External damper for long suspender

Abstract

The utility model belongs to the technical field of bridge vibration reduction (shock absorption), and discloses an external damper for a long suspender. The long suspender comprises 1-4 cable strands, dividers are arranged among the cable strands at equal intervals, and a plurality of external dampers are installed at the bottom and the top of each cable strand and on the two sides adjacent to the dividers respectively. The damper comprises an outer restraint layer, a damping layer, an inner restraint layer, an upper rubber gasket, a lower rubber gasket, an upper shear deformation annular guide groove, a lower shear deformation annular guide groove and an annular clamping plate. The two ends of the outer restraint layer and the two ends of the inner restraint layer are coaxially arranged in a staggered mode. A semi-annular cavity body formed by the annular clamping plate and the rubber gasket is filled with a damping layer, the annular clamping plate and the rubber gasket form a clamping assembly, a vertical distance is reserved between the clamping assembly and the restraint layer, and a shear deformation annular guide groove is formed. The external damper for the long suspender can simultaneously restrain in-phase and out-phase vibration of multiple suspenders, has an effect on opposite internal and external vibration, can meet the temporary vibration reduction requirement in the construction period, and is convenient to install on site.

Description

Technical Field

[0001] The utility model belongs to the technical field of bridge shock absorption, and in particular relates to a long suspension rod external damper. Background Art

[0002] The cable is the main connection and force transmission member between the stiffening beam and the main cable (main arch) of a suspension bridge (arch bridge). As the main span of a suspension bridge or arch bridge increases, the characteristics of the cable being slender, having low damping, and having multiple vibration modes become increasingly obvious. Under the action of external loads, various forms of vibrations such as vortex-induced vibration, wake galloping, and parametric vibration are prone to occur. Most modern large-span suspension bridge cables are double cables or multiple cables arranged vertically in parallel. Compared with a single cable, the vibration is more complex and diverse. From the perspective of vibration mode, there are both vibration modes of relative motion between cables and vibration modes of synchronous motion between cables. From the perspective of frequency, the cable may experience a combination of vibrations of multiple frequencies depending on the external excitation. The continuous vibration of the cable may not only cause fatigue and corrosion at the anchor end of the cable, seriously affecting the service life of the cable and increasing the maintenance cost, but also cause pedestrians to question the safety of the bridge.

[0003] In the prior art, a pendulum lever damper is generally used, which utilizes the lever amplification principle to amplify the vibration displacement of the hanger and transmit it to the viscous shear damper at the bottom. The damper needs to be equipped with a separate bracket or a rigid guardrail as a bracket. In order not to affect the bridge landscape, the bracket height is limited, and the vibration displacement at one end of the lever (at the hanger) is relatively small, which affects the effect of the viscous shear damper. In addition, due to the effect of temperature, the bracket and the hanger are deformed non-uniformly, which reduces the vibration reduction effect of the damper. To this end, the utility model proposes a long hanger external damper, which is not affected by the hanger temperature. The vertical displacement difference of the damper beam end can be freely adjusted through the height of the damper, and there is no need to worry about the impact on the bridge landscape. Utility Model Content

[0004] In view of this, the utility model aims at the deficiencies of the prior art and provides a long suspension rod external damper, which can simultaneously suppress the in-phase and out-of-phase vibrations of multiple suspension cables, and has an effect on both in-plane and out-of-plane vibrations, and reduces the local vibration of the long suspension rod under the loads of cars, wind, etc., thereby extending the life of the long suspension rod and reducing the collapse accidents of arch bridges or suspension bridges caused by suspension rod breakage. At the same time, after adopting the device, there is no need to set a stainless steel sleeve separately under the suspension rod, which can meet the deformation requirements of temperature effects.

