Stayed cable with discontinuous interlaced ribs

Abstract

The application discloses a stay cable with intermittent staggered ribs and relates to the technical field of cable-stayed bridge engineering, which comprises a cable body, the cable body comprises a plurality of continuous segments in the axial direction, a plurality of ribs are uniformly distributed on the circumferential surface of each segment, the length direction of each rib is parallel to the axial direction of the cable body, and the ribs on the adjacent two segments are staggered in the circumferential direction. The stay cable with intermittent staggered ribs can reduce the occurrence of vortex-induced vibration and improve the aerodynamic stability, so that the overall safety is improved.

Description

Technical Field

[0001] This invention relates to the field of cable-stayed bridge engineering technology, and in particular to a cable-stayed cable with intermittently interlaced ribs. Background Technology

[0002] Cable-stayed bridges, as a typical form of long-span bridge, are characterized by their strong spanning capacity and aesthetically pleasing design, making them a common structural choice for crossing rivers, seas, and mountain canyons. With the continuous increase in the span of cable-stayed bridges, the length of the stay cables, a crucial load-bearing component, is also constantly increasing, leading to greater wind loads. Due to their high slenderness ratio, low stiffness, and low damping, stay cables are prone to various wind-induced vibrations, primarily vortex-induced vibrations. Vortex-induced vibration occurs when a stay cable is subjected to a relatively low-speed uniform wind flow, causing alternating asymmetrical vortices to form on both sides of the cable. These vortices induce periodically varying aerodynamic lift on the cable surface in both crosswind and downwind directions, thus triggering cable vibration. Vortex-induced vibration is self-excited; if the natural frequency of the stay cable is close to the vortex shedding frequency, it can cause structural resonance failure, known as vortex-induced resonance. Currently, standard cylindrical stay cables are used, but their vortex-induced vibration phenomenon and aerodynamic stability are relatively poor. Summary of the Invention

[0003] The purpose of this invention is to provide a cable-stayed cable with intermittent interlaced ribs to solve the problems existing in the prior art, reduce the occurrence of vortex-induced vibration, and improve aerodynamic stability, thereby enhancing overall safety.

[0004] To achieve the above objectives, the present invention provides the following solution:

[0005] The present invention provides a stay cable with intermittent staggered ribs, comprising a cable body, the cable body comprising a plurality of continuous segments along the axial direction, each segment having a plurality of ribs distributed circumferentially on its outer circumferential surface, the length direction of each rib being parallel to the axial direction of the cable body, and the ribs on adjacent segments being staggered circumferentially.

[0006] Preferably, the plurality of ribs on the outer peripheral surface of each segment are evenly distributed circumferentially.

[0007] Preferably, the ribs on two adjacent segments are evenly staggered in the circumferential direction.

[0008] Preferably, the multiple ribs on each segment are of the same length, and the length of the rib is the same as the axial length of the segment.

[0009] Preferably, the ribs on adjacent segments have the same length.

[0010] Preferably, each of the ribs has the same width in the circumferential direction of the cable body and the ratio of the width to the diameter of the cable body is 0.067-0.133.

[0011] Preferably, each of the ribs has the same thickness on the surface away from the cable body and the ratio of the thickness to the diameter of the cable body is 0.067-0.133.

[0012] Preferably, each of the ribs is made of a polymer or metal.

[0013] The present invention achieves the following technical effects compared to the prior art:

[0014] The cable-stayed bridge with intermittently staggered ribs provided by this invention features multiple ribs arranged axially on the outer periphery of the cable body. These ribs are intermittently staggered along the axial direction, giving the entire outer periphery of the cable a distinct three-dimensional geometric feature. Due to the intermittently staggered rib arrangement, when gas flows through both sides of the cable, the ribs act as a barrier, causing the surface gas to flow axially or separate prematurely. After the gas flows through the cable, longitudinal vortices are generated, accumulate, and detach on the leeward side where there are no ribs, while vortex detachment is affected on the leeward side where there are ribs. The presence of ribs results in different vortex detachment patterns at different cross-sections along the axial direction. This creates significant differences in the axial gas flow state, gas separation points, vortex detachment patterns in the wake, and aerodynamic characteristics on the cable surface at the same time. This weakens the axial correlation of wind load, thereby improving the aerodynamic stability of the cable-stayed bridge, reducing vortex-induced vibration, and enhancing overall safety. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 A schematic diagram of the axial structure of the stay cable with intermittent interlaced ribs provided in Embodiment 1;

[0017] Figure 2 A front view schematic diagram of a stay cable with intermittently interlaced ribs provided in Embodiment 1;

[0018] Figure 3 for Figure 2 A left-side view of a cable-stayed structure with intermittently interlaced ribs is provided.

