Abstract
A damping device for damping vibrations of a bridge with a bridge deck comprises at least one damping wing comprising a center and configured to dampen vibrations of the bridge. A longitudinal direction of the at least one damping wing is disposed parallel to a longitudinal direction of the bridge deck and the at least one damping wing is stationary upon wind acting on the bridge in a given direction. At least one support structure is laterally attached to at least one side of the bridge deck and configured to attach the at least one damping wing to the bridge deck such that the at least one damping wing is disposed with a lateral offset from an outer edge of the bridge deck facing the at least one damping wing.
Claims
1-21. (canceled)
22. A damping device for damping vibrations of a bridge having a bridge deck, the damping device comprising: at least one damping wing comprising a center and configured to dampen vibrations of the bridge, wherein a longitudinal direction of the at least one damping wing is disposed parallel to a longitudinal direction of the bridge deck, and wherein the at least one damping wing is stationary upon wind acting on the bridge in a given direction; and at least one support structure laterally attached to at least one side of the bridge deck and configured to attach the at least one damping wing to the bridge deck such that the at least one damping wing is disposed with a lateral offset from an outer edge of the bridge deck facing the at least one damping wing, wherein a distance between the center of the at least one damping wing and a center of the bridge deck is at least 1.2 times larger than half a width of the bridge deck.
23. The damping device according to claim 22, wherein the width of the at least one damping wing in a direction transverse to the longitudinal direction of the at least one damping wing is at least 0.02 times the width of the bridge deck.
24. The damping device according to claim 22, wherein the at least one damping wing is coupled to the at least one support structure such that the at least one damping wing is laterally offset from the outer edge of the bridge deck facing the at least one damping wing and positioned above or below the bridge deck.
25. The damping device according to claim 22, wherein the at least one damping wing comprises a profile in a direction transverse to its longitudinal direction that is symmetrical relative to a horizontal plane.
26. The damping device according to claim 22, further comprising a plurality of damping wings coupled to the at least one support structure and laterally offset from the outer edge of the bridge deck facing the plurality of damping wings, wherein the plurality of damping wings are disposed above one another.
27. The damping device according to claim 26, wherein the plurality of damping wings are laterally offset from one another.
28. The damping device according to claim 27, wherein a sum of widths of the plurality of damping wings is at least 0.02 times the width of the bridge deck.
29. The damping device according to claim 27, wherein the plurality of damping wings are disposed along both sides of the bridge deck and are identical with regard to their form and arrangement relative to the bridge deck.
30. The damping device according to claim 27, wherein the plurality of damping wings are disposed along both sides of the bridge deck and differ from one another with regard to at least one of their form or their arrangement relative to the bridge deck.
31. The damping device according to claim 29, wherein the plurality of damping wings are movably coupled to the at least one support structure and configured to change aerodynamic properties of the plurality of damping wings such that at least one leeward damping wing dampens vibrations of the bridge and at least one windward damping wing is aerodynamically ineffective.
32. The damping device according to claim 29, wherein the plurality of damping wings further comprise one or more movable elements configured to change aerodynamic properties of the plurality of damping wings such that at least one leeward damping wing dampens vibrations of the bridge and at least one windward damping wing is aerodynamically ineffective.
33. The damping device according to claim 31, wherein movement of the plurality of damping wings is effected solely by wind direction.
34. The damping device according to claim 31, further comprising one or more mechanical links configured to drive movement of the plurality of damping wings.
35. The damping device according to claim 22, wherein the at least one damping wing is rotatably coupled to the at least one support structure and configured to rotate about an axis, the axis disposed transverse to the longitudinal direction of the bridge deck.
36. The damping device according to claim 35, wherein the at least one damping wing further comprises an outer edge having an S-shape, wherein the at least one damping wing is configured to rotate about the axis by approximately 90.
37. The damping device according to claim 32, wherein the one or more movable elements are flaps configured to pivot between a closed position and an open position, wherein the closed position is configured to dampen vibrations of the bridge, and wherein the open position is configured to be essentially aerodynamically ineffective.
38. The damping device according to claim 32, wherein the one or more movable elements are slats configured to slide between a closed position and an open position, wherein the closed position is configured to dampen vibrations of the bridge, and wherein the open position is configured to be essentially aerodynamically ineffective.
39. The damping device according to claim 22, wherein the one or more damping wings are rotatably coupled to the at least one support structure and configured to rotate about an axis, the axis disposed parallel to the longitudinal direction of the bridge deck.
40. The damping device according to claim 32, wherein movement of the one or more movable elements is effected through movement of the plurality of damping wings by a change in wind direction.
41. The damping device according to claim 22, further comprising a plurality of damping wings disposed behind one another along the longitudinal direction of the bridge deck.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] Further exemplary embodiments of the invention will be explained below with reference to schematic drawings.
