A design method for staggered widening of old bridge

Abstract

The application discloses a kind of old bridge staggered storey widening design method, comprising the following steps: at least one bridge tower is newly set on old bridge;With staggered storey way, beam is arranged in the space range above old bridge, and the newly-built separated double main girder located on both sides of old bridge is connected, and a plurality of cable-stayed cables are installed between the main girder and the bridge tower on both sides, and the cable-stayed cable is initially tensioned;The construction of new bridge auxiliary facilities is carried out, and then the cable-stayed cable is secondly tensioned, and the construction of new bridge is completed.The method of the application uses the bridge tower structure of cross setting type, so that the newly-built main girder on both sides can be pulled and fixed using the same bridge tower, effectively saving the cost, and the construction process will not have too much impact on the traffic of old bridge;After the old bridge is removed in the later period, the central hollow belt can be transformed into a bridge deck by adding a bridge deck system supported by the new bridge beam, the function of the old bridge is directly converted to the new bridge without the need to rebuild the old bridge, which can further save the cost and construction period.

Description

Technical Field

[0001] This invention belongs to the field of existing bridge widening technology, specifically relating to a staggered widening design method for old bridges. Background Technology

[0002] With societal development, many existing bridges, due to their limited number of lanes in their early construction, cannot meet the demands of modern transportation and require widening and renovation. When designing bridge widening projects, there are often situations where the old bridge needs to be preserved and utilized in the short term, but will need to be demolished in the long term. For example, an old bridge located on a navigable waterway may meet current navigation needs in the short term, but will need to be demolished as the waterway's grade improves with future shipping development.

[0003] Traditional bridge reconstruction includes two methods: separate widening and connecting widening, as detailed below:

[0004] (1) Separate widening: Separate widening refers to the new bridge and the old bridge being two independent structures, with no connection between the upper and lower structures; expansion joints are set between the new and old bridges, or a partition is set between the new and old bridges, and the lanes are used separately.

[0005] (2) Connecting widening: Connecting widening includes hinged, semi-rigid and rigid connections, all of which connect the structures of the old and new bridges, allowing the lanes of the old and new bridges to be interconnected.

[0006] The two bridge widening methods mentioned above are widely used, but they also have their shortcomings:

[0007] (1) Separate widening

[0008] Hard separation between lanes in the same direction results in poor driving experience; it also requires two sets of substructures, leading to high costs.

[0009] Connectivity Expansion

[0010] a. Due to differences in settlement between the old and new bridges, differences in lateral stiffness, and uneven lateral vehicle load, long-term use has led to damage at the connection points, resulting in longitudinal cracks and water seepage and leakage.

[0011] b. The service life of the old bridge determines the service life of the entire bridge. Once the old bridge becomes a dangerous bridge and is not suitable for reinforcement and use, it needs to be demolished. Demolition is difficult and will have a certain impact on the main structure of the new bridge.

[0012] c. Traffic on the old bridge needs to be restricted during the construction of the connection to prevent vibrations from affecting the quality of the connection and causing significant disruption to existing traffic. Summary of the Invention

[0013] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a staggered widening design method for old bridges. A new bridge tower is constructed above the old bridge, and crossbeams are installed in a staggered manner within the space above the old bridge to connect the newly constructed separate double main beams located on both sides of the old bridge. While ensuring sufficient clearance for passage on the old bridge deck, the newly constructed main beams on both sides of the old bridge can be secured using the same bridge tower, effectively saving costs and minimizing disruption to traffic during construction. After the old bridge is demolished, the new bridge's crossbeams can be used as supports to add a bridge deck system, and the central openwork strip can be transformed into the bridge deck, directly transferring the function of the old bridge to the new bridge without rebuilding the old bridge, further saving costs and time.

[0014] To address the aforementioned technical problems, this invention provides another method for widening old bridges by staggered design, comprising the following steps:

[0015] S1. Construct at least one new bridge tower spanning above the existing bridge;

[0016] S2. A crossbeam is installed in the space above the old bridge to connect the newly built separate double main beams located on both sides of the old bridge in a staggered manner;

[0017] S3. Install several stay cables between the main beams and bridge towers on both sides, and perform initial tensioning on the stay cables;

[0018] S4. Carry out the construction of the ancillary facilities of the new bridge, and then perform secondary tensioning of the stay cables to complete the construction of the new bridge.