[0019] Figure 4 A schematic diagram simulating the airflow state of a cable-stayed bridge with intermittently interlaced ribs, provided in Example 1;

[0020] Figure 5 A schematic diagram simulating the shedding of a cable-stayed bridge wake vortex with intermittently interlaced ribs, provided in Example 1;

[0021] Figure 6 A schematic diagram comparing the average resistance coefficient of a stay cable with intermittently interlaced ribs provided in Example 1 with that of a standard cylindrical stay cable;

[0022] Figure 7 This is a schematic diagram comparing the average lift coefficient of a stay cable with intermittently interlaced ribs provided in Example 1 with that of a standard cylindrical stay cable.

[0023] Icons: 1-Cable with intermittent interlaced ribs; 10-Cable body; 11-Segment; 12-Rib; 13-Wire; 14-Wire grease protective layer; 15-Wire anti-corrosion protective layer; 16-PE sheath. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] The purpose of this invention is to provide a cable-stayed cable with intermittent interlaced ribs to solve the problems existing in the prior art, reduce the occurrence of vortex-induced vibration, and improve aerodynamic stability, thereby enhancing overall safety.

[0026] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Example 1

[0028] This embodiment provides a cable-stayed cable 1 with intermittently interlaced ribs. Please refer to [link to relevant documentation]. Figures 1-3 The cable body 10 includes a continuous plurality of segments 11 along the axial direction. Each segment 11 has a plurality of ribs 12 distributed along the circumferential direction on its outer circumferential surface. The length direction of each rib 12 is parallel to the axial direction of the cable body 10, and the ribs 12 on two adjacent segments 11 are staggered in the circumferential direction.

[0029] By providing multiple ribs 12 along the axial direction on the outer circumference of the cable body 10, and discontinuously and alternately distributing these ribs 12 along the axial direction of the cable body 10, the entire outer circumference of the stay cable exhibits distinct three-dimensional geometric features. For details regarding the arrangement of the discontinuous and alternate ribs 12, please refer to [link to relevant documentation]. Figure 4 and Figure 5 When gas flows across both sides of the cable, the ribs 12 act as a barrier, causing the surface gas to flow axially or separate prematurely. After the gas flows over the cable, longitudinal vortices are generated, accumulate, and detach on the leeward side where there are no ribs 12, while vortex detachment is affected on the leeward side where there are ribs 12. The presence of ribs 12 leads to different vortex detachment at different cross-sections along the axial direction. This results in significant differences in the axial flow state of the gas on the cable surface, the gas separation point, the vortex detachment of the wake, and the aerodynamic characteristics at the same time. This weakens the correlation of wind load in the axial direction, thereby improving the aerodynamic stability of the cable and reducing the generation of vortex-induced vibration, thus improving overall safety.

[0030] Specifically, the structure of cable 10 can be a conventional structure; please refer to [link / reference]. Figure 3 From the inside out, the layers are: steel wire 13, steel wire grease protective layer 14, steel wire anti-corrosion protective layer 15, and PE wrapping sheath 16.

[0031] More preferably, each rib 12 is made of a polymer or metal, such as PVC or stainless steel.

[0032] More preferably, the multiple ribs 12 on the outer circumferential surface of each segment 11 are evenly distributed in the circumferential direction to improve the uniformity of the weight distribution of the cable.

[0033] More preferably, the multiple ribs 12 on two adjacent segments 11 are evenly staggered in the circumferential direction, that is, the multiple ribs 12 on two adjacent segments 11 are evenly distributed in the circumferential direction at an angle. The multiple ribs 12 on two adjacent segments 11 can be regarded as a periodic structure and extend side by side in the axial direction of the cable body 10. The number of ribs 12 on each periodic structure can be 6, 8 or 12, that is, there are 3, 4 or 6 ribs distributed in the circumferential direction on each segment 11. The included angles between two adjacent ribs 12 in the circumferential direction on the corresponding periodic structure are 60°, 45° and 30° respectively.

[0034] More preferably, the multiple ribs 12 on each segment 11 are of the same length, and the length of the rib 12 is the same as the axial length of the segment 11. In this way, the three-dimensional geometric features of the outer surface of the cable body 10 change periodically in the axial direction, which can improve the aerodynamic stability of the cable, reduce the generation of vortex-induced vibration, and improve the overall safety.

