Method of strengthening suspension bridges using cable-stay system

Abstract

FIELD: bridge construction.SUBSTANCE: invention can be used in the repair and strengthening of existing suspension bridges in operation. A method of strengthening suspension bridges using a cable-stayed system consists of a preliminary diagnostic test of the operating suspension bridge structure, during which the condition of the pylons, load-bearing cables and decking is checked. A reinforcement project is then developed. Next, the base of each pylon is strengthened by installing additional piles and constructing additional formwork of the calculated size, followed by concreting it. Then, additional pylons are erected on the reinforced foundation, the height of which is calculated taking into account the future load on the cables. After this, the outer cables are installed, securing them with anchor fastenings at the calculated points, whereas the attachment points of the outer cables do not coincide with the attachment points of the cables. Then the calculated number of cables is installed to strengthen the bridge span itself.EFFECT: reliability of pylons for balancing horizontal components of the load and reducing wind load.1 cl, 2 dwg

Description

[0001] The proposed invention relates to bridge construction and can be used in the repair and strengthening of existing suspension bridges in operation.

[0002] The main problems with old suspension bridges are related to corrosion of the fastening elements, wind and seismic loads that deform the bridge, and outdated construction technologies. Strengthening such bridges requires special attention due to the partial failure of the cable stays. When preparing for reinforcement, it is crucial to calculate the load on each suspension cable stay. It is also important to pay attention to the lack of supports in the middle section of suspension bridges and their unevenness. Typically, longitudinal beams or stiffening trusses are used to strengthen such bridges (reduce structural deflection), but such reinforcement is not always possible or cost-effective.

[0003] Russian Federation patent for invention No. 2228471 “METHOD FOR STRENGTHENING AN OVERHEAD PIPELINE CROSSING” is known.

[0004] The invention relates to construction and is used in the construction and operation of overhead pipeline crossings. The horizontal rigidity of an overhead pipeline crossing is maintained by adjusting the varying degrees of sag of horizontal guy wires through tensioning them. This is accomplished by hanging systems of prefabricated weights on horizontal guy wires whose sag exceeds the permissible limit. This expands the range of technical means available.

[0005] The disadvantage of this solution is that the calculation of the loads that are hung on the guy wires is very complex, and with this reinforcement system it is impossible to guarantee the required tension of the intermediate cables.

[0006] The closest to the proposed solution is French patent No. 2534948 “METHOD FOR REPLACING A LAYER OF SUSPENSION CABLES OF A SUSPENSION BRIDGE, ALLOWING THE BRIDGE TO REMAIN IN OPERATION THROUGHOUT ITS ENTIRE SERVICE LIFE.”

[0007] A method of replacing the carrier cable layer of a suspension bridge, allowing the bridge to remain in service throughout its service life, is achieved (according to Figure 3) by slinging a new hanger g over the existing a, with the new cables attached to the same existing attachment points j, then k and 1. The axis of the new support layer is deflected by means of auxiliary support elements n and o, which allows the new cables and their attachments to not bend around the already installed elements until the top of the supports R and S, where special support t and u, placed above the existing one, allow linear and opposite movements between them. Devices m for connecting and approaching in successive and controlled phases allow the deck loads to be transferred from the old to the new layer. The operation can be stopped and resumed at any time. No additional load is ever added to the old hanger. The use of temporary suspension is excluded.

[0008] The disadvantage of this solution is that the new “layer” of suspensions (cables) adds a serious load to the existing old pylons, which may be in unsatisfactory condition due to the wear of metal and metal-concrete elements.

[0009] Disclosure of invention

[0010] The objective of the proposed solution is to create a method for strengthening suspension bridges using a cable-stayed system, which will ensure reliable and safe operation of the existing suspension bridge by increasing the stability and rigidity of the structure.

[0011] The technical result of the proposed solution is: ensuring the reliability of pylons to balance the horizontal components of the load and reduce the wind load.

[0012] The technical result is achieved by strengthening suspension bridges using a cable-stayed system. This involves first conducting a diagnostic of the existing suspension bridge structure, inspecting the condition of the pylons, supporting cables, and decking. A reinforcement plan is then developed. Next, the foundation of the old pylon is reinforced by installing additional piles and constructing additional formwork of the calculated size, followed by concreting. New pylons are then erected on the reinforced foundation without dismantling the old ones. The height of the new pylons is calculated taking into account the future load on the cables. After this, the outer cables are installed, securing them with anchors at the calculated points. The attachment points of the new outer cables do not coincide with the attachment points of the old cables. The calculated number of cables is then installed, strengthening the bridge span itself.In this case, the old supporting cables of the bridge are not dismantled, resulting in a combined suspension bridge system with a cable-stayed system.

