A self-anchored suspension bridge with a root-shaped layout of main cables

Abstract

The present invention belongs to the technical field of bridge engineering, and particularly relates to a self-anchored suspension bridge with a root-shaped main cable arrangement. The suspension bridge includes a foundation, on which a tower base is installed, and a bridge tower is installed through the tower base. The main beam is installed through the bridge tower. The bridge tower includes a steel box-concrete main arch and several steel box-concrete secondary arches that are cross-fixed to each other. The main arch and several secondary arches are all arc-shaped structures. A main cable is arranged on the saddle on the bridge tower. The main beam passes through the space separated by the main arch and several secondary arches. The main cable is connected to the main beam through a suspender. The invention innovatively proposes a main cable with a dispersed root-shaped arrangement, which can not only reduce the compressive stress level of the main beam, but also reduce the uplift force at the beam end and the local anchoring stress, and at the same time can form a unique landscape effect. The suspension bridge has a light structure, a clear force transmission path, high material utilization rate, a unique landscape effect, mature construction technology, a short construction period, and a safe and reliable structure.

Description

Technical Field

[0001] The invention belongs to the technical field of bridge engineering, and particularly relates to a self-anchored suspension bridge with a root-shaped main cable arrangement. Background Art

[0002] Suspension bridges have the advantages of large spanning capacity, good mechanical properties, light and beautiful structure, etc., and have become the preferred bridge type for extra-large-span bridges. In recent years, with the development and changes of the world economy, the focus of suspension bridge construction has shifted from Europe and the United States to Asian countries. A series of extra-large-span suspension bridges have been built in China successively, and both the scale and the design and construction technologies have entered the world's advanced ranks.

[0003] Although the existing suspension bridges meet the structural stress requirements, most of them have a rigid structure, a single shape, and limited spatial expressiveness, and cannot well highlight the towering and straight posture of the suspension bridge; in addition, the main problem brought about by the large increase in the span is the sharp decline in the structural stiffness, making the influence of wind-induced vibration on the bridge safety more prominent, mainly manifested as the overall low stiffness of the system, poor structural vibration characteristics and aerodynamic performance of the bridge deck. In a traditional self-anchored suspension bridge, the bridge deck load is transmitted to the main cable through the suspenders. The main cable needs to bear a huge axial tension. The main cable is anchored at the beam end and directly transmits the tension to the main beam, resulting in a large axial force in the main beam. Due to the problem of buckling stability of the main beam members, the main beam needs to adopt a larger cross-sectional size. Moreover, in order to overcome the large uplift force in the beam end anchorage area, concrete ballast is often required or additional holes are provided. Summary of the Invention

[0004] To solve the deficiencies and defects in the mechanical properties of the above-mentioned conventional suspension bridges, the invention provides a self-anchored suspension bridge with a root-shaped main cable arrangement. In this suspension bridge, a cable splitter is used at the suspender to separate two strands of the main cable to serve as suspenders and disperse the anchorage on the beam body, canceling the vertical suspenders and making the main cable arranged in a root shape, which can shunt the huge tension of the main cable, not only reducing the compressive stress level of the main beam but also solving the problems of local stress concentration and large uplift force in the main cable anchorage area at the beam end. This makes the mechanical properties of the suspension bridge better, the structural stress more uniform, and the material properties more fully utilized.

[0005] To achieve the above object, the technical solution adopted by the invention is as follows:

[0006] A self-anchored suspension bridge with a root-shaped main cable arrangement, including a foundation 9, a bridge tower is installed on the tower base 8 of the foundation 9, and a main beam is installed through the bridge tower. It is characterized in that: the bridge tower includes a steel box-concrete main arch 1 and several steel box-concrete secondary arches 2 that are cross-fixed to each other. The one main arch 1 and several secondary arches 2 are all arc-shaped structures. A main cable 5 is arranged on the saddle 18 on the bridge tower. The main beam passes through the space separated by the main arch 1 and several secondary arches 2, and the main cable 5 is connected to the main beam through the suspenders 6.

[0007] The main arch 1 and the plurality of auxiliary arches 2 constrain the main beam through vertically arranged rigid supports, longitudinally arranged movable steel supports and shock-absorbing viscous dampers, and transversely arranged unidirectional movable supports.

[0008] The main arch 1 and the auxiliary arch 2 are provided with reinforcing ribs 14 and shear studs 15, and are filled with micro-expansive concrete.

[0009] The main arch 1 and the auxiliary arches 2 above the main beam are connected by a shell steel plate 16, and the main arch 1 and the auxiliary arches 2 below the main beam are connected by steel concrete 17, and are consolidated with the foundation 9 through the tower base 8.

[0010] The shell steel plate 16 is symmetrically provided with an elliptical opening 10 on the front of the bridge tower at the main beam position to reserve a passage for the main beam; and an elliptical opening 11 on the side of the bridge tower is provided on the side of the tower body.

[0011] The main cable 5 and the sling 6 are made of high-strength and low-relaxation galvanized steel wires. The main cable 5 is provided with a plurality of cable separators 7 at the suspension point, and the sling 6 is separated from the main cable 5 by the cable separators 7 .