[0005] In order to achieve the above-mentioned object, the utility model provides a long suspension rod external damper, the external damper comprising an outer constraint layer, a damping layer, an inner constraint layer, an upper rubber gasket, a lower rubber gasket, an upper shear deformation annular guide groove, a lower shear deformation annular guide groove and an annular clamping plate;

[0006] The two ends of the outer constraint layer and the inner constraint layer are staggered and coaxially placed; the semi-annular cavity body formed by the outer constraint layer and the inner constraint layer is filled with a damping layer, and the damping layer is respectively bonded to the outer constraint layer and the inner constraint layer, and the three form a semi-annular body; the outer constraint layer and the inner constraint layer are buckled at both ends into a ring through an annular clamp and a rubber gasket so as to be fixed to the long suspension rod; at one end of the semi-annular body, a rubber gasket is placed between the outer constraint layer and the long suspension rod, and the annular clamp cooperates with bolts to act on the outer constraint layer to squeeze the rubber gasket, so that the semi-annular body is fixed to the long suspension rod; at the other end of the semi-annular body, the annular clamp cooperates with bolts to squeeze the inner constraint layer through the rubber gasket, so that the semi-annular body is fixed to the long suspension rod;

[0007] The annular clamping plate and the rubber gasket form a clamping assembly, and a vertical spacing is reserved between the clamping assembly and the constraint layer to form a shear deformation annular guide groove; specifically, the upper shear deformation annular guide groove is located below the upper rubber gasket, and the lower shear deformation annular guide groove is located above the upper rubber gasket, and is formed by reserving a vertical spacing between the rubber gasket and the constraint layer, and the spacing is determined by calculating the shear deformation of the damping layer; the shear deformation annular guide groove is mainly used to increase space for the damping layer to move up and down;

[0008] Preferably, in order to eliminate the occurrence of wind and rain vibration, the surface of the outer constraint layer is loaded with spiral lines or pits are set on the surface;

[0009] The damping layer is a shear thickening liquid containing 35% by mass of silicon dioxide (SiO2) encapsulated by EVA and / or EPE foam material. The dispersion medium in the shear thickening liquid is polyethylene glycol (PEG) with a molecular weight of 300, and the dispersed phase is SiO2 with a diameter of 35nm. The thickness of the damping layer is calculated and determined based on the vibration characteristics of the cable, and the thickness is usually between 2mm and 10mm; preferably, the thickness of the damping layer is 2.0mm, 4.0mm, 6.0mm, 8.0mm or 10.0mm;

[0010] When the long suspension rod contains one strand, one external damper is installed at the bottom of the long suspension rod, or a plurality of external dampers are evenly installed over the entire length of the long suspension rod. Preferably, the plurality of dampers are generally 2-6, and are respectively installed at equal distances between the bottom and the middle of the top of the long suspension rod.

[0011] When the long suspension rod contains multiple cable strands, dividers are equidistantly arranged between the multiple cable strands, and a plurality of external dampers are respectively installed at the bottom, top and both sides of each cable strand adjacent to the divider; preferably, the long suspension rod contains 2-4 cable strands, 1-2 dividers are equidistantly arranged between every two cable strands, and at least 4 external dampers are respectively installed at the bottom, top and both sides of each cable strand adjacent to the divider.

[0012] Compared with the prior art, the advantages of the utility model are:

[0013] (1) Based on the excellent shear thickening effect of the sandwich tube, the long hanger external damper has strong adaptability, small size, fits tightly with the hanger or cable strand, does not require additional brackets, occupies almost no bridge space, can be flexibly arranged at any position of the hanger, and has the excellent feature of simultaneously suppressing the in-phase and out-of-phase vibrations of multiple cables.

[0014] (2) Since the damping effect of the sandwich tube structure with an external damper mainly depends on the middle damping layer, for cables with different vibration characteristics, it is only necessary to change the thickness of the damping layer to meet the resonant frequency and damping.

[0015] (3) The outer constraint layer of the external damper is made of ultra-thin steel plate, which can act as a stainless steel sleeve to protect the bottom sling from direct mechanical impact and improve the fire resistance of the boom.

