JP2006057436A - Girder type bridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a girder type bridge of an extremely simple composition, which reduces a vibration due to a vortex excitation, a deflection vibration and a torsion vibration and prevents occurrences of vehicle travelling hindrance without increasing in a weight and manufacturing cost nor installing any special members. <P>SOLUTION: The girder type bridge is composed by fixing a plurality of main girders to the undersurface of a floor plate. The main girder has a regulating plate projected on the outer side of a middle portion of its web in a vertical direction, so that a negative pressure is formed by an air stream flowing in the vicinity of the lower part of the main girder in a space enclosed by an undersurface of the regulating plate and the outer side of the web, and thus the air stream can be rectified by the negative pressure. Furthermore, between the adjacent webs of the main girders, a communication pipe is provided so as to let the air of the upstream side of the main girder flow into the under-stream side of the main girder through the communication pipe. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a girder-type bridge in which a plurality of main girders are fixed to the lower surface of a floor board, and vortex excitation at low wind speeds can be avoided by rectifying the air flow flowing around the lower part of the main girder. Related to the girder type bridge.

  FIG. 9 shows an example of a girder bridge 100 in which a plurality of main girders are fixed to the lower surface of a floor board. In the figure, 1 is a floor plate on which a roadway through which a vehicle passes is provided, 2 is a plurality of (in this example, two) main girders fixed to the lower surface of the floor plate 1, and 7 is erected on both ends of the floor plate 1. This is a handrail. The main girder 2 includes a horizontal upper flange 3 fixed to the lower surface of the floor plate 1, a web 5 fixed to the lower surface of the upper flange 3 and extending in the vertical direction, and a lower flange 6 fixed to the lower end of the web 5. It is comprised by.

In the girder type bridge as shown in FIG. 9, reduction of bending vibration or torsional vibration due to multidirectional winds such as horizontal wind, blowing wind, and blowing wind acting on the bridge has been an issue. Various vibration reducing means for flexural vibration or torsional vibration have been proposed, and one of them is a technique disclosed in Japanese Patent Application Laid-Open No. 4-108605.
In the technique of Patent Document 1, an end beam (edge plate) is provided at the end of a floor plate overhanging portion that is formed on both ends of a horizontal floor plate (steel floor plate) connected to the upper part of the main girder of the girder bridge, A horizontal plate (tip plate) is formed on the outer side of the lower end of the end girder to improve the torsional flutter limit wind speed and reduce the vortex excitation amplitude for multi-directional winds such as horizontal winds, blow-up winds, and blow-down winds. This improves the wind resistance stability of the bridge.

Japanese Utility Model Publication No. 4-108605

In the girder-type bridge 100, two modes of vibration as shown in FIG. 10 are generated by the wind (air flow) blowing through the main girder 2.
FIG. 10A shows the relationship between the amplitude of the flexural vibration and the wind speed, and FIG. 10B shows the relationship between the amplitude of the torsional vibration and the wind speed. As shown in FIGS. 10A and 10B, the bending vibration and torsional vibration include vortex excitation A generated at a low wind speed and divergent vibration B generated at a high wind speed.
Among these, as shown in FIG. 9, the vortex excitation A is generated by the vortex W generated in the lower part of the downstream web 5 by the wind (air flow) V blown substantially horizontally below the main girder 2 and applied. Resonance between the vortex excitation A and the natural frequency of the main girder 2 causes an operation failure in a vehicle traveling on the roadway above the floor board 1.
Further, when a vortex is formed on the downstream side of the main girder 2, a fluctuation in the lift is generated by the vortex, and the vibration of the lift causes a bending vibration and a torsional vibration.

