Railing for improving wind resistance stability and driving safety of long-span bridges

Abstract

The present invention belongs to the technical field of bridge engineering, and provides a railing for improving wind resistance stability and driving safety of long-span bridges. Under conventional wind speed and normal traffic conditions on a bridge deck, the inflated airbags tension the double-layer cable nets to ensure the stiffness of the double-layer cable nets in the bridge-transverse direction; the high-strength flexible double-layer cable nets and the inflated airbags endow the railing with both anti-collision tensile strength and buffering and energy absorption effects. Before the arrival of strong wind threatening the bridge, the airbags are rapidly deflated to loosen the double-layer cable nets, the self-resetting retractors rapidly stow the double-layer cable nets and the airbags into the uprights, and part or all of the railings are rapidly disassembled, thereby temporarily and greatly improving the wind resistance stability of the bridge.

Description

TECHNICAL FIELD

[0001] The present invention belongs to the technical field of bridge engineering, and relates to a railing for improving wind resistance stability and driving safety of long-span bridges.BACKGROUND

[0002] Wind load is a control load in the design of long-span bridges, and strong wind may cause aerostatic instability and / or flutter instability failure of bridges. The wind resistance stability of the bridges mainly depends on the wind load on the main girder; and a bridge deck railing blunts the aerodynamic shape of the main girder and degrades the aerostatic stability and the flutter stability of the bridges.

[0003] In the past, there was no fortification concept or technical solution of rapidly removing the bridge deck railings of long-span bridges before the arrival of strong wind, to temporarily reduce the wind load on the main girder and improve the wind resistance performance of the bridges. The main reason may be that almost all long-span bridges adopt stiff railings with large self-weight (such as reinforced concrete bases, steel uprights, and crossbars), which are inconvenient to assemble and disassemble, time-consuming, labor-consuming, and costly. The stiff railing mainly has the following disadvantages: (1) the self-weight of the main girder is greatly increased. The mass per linear meter of each steel railing may exceed 0.15 ton, and that of a steel-concrete composite railing may exceed 0.3 ton. A long-span bridge is provided with at least three railings along the bridge-transverse direction, and even possibly up to six railings, and thus, the total mass per linear meter of bridge railings may reach 1-2 tons. This puts forward higher requirements for the bearing capacity of members such as the main girder, main cables, stay cables, hangers, arch ribs, pylons, and foundations, and increases material usage, construction difficulty, and project cost. (2) The stiff railing has poor buffering and energy absorption effects, and energy is mainly dissipated by the plastic deformation of impacting vehicles, thereby causing great damage to the vehicles and occupants. (3) The stiff railing is mainly subjected to bending, and the working efficiency thereof is inferior to that of cable members under basically uniform tension over the entire cross-section. Moreover, the tensile strength of concrete material is only several megapascals, and that of steel material or aluminum material is only several hundred megapascals, which are significantly lower than that of high-strength fiber materials that can reach several thousand megapascals; and the material density, buffering performance and durability are also inferior to those of the high-strength fiber materials. (4) Due to large self-weight of the stiff railing, component connection is generally by welding, bolting, riveting or integral pouring, thereby resulting in long assembly and disassembly periods and making it difficult or even impossible to achieve rapid removal and restoration.

[0004] For extreme strong wind that can reach the design wind speed for aerostatic instability and / or flutter instability, based on meteorological data, the prior art can predict the occurrence probability and approximate time of the extreme strong wind several days in advance, thereby providing sufficient time for taking prevention and control measures. If the bridge deck railing can be partially or completely removed rapidly (e.g., within 12 hours), economically (at the level of 100,000 yuan), safely and reliably before the arrival of the extreme strong wind, and restored to the bridge normal service condition with open traffic in a short time (e.g., within 12 hours) after the strong wind, it can not only significantly increase the critical wind speed of aerostatic instability and the flutter critical wind speed of the bridge to ensure the wind resistance safety of the long-span bridge, but also greatly reduce the wind resistance design standards and project cost. For a suspension bridge with a main span of 2000 m level, project investment at the level of 100 million yuan may be saved. If the bridge deck railing can be assembled and disassembled in a short time, be sufficiently lightweight, and have reliable anti-collision performance and low cost, the above wind resistance fortification concepts for the long-span bridge can be realized.