[0038] FIG. 1 shows a first embodiment of a bridge fitted with an inventive device in a cross sectional view,
[0039] FIG. 2 shows the embodiment of FIG. 1 in a top view,
[0040] FIG. 3 shows a top view similar to FIG. 2 according to a further embodiment,
[0041] FIG. 4 shows a top view similar to FIG. 2 according to a further embodiment,
[0042] FIG. 5 shows a cross sectional view through the embodiment of FIG. 4,
[0043] FIG. 6 shows a further embodiment of a bridge fitted with an inventive device in a partial cross sectional view,
[0044] FIG. 7 shows a damping wing of an inventive device in a perspective view according to a further embodiment,
[0045] FIG. 8 shows part of an inventive device in a cross sectional view according to a further embodiment,
[0046] FIG. 9 shows an enlarged detail of the device of FIG. 8,
[0047] FIG. 10 shows a damping wing of an inventive device according to a further embodiment in a first state in a cross sectional view,
[0048] FIG. 11 shows the damping wing of FIG. 10 in a second state in a cross sectional view,
[0049] FIG. 12 shows a bridge fitted with an inventive device with damping wings as shown in FIGS. 13 and 14,
[0050] FIG. 13 shows a damping wing of an inventive device according to a further embodiment in a first state in a cross sectional view, as shown in FIG. 12, and
[0051] FIG. 14 shows the damping wing in a second state in a cross sectional view, as shown in FIG. 12.
DETAILED DESCRIPTION OF THE INVENTION
[0052] Unless specified otherwise, the same reference numerals in the drawings denote the same parts. In FIG. 1, reference numeral 10 denotes a bridge deck of a suspension bridge with a large span length. The longitudinal direction of the bridge deck 10 is perpendicular to the plane of projection in FIG. 1. In FIG. 2, which shows a top view of the bridge shown in FIG. 1, two bridge pylons can be seen at reference numerals 12, 14. In FIG. 2 the longitudinal direction of the bridge deck 10 runs from left to right.
[0053] In the embodiment shown in FIGS. 1 and 2, one damping wing 16 is provided on each side of the bridge deck 10. As can be seen in particular in FIG. 2, the damping wings 16 are arranged with their longitudinal axes parallel to the longitudinal direction of the bridge deck 10. The damping wings 16 have the form of airfoils in this example and are identical in this embodiment. Each damping wing 16 is held on the bridge deck 10 through a support structure 22. The support structures 22 are each laterally attached to the bridge deck such that each damping wing 16 is arranged with a lateral offset from the outer edge of the bridge deck 10 facing the respective damping wing 16. In the embodiment shown in FIGS. 1 and 2, the distance a.sub.c between the center of each of the damping wings 16 and the center of the bridge deck 10 is approximately 2 times larger than half the width of the bridge deck 10. Also, in this example the width of the damping wings 16 in a direction transverse to their respective longitudinal direction, which is denoted in FIG. 1 by 2*b.sub.c is at least 0.1 times the width of the bridge deck 10, which is denoted by 2*b in FIG. 1. Furthermore, through the support structures 22 each of the damping wings 16 is positioned above the bridge deck 10 (i.e. also has a vertical offset from the bridge deck 10). The profile of the damping wings 16, which can be seen in FIG. 1, is symmetrical relative to a horizontal plane in this example. The damping wings 16 are stationary (i.e. do not move upon wind acting on the bridge in a given direction) as shown in FIGS. 1 and 2 by arrows 24.
[0054] FIG. 3 shows an alternative embodiment which is similar to the embodiment shown in FIGS. 1 and 2. The only difference in this embodiment is that on each side of the bridge deck 10 two shorter damping wings 16 are provided behind one another, seen in the longitudinal direction of the bridge deck 10. While in FIG. 2 the damping wings 16 are arranged at the center of the main span of the suspension bridge over a length Lc, wherein L is the overall span length between the two pylons 12, 14, in FIG. 3 damping wings 16 are arranged in regions around the quarter points of the main span of the bridge deck 10, each with a length of Lc/2. In both cases Lc is smaller than L. The embodiment of FIG. 2 is particularly suitable in case flutter of the bridge is governed by the first symmetric modes of vibrations. The embodiment of FIG. 3 is particularly suited in case flutter of the bridge is governed by the first antisymmetric modes of vibration.
[0055] In the embodiment shown in FIGS. 1 to 3, damping wings 16 are provided on both sides of the bridge deck 10, thus being able to deal with changing transverse wind directions. If the wind essentially only comes from one transverse direction, it may be preferable to provide a damping wing 16 only on one side of the bridge deck 10, as shown in FIGS. 4 and 5. In this case the damping wing 16 is provided on the leeward side and may otherwise be arranged and formed identical to the damping wings 16 shown in FIGS. 1 to 3.