[0013] The essence of the invention is explained by drawings, where:

[0014] Fig. 1. - Shows the suspension bridge before reinforcement.

[0015] Fig. 2 - Shows a suspension bridge reinforced with a cable-stayed system.

[0016] The method for strengthening suspension bridges 1 using a cable-stayed system 2 involves a preliminary inspection of the operating suspension bridge structure 1, including checking the condition of the pylons 3, load-bearing cables 4, and decking. A reinforcement plan is then developed. Next, the foundation of the old pylon 5 is reinforced by installing additional piles 6 and constructing additional formwork 7 of the calculated size, followed by concreting. Then, new pylons 8 are erected on the reinforced foundation, without dismantling the old ones 3. The height of the new pylons 8 is calculated taking into account the future load on the cables 9 and 13. After this, the outer cables 9 are installed, securing them with anchor fastenings 10 at the calculated points 11, while the attachment points of the new outer cables 11 do not coincide with the attachment points of the old cables 12. Then the calculated number of cables 13 is installed, strengthening the bridge span itself.In this case, the old supporting cables 4 of the bridge are not dismantled, resulting in a combined suspension bridge system 1 with a cable-stayed system 2.

[0017] Bridges with a combined suspension and cable-stayed system combine the advantages of cable-stayed and suspension bridges while eliminating their disadvantages. They allow for large spans, exhibit high flexural rigidity, and deliver excellent technical and economic performance.

[0018] In the proposed method for strengthening suspension bridges using a cable-stayed system, additional piles are installed in the design area to strengthen the old foundation, and formwork is installed, followed by concreting.

[0019] Installing new bridge pylons without dismantling existing ones is a common practice in bridge construction, especially when reconstructing existing structures. This allows the old pylons to be used for supporting support.

[0020] Extreme cable anchors are structural elements at the ends of cables that transfer loads from the stiffening beam to the pylon, arch or supporting cable through the cable strands.

[0021] Advantages of combined suspension and cable-stayed bridge system:

[0022] - the stiffening beam is always held by cables and shrouds;

[0023] - resistant to wind loads and seismic effects, when cables and stays work only in tension, which allows the efficient use of high-strength materials;

[0024] - can withstand heavy loads and adapt to various environmental conditions, as the cables and stays are protected from corrosion through the use of lubricants;

[0025] - cover large spans (for example, 500-3500 m), which is effective when constructing bridges across wide gorges, fast-flowing water barriers, where the construction of intermediate supports is complicated;

[0026] - installation of elements in a combined system is possible without temporary supports, which reduces the time, labor intensity and cost of construction and / or reconstruction;

[0027] - cost-effective due to the possibility of surface mounting, rational use of materials, and also due to the simplification of the production of elements.

[0028] Industrial applicability

[0029] All of the above indicates the completion of the task and the achievement of the technical result, as well as the industrial applicability of the proposed method.

[0030] List of items:

[0031] 1. Suspension Bridge

[0032] 2. Cable-stayed system

[0033] 3. Old pylon

[0034] 4. Carrier cables

[0035] 5. old pylon base

[0036] 6. Additional piles

[0037] 7. Additional formwork

[0038] 8. New pylon

[0039] 9. Outer shrouds

[0040] 10. Anchor fastening

[0041] 11. Calculated attachment points of the outer cables

[0042] 12. Old cable attachment points

[0043] 13. Cables reinforcing the bridge span

Claims

1. A method for strengthening a suspension bridge using a cable-stayed system, which consists of first conducting a diagnostic of the operating suspension bridge structure, during which the condition of the pylons, load-bearing cables and decking is checked, a reinforcement project is drawn up, after which the base of each pylon is strengthened by installing piles and constructing formwork of the calculated size, followed by concreting it, then additional pylons are erected on the strengthened base, the height of which is calculated taking into account the future load on the cables, after which the outer cables are installed, the anchor fastening of which is carried out at calculated points that do not coincide with the attachment points of the cables, and then the calculated number of cables are installed to strengthen the span of the bridge.

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