[0016] (4) Flexible operation, easy replacement, good robustness, extremely low maintenance cost, outstanding vibration reduction effect, easy on-site installation, and very suitable for large-span mid-through arch bridges and suspension bridges with flexible hangers.

[0017] (5) The external damper of the long hanger can reduce the vibration of the anchor end of the long hanger, delay the aging and cracking process of the PE sheath of the cable body and the waterproof cover sealing putty at the junction of the hanger and the bridge deck, thereby reducing the probability of water entering the anchor head, and ultimately achieving the effect of reducing the probability of hanger breakage.

[0018] (6) Several identical temperature adaptive dampers are evenly arranged and installed throughout the entire length of the cable strand, which can significantly shorten the effective length of the boom vibration, significantly increase the critical wind speed of the boom wake galloping, and enhance the negative damping delay effect of the vibration.

[0019] (7) The external damper of the long boom can be installed immediately after the boom is tensioned for the first time, eliminating the temporary vibration reduction process during the boom construction period and achieving the purpose of speeding up the construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is an elevation view and a plan view of the external damper described in the utility model.

[0021] Wherein: 1-outer constraint layer, 2-damping layer, 3-inner constraint layer, 4-upper rubber gasket, 5-lower rubber gasket, 6-upper shear deformation annular guide groove, 7-lower shear deformation annular guide groove, 8-annular clamping plate.

[0022] Figure 2 This is a schematic diagram of the long suspension rod external damper described in Example 2.

[0023] Figure 3 It is a schematic diagram of the long suspension rod external damper described in Example 4. DETAILED DESCRIPTION

[0024] The technical solution of the utility model is described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0025] Example 1

[0026] The present embodiment provides an external damper for a long suspension rod, the external damper comprising an outer constraint layer 1, a damping layer 2, an inner constraint layer 3, an upper rubber gasket 4, a lower rubber gasket 5, an upper shear deformation annular guide groove 6, a lower shear deformation annular guide groove 7 and an annular clamping plate 8; the two ends of the outer constraint layer 1 and the inner constraint layer 3 are staggered and coaxially placed; the surface of the outer constraint layer 1 is loaded with a spiral line or pits are set on the surface; the semi-annular cavity body formed by the outer constraint layer 1 and the inner constraint layer 3 is filled with the damping layer 2, and the damping layer 2 is respectively connected to the outer constraint layer 1 and the inner constraint layer 3. The outer constraint layer 1 and the inner constraint layer 3 are bonded to form a semi-circular body; the outer constraint layer 1 and the inner constraint layer 3 are fastened to the long suspension rod at both ends by an annular clamping plate 8 and a rubber gasket 4 to form a ring; at one end of the semi-circular body, a rubber gasket 4 is placed between the outer constraint layer 1 and the long suspension rod, and the annular clamping plate 8 cooperates with bolts to act on the outer constraint layer 1 to squeeze the rubber gasket 4, so that the semi-circular body is fixed to the long suspension rod; at the other end of the semi-circular body, the annular clamping plate 8 cooperates with bolts to squeeze the inner constraint layer 3 through the rubber gasket 4, so that the semi-circular body is fixed to the long suspension rod;

[0027] The annular clamping plate 8 and the rubber gasket 4 form a clamping assembly, and a vertical spacing is reserved between the clamping assembly and the constraint layer 2 to form a shear deformation annular guide groove; specifically, the upper shear deformation annular guide groove 6 is located below the upper rubber gasket 4, and the lower shear deformation annular guide groove 7 is located above the upper rubber gasket 5, and is formed by reserving a vertical spacing between the rubber gasket and the constraint layer 2, and the spacing is determined by the shear deformation calculation of the damping layer 2; the shear deformation annular guide groove is mainly used to increase the space for the damping layer 2 to move up and down;