[0056] FIG. 6 shows a further embodiment wherein instead of one damping wing, a plurality of damping wings 16 are arranged on the support structure 22 above one another and possibly with a slight lateral offset from one another. The sum of the widths of the three damping wings 16 shown in FIG. 6 may be the same as the width of one of the damping wings 16 shown in FIGS. 1 to 5. The plurality of damping wings 16 in FIG. 6 may then have the same efficiency with regard to vibrational damping while being less susceptible to vertical velocity components of turbulent wind by taking advantage of the wind shielding effect provided by the uppermost or lowermost damping wings 16.
[0057] FIG. 7 shows a further embodiment of a damping wing 16 in a perspective view. As can be seen, the damping wing 16 in FIG. 7 is supported rotatably about an axis 26, as also visualised by arrow 28. The outer edge 30 of damping wing 16 has an S-shape. In this embodiment the S-shaped outer edge for damping wings provided on both sides of the bridge deck always faces away from the bridge deck, irrespective of the wind direction (i.e. irrespective of whether the damping wing is leeward or windward). Upon wind acting along the arrow 24 shown in FIG. 7 the damping wing 16 in FIG. 7 rotates about rotational axis 26 as shown by arrow 28 by 90. Corresponding stops can limit the rotation to the value of 90. The wind acting onto the front edge 32 of the damping wing 16 as shown by arrow 24 in FIG. 7 leads to the damping wing 16 assuming a horizontal position, as shown in FIG. 7 which renders the damping wing 16 aerodynamically effective such that it dampens vibrations. If, on the other hand, the wind direction would be opposite than shown in FIG. 7 the damping wing 16 would rotate in the counter direction than shown by arrow 28 in FIG. 7 and to a vertical position which renders the damping wing aerodynamically ineffective so that it does not negatively affect the damping efficiency of the inventive device.
[0058] A further embodiment is shown in FIGS. 8 and 9. The damping wing 18 in this embodiment is provided with a number of flaps 34 each pivotable about an axis 36. In the position shown in FIG. 8 the flaps 34 form part of the closed surface of the damping wing 18 such that the damping wing 18 is aerodynamically effective for damping vibrations. This position is taken upon a wind direction as shown by arrow 24 in FIG. 8. The damping wing 18 is then the leeward damping wing. If the wind direction is opposite, as shown in FIG. 9 by arrow 38, the flaps 34 pivot about axis 36 as shown in FIG. 9 by arrow 40 by approximately 180 such that the openings in the surface of the damping wing 18 previously closed are now open which thus renders the damping wing 18 aerodynamically ineffective. This position is assumed when the damping wing is the windward wing.
[0059] A further embodiment is shown in FIGS. 10 and 11. In this damping wing 18 slats 42 are provided which are slideable between the position shown in FIG. 10 where the slats 42 form part of the closed surface of the damping wing 18 and the position shown in FIG. 11 where the slats 42 uncover openings in the surface of the damping wing 18. The position shown in FIG. 10 is assumed upon a wind direction as shown at reference numeral 24 when the damping wing 18 is the leeward wing and thus aerodynamically effective for damping vibrations. The position shown in FIG. 11 is assumed upon an opposite wind direction 38 when the damping wing 18 is the windward wing and thus aerodynamically ineffective.
[0060] FIGS. 12 to 14 show a further embodiment of damping wings 18, 18, wherein these damping wings 18, 18 are each rotatably supported around rotational axis 44 on support structures 22. Again, a number of slideable slats 46 are provided which in a first position, shown in FIG. 13 for damping wing 18, form part of the closed surface of the damping wings 18, 18 and in a second position, shown in FIG. 14 for damping wing 18, uncover openings in the surface of the damping wings 18, 18. In the embodiment shown in FIGS. 12 to 14, the damping wings 18, 18 can rotate about rotational axis 44 which is parallel to the longitudinal direction of the bridge deck 10. They are ballasted, supported, and aerodynamically shaped so that a wind force in the direction of arrow 24 leads to the damping wings 18, 18 assuming the same orientation towards the wind, as shown in particular in FIG. 12. Arrows 48 visualise the rotational movement of the damping wings 18, 18. In the embodiment shown in FIGS. 12 to 14, there is a link, for example a mechanical link or gear, which makes the slats 46 move between the positions shown in FIGS. 13 and 14 upon a rotation of the damping wings 18, 18.
[0061] While the damping wings 18, 18 assume the same position relative to the wind as shown in FIG. 12, their slats 46 assume different positions as seen from a comparison of FIGS. 13 and 14. More specifically, in the situation shown in FIG. 12 the slats 46 of the windward damping wing 18 are uncovering the openings in the surface of the damping wing 18 while the slats 46 in the leeward damping wing 18 are closing these openings thus forming part of the closed surface of the damping wing 18. As a result, damping wing 18 is aerodynamically effective to dampen vibrations of the bridge while damping wing 18 is aerodynamically ineffective.
[0062] All of the above explained embodiments can be combined with one another.
