Large-span split type steel box girder bridge vortex vibration control device

Abstract

The utility model belongs to the technical field of bridge vibration control, and provides a large-span split type steel box girder bridge vortex vibration control device. The novel control concept and measure are provided, the lifting lugs, the lock catches and the control net are utilized to assemble the efficient and reliable control device which is low in cost, convenient to assemble and disassemble, light, handy and durable, and the control device is installed at the open groove in the daily operation state of a single-width or double-width bridge to restrain vortex vibration response. According to weather forecast, before extremely strong wind comes, the device is quickly dismantled, the original aerodynamic configuration of the bridge is recovered, the flutter stability is ensured, and installation is recovered after the strong wind. The large-span split type steel box girder bridge vortex vibration control device is simple in structure, free of complex mechanical parts, convenient to assemble and disassemble, economical, practical, not limited by the bridge vortex vibration frequency and the vortex vibration order, capable of reducing the lateral wind load of a bridge and excellent in comprehensive performance.

Description

TECHNICAL FIELD

[0001] The utility model belongs to bridge vibration control technical field relates to a kind of large-span split type steel box girder bridge vortex vibration control device. BACKGROUND

[0002] Large-span split type steel box girder bridge is provided with one or two grooves in the middle of main girder, which can greatly improve the flutter critical wind speed of the bridge. The split type steel box girder bridges built at home and abroad at present include China Gaolan Port Bridge (main span 700m), Huangmaohai Bridge (main span 720m), Tsing Ma Bridge (main span 1018m), Xihoumen Bridge (main span 1650m) and Turkey Chana Kalai Bridge (main span 2023m), Italy Messina Strait Bridge (main span 3300m) and so on. However, this central groove structure also significantly changes the airflow separation and vortex shedding characteristics of the bridge main girder section, and due to the light and flexible structure, the damping is low, which leads to more prone to multi-stage large vortex vibration. For example, a split type steel box girder suspension bridge in Zhejiang, the real bridge found six-order vortex vibration of 0.095Hz, 0.133Hz, 0.183Hz, 0.230Hz, 0.276Hz and 0.324Hz, with the maximum amplitude of 24cm (the data is from the public foreign language literature "Vortex-induced vibration analysis of long-span bridges with twin-box decks under non-uniformly distributed turbulent winds"; Journal of Wind Engineering & Industrial Aerodynamics, 2018, Vol. 172, Q. Zhu, Y. L. Xu, L. D. Zhu, etc., pp. 31-41). Wind tunnel test and numerical simulation research show that if the main girder groove is closed, the vortex vibration response of the bridge is greatly reduced, or even completely suppressed. Since the span of the split type steel box girder bridge is generally large, the vibration frequency is low, so low-frequency (such as <0.2Hz) vortex vibration is also prone to occur. In addition, large-span double-width steel bridges are arranged side by side, with a gap in the middle, which is also prone to vortex vibration, such as Foshan Pingsheng Bridge, Qingdao Haiguan Hongdao Channel Bridge, Japan Meigangxi Bridge and USA Fred Hartman Bridge. Therefore, the large vortex vibration of split type steel box girder bridge and double-width steel bridge needs to be controlled by effective measures.

[0003] Currently, vortex-induced vibration control for split-type steel box girder bridges mainly relies on tuned mass dampers (TMDs) in addition to aerodynamic measures. However, TMDs sometimes have some shortcomings: 1) A single device can only effectively control very narrow-band frequency vortex-induced vibrations. Multi-order vortex-induced vibrations require multiple independent devices for control, and the control effect of all orders of vortex-induced vibrations is relatively sensitive to frequency. Since the bridge vibration frequency is related to temperature and traffic loads on the bridge, the robustness is poor; 2) The mass block is relatively heavy, adding extra load to the bridge structure, and the material and installation costs are high; 3) Due to the limitation of vertical space in the main girder, the spring deformation is limited, making it difficult to use for low-frequency vortex-induced vibration control. Therefore, there is an urgent need to develop a device that is cost-effective, easy to install and maintain, and can effectively control multi-order and low-frequency vortex-induced vibrations in split-type steel bridges.