[0019] Furthermore, the bridge tower has a herringbone structure.

[0020] Furthermore, when the old bridge includes a main bridge in the middle and approach bridges at both ends, the bridge tower is installed above the main bridge of the old bridge.

[0021] Furthermore, in step S2, the main beams of the corresponding main bridge sections of the new bridge are hoisted onto both sides of the bridge tower. The height of the main beams of the new bridge is higher than that of the main bridge of the old bridge. Then, several first crossbeams connecting the two main beams are installed between them, so that crossbeams are set in the space above the old bridge in a staggered manner to connect the newly built separate double main bridge beams located on both sides of the old bridge. In step S3, several stay cables are installed between the main beams of the main bridge on both sides and the bridge tower.

[0022] Furthermore, the steps between steps S3 and S4 include the following:

[0023] S31. The main beams of the approach bridges of the new bridge are hoisted on both sides of the approach bridge of the old bridge, and the main beams of the main bridge and the main beams of the approach bridges are joined together to form the bridge.

[0024] Furthermore, in step S1, when constructing the bridge tower, a second crossbeam is provided on the inner side of the bridge tower at the position corresponding to the main beam of the main bridge, and the second crossbeam is located above the main beam of the old bridge.

[0025] Furthermore, in step S4, the construction of the ancillary facilities includes installing sunshades between two adjacent first crossbeams and between the first and second crossbeams.

[0026] Furthermore, in step S4, the construction of ancillary facilities also includes: installing a viewing platform between the bottom of the main beam of the main bridge at the corresponding bridge tower location and the top of the main bridge of the old bridge.

[0027] Furthermore, the following steps are included after step S4:

[0028] S5. After the old bridge is demolished, a bridge deck system is laid between the main beams of the main bridge and the main beams of the approach bridge on both sides, and the laid bridge deck system is located on the first crossbeam and the second crossbeam.

[0029] Furthermore, the top surfaces of both the first and second crossbeams are lower than the top surface of the main beam of the main bridge, so that the surface of the laid bridge deck system is flush with the surface of the main beams on both sides.

[0030] The present invention has the following beneficial effects:

[0031] (1) The bridge tower structure is adopted in a span-type manner. The bridge is widened on both sides of the old bridge, and the bridge towers are set in a bifurcated manner on both sides of the old bridge. This allows the main beams on both sides of the new bridge to be tied and fixed by the same bridge tower, which effectively saves the cost and does not have a significant impact on the traffic of the old bridge during the construction process. Secondly, in view of the need to retain and utilize the existing old bridge, only motor vehicle lanes can be set on the new bridge, and the slow traffic system (such as pedestrian walkways and non-motor vehicle lanes) can be transferred to the original old bridge. This avoids investment waste and reduces the load on the old bridge to improve its service life. In addition, the new double main beams are connected by crossbeams to form an integral cross section. With the cooperation of the cable stays, the bridge has better spatial stability and better wind resistance.

[0032] (2) The construction will affect the traffic of the existing old bridge. When only the main beam of the new bridge is hoisted and erected, one lane of the old bridge needs to be temporarily closed for construction. After the crossbeam is installed, the clearance of the old bridge deck will be no less than 3.5m, which can meet the passage of passenger cars. Oversized vehicles need to detour, without interrupting the traffic of the old bridge.

[0033] (3) Renovation and upgrading of the old bridge: A viewing platform will be set up under the main beam of the new bridge at the location of the bridge tower to connect the old bridge deck and create an excellent view of the scenery on both sides; a sunshade will be set up on the old bridge to further improve pedestrian comfort and bridge landscape.

[0034] (4) The main beams of the newly built bridges on both sides adopt the design of "separated structure + crossbeam connection". In the long term, after the old bridge reaches the end of its service life or does not meet the functional requirements, the bridge deck system (which includes at least the non-motorized vehicle lane) can be laid with the crossbeams as support. The central hollow strip will be transformed into a slow-moving system and integrated with the new bridge. There is no need to rebuild the old bridge, which can save the cost and construction period of the substructure.

[0035] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of the invention. Attached Figure Description

[0036] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, do not constitute an undue limitation of the invention. In the drawings:

[0037] Figure 1 This is a schematic diagram of the construction of a single-cable-stayed bridge at the site of the original old bridge in the embodiment.