However, in the above-mentioned Patent Document 1, end girders (edge plates) are provided at the ends of the floor plate overhanging portions formed on both ends of a horizontal steel floor plate connected to the upper part of the main girder of the girder type bridge. Since a horizontal material (tip plate) is formed on the outer side of the lower end of the frame, the vibration reduction effect on the divergent vibration B can be achieved, but the wind (air flow) V blows through the lower part of the main girder 2 in a substantially horizontal direction. There is little vibration reduction effect with respect to the vortex excitation W.
Further, as described above, the technique of Patent Document 1 has a problem that the vibration reduction effect with respect to the vortex excitation W is small, so that bending vibration and torsional vibration are likely to occur in the bridge due to the fluctuation of lift due to the vortex flow. Also have.
Furthermore, in the technique of Patent Document 1, it is necessary to attach special members that do not have the function of strength members, such as end girders (edge plates and horizontal members (tip plates)), to both ends of the steel floor plate. For this reason, there is also a problem of accompanying an increase in weight and an increase in product cost.

  In view of the problems of the prior art, the present invention is not accompanied by an increase in weight and product cost, and without installing a special member, and with a very simple configuration, vibration caused by vortex excitation, bending vibration, An object of the present invention is to provide a girder-type bridge that reduces torsional vibrations and prevents the occurrence of vehicle operation troubles.

The present invention achieves such an object. In a girder-type bridge in which a plurality of main girders are fixed to the lower surface of a floor board, the main girder is provided with a control plate projecting on the outer side surface of the intermediate portion in the height direction of the web. In the space surrounded by the lower surface of the control plate and the outer surface of the web, a negative pressure is formed by the air flow flowing around the lower part of the main girder, and the air flow can be rectified by the negative pressure. It is characterized by.
Here, it is preferable that the control plate protrudes in the horizontal direction from the web. However, the position of the front end of the control plate is the same as that provided in the horizontal direction, and the outer surface of the web extends from the front end. You may incline to a certain extent.

According to this invention, when the wind (air flow) blowing through the lower part of the main girder in a substantially horizontal direction blows through the lower part of the main girder located on the upstream side of the air flow, the air flow velocity (wind speed) The pressure (static pressure) of the space formed between the lower surface of the control plate projecting on the outer surface of the intermediate portion in the height direction of the web and the outer surface of the web decreases, and the space portion and its vicinity A fixed vortex is formed on the surface and negative pressure is generated.
By such negative pressure, the air flow flowing under the main girder is drawn toward the main girder, and the air flow flowing under the main girder on the downstream side is rectified to become a smooth horizontal flow. Thereby, generation | occurrence | production of the vortex | eddy_current in the lower downstream part of the downstream main girder is avoided, and the eddy excitation accompanying the formation of this vortex | eddy_current can be reduced.
According to the invention, as described above, the control plate can prevent the formation of vortex on the outer surface of the web. Therefore, the fluctuation of the lift of the bridge caused by the vortex and the bending vibration and torsion of the bridge due to the fluctuation of the lift. Vibration can be suppressed.
Therefore, according to such an invention, vibrations caused by vortex excitation and flexural vibrations can be achieved by a very simple and low-cost means of attaching a control plate having a function of a strength member to the main girder. Torsional vibration can be reduced, and vehicle operation failure due to the vortex excitation can be prevented.

In this invention, if the following two means are used, the effect of reducing the vortex excitation can be obtained more remarkably.
That is, the first means is that the control plate is formed such that an angle (α) formed by a line connecting the tip of the control plate and the lower end of the web and a horizontal line is 45 ° ± 5 °.
The second means sets the ratio (L / B) between the length (L) of the control plate protruding from the outer surface of the web and the width (B) of the bridge floor plate, L / B = 3% to 8 % To form.
As a result of calculating the relationship between the ratio (L / B) of the protrusion length (L) of the control plate and the width (B) of the floor plate and the amplitude of vortex excitation of the main girder by the inventors' simulation calculation, In the range of L / B = 3% to 8%, the amplitude of the vortex excitation becomes an allowable amplitude _A0 or less, and a good vortex excitation reduction effect can be obtained.
In the invention, in the girder type bridge having three or more main girders, if the control plate protrudes only on the outer main girders of the three or more main girders, the vortex similar to the above is provided. Since the excitation reduction effect is obtained, the required vortex excitation reduction effect can be obtained with a minimum of equipment.