[0004] The primary purpose of slotting in split-type steel box girder bridges is to increase the bridge's flutter critical wind speed and ensure flutter safety. However, extreme wind conditions that reach the bridge's flutter critical wind speed are extremely rare, while vortex-induced vibration in long-span bridges typically occurs under low to medium wind speed conditions. Therefore, based on these characteristics, the following control concept is proposed: Under non-extreme wind speed conditions for the vast majority of the time, a shielding device is installed in the slot to restrict or prevent free airflow between the top and bottom surfaces of the main girder, improving the flow field around the main girder; according to weather forecasts, before the bridge encounters extreme wind speeds that pose a flutter threat to the bridge section with the shielding device installed (which may occur very rarely during the bridge's lifespan), the device installed at the slot can be easily removed. Adopting the above control concept and measures can effectively suppress vortex-induced vibration that may occur under low to medium wind speed conditions, ensure that the bridge will not flutter under extreme wind speed conditions, and eliminate the need for frequent device installation and removal, ensuring its applicability.

[0005] To address the aforementioned problems, this invention proposes a vortex-induced vibration control device for large-span split-type steel box girder bridges. This device is simple in structure, low in cost, and offers excellent ease of installation and disassembly, as well as durability. It can effectively optimize the airflow distribution at the slotted section of the main girder, reduce the vortex shedding effect, and thus suppress vortex-induced vibration in split-type steel box girder bridges and double-span steel box girder bridges. Utility Model Content

[0006] The technical solution of this utility model:

[0007] A vortex-induced vibration control device for a large-span split-type steel box girder bridge includes a lifting lug 1, a locking buckle 2, and a control net 3. The lifting lug 1 is fixed on both sides of the slotted area of ​​the steel box girder or the edges of the two main beams of the double-span box girder bridge. The locking buckle 2 connects the control net 3 to the lifting lug 1, thereby suspending the control net 3 in the slotted area of ​​the split-type steel box girder bridge or between the main beams of the double-span steel box girder bridge.

[0008] The tension and sag of the control net 3 can be adjusted by the movable locking buckle 2.

[0009] The control net 3 can adopt different opening forms and opening rates, and can be provided with multiple layers, so that the flow field around the main beam can be significantly optimized, vortex shedding and vortex intensity can be inhibited, and the vortex vibration response of the bridge can be effectively reduced or even completely inhibited.

[0010] The device is installed on a split steel box girder bridge and a nearby parallel double-width steel box girder bridge, can inhibit bridge vortex vibration, and can be temporarily and quickly removed before an extreme strong wind (predicted by meteorology) that threatens the bridge arrives, so as to restore the initial setting aerodynamic shape of the bridge, improve the critical wind speed of the bridge flutter, and ensure the flutter safety. After the strong wind, the control net 3 is quickly and conveniently installed again. Since the probability of the occurrence of the extreme strong wind that threatens the bridge flutter is very low, the number of repeated installation and removal of the control net 3 in the service life of the bridge can be only a few times, or even unnecessary, and therefore the related cost is very low.

[0011] The lug 1 is guaranteed to have sufficient strength, rigidity and durability, and the specific material type, specification, size and number are not limited, and are determined according to the vortex vibration control requirement and are reasonably arranged along the main beam.

[0012] The lock buckle 2 is guaranteed to have sufficient strength, rigidity and durability, can conveniently, quickly and reliably connect or disconnect the control net 3 with the lug 1, and can conveniently adjust the distance between the control net 3 and the lug 1, so as to adjust the tension and sag of the control net 3, and the specific material type, specification, size and number are not limited.