[0028] The outer constraint layer 1 and the inner constraint layer 3 are made of galvanized ultra-thin steel plates, with the same thickness, not less than 0.5 mm, and usually between 1.0 mm and 3.0 mm; the same length, usually between 0.5 m and 3.0 m; the difference between the inner diameter of the outer constraint layer 1 and the outer diameter of the inner constraint layer 2 is equal to the thickness of the damping layer 2, and the thickness of the damping layer 2 is usually between 2 mm and 10 mm; the inner diameter of the inner constraint layer 3 is the same as the outer diameter of the cable, usually between 3 cm and 15 cm;

[0029] The damping layer 2 uses a shear thickening fluid containing 35% by mass of silicon dioxide (SiO2) encapsulated by EVA and / or EPE foam material. The shear thickening fluid uses polyethylene glycol (PEG) with a molecular weight of 300 as the dispersion medium and SiO2 with a diameter of 35nm as the dispersed phase. The damping ratio peak of the shear thickening fluid is about 5Hz, which can take into account the suppression of vibrations of most arch bridges and suspension bridge hangers, and also has a good effect on suppressing high-frequency vibrations above 15Hz.

[0030] In this embodiment, the length of the external damper is 3.0m, and the thickness of the damping layer is 4.0mm. The long suspension rod is 52m long and contains one strand of cable. The external damper is directly installed at the bottom of the suspension rod by snapping, which is convenient for later maintenance and replacement. It can completely replace the stainless steel sleeve and suppress the vibration reduction effect of the suspension rod. In this embodiment, the damping rate of each modal of the suspension rod with a length of more than 50m is not less than 58%.

[0031] Example 2

[0032] In this embodiment, the external damper is the same as that in the embodiment 1, except that the length of the outer constraint layer 1 and the inner constraint layer 3 is the same, 1.5 m, and the thickness of the damping layer is 4.0 mm. The length of the suspension rod is 52 m, and it contains one strand of cable. Before hanging the cable, the two identical external dampers are arranged at the top and bottom of the suspension rod, respectively. Figure 2 This can shorten the effective vibration length of the boom, further enhance the vibration reduction effect without increasing the construction cost and material usage. In this embodiment, the vibration reduction rate of each modal of the boom with a length of more than 50m is not less than 65%.

[0033] Example 3

[0034] In this embodiment, the external damper is the same as that in the embodiment 1, except that in the external damper, the length of the outer constraint layer 1 and the inner constraint layer 3 are the same, both are 1.0m, and the thickness of the damping layer is 8.0mm. The length of the boom is about 86m, including 1 strand, and 3 identical external dampers are evenly arranged within the entire length of the boom, that is, 2 external dampers are installed at the top and bottom of the boom, and 1 external damper is installed in the middle position, so that the effective length of the boom vibration can be shortened to 1 / 3 of the original. The inventor unexpectedly found that this alone can increase the critical wind speed of the boom wake galloping by 3 times and enhance the negative damping delay effect of the vibration.

[0035] Example 4

[0036] In this embodiment, the external damper is the same as that in the embodiment 1, except that in the external damper, the lengths of the outer constraint layer 1 and the inner constraint layer 3 are the same, both 0.5 m, and the thickness of the damping layer is 4.0 mm. The length of the long suspension rod is about 110 m, and each suspension rod comprises two long, thin and flexible cables, and two dividers are arranged between the cables, such as Figure 3 The above 12 identical external dampers are used for the booms that have not yet been completed and have particularly significant wind-induced vibrations. The 12 identical external dampers are evenly arranged at both ends of each cable strand and the upper and lower beam ends of the divider. This can shorten the effective vibration length of the boom to 1 / 6 of the original. The inventor unexpectedly discovered that this alone can increase the vibration starting wind speed of the suspension cable in the same phase and out of phase, increase the critical wind speed of the boom wake galloping vibration by approximately 6 times, and enhance the negative damping delay effect of the vibration.