Further, the present invention provides a girder-type bridge in which a plurality of main girders are fixed to the lower surface of a floor board, and a communication pipe through which air can pass is installed between adjacent webs of the main girders. It is configured that the air on the upstream side of the gas flows through the inside of the communication pipe to the downstream side of the main girder.
According to this invention, when air on the upstream side of the main girder flows through the inside of the communication pipe to the downstream side of the main girder, a vortex formed in the vicinity of the communication pipe air outlet outside the web is Entrained in the air flow at the tube outlet, this makes it difficult to form air vortices on the outside of the web.
According to the invention, since the communication pipe is installed between the main girder webs, the rigidity of the main girder increases, the torsional natural frequency shifts to the high wind speed side, and resonance with the air flow occurs. Occurrence can be avoided.
Therefore, according to this invention, the generation of vortices can be suppressed by a very simple and low-cost means of installing the communication pipe having the function of the strength member between the webs of the main girders. Can be prevented from occurring.

Further, the present invention provides a girder-type bridge in which a plurality of main girders are fixed to the lower surface of a floor board, and a communication pipe that allows air to pass therethrough is installed between adjacent webs of the main girders. And a control plate is provided on the outer surface of the intermediate portion in the height direction of the web of the main girder. In the space surrounded by the lower surface of the web and the outer side surface of the web, a negative pressure is formed by the air flow flowing around the lower part of the main girder, and the air flow can be rectified by the negative pressure.
In this invention, preferably, the communication pipe is provided at an upper portion of the control plate in the web, and an angle (α) formed by a line connecting a front end of the control plate and a lower end of the web and a horizontal line is 45 °. Form at ± 5 °.

According to this invention, the synergistic effect which combined installation of the said communicating pipe and installation of a control board can be acquired.
That is, according to this invention,
(1) When air on the upstream side of the main girder flows through the communication pipe to the downstream side of the main girder, a vortex formed in the vicinity of the communication pipe air outlet on the outside of the web causes air flow at the communication pipe outlet. It becomes difficult for air vortices to be formed on the outside of the web. Further, since the communication pipe is installed between the main girder webs, the rigidity of the main girder is increased, and the natural frequency of torsion is shifted to the high wind speed side, thereby avoiding the occurrence of resonance with the air flow.
(2) The negative pressure generated in the vicinity of the lower surface of the control plate attracts the airflow flowing below the main girder to the main girder, and the airflow flowing below the main girder on the downstream side is rectified to provide a smooth horizontal flow It becomes. Thereby, generation | occurrence | production of the vortex | eddy_current in the lower downstream part of the downstream main girder is avoided, and the eddy excitation accompanying the formation of this vortex | eddy_current can be reduced.

  Further, when the invention is used for a girder type bridge having a steel rail that is formed by standing steel rails on both upper surfaces of the floor plate, by combining the steel rail and the control plate, It has been confirmed by experiments by the inventors that the effect of reducing vortex excitation is greater than in the case of the above.

According to the present invention, when the air flow blows under the main girder located upstream, the control plate is provided on the outer surface of the intermediate portion in the height direction of the web by the flow velocity (wind velocity) of the air flow. A fixed vortex is formed in the space formed between the lower surface of the web and the outer surface of the web and in the vicinity thereof, and negative pressure is generated. By this negative pressure, the air flow flowing under the main girder is attracted to the main girder side. Thus, the air flow flowing under the main girder on the downstream side is rectified and becomes a smooth horizontal flow.
As a result, generation of vortex in the lower part of the downstream main girder is avoided, and vortex excitation, bending vibration and torsional vibration associated with the formation of the vortex can be reduced, and the main girder has a function of a strength member. The vortex excitation can be reduced by means of a very simple and low-cost means of mounting the control plate and not accompanied by an increase in weight, and the occurrence of a vehicle operation failure due to the vortex excitation can be prevented.

