barrier height are not unambiguous, as they are simultaneously influenced by the aerodynamic shape of bridge decks as well.

Introduction

Strong cross-winds on bridges and viaducts cause dynamic instabilities of vehicles and trains. Due to these adverse wind effects, vehicles may overturn, collide with each other or with structural elements. Hence, during extreme wind events, viaducts and bridges are often closed to traffic.

To protect vehicles from cross winds, roadway wind barriers are commonly designed, e.g. Kozmar et al., 2009, Kozmar et al., 2012a, Chu et al., 2013, Chen et al., 2015, as vehicles are particularly vulnerable to cross-wind effects on viaducts and bridges, e.g. Argentini et al., 2011, Dorigatti et al., 2012, Kozmar et al., 2012b, Kozmar et al., 2015, Zhou and Chen, 2015.

The major properties of wind barriers that determine their sheltering efficiency for vehicles are porosity and height. Flow characteristics on bridges equipped with wind barriers are predominantly influenced by the bleed flow through the wind-barrier cavities, separated shear layer and the reversed flow downwind of the barrier, e.g. Telenta et al. (2014).

Chen et al. (2015) indicate that larger porosity of wind barriers is unfavorable for dynamic stability of vehicles on bridges, as the obtained velocity reduction may not be sufficient in case the wind-barrier cavities are too large. Sheltering efficiency of wind barriers is strongly affected by the wind-barrier height, Chu et al. (2013). An optimal wind-barrier design with respect to wind perpendicular to bridges is considered the one with 30% porosity and 5 m height, e.g. Kozmar et al. (2014).

While the protective effects of wind barriers for vehicles are fairly known, their influence on aerodynamic forces and dynamic stability of bridges is quite unknown. Only some recent studies consider aerodynamic forces for bridges with wind barriers, Guo et al. (2015). The effects of bird-protection barriers on aerodynamic and aeroelastic behavior of high-speed train bridges are reported in Ogueta-Gutierrez et al. (2014).

Apart from wind barriers, other structural elements of bridges and viaducts, e.g. railings, crash barriers, central slotting, prove to influence aerodynamic forces and moments of bridges as well, e.g. Raggett, 2007, Diana et al., 2013, Xu et al., 2014a.

Design of bridge-deck cross sections may influence their aeroelastic behavior as well, Xu et al. (2014b), while bluff cross sections are commonly more susceptible to flutter, e.g. Nikitas et al. (2011). Vehicles can significantly alter the dynamic stability of bridge decks, e.g., Han et al., 2014, Han et al., 2015, Pospíšil et al., 2016.

The 5 m high wind barrier with 30% porosity, suggested by Kozmar et al. (2014) with respect to the protection of vehicles on bridges from cross-winds, proved to deteriorate dynamic stability of bridge decks, Buljac et al. (2017). However, in practice, wind barriers are manufactured with various porosities and heights, depending on specific wind characteristics for a certain geographic location and respective terrain characteristics. At this moment, it is not completely known whether and to what extent the aerodynamic and aeroelastic characteristics of cable-supported bridges alter due to wind-barrier porosity and height.

The present study focuses on effects of the wind-barrier porosity and height on aerodynamic characteristics of three typical wide long-span cable-supported bridge decks and their sensitivity to self-excited vibrations. Wind-barrier models with different porosities and heights are placed at the windward (leading) edge of the bridge-deck section models, as strong cross winds that may destabilize or overturn vehicles on bridges predominantly blow from one direction only, and wind barriers are commonly placed at the windward bridge-deck edge with respect to the dominant wind direction. Aerodynamic drag and lift force, as well as the pitch moment coefficients, are determined in a boundary layer wind tunnel for various flow incidence angles, and the susceptibility of the studied bridge-deck sections to galloping and flutter is analyzed.

Section snippets

Aerodynamic loads and galloping instability

The aerodynamic coefficients are determined for flow incidence angles from −10° to +10° with an increment of 1° using the following equations:CD(α)=2FD(α)ρν2HL,CL(α)=2FL(α)ρν2BL,CM(α)=2M(α)ρν2B2L,where FD and FL are aerodynamic drag and lift forces, respectively, M is aerodynamic pitch moment. CD, CL and CM are aerodynamic drag force, lift force and pitch moment coefficients, respectively. v is average flow velocity in undisturbed freestream flow, α is flow incidence angle, ρ is air

Description of the wind tunnel and bridge-deck section models

Experiments are carried out in the climatic boundary-layer wind tunnel of the Institute of Theoretical and Applied Mechanics in Prague, Czech Republic. The aerodynamic section of this wind tunnel is 1.9 m wide and 1.8 m high rectangular cross-section. The flow is uniform along the wind-tunnel aerodynamic cross section and the turbulence intensity is less than 2%.

The studied bridge-deck sections are: (i) Great Belt Bridge (GBB) with a streamlined cross section, e.g. Bruno and Mancini (2002),

Aerodynamic force and moment coefficients and galloping instability

Coefficients of the aerodynamic drag and lift forces and the pitch moment are reported in Fig. 4, Fig. 5, Fig. 6, Fig. 7 for flow incidence angles between −10° and +10° with an increment of 1°.