[0005] Therefore, the present invention provides a lightweight, flexible and high-strength bridge deck railing capable of rapid assembly and disassembly, which can economically and safely improve the wind resistance stability of the long-span bridge temporarily, thereby significantly reducing the wind resistance fortification standards and design difficulty of the bridge, simultaneously reducing the bridge dead load, and comprehensively saving the project cost. In addition, the present invention can also have anti-collision stiffness, strength, and buffering and energy absorption effects, so as to reduce the adverse effects of vehicle collision on vehicles, drivers and passengers.SUMMARY

[0006] The technical problem to be solved by the present invention is to provide a lightweight, flexible and high-strength bridge deck railing capable of rapid assembly and disassembly, with respect to the problems of degraded wind resistance stability of bridges, large self-weight that causes inconvenience for rapid assembly and disassembly, and poor anti-collision buffering and energy absorption effects in the current stiff railings of long-span bridges. Under the bridge normal service condition, the bridge deck railing can have the effects of anti-collision stiffness, strength, and buffering energy absorption, and can also improve the driving wind environment on a bridge deck as required. The lightweight bridge deck railing reduces the bridge dead load and facilitates rapid assembly and disassembly. According to the weather forecast, before the arrival of threatening strong wind, traffic is closed and the bridge deck railing is rapidly removed; and after the strong wind, the bridge deck railing is rapidly installed to restore the traffic. Based on the above concepts and measures, the wind resistance stability of the bridge can be temporarily greatly improved, and the existing wind resistance fortification standards and design difficulty of the bridge can be reduced, aiming to greatly save project investment.

[0007] The technical solution of the present invention is as follows:

[0008] A railing for improving wind resistance stability and driving safety of long-span bridges comprises uprights 1, self-resetting retractors 2, a first cable net 3, a second cable net 4, end bodies 5, and airbags 6.

[0009] The uprights 1 are arranged on a bridge deck of a long-span bridge, and the connection mode between the uprights 1 and the bridge deck of the long-span bridge is not limited, which shall ensure reliable fixation and facilitate rapid assembly and disassembly; the self-resetting retractors 2 are arranged in the uprights 1; one end of the first cable net 3 and the second cable net 4 which are made of high-strength fiber materials is connected to the self-resetting retractor 2 in one upright 1, and the other end is connected to the end body 5 connected to another adjacent upright 1, to form an integrated double-layer cable net between two uprights 1; a plurality of airbags 6 are placed between the first cable net 3 and the second cable net 4, connected to the first cable net 3 and / or the second cable net 4, and inflated.

[0010] Under normal wind speed and the bridge normal service condition, the inflated airbags 6 tension the first cable net 3 and the second cable net 4 to ensure the stiffness of the first cable net 3 and the second cable net 4 in the bridge-transverse direction; the first cable net 3 and the second cable net 4 have sufficient anti-collision tensile strength, and the inflated airbags 6 have anti-collision buffering and energy absorption effects; and the first cable net 3 and the second cable net 4 are arranged with different configurations and ventilation rates as required to improve the driving wind environment on the bridge deck.

[0011] Before the arrival of strong wind threatening the bridge, gas in the airbags 6 is released to loosen the first cable net 3 and the second cable net 4, the end bodies 5 are removed from the uprights 1, the self-resetting retractors 2 wind and stow the first cable net 3, the second cable net 4, and the deflated airbags 6 into the uprights 1, and the end bodies 5 are constrained outside the uprights 1 to facilitate rapid unfolding and installation after the strong wind. The following treatment solution is adopted for the uprights 1 according to actual conditions: (1) the uprights are maintained in an original status and vertically fixed on the bridge deck; (2) the uprights are released from the vertically fixed state, laid horizontally along the bridge-transverse direction, then fixed on the bridge deck; and (3) the uprights are detached from the bridge deck and then transported away from the bridge deck.

[0012] Each upright 1 comprises a column body 101, a slotted opening 102, a plurality of ring buckles 103, and a protective sleeve 104; the materials of the column bodies 101 are not limited, and high-strength aluminum material is recommended, which has the advantages of light weight, impact resistance and no need for anti-rust treatment compared with steel material; the slotted openings 102 are arranged on the sides of the column bodies 101 whose normals are parallel to the longitudinal direction of the bridge (hereinafter referred to as the “bridge-longitudinal side”), and the opening dimension of the slotted openings 102 ensures passage of the first cable net 3, the second cable net 4, and deflated airbags 6; a plurality of ring buckles 103 are arranged on the other bridge-longitudinal sides of the column bodies 101 for connecting the end bodies 5; and semi-stiff or flexible protective sleeves 104 are arranged on the periphery of the column bodies 101.