  Further, according to the present invention, when the air on the upstream side of the main girder flows through the communication pipe to the downstream side of the main girder, the vortex formed in the vicinity of the communication pipe air outlet outside the web is It is difficult to form an air vortex outside the web because it is caught in the air flow at the outlet, and the communication pipe is installed between the main girder webs to increase the rigidity of the main girder and It is possible to avoid the occurrence of resonance with the air flow because the natural frequency shifts to the high wind speed side. This makes it possible to suppress the generation of vortices by a very simple and low-cost means of installing a communication pipe having the function of a strength member between the webs of the main girder. Occurrence can be prevented.

  Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this example are not intended to limit the scope of the present invention only to specific examples unless otherwise specified. Only.

FIG. 1 is a front view of an essential part of a girder bridge according to a first embodiment of the present invention. 2A and 2B are operation comparison diagrams of the first embodiment, wherein FIG. 2A shows the prior art and FIG. 2B shows the present invention. FIG. 3 is a relationship diagram between the control plate mounting angle and the vibration amplitude in the first embodiment. 4A and 4B are a relationship diagram and an explanatory diagram of the control plate length and the vibration amplitude in the first embodiment. FIG. 5 is a front view of an essential part of a girder bridge according to a second embodiment of the present invention.
FIG. 6 is a view corresponding to FIG. 1 showing a third embodiment of the present invention. FIG. 7 is a view corresponding to FIG. 1 showing a fourth embodiment of the present invention, and FIG. 8 is a perspective view of an essential part in the fourth embodiment.

In FIG. 1 showing the first embodiment, 1 is a floor plate on which the roadway through which the vehicle passes is provided, 2 is a plurality (two in this example) main girders fixed to the lower surface of the floor plate 1, and 7 is the It is a handrail erected on both ends of the floor board 1. The main girder 2 includes a horizontal upper flange 3 fixed to the lower surface of the floor plate 1, a web 5 fixed to the lower surface of the upper flange 3 and extending in the vertical direction, and a lower flange 6 fixed to the lower end of the web 5. Furthermore, the web 5 is constituted by a control plate 4 protruding from the outer side surface of the intermediate portion in the height direction.
The floor board is preferably a steel floor board, but a PC (concrete) floor board, a synthetic floor board, or the like can also be used.
As shown in FIG. 1, the control plate 4 has an angle (mounting angle) α formed by a line connecting the front end of the control plate 4 and the lower end 5a of the web 5 and a horizontal line of 45 ° on the basis described later. The web 5 is projected so as to be ± 5 °.
Here, as shown in FIG. 1, the control plate 4 preferably protrudes horizontally from the outer surface of the web 5, but the position of the tip of the control plate 4 is provided in the horizontal direction. You may provide it inclining to some extent from this front-end | tip to the outer surface of the said web 5, after setting it as the same position.
Further, as shown in FIG. 4B, the ratio L / B between the protruding length L of the control plate 4 from the outer surface of the web 5 and the width B of the bridge floor plate 1 is L on the basis described later. / B = 3% to 8% (in FIG. 4B, the same members as those in FIG. 1 are denoted by the same reference numerals).

In the first embodiment, in the prior art shown in FIG. 2 (A), a wind (air flow) V blown substantially horizontally below the main girder 2 is generated in the lower part of the downstream web 5. The eddy current W generates vortex excitation, and the resonance between the vortex excitation and the natural frequency of the main girder 2 causes an operation failure to the vehicle traveling on the roadway above the floor plate 1.
On the other hand, in the embodiment (first embodiment) of the present invention shown in FIG. 2 (B), the wind (air flow) V blown substantially horizontally below the main girder 2 is the air flow V. The lower surface of the control plate 4 projecting from the outer surface of the intermediate portion in the height direction of the web 5 by the flow velocity (wind velocity) of the air flow V when blowing through the lower part of the main girder 2 located on the upstream side of the web 5 The pressure (static pressure) of the space portion 2a formed between the web 5 and the outer surface is reduced, and a fixed vortex U is formed in the space portion 2a and the vicinity thereof to generate a negative pressure.