The trends in aerodynamic coefficients obtained for the empty Great Belt Bridge without the wind barrier correspond relatively well with previous studies on similar bridge-deck sections, e.g. Reinhold et al. (1992). Some differences in the results are likely due to minor discrepancies in the Reinhold

Conclusions

The influence of wind-barrier porosity and height on aerodynamic and aeroelastic characteristics of wide long-span cable-supported bridges is studied experimentally in a boundary layer wind tunnel. The experiments are carried out on sectional models of the Golden Gate Bridge (USA), Kao-Pin Hsi Bridge (Taiwan), and Great Belt Bridge (Denmark). The wind-barrier models are placed at the windward (leading) edge of the studied bridge-deck section models only.

The obtained results indicate a strong

Acknowledgments

The support of the Croatian Science Foundation, GAČR No. 15-01035S, CET sustainability project LO12 (SaDeCET) is gratefully acknowledged.

References (54)

  • G. Diana et al.

    Aerodynamic instability of a bridge deck section model: linear and nonlinear approach to force modelling

    J. Wind Eng. Ind. Aerodyn.

    (2010)
  • G. Diana et al.

    Construction stages of the long span suspension Izmit Bay Bridge: wind tunnel test assessment

    J. Wind Eng. Ind. Aerodyn.

    (2013)
  • F. Dorigatti et al.

    Wind tunnel measurements of crosswind loads on high sided vehicles over long span bridges

    J. Wind Eng. Ind. Aerodyn.

    (2012)
  • M. Gu et al.

    Identification of flutter derivatives of bridge decks

    J. Wind Eng. Ind. Aerodyn.

    (2000)
  • M. Gu et al.

    Parametric study on flutter derivatives of bridge decks

    Eng. Struct.

    (2001)
  • Y. Han et al.

    Experimental study on aerodynamic derivatives of a bridge cross-section under different traffic flows

    J. Wind Eng. Ind. Aerodyn.

    (2014)
  • H. Kozmar et al.

    Sheltering efficiency of wind barriers on bridges

    J. Wind Eng. Ind. Aerodyn.

    (2012)
  • H. Kozmar et al.

    Transient cross-wind aerodynamic loads on a generic vehicle due to bora gusts

    J. Wind Eng. Ind. Aerodyn.

    (2012)
  • H. Kozmar et al.

    Optimizing height and porosity of roadway wind barriers for viaducts and bridges

    Eng. Struct.

    (2014)
  • R. Král et al.

    Wind tunnel experiments on unstable self-excited vibration of sectional girders

    J. Fluids Struct.

    (2014)
  • C. Mannini et al.

    Aerodynamic uncertainty propagation in bridge flutter analysis

    Struct. Saf.

    (2015)
  • C. Mannini et al.

    VIV – galloping instability of rectangular cylinders: review and new experiments

    J. Wind Eng. Ind. Aerodyn.

    (2014)
  • C. Mannini et al.

    Analysis of self-excited forces for a box-girder bridge deck through unsteady RANS simulations

    J. Fluids Struct.

    (2016)
  • M. Noda et al.

    Effects of oscillation amplitude on aerodynamic derivatives

    J. Wind Eng. Ind. Aerodyn.

    (2003)
  • M. Ogueta-Gutierrez et al.

    Effects of bird protection barriers on the aerodynamic and aeroelastic behavior of high speed train bridges

    Eng. Struct.

    (2014)
  • N.K. Poulsen et al.

    Determination of flutter derivatives for the Great Belt bridge

    J. Wind Eng. Ind. Aerodyn.

    (1992)
  • H. Ruscheweyh et al.

    Vortex-induced vibrations and galloping of slender elements

    J. Wind Eng. Ind. Aerodyn.

    (1996)
  • Cited by (25)

    • A pressure–velocity jump approach for the CFD modelling of permeable surfaces

      2023, Journal of Wind Engineering and Industrial Aerodynamics
    • A renewable energy harvesting wind barrier based on coaxial contrarotation for self-powered applications on railways

      2022, Energy
      Citation Excerpt :

      From the results, the wind barriers significantly improved the safety of vehicles in crosswind environments. Buljac et al. [16] conducted experiments on different bridge-deck section models with wind barriers. The obtained results indicated that the drag force coefficients of the bridge decks increase with decreasing porosity of the wind barrier and with increasing height of the wind barrier.

    • Bridge vibration under complex wind field and corresponding measurements: A review

      2022, Journal of Traffic and Transportation Engineering (English Edition)
      Citation Excerpt :

      Although similar serious accidents are uncommon nowadays, bridges are still sometimes set into oscillations due to an incoming wind field. Notable examples include the Golden Gate Bridge (USA) in 1951 (Buljac et al., 2017), the Storebaelt Suspension Bridge (Denmark) in 1998 (Larsen et al., 2000), the Østerøy Suspension Bridge (Norway) in 1999 (Cao et al., 2020), and the Volgograd Bridge (Russia) in 2010 (Weber and Maslanka, 2012). To prevent accidents and economic disruption in future, the coupling motion between wind and bridge is extensively studied.

    • Simulation strategies for wind shields and porous barriers for bridge deck optimization

      2022, Structures
      Citation Excerpt :

      This aspect of the PJ approach is particularly important for optimization-oriented studies, which currently represent an important application of numerical simulations. Here we focus on two-dimensional Unsteady Reynolds-Averaged Navier–Stokes, 2D-URANS, based models and consider the experimental results reported in [5–7]. It should be noticed that, despite their well-known limitations, 2D-URANS are currently the most widely adopted numerical model typology for the study of bridge decks, especially for preliminary and optimization analyses [22].

    View all citing articles on Scopus
    View full text