[0013] Each self-resetting retractor 2 comprises a round rod 201, two rotating bases 202, a bracket 203, and a torsion spring 204; the upper and lower ends of the round rods 201 are connected to the rotating bases 202; the rotating bases 202 on the upper ends are fixed on a top plate of the column bodies 101, and the rotating bases 202 on the lower ends are fixed on a bottom plate of the column bodies 101 through the brackets 203; the rotating bases 202, with bearings fitted therein, enable the round rods 201 to rotate around their own central axes, and constrain all other degrees of freedom of the round rods 201; the upper ends of the torsion springs 204 are connected to the lower ends of the round rods 201, and the lower ends of the torsion springs 204 are fixed on the bottom plate of the column bodies 101; the round rods 201 are connected to one end of the first cable net 3 and the second cable net 4; and during retraction of the railing, the torsion springs 204 provide self-resetting restoring torques to wind the first cable net 3, the second cable net 4, and the deflated airbags 6 around the round rods 201.

[0014] The end bodies 5 shall have sufficient strength and stiffness to ensure connection reliability.

[0015] Each airbag 6 comprises a bag body 601 and an air valve 602; the bag bodies 601 are made of lightweight and flexible materials, and shall have sufficient stiffness, strength and weatherability when being inflated and expanded, with no limitation on shape, size, and quantity; the bag bodies 601 are fixed between the first cable net 3 and the second cable net 4, and are stowed into the uprights 1 together after being deflated, or removed from the first cable net 3 and the second cable net 4 after being deflated and separately stowed and fixed outside the uprights 1.

[0016] When no slotted opening 102 is arranged on the uprights 1 and no self-resetting retractor 2 is arranged in the uprights 1, a plurality of ring buckles 103 are arranged on both bridge-longitudinal sides of the column bodies 101, one end of the first cable net 3 and the second cable net 4 is connected to one end body 5 connected to one upright 1, the other end is connected to another end body 5 connected to another adjacent upright 1, and the two end bodies 5 are each connected to the ring buckles 103 of the corresponding uprights 1; before the arrival of the strong wind threatening the bridge, the gas in the airbags 6 is released to loosen the first cable net 3 and the second cable net 4, the two end bodies 5 are removed from the uprights 1 respectively, and the two end bodies 5, the first cable net 3, the second cable net 4, and the deflated airbags 6 are wound by a winding device and transported away from the bridge deck.

[0017] The present invention has the following beneficial effects: (1) compared with a stiff bridge deck railing, the present invention greatly reduces the self-weight, reduces the dead load of the bridge deck, directly saves material usage of the main girder, cables, arch ribs, pylons and foundations, and reduces project cost; (2) compared with the stiff bridge deck railing, the airbags and the cable nets of the present invention can effectively buffer and absorb energy, reduce adverse effects on vehicles, drivers and passengers, and make the overall anti-collision performance safer and more reliable; (3) through the airbags, the present invention achieves rapid and reliable out-of-plane and in-plane tensioning on the cable nets; the convex cable nets have higher impact resistance stiffness and better protection effect than planar cable nets; rapid deflation of the airbags relaxes the double-layer cable nets to facilitate rapid restoration; and the airbags and the cable nets are convenient to replace; (4) the cable nets with different configurations and ventilation rates can improve the driving wind environment; (5) the railing structure and assembly / disassembly mode of the present invention can ensure completion of disassembly and installation in a short time, making it possible to perform temporary, rapid, complete or partial disassembly before the arrival of predictable extreme strong wind, and rapid restoration of traffic after the strong wind. After the railing is retracted and removed, the aerodynamic shape of the main girder can be significantly improved, and the aerostatic stability and the flutter stability of the bridge can be greatly enhanced, thereby reducing the wind resistance fortification standards and wind resistance design difficulty, and finally achieving the goal of saving project cost; and (6) the present invention can be applied not only to long-span bridges, but also to ordinary bridges and protection and isolation facilities for highways and railways at all levels, and thus has broad application scenarios.DESCRIPTION OF DRAWINGS

[0018] FIG. 1 is a sectional front view of a railing under the bridge normal service condition with open traffic.