In the first embodiment, the air flow V flowing below the main girder 2 is drawn to the main girder 2 side by the negative pressure generated in the space 2a and the vicinity thereof, and the main girder 2 on the downstream side is drawn. The air flow V flowing below is rectified into a smooth horizontal flow. As a result, the generation of the vortex W in the downstream lower portion of the downstream main girder 2 as in the prior art is avoided, and the vortex excitation accompanying the formation of the vortex W can be reduced.
Therefore, according to the first embodiment, the control plate 4 has the role of a lower flange having the function of the strength member of the main girder 2, so that the control plate 4 having the function of the strength member in the main girder 2 is provided. It is possible to reduce the vortex excitation by using a very simple and low-cost means without attaching a weight to the vehicle, and it is possible to prevent the occurrence of a vehicle operation failure due to the vortex excitation.
Note that the control plate also has the strength member function of the main girder (having the role of the lower flange), so there is no increase in product cost.
In addition, in the case of carrying out the delivery construction, it is reasonable that the control plate plays a role of buckling reinforcement of the main girder web.

  Furthermore, if the said Example is applied to the girder type bridge | bridging provided with the steel rail 7 by standing up the steel rail 7 on the both-sides upper surface of the said floor board 1, this steel rail 7 and the said control board 4 will be provided. It has been confirmed by experiments by the inventors that the effect of reducing vortex excitation is greater than that of the other handrails when combined.

Here, FIG. 3 is a diagram showing the relationship between the mounting angle α (see FIG. 1) of the control plate 4 and the amplitude of vortex excitation of the main beam 2 obtained by the inventors' experiment. As is apparent from the figure, when the mounting angle α of the control plate 4 is around 45 °, the effect of the control plate 4 is large and the amplitude of vortex excitation is minimized. Accordingly, the mounting angle α of the control plate 4 is preferably 45 ° ± 5 ° in the vicinity of 45 °.
4A shows the ratio L / B between the protrusion length L of the control plate 4 and the width of the floor plate 1 and the amplitude of the vortex excitation of the main girder 2 obtained by the inventors' simulation calculation. It is a diagram which shows the relationship of these. As is apparent in FIG., The amplitude of the vortex-induced vibration is allowable amplitude A ₀ or less at the L / B = 3% ~8% range. Therefore, a ratio L / B = 3% to 8% of the protruding length L and the width B of the floor board 1 is suitable.

Further, as described above, when a vortex is formed on the downstream side of the main girder 2, a fluctuation in lift occurs in the bridge 100 due to the vortex, and a bending vibration and a torsional vibration occur in the bridge 100 due to the fluctuation in the lift.
However, according to the first embodiment, since the control plate 4 can prevent the formation of vortex on the outer surface of the web 5, it is possible to prevent the fluctuation of the lift of the bridge 100 due to the vortex and thereby the fluctuation of the lift. It is possible to suppress bending vibration and torsional vibration of the bridge 100 due to the above.

  In the second embodiment of the present invention shown in FIG. 5, in the girder-type bridge having four (3 or more) main girder 2, only the main girder on both outer sides of the main girder 2 is used. The control plate 4 is provided in a protruding manner, and the control plate 4 is not provided on the inner main beam 2. That is, in the girder type bridge having three or more main girders 2, if the control plate 4 protrudes only on the main girders 2 on both outer sides, the required effect of reducing vortex excitation can be obtained.