[0012] The slings 6 are dispersedly anchored on the transverse I-beam 4 at the central dividing strip 12 on the main beam, two bundles of slings 6 are transversely arranged at each anchoring position, and the transverse spacing of the anchoring points 13 of the slings 6 is 1.5m.

[0013] The beneficial effects of the present invention are as follows: the main cable of the suspension bridge of the present invention is arranged on one side, and the slings are centrally anchored in the central dividing strip. The slings are formed by separating the main cable strands by a cable splitter, and are arranged on both sides in the central dividing strip. The arrangement of the main cable and the slings is similar to the trunk and branches of a tree, which are separated but not separated. This root-shaped arrangement of the slings helps to divert the huge tension of the main cable, thereby reducing the stress level of the main beam, and can effectively improve the problems of local stress concentration and large upward pull force in the anchoring area of the main cable at the beam end.

[0014] The suspension bridge of the present invention adds several cross-sub-arches on the basis of the plane arch tower, forming a multi-rib cross-arch bridge tower shape, which greatly improves the seismic resistance of the bridge tower in all directions and the overall stability of the bridge. At the same time, it also strengthens the spatial expression effect of the bridge tower, and truly achieves the coordination and unity of strength and beauty. The main line of the bridge tower is mainly curves, with a smooth appearance and natural transition, which has both beautiful ornamental and good practicality; the bridge tower structure is mainly steel box-concrete, and can be prefabricated in the factory and installed on site. The construction plan has the advantages of short construction period, energy saving and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the suspension bridge type of the present invention;

[0016] Figure 2Front view of the suspension bridge described in the present invention;

[0017] Figure 3 Side view of the suspension bridge described in the present invention;

[0018] Figure 4 Partial plan view of the suspension bridge described in the present invention;

[0019] Figure 5 Cross-sectional view of the main girder of the suspension bridge described in the present invention;

[0020] Figure 6 Schematic diagram of the main cable and suspension cables of the suspension bridge described in the present invention;

[0021] Figure 7 Side position relationship diagram of the main cable and suspension cables of the suspension bridge described in the present invention;

[0022] Figure 8 Front position relationship diagram of the main cable and suspension cables of the suspension bridge described in the present invention;

[0023] Figure 9 Schematic diagram of the cross-section of the tower column of the bridge tower of the suspension bridge described in the present invention;

[0024] Figure 10 Front sectional view of the foundation of the suspension bridge described in the present invention;

[0025] Figure 11 Side sectional view of the foundation of the suspension bridge described in the present invention;

[0026] As shown in the figure: 1. Main arch; 2. Sub-arch; 3. Longitudinal beam; 4. Transverse I-shaped steel beam; 5. Main cable; 6. Suspension cable; 7. Cable separator; 8. Tower base; 9. Foundation; 10. Oval opening on the front of the bridge tower; 11. Oval opening on the side of the bridge tower; 12. Central median strip; 13. Suspension cable anchorage point; 14. Stiffening rib; 15. Shear stud; 16. Shell steel plate; 17. Steel-concrete composite section; 18. Saddle. Detailed implementation manners

[0027] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0028] Embodiment 1

[0029] The structure of the suspension bridge is as Figure 1 shown. The bridge tower is a spatial three-ribbed steel box-concrete arch structure. The main cable and suspension cables are arranged in a root shape and are anchored to the main girder.

[0030] In this embodiment, the main bridge structure is a single-tower two-span self-anchored suspension bridge with a span of 180m + 110m. The main bridge is 290m long, the bridge deck width is 31m, the tower height is 65m, and the height above the bridge deck is 45m. In this embodiment, the bridge tower has a vertically arranged main arch (1), which is a steel box-concrete arch with a side length of 1m and a wall thickness of 38mm. The arch axis consists of two elliptical arcs. The upper elliptical arc has a major axis of 39.5m and a minor axis of 19m, and the lower elliptical arc has a major axis of 24.5m and a minor axis of 19m. Horizontally, the bridge tower adopts two symmetrically crossed secondary arches 2, which can improve the seismic resistance of the bridge tower in multiple directions. The crossing angle of the two secondary arches 2 is 36°. The crossed secondary arches 2 are steel box-concrete arches with a side length of 1m and a wall thickness of 38mm. The arch axis of the secondary arch 2 consists of two elliptical arcs. The upper elliptical arc has a major axis of 39.5m and a minor axis of 30.5m, and the lower elliptical arc has a major axis of 24.5m and a minor axis of 30.5m.

[0031] The tower and the arch are connected by Q235 shell steel plates 16. Four elliptical openings 10 on the front of the bridge tower are symmetrically opened at the main beam position on the front of the tower body. The horizontal width of this hole is 12.4m and the height is 28.6m. Four elliptical openings 11 on the side of the bridge tower are opened on the side of the tower body. The horizontal width of this hole is 3.7m and the height is 13.3m. The connecting shell below the elliptical hole of the tower body is a solid structure, using steel reinforced concrete 17, which improves the structural durability. The tower bottom is a steel reinforced concrete tower base 8.