[0019] FIG. 2 is a top view of a railing under the bridge normal service condition.

[0020] FIG. 3 is a main view and a sectional top view of an upright under the bridge normal service condition, wherein (a) is the main view of the upright, and (b) is the sectional top view of the upright.

[0021] FIG. 4 is a main view and a sectional top view of an upright under retracted storage condition of the railing, wherein (a) is the main view of the upright, and (b) is the sectional top view of the upright.

[0022] FIG. 5 is a main view of the railings and a main girder under different conditions, wherein (a) is the bridge normal service condition, (b) is a retracted storage condition: the uprights are vertically fixed on the bridge deck, (c) is a retracted storage condition: the uprights are laid horizontally along the bridge-transverse direction and fixed on the bridge deck, and (d) is a retracted storage condition: the uprights are detached from the bridge deck and transported away.

[0023] FIG. 6 is a sectional front view of a railing under the bridge normal service condition when a slotted opening and a self-resetting retractor are not provided.

[0024] FIG. 7 is a top view of a railing under the bridge normal service condition when a slotted opening and a self-resetting retractor are not provided.In the figures: 1 upright; 101 column body; 102 slotted opening; 103 ring buckle; 104 protective sleeve; 2 self-resetting retractor; 201 round rod; 202 rotating base; 203 bracket; 204 torsion spring; 3 first cable net; 4 second cable net; 5 end body; 6 airbag; 601 bag body; and 602 air valve.DETAILED DESCRIPTION

[0026] Specific embodiments of the present invention are described below in detail in combination with the technical solution and the drawings.

[0027] As shown in FIG. 1, a railing for improving wind resistance stability and driving safety of long-span bridges comprises uprights 1, self-resetting retractors 2, a first cable net 3, a second cable net 4, end bodies 5, and airbags 6. The uprights 1 are arranged on a bridge deck of a long-span bridge, and the connection mode between the uprights 1 and the bridge deck of the long-span bridge is not limited, which shall ensure reliable fixation and facilitate rapid assembly and disassembly; the self-resetting retractors 2 are arranged in the uprights 1; one end of the first cable net 3 and the second cable net 4 which are made of high-strength fiber materials is connected to the self-resetting retractor 2 in one upright 1, and the other end is connected to the end body 5 connected to another adjacent upright 1, to form an integrated double-layer cable net between two uprights 1; and a plurality of airbags 6 are placed between the first cable net 3 and the second cable net 4, connected to the first cable net 3 and / or the second cable net 4, and inflated.

[0028] As shown in FIG. 1, FIG. 2 and FIG. 3, each upright 1 comprises a column body 101, a slotted opening 102, a plurality of ring buckles 103, and a protective sleeve 104; the materials of the column bodies 101 are not limited, and high-strength aluminum material is recommended, which has the advantages of light weight, impact resistance and no need for anti-rust treatment compared with steel material; the slotted openings 102 are arranged on bridge-longitudinal sides of the column bodies 101, and the opening dimension of the slotted openings 102 ensures passage of the first cable net 3, the second cable net 4, and deflated airbags 6; a plurality of ring buckles 103 are arranged on the other bridge-longitudinal sides of the column bodies 101 for connecting the end bodies 5; and semi-stiff or flexible protective sleeves 104 are arranged on the periphery of the column bodies 101 to protect the column bodies 101 and perform the function of buffering impacting vehicles, with no limitation on material, form, size, etc.

[0029] As shown in FIG. 1, each self-resetting retractor 2 comprises a round rod 201, two rotating bases 202, a bracket 203, and a torsion spring 204; the upper and lower ends of the round rods 201 are connected to the rotating bases 202; the rotating bases 202 on the upper ends are fixed on a top plate of the column bodies 101, and the rotating bases 202 on the lower ends are fixed on a bottom plate of the column bodies 101 through the brackets 203; the rotating bases 202, with bearings fitted therein, enable the round rods 201 to rotate around their own central axes, and constrain all other degrees of freedom of the round robs 201; the upper ends of the torsion springs 204 are connected to the lower ends of the round rods 201, and the lower ends of the torsion springs 204 are fixed on the bottom plate of the column bodies 101; the round rods 201 are connected to one end of the first cable net 3 and the second cable net 4; and during retraction of the railing, the torsion springs 204 provide self-resetting restoring torques to wind the first cable net 3, the second cable net 4, and the deflated airbags 6 around the round rods 201.