In FIG. 6 showing the third embodiment, 1 is a floor plate on which the roadway through which the vehicle passes is provided, 2 is a plurality (two in this example) main girders fixed to the lower surface of the floor plate 1, and 7 is the It is a handrail erected on both ends of the floor board 1. The main girder 2 includes a horizontal upper flange 3 fixed to the lower surface of the floor plate 1, a web 5 fixed to the lower surface of the upper flange 3 and extending in the vertical direction, and a lower flange 6 fixed to the lower end of the web 5. In addition, it is constituted by a communication pipe 10 installed in the intermediate portion in the height direction of the adjacent webs 5.
The communication pipe 10 is formed such that the air flow S flowing in from the upstream web 5 passes through the communication pipe 10 and flows out to the downstream web 5, and as shown in FIG. Are installed along the longitudinal direction of the vehicle (the traveling direction of the vehicle).

According to the third embodiment, when the air on the upstream side of the main beam 2 flows through the communication tube 10 to the downstream side of the main beam 2, the communication tube of the web 5 on the downstream side of the communication tube 10. The vortex formed in the vicinity of the 10 air outlet is entrained in the air flow S flowing through the outlet of the communication pipe 10 by the ejector effect. Thereby, it becomes difficult to form an air vortex in the vicinity of the outlet of the communication pipe 10.
According to the third embodiment, since the communication pipe 10 is installed between the webs 5 and 5 of the main girder 2, the rigidity of the main girder 2, in particular, the torsional rigidity is increased, and the natural frequency of torsion is increased. Shift to high wind speed side. Thereby, the occurrence of resonance between the main beam 2 and the air flow S can be avoided.

The fourth embodiment shown in FIGS. 7 to 8 is a combination of the first embodiment shown in FIG. 1 and the third embodiment shown in FIG.
That is, in FIGS. 7 to 8, 1 is a floor plate on which a roadway through which a vehicle passes is provided, 2 is a plurality of (two in this example) main girders fixed to the lower surface of the floor plate 1, and 7 is the floor plate 1. It is a railing erected on both ends of the. The main girder 2 includes a horizontal upper flange 3 fixed to the lower surface of the floor plate 1, a web 5 fixed to the lower surface of the upper flange 3 and extending in the vertical direction, and a lower flange 6 fixed to the lower end of the web 5. Furthermore, the web 5 is constituted by a control plate 4 protruding from the outer side surface of the intermediate portion in the height direction.
As shown in FIG. 1, the control plate 4 has an angle (mounting angle) α formed by a line connecting the front end of the control plate 4 and the lower end 5a of the web 5 and a horizontal line of 45 ° on the basis described later. The web 5 is projected so as to be ± 5 °.
The main points, structure, etc. of the control plate 4 are the same as those of the first embodiment shown in FIGS.

  Reference numeral 10 denotes a communication pipe 10 installed in the middle in the height direction of the adjacent webs 5. The communication pipe 10 is installed on the upper side of the control plate 4 of the web 5, and the air flow S flowing from the upstream web 5 passes through the communication pipe 10 and flows out to the downstream web 5. As shown in FIG. 8, a plurality of bridges are installed along the longitudinal direction of the bridge (traveling direction of the vehicle).

According to this 4th Example, the synergistic effect which combined installation of the said communicating pipe 10 and installation of the control board 4 can be acquired. That is, according to the fourth embodiment, when the air on the upstream side of the main girder 2 flows through the communication pipe 10 to the downstream side of the main girder 2, the web 5 on the downstream side of the communication pipe 10 is used. The vortex formed in the vicinity of the air outlet of the communication pipe 10 is engulfed in the air flow S flowing through the outlet of the communication pipe 10 by the ejector effect. This makes it difficult to form an air vortex in the vicinity of the outlet of the communication pipe 10. .
Further, since the communication pipe 10 is installed between the webs 5 and 5 of the main girder 2, the rigidity of the main girder 2, in particular, the torsional rigidity increases, and the natural frequency of torsion shifts to the high wind speed side. Thereby, the occurrence of resonance between the main beam 2 and the air flow S can be avoided.