[0037] Comparative Example 1

[0038] This comparative example provides an external damper for a long boom, which is the same as Example 1, except that the external constraint layer 1 and the internal constraint layer 3 of the external damper are axially misaligned. When the external damper is applied to a boom with a length of more than 50 m, the first-order modal damping rate is only 70% of that of Example 1, which limits the damping effect of the boom damper.

Claims

1. A long suspension rod external damper, characterized in that: The external damper comprises an outer constraint layer, a damping layer, an inner constraint layer, an upper rubber gasket, a lower rubber gasket, an upper shear deformation annular guide groove, a lower shear deformation annular guide groove and an annular clamping plate; The two ends of the outer constraint layer and the inner constraint layer are staggered and coaxially placed; the semi-annular cavity body formed by the outer constraint layer and the inner constraint layer is filled with a damping layer, and the damping layer is respectively bonded to the outer constraint layer and the inner constraint layer, and the three form a semi-annular body; the outer constraint layer and the inner constraint layer are buckled at both ends into a ring through an annular clamp and a rubber gasket so as to be fixed to the long suspension rod; at one end of the semi-annular body, a rubber gasket is placed between the outer constraint layer and the long suspension rod, and the annular clamp cooperates with bolts to act on the outer constraint layer to extrude the rubber gasket, so that the semi-annular body is fixed to the long suspension rod; at the other end of the semi-annular body, the annular clamp cooperates with bolts to extrude the inner constraint layer through the rubber gasket, so that the semi-annular body is fixed to the long suspension rod.

2. The long suspension rod external damper according to claim 1, characterized in that: The annular clamp and the rubber gasket form a clamping assembly, and a vertical spacing is reserved between the clamping assembly and the constraint layer to form a shear deformation annular guide groove; specifically, the upper shear deformation annular guide groove is located below the upper rubber gasket, and the lower shear deformation annular guide groove is located above the upper rubber gasket, and is formed by reserving a vertical spacing between the rubber gasket and the constraint layer.

3. The long suspension rod external damper according to claim 1, characterized in that: Spiral lines are added to the surface of the outer constraint layer or pits are set on the surface.

4. The long suspension rod external damper according to claim 1, characterized in that: The outer constraint layer and the inner constraint layer are made of galvanized ultra-thin steel plates with the same thickness, ranging from 1.0 mm to 3.0 mm; the same length, ranging from 0.5 m to 3.0 m; the difference between the inner diameter of the outer constraint layer and the outer diameter of the inner constraint layer is equal to the thickness of the damping layer, ranging from 2.0 mm to 10.0 mm; the inner diameter of the inner constraint layer is the same as the outer diameter of the cable, ranging from 3 cm to 15 cm.

5. The long suspension rod external damper according to claim 4, characterized in that: The thickness of the damping layer is 2.0 mm, 4.0 mm, 6.0 mm, 8.0 mm or 10.0 mm; the lengths of the outer constraint layer and the inner constraint layer are the same, which are 0.5 m, 0.75 m, 1.0 m or 1.5 m.

6. A long suspension rod external damper according to any one of claims 1 to 4, characterized in that: When the long boom contains one cable strand, one external damper is installed at the bottom of the long boom, or a plurality of external dampers are evenly installed over the entire length of the long boom.

7. The long suspension rod external damper according to claim 6, characterized in that: Install 2-6 external dampers at equal distances between the bottom and top of the long boom.

8. A long suspension rod external damper according to any one of claims 1 to 4, characterized in that: When the long suspension rod contains multiple cable strands, dividers are equidistantly arranged between the multiple cable strands, and a plurality of external dampers are respectively installed at the bottom, the top and both sides of the dividers close to each cable strand.

9. The long suspension rod external damper according to claim 8, characterized in that: The long suspension rod comprises 2-4 cable strands, 1-2 dividers are equidistantly arranged between every two cable strands, and at least 4 external dampers are respectively installed at the bottom, the top and both sides of the dividers close to each cable strand.

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