[0035] More preferably, the ribs 12 on adjacent segments 11 have the same length; specifically, the length of each rib 12 can be determined according to the actual length or diameter of the cable body 10; specifically, the length of each rib 12 can be 1.417 times the diameter of the cable body 10; furthermore, the width dimension of each rib 12 in the circumferential direction of the cable body 10 is the same and the ratio to the diameter of the cable body 10 is 0.067-0.133, wherein the ratio can be 0.067 or 0.133; the thickness dimension of each rib 12 on the surface away from the circumference of the cable body 10 is the same and the ratio to the diameter of the cable body 10 is 0.067-0.133, wherein the ratio can be 0.067, 0.1 or 0.133.

[0036] Specifically, a wind tunnel test was conducted on a cable 10 model with a rib length of 212.5 mm (1.417 times the diameter of cable 10 and 1 / 8 of the length of cable 10), an axial length L of 1700 mm, and a diameter D of 150 mm to determine the maximum vortex-induced vibration amplitude A / D and the average drag coefficient. and average lift coefficient The comparative evaluation specifically uses a standard cylindrical cable (i.e., cable body 10 without ribs 12) as a control, and ribs 12 with different widths and thicknesses as experimental examples. The width and thickness matching dimensions are 10mm:15mm, 20mm:10mm, 20mm:15mm and 20mm:20mm. Furthermore, the number of ribs 12 on the periodic structure can be 6, 8 or 12, as well as different wind attack angles β.

[0037] The wind tunnel is a series-connected dual-section return / direct flow boundary layer wind tunnel. Its low-speed test section is 24.0m long, 4.4m wide, and 3.0m high, with a maximum wind speed exceeding 30.0m / s and a free-flow turbulence intensity of less than 0.4%. Its high-speed test section is 5.0m long, 2.2m wide, and 2.0m high, with a maximum wind speed exceeding 80.0m / s and a free-flow turbulence intensity of less than 0.2%.

[0038] Regarding the maximum vortex-induced vibration amplitude A / D, where A is the amplitude of the stay cable, to facilitate comparison of vibration results, it is represented by the average value of the periodic maximum amplitude of the displacement time history of the stay cable model vortex-induced vibration:

[0039] A = (A1 + A2) / 2;

[0040] In the formula: A1 and A2 are the average values ​​of the maximum amplitude of the vortex-induced displacement time history of the cable-stayed model recorded by two laser displacement gauges in the wind tunnel test; the amplitude A is divided by the characteristic dimension diameter D of the model and then processed to be dimensionless, and the dimensionless amplitude of the vortex-induced vibration of the model is denoted as A / D.

[0041] Regarding the average drag coefficient and average lift coefficient, the reduced wind speed Ur is obtained by also dimensionlessly processing the wind speed.

[0042] U r =U / fD;

[0043] In the formula: f is the natural frequency, and U is the average incoming air velocity;

[0044] The aerodynamic coefficients (mean drag coefficient and mean lift coefficient) are calculated as follows:

[0045]

[0046] In the formula: F D F is the drag force acting on the model. L The lift force acting on the model is ρ, where ρ is the air density; and These represent the average drag coefficient and the average lift coefficient.

[0047] See the table below for specific simulation data:

[0048] Table 1 Wind tunnel simulation data of vortex-induced vibration and aerodynamic forces of ribbed cable-stayed cables and standard cylindrical cable-stayed cables.

[0049]

[0050]

[0051] In the table above, compared to standard cylindrical stay cables, when the width-to-thickness ratio is 10mm:15mm, the number of periodic structural ribs (12) is 6, with wind attack angles of 15° and 30°; and when the number of periodic structural ribs (12) is 8, with a wind attack angle of 0°, the maximum vortex-induced vibration amplitude is significantly reduced, and the rate of change of the average drag coefficient is relatively small. When the width-to-thickness ratio is 20mm:10mm, the number of periodic structural ribs (12) is 8, with a wind attack angle of 0°, the maximum vortex-induced vibration amplitude is significantly reduced, and the rate of change of the average drag coefficient is relatively small. When the thickness is 20mm:15mm, there are 6 periodic structural ribs 12 with a wind attack angle of 0°, and 8 periodic structural ribs 12 with wind attack angles of 0°, 10° and 20°, the maximum vortex-induced vibration amplitude is significantly reduced. When the width and thickness are 20mm:20mm, there are 6 periodic structural ribs 12 with wind attack angles of 0°, 15° and 30°, and 8 periodic structural ribs 12 with a wind attack angle of 0°, the maximum vortex-induced vibration amplitude is significantly reduced, and the rate of change of the average drag coefficient is small.