[0013] The control net 3 is guaranteed to have sufficient strength, rigidity, flexibility and durability, and can be arranged continuously or in sections, and the specific material type, specification, size and opening rate are not limited, and it is suggested to adopt a low-opening-rate, high-strength and flexible fiber woven net and a nylon net. The control net 3 can also be made of a zero-opening-rate flexible cloth and a rigid plate in principle, but since the wind load is large, sufficient thickness needs to be guaranteed to avoid damage or tearing, and once damaged, the damage can seriously affect the driving safety, so that the economy, installation and removal convenience, durability and safety of the control net are far lower than those of the control net, and therefore the control net does not have competitiveness.

[0014] The device has the advantages that: the device has simple structure, no complex mechanical parts, light weight, convenient installation and removal, low material cost, installation and removal cost and maintenance cost, can inhibit the bridge vortex vibration response, can reduce the lateral wind load of the bridge, and can be temporarily and quickly removed according to the requirement, so as to ensure the flutter stability of the bridge. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a large-span split steel box girder bridge vortex vibration control device schematic view (applied to a split steel box girder bridge).

[0016] Figure 2It is a large span split type steel box girder bridge vortex vibration control device schematic diagram (applied to double width steel box girder bridge);

[0017] In the figure: 1 ear, 2 lock, 3 control net. DETAILED DESCRIPTION

[0018] The specific implementation of the utility model will be described in detail in combination with the technical scheme and the drawings, but the implementation of the utility model is not limited to this:

[0019] As Figure 1 and Figure 2 shown, a large span split type steel box girder bridge vortex vibration control device is proposed, which comprises, ear 1, lock 2, control net 3. For split type steel box girder bridge or double width steel box girder bridge, a plurality of ears 1 are fixed on both sides of the main beam slot or the edge of the double width steel box girder bridge main beam, and a plurality of control nets 3 are hung on the ears 1 through the lock 2 in the daily service state of the bridge, the tension and sag of the control net 3 are adjusted through the lock 2, and the control effect of vortex vibration is avoided due to the excessive sag of the control net 3 under the action of wind load. Control net 3 can be used with different opening rates, and multiple layers can also be set. In the longitudinal direction of the bridge, it can be arranged continuously and longitudinally, or it can be arranged in sections (the control effect is not obvious in some areas), and the vortex vibration control effect and the economy of the device are considered comprehensively. According to the weather forecast, before the arrival of the extreme strong wind which threatens the flutter of the bridge on which the device is installed, the control net 3 is temporarily and quickly removed, the original aerodynamic shape of the bridge is restored, and the flutter safety of the bridge is ensured. After the strong wind, the control net 3 is reinstalled quickly and conveniently.

[0020] The above is only a preferred embodiment of the utility model, and does not limit the utility model in any form. Any equivalent changes, modifications or evolution of the above examples by those skilled in the art using the technical scheme of the utility model still belongs to the scope of the technical scheme of the utility model.

Claims

1. A vortex-induced vibration control device for a large-span split-type steel box girder bridge, characterized in that, The vortex vibration control device of the large-span split steel box girder bridge comprises a lug (1), a lock catch (2) and a control net (3); the lug (1) is fixed on the edges of the slot sides of the steel box girder or the two main girders of the double-width box girder bridge, and the lock catch (2) connects the control net (3) to the lug (1), so that the control net (3) is suspended in the slot area of the split steel box girder bridge or between the main girders of the double-width steel box girder bridge.

2. The vortex-shedding control device for long-span split steel box girder bridges according to claim 1, characterized in that, The distance between the control net (3) and the lug (1) is adjusted through the lock catch (2), so as to control the tension and sag of the control net (3).

3. The vortex-shedding control device for long-span split steel box girder bridges according to claim 1, characterized in that, The control net (3) adopts different opening forms and opening rates, is provided with one or more layers, and is arranged continuously or in sections.

4. The vortex-shedding control device for long-span split steel box girder bridges according to claim 1, characterized in that, The control net (3) adopts a fiber woven net, a nylon net, a flexible cloth and a rigid plate.

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