  Further, according to the fourth embodiment, since the control plate 4 is installed, the negative flow generated near the lower surface of the control plate 4 flows under the main girder 2 as in the first embodiment. When the air flow V is attracted to the main beam 2 side, the air flow flowing below the downstream main beam 2 is rectified and becomes a smooth horizontal flow. Thereby, generation | occurrence | production of the vortex | eddy_current in the lower downstream part of the downstream main girder 2 is avoided, and the vortex excitation accompanying formation of this vortex | eddy_current can be reduced.

  According to the present invention, vibration due to vortex excitation, bending vibration, and torsional vibration can be reduced with a very simple configuration without increasing the weight and increasing the product cost and without installing any special member. Thus, it is possible to provide a girder bridge that prevents the occurrence of vehicle operation troubles.

It is a principal part front view of the girder type bridge concerning the 1st example of the present invention. In the operation comparison diagram of the first embodiment, (A) shows the prior art and (B) shows the present invention. It is a relationship diagram of the control board attachment angle and vibration amplitude in the first embodiment. (A), (B) is the relationship diagram and explanatory drawing of the control board length and vibration amplitude in the said 1st Example. It is a principal part front view of the girder-type bridge which concerns on 2nd Example of this invention. FIG. 6 is a view corresponding to FIG. 1 showing a third embodiment of the present invention. FIG. 6 is a view corresponding to FIG. 1 showing a fourth embodiment of the present invention. It is a principal part perspective view in the said 4th Example. It is a figure corresponding to FIG. 1 which shows a prior art. It is a related line figure of the wind speed and vibration amplitude concerning a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Bridge 1 Floor board 2 Main girder 3 Upper flange 4 Control board 5 Web 6 Lower flange 7 Hand rail 10 Communication pipe V, S Air flow U Fixed vortex

Claims (8)

  In a girder-type bridge in which a plurality of main girders are fixed to the lower surface of a floor plate, the main girder has a control plate projecting from the outer side surface of the intermediate portion in the height direction of the web, and the lower surface of the control plate and the web A girder-type bridge, wherein a negative pressure is formed by an air flow flowing around a lower portion of the main girder in a space surrounded by an outer side surface, and the air flow can be rectified by the negative pressure.   2. The girder bridge according to claim 1, wherein the control plate is protruded from only the main girder on both outer sides of the girder bridge having three or more main girder.   2. The girder according to claim 1, wherein the control plate is formed such that an angle (α) formed between a line connecting a front end of the control plate and a lower end of the web and a horizontal line is 45 ° ± 5 °. Type bridge.   The ratio (L / B) between the length (L) of the control plate protruding from the outer surface of the web and the width (B) of the bridge floor plate is L / B = 3% to 8%. The girder-type bridge according to claim 1, wherein   The girder-type bridge according to claim 1, wherein the girder-type bridge is a girder-type bridge having a steel rail that is formed by standing steel rails on both upper surfaces of a floor board.   In a girder-type bridge in which a plurality of main girders are fixed to the lower surface of a floor plate, a communication pipe that allows air to pass through is installed between adjacent main girder webs, and air on the upstream side of the main girder The girder-type bridge is configured to flow to the downstream side of the main girder through the communication pipe.   In a girder-type bridge in which a plurality of main girders are fixed to the lower surface of a floor plate, a communication pipe that allows air to pass through is installed between adjacent main girder webs, and air upstream of the main girder Through the inside of the communication pipe and to the downstream side of the main girder, and a control plate protrudes from the outer side surface of the web of the main girder in the height direction, and the lower surface of the control plate and the web A girder type bridge in which a negative pressure is formed by an air flow flowing around the lower part of the main girder in a space surrounded by an outer surface of the main girder, and the air flow can be rectified by the negative pressure. The communication pipe is provided at an upper portion of the web on the control plate, and an angle (α) formed between a line connecting a tip of the control plate and a lower end of the web and a horizontal line is formed at 45 ° ± 5 °. The girder bridge according to claim 7, wherein:

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