[0032] The longitudinal beam 3 adopts an equal-section steel box girder. The center height of the box body is 3m, the width is 8m, the thickness of the top plate is 30mm, the thickness of the bottom plate is 50mm, and the thickness of the web plate is 20mm. The transverse I-shaped steel beam 4 adopts a fish-belly I-shaped steel beam. The beam height is 0.5m - 3.8m, the width of the upper and lower flanges is 40cm, the thickness of the flange is 20mm, and the thickness of the web plate is 16mm. The bridge deck adopts a C55 concrete slab with a thickness of 25cm and a width of 31m.

[0033] In this embodiment, the main cable 5 is arranged in a single-plane layout, and the suspender 6 is a transverse double suspender. The vertical-to-span ratio of the main cable on the 180m-span side is 1 / 9, and the vertical-to-span ratio of the main cable on the 110m-span side is 1 / 4.6. The main cable 5 adopts 44 strands of φ5mm high-strength low-relaxation galvanized steel wires with 127 wires in each strand. At the suspender 6, a cable separator 7 is used to separate two strands of the main cable 5 to serve as the suspender 6. 20 pairs of cable strands are separated on the 180m-span side, and 11 pairs of cable strands are separated on the 110m-span side. The remaining cable strands are anchored at the beam end of the main beam.

[0034] In this embodiment, the main bridge foundation adopts a row-pile type diaphragm wall foundation 9, which unifies the temporary support of the enclosure and the permanent foundation. The diaphragm wall foundation 9 adopts a single-box double-chamber structure. The longitudinal width of the top and bottom plates is 14m, the transverse width is 18m, and the height is 20m. The thickness of the top plate is 300cm, the thickness of the bottom plate is 300cm, and the thickness of the side wall and the middle partition wall is 125cm.

[0035] During the construction of the suspension bridge in this embodiment, the construction method of "beam first and cable later" is adopted, including the following steps:

[0036] 1. Foundation construction: The foundation 9 of the bridge tower adopts a diaphragm wall. Taking advantage of the shallow depth of the pervious pebble layer, the retaining pile row is constructed. The thickness of the pile foundation entering the impervious mudstone layer is determined according to the excavation depth. High-pressure jet grouting cement slurry is used to form a curtain between the pile rows. After pumping, the side walls are constructed while excavating, and then the concrete of the bottom slab, partition wall and top slab is poured.

[0037] 2. Bridge tower construction: The bridge tower adopts a steel box-concrete space cross-arch structure, and decorative steel plates are provided for connection between the tower and the arch. During construction, the tower crane is first assembled, and the empty steel boxes are hoisted in sections and welded in the air; the connecting steel plates are welded in pieces at the factory, and after being transported to the site, they are installed in place and welded by using the tower crane.

[0038] 3. Girder erection: Temporary construction piers are constructed, and the steel girder is divided into several processing sections, and the installation of the steel girder is completed by setting up temporary piers.

[0039] 4. Using the steel girder as a support, the concrete bridge deck is poured.

[0040] 5. Erection of the main cable and inclined suspension cables, and adjustment of the initial tension of the inclined suspension cables.

[0041] 6. Construction of the bridge deck system.

[0042] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

[0043] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A self-anchored suspension bridge with a root-shaped main cable arrangement, comprising a foundation, a bridge tower is installed on the tower base of the foundation, and a main beam is installed through the bridge tower, characterized in that: The bridge tower comprises a steel box-concrete main arch and a plurality of steel box-concrete secondary arches which are cross-fixed to each other, the main arch and the secondary arches are all arc-shaped structures, a main cable is arranged on the saddle on the bridge tower, the main beam passes through the space separated by the main arch and the secondary arches, and the main cable is connected to the main beam through a sling; The main arch and several auxiliary arches are constrained by the main beam through the vertically arranged rigid supports, the longitudinally arranged movable steel supports and the shock-absorbing viscous dampers, and the transversely arranged one-way movable supports; The main arch and the auxiliary arch are provided with stiffening ribs and shear nails, and are filled with micro-expansion concrete; The main arch and several auxiliary arches above the main beam are connected by a shell steel plate, and the main arch and several auxiliary arches below the main beam are connected by steel concrete, and are consolidated with the foundation through the tower base; The front main beam position of the shell steel plate is symmetrically provided with an elliptical opening on the front of the bridge tower to reserve a passage for the main beam; the side of the tower is provided with an elliptical opening on the side of the bridge tower; The main cable and the sling are made of high-strength and low-relaxation galvanized steel wire. The main cable is provided with a plurality of cable separators at the suspension point, and the sling is separated from the main cable through the cable separators.

2. The self-anchored suspension bridge with a root-shaped main cable arrangement according to claim 1, characterized in that: The slings are dispersedly anchored on the transverse I-beam at the central dividing strip on the main beam, two bundles of slings are transversely arranged at each anchoring position, and the transverse spacing of the sling anchoring points is 1.5m.

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