[0030] As shown in FIG. 1 and FIG. 2, each airbag 6 comprises a bag body 601 and an air valve 602; the bag bodies 601 are made of lightweight and flexible materials, and shall have sufficient stiffness, strength and weatherability when being inflated and expanded, with no limitation on shape, size, and quantity; the bag bodies 601 are fixed between the first cable net 3 and the second cable net 4, and are stowed into the uprights 1 together after being deflated, or removed from the first cable net 3 and the second cable net 4 after being deflated and separately stowed and fixed outside the uprights 1; and the shape, the size and the quantity of the air valves 602 are not limited.

[0031] As shown in FIG. 1 and FIG. 2, under normal wind speeds and the bridge normal service condition with open traffic, the inflated airbags 6 tension the first cable net 3 and the second cable net 4 to ensure the stiffness of the two cable nets in the bridge-transverse direction; the first cable net 3 and the second cable net 4 have sufficient anti-collision tensile strength, and the inflated airbags 6 have anti-collision buffering and energy absorption effects; and the first cable net 3 and the second cable net 4 are arranged with different configurations and ventilation rates as required to improve the driving wind environment on the bridge deck.

[0032] As shown in FIG. 4 and FIG. 5, before the arrival of strong wind threatening the bridge, gas in the airbags 6 is released to loosen the first cable net 3 and the second cable net 4, the end bodies 5 are removed from the uprights 1, the self-resetting retractors 2 wind and stow the first cable net 3, the second cable net 4, and the deflated airbags 6 into the uprights 1, and the end bodies 5 are constrained outside the uprights 1 to facilitate rapid unfolding and installation after the strong wind. The following treatment solution is adopted for the uprights 1 according to actual conditions: (1) the uprights are maintained in an original status and vertically fixed on the bridge deck; (2) the uprights are released from the vertically fixed state, laid horizontally along the bridge-transverse direction, then fixed on the bridge deck; and (3) the uprights are detached from the bridge deck and then transported away from the bridge deck. The mode (1) requires no assembly or disassembly treatment, which thus has the advantages of labor saving, time saving, and effort saving, and the disadvantage is that the uprights 1 block wind; for the latter two treatment modes, after the strong wind, the uprights 1 are erected from the bridge deck or transported from the outside of the bridge to an original position for installation on the bridge deck; the mode (3) has the advantage of being most favorable for wind resistance of the bridge, but is time-consuming, effort-consuming, and labor-consuming; the advantages and the disadvantages of the mode (2) are between those of the mode (1) and the mode (3); Before the arrival of extreme strong wind, based on the above storage and removal operation for the railing, the aerodynamic interference of the railing on the main girder can be greatly reduced or even completely eliminated, thereby greatly improving the aerostatic stability and the flutter stability of the bridge.

[0033] As shown in FIG. 6 and FIG. 7, when no slotted opening 102 is arranged on the uprights 1 and no self-resetting retractor 2 is arranged in the uprights 1, a plurality of ring buckles 103 are arranged on both bridge-longitudinal sides of the column bodies 101, one end of the first cable net 3 and the second cable net 4 is connected to one end body 5 connected to one upright 1, the other end is connected to another end body 5 connected to another adjacent upright 1, and the two end bodies 5 are each connected to the ring buckles 103 of the corresponding uprights 1; before the arrival of the strong wind threatening the bridge, the gas in the airbags 6 is released to loosen the first cable net 3 and the second cable net 4, the two end bodies 5 are removed from the uprights 1 respectively, and the two end bodies 5, the first cable net 3, the second cable net 4, and the deflated airbags 6 are wound by a winding device and transported away from the bridge deck; and for a long-span bridge where threatening strong wind rarely occurs at the bridge site, this solution can not only temporarily greatly improve the wind resistance stability of the bridge, but also reduce the structural design requirements of the uprights 1, with high operability and lower cost.