[0052] Further, please see Figure 4 and Figure 5The figures show a simulated state diagram of gas flowing through a ribbed cable-stayed bridge with 6 periodic structural ribs 12 and a wind attack angle β = 0°, and a simulated diagram of wake vortex shedding. When the gas flows through both sides of the cable-stayed bridge, the surface gas flows axially or separates prematurely due to the obstruction of the ribs 12. After the gas flows through the cable-stayed bridge, longitudinal vortices are generated, accumulate, and detach at the leeward side of the cable-stayed bridge where there are no ribs 12, while the vortex shedding is affected at the leeward side where there are ribs 12. That is, the presence of ribs 12 causes different vortex shedding situations at different cross-sections in the axial direction.

[0053] Further, please see Figure 6 This diagram illustrates a comparison of the average drag coefficients of a stay cable with intermittently interlaced ribs and a standard cylindrical stay cable. The comparison is based on ribs 12 with widths and thicknesses of 10mm and 15mm, respectively, and eight ribs in a periodic structure, with wind angles of attack of 0°, 10°, and 20°. The comparison is made when the Reynolds number Re = 1.0 × 10⁻⁶. 5 ~1.5×10 5 When Re > 1.5 × 10⁻⁶, the average drag coefficient stabilizes at around 1.1; when Re > 1.5 × 10⁻⁶, the average drag coefficient stabilizes at around 1.1. 5 When Re = 3.1 × 10⁻⁶, the average drag coefficient begins to decrease; when Re = 3.1 × 10⁻⁶... 5 ~3.8×10 5 When β = 0° and 10°, the average drag coefficient decreases to about 0.5. After the ribs are installed, within the range of the test Reynolds number, the average drag coefficient changes very little with the Reynolds number, indicating that the Reynolds number effect is not obvious. When β = 0° and 10°, the average drag coefficient of the rib cable remains at about 1.10. When β = 20°, the average drag coefficient of the rib cable is about 1.40.

[0054] Further, please see Figure 7 This diagram illustrates a comparison of the average lift coefficient between a stay cable with discontinuous interlaced ribs and a standard cylindrical stay cable. The comparison is based on ribs 12 with widths and thicknesses of 10mm and 15mm, respectively, and eight ribs in a periodic structure, under wind angles of attack of 0°, 10°, and 20°. The comparison is made when the Reynolds number Re < 2.2 × 10⁻⁶. 5 When Re > 2.2 × 10⁻⁶, the average lift coefficient remains relatively stable near 0; when Re > 2.2 × 10⁻⁶, the average lift coefficient remains relatively stable near 0. 5 At this point, the average lift coefficient begins to increase, reaching 0.65; when Re = 3.1 × 10⁻⁶. 5 At that time, the average lift coefficient stabilized at -0.43. After the ribs were installed, the Reynolds number effect on the average lift coefficient of the rib cable was not obvious, and the average lift coefficient stabilized at around -0.1 to 0 at different angles of attack. The overall fluctuation was much smaller than that of the standard cable, indicating better aerodynamic stability.

[0055] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A cable-stayed cable with intermittently interlaced ribs, characterized in that: The cable body (10) includes a plurality of continuous segments (11) along the axial direction. Each segment (11) has a plurality of ribs (12) distributed along the circumferential direction on its outer circumferential surface. The length direction of each rib (12) is parallel to the axial direction of the cable body (10), and the ribs (12) on two adjacent segments (11) are staggered in the circumferential direction. The multiple ribs (12) on the outer circumferential surface of each segment (11) are evenly distributed in the circumferential direction; the multiple ribs (12) on two adjacent segments (11) are evenly staggered in the circumferential direction; the multiple ribs (12) on each segment (11) have the same length, and the length of the rib (12) is the same as the axial length of the segment (11); the length of the ribs (12) on adjacent segments (11) is the same; the multiple ribs (12) on two adjacent segments (11) form a periodic structure and extend side by side in the axial direction of the cable body (10), and the number of ribs (12) on each periodic structure can be 6, 8 or 12, corresponding to 3, 4 or 6 ribs (12) distributed in the circumferential direction on each segment (11).

2. The stay cable with intermittently interlaced ribs according to claim 1, characterized in that: Each of the ribs (12) has the same width dimension in the circumferential direction of the cable body (10) and the ratio of the width to the diameter of the cable body (10) is 0.067-0.

133.

3. The cable-stayed bridge with intermittently interlaced ribs according to claim 1, characterized in that: Each of the ribs (12) has the same thickness on the circumferential surface away from the cable body (10) and the ratio of the thickness to the diameter of the cable body (10) is 0.067-0.

133.

4. The cable-stayed bridge with intermittently interlaced ribs according to claim 1, characterized in that: The material of each of the ribs (12) is a polymer or metal.

Images