[0034] The above only describes preferred embodiments of the present invention and is not intended to limit the present invention in any form. Any equivalent change, modification or evolution made to the above embodiments by those skilled in the art through the technical solution of the present invention shall still belong to the scope of the technical solution of the present invention.

Claims

1. A railing for improving wind resistance stability and driving safety of long-span bridges, comprising uprights, self-resetting retractors, a first cable net, a second cable net, end bodies, and airbags, whereineach upright is of a cavity structure, and comprises a column body, a slotted opening, a plurality of ring buckles, and a protective sleeve; the slotted openings are arranged on the sides of the column bodies whose normals are parallel to the longitudinal direction of the bridge (hereinafter referred to as the “bridge-longitudinal side”), and the opening dimension of the slotted openings ensures passage of the first cable net, the second cable net, and deflated airbags; a plurality of ring buckles are arranged on the other bridge-longitudinal sides of the column bodies for connecting the end bodies; semi-stiff or flexible protective sleeves are arranged on the periphery of the column bodies;each self-resetting retractor comprises a round rod, two rotating bases, a bracket, and a torsion spring; the upper and lower ends of the round rods are connected to the rotating bases; the rotating bases on the upper ends are fixed on a top plate of the column bodies, and the rotating bases on the lower ends are fixed on a bottom plate of the column bodies through the brackets; the rotating bases, with bearings fitted therein, enable the round rods to rotate around own central axes, and constrain all other degrees of freedom of the round rods ; the upper ends of the torsion springs are connected to the lower ends of the round rods, and the lower ends of the torsion springs are fixed on the bottom plate of the column bodies; the round rods are connected to one end of the first cable net and the second cable net; during retraction of the railing, the torsion springs provide self-resetting restoring torques to wind the first cable net, the second cable net, and the deflated airbags around the round rods;the uprights are arranged on a bridge deck of a long-span bridge, and the self-resetting retractors are arranged in the uprights; one end of the first cable net and the second cable net is connected to the self-resetting retractor in one upright, and the other end is connected to the end body connected to another adjacent upright, to form an integrated double-layer cable net between two uprights; a plurality of airbags are placed between the first cable net and the second cable net, connected to the first cable net and / or the second cable net, and inflated;under the bridge normal service condition with open traffic, the inflated airbags tension the first cable net and the second cable net to ensure the stiffness of the first cable net and the second cable net in the bridge-transverse direction;before the arrival of strong wind threatening the bridge, gas in the airbags is released to loosen the first cable net and the second cable net, the end bodies are removed from the adjacent uprights, the self-resetting retractors wind and stow the first cable net, the second cable net, and the deflated airbags into the uprights, and the end bodies are constrained outside the uprights.

2. The railing for improving wind resistance stability and driving safety of long-span bridges according to claim 1, wherein before the arrival of the strong wind threatening the bridge, the following treatment solution is adopted for the uprights according to actual conditions: the uprights are maintained in an original status and vertically fixed on the bridge deck; or the uprights are released from the vertically fixed state, laid horizontally along the bridge-transverse direction, then fixed on the bridge deck; or the uprights are detached from the bridge deck and then transported away from the bridge deck.

3. The railing for improving wind resistance stability and driving safety of long-span bridges according to claim 1, wherein each airbag comprises a bag body and an air valve; the bag bodies are fixed between the first cable net and the second cable net, and are stowed into the uprights together after being deflated, or removed from the first cable net and the second cable net after being deflated and separately stowed and fixed outside the uprights.

4. The railing for improving wind resistance stability and driving safety of long-span bridges according to claim 1, wherein when no slotted opening is arranged on the uprights and no self-resetting retractor is arranged in the uprights, a plurality of ring buckles are arranged on both bridge-longitudinal sides of the column bodies, one end of the first cable net and the second cable net is connected to one end body connected to one upright, the other end is connected to another end body connected to another adjacent upright, and the two end bodies are each connected to the ring buckles of the corresponding uprights; before the arrival of the strong wind threatening the bridge, the gas in the airbags is released to loosen the first cable net and the second cable net, the two end bodies are removed from the uprights respectively, and the two end bodies, the first cable net, the second cable net, and the deflated airbags are wound by a winding device and transported away from the bridge deck.

5. The railing for improving wind resistance stability and driving safety of long-span bridges according to claim 1, wherein the first cable net and the second cable net are arranged with different configurations and ventilation rates as required.

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