[0038] Figure 2 for Figure 1 A sectional perspective view located at the bridge tower;

[0039] Figure 3 for Figure 1 Cross-sectional view of the bridge tower;

[0040] Figure 4 This is a schematic diagram of the bridge tower in the embodiment;

[0041] Figure 5 This is a cross-sectional view of the main bridge beams on both sides after they are connected to the first cross beam in the embodiment.

[0042] Figure 6 This is a cross-sectional perspective view of another embodiment after the old bridge has been demolished and a non-motorized vehicle lane has been paved. Detailed Implementation

[0043] To better understand the technical content of the present invention, the present invention will be further introduced and described below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the use of terms such as "first" and "second" in the text is for distinguishing different components, and does not represent the order of events, nor does it limit "first" and "second" to different types.

[0044] In the description of this invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0045] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0046] Example 1

[0047] In a specific implementation case, the original old bridge's main span was a T-shaped steel structure bridge with a span of (65+100+65)m, meaning there were four piers 102 under the main span, with the spans between the four piers distributed in the pattern of (65+100+65)m. The bridge was 11.5m wide and had two lanes in both directions. Approach bridges 101 were also provided at both ends of the original old bridge's main span, with the piers under the approach bridges spaced 30m apart. The distance between the main bridge piers and the approach bridge piers was also 30m. The main span of the newly built bridge after the renovation was a single-cable-stayed bridge with a separated flat streamlined steel box girder of (165+125)m. That is, the main span lengths on both sides of the bridge tower were 165m and 125m respectively, and they were tensioned by cable stays, forming an asymmetrical cable-stayed bridge structure. The new bridge width was 19+13.5+19=51.5m, where 13.5m was the width occupied by the old bridge and 19m was the width of the main beam on one side of the new bridge.

[0048] Specifically, the old bridge staggered widening design method shown in this embodiment includes the following steps:

[0049] Construction will involve building a new bridge tower 1 spanning above the existing main bridge (e.g., Figure 1-3As shown), the bridge tower 1 is aligned with the axis of one of the piers below the original main bridge 100. The specific construction process of the bridge tower is as follows: first, a trestle bridge and steel platform are erected for construction, and then the pile foundations of the new main bridge and approach bridge are constructed on both sides of the original old bridge. The steel cofferdam is used to construct the pier cap. CNC steel formwork is used to pour concrete for the lower tower column (i.e., the bifurcated part at the lower end) at the lower end of the bridge tower 1. The bifurcated lower tower column is set on both sides of the original main bridge. Temporary piers are set on the original main bridge 100 to install the upper tower column at the upper end of the bridge tower 1 and the second crossbeam 2 for connecting the two bifurcations at the lower end. The second crossbeam 2 is located above the original main bridge 100 to improve the rigidity of the bridge tower and provide support for the newly built main beams on both sides of the bridge tower. After the second crossbeam is installed, the clear height of the original main bridge deck is not less than 3.5m, which can meet the passage of small passenger cars. Oversized vehicles need to detour, so as not to interrupt the traffic of the old bridge.

[0050] In the above, bridge tower 1 has a herringbone structure.

[0051] In one embodiment, the bridge tower 1 is a four-sided hyperbolic and double-straight variable cross-section concrete-steel tower with a height of 63m above the bridge deck and a total tower height of 98m. The lower tower column adopts a C50 concrete box structure, while the tower beam fixed part and the upper tower column above the bridge deck adopt a Q420qD steel box structure for easy construction. The cross-sectional dimensions of the bridge tower gradually decrease from the bottom to the top, with dimensions of 7.5x5m at the bottom and 3x1.5m at the top. The steel box structure in the bridge tower is made of steel plates with a thickness of 28~46mm.

[0052] Using floating cranes, the main beams 3 of the corresponding main bridge sections of the new bridge are first hoisted onto both sides of bridge tower 1, forming two separate main beam structures, each serving as a one-way bridge for single-sided traffic. The height of these main beams 3 is 100 mm higher than the original main bridge to avoid affecting the passage of the original main bridge. Then, several first crossbeams 6 (such as...) are installed between the two main beams, connecting them and spaced apart. Figure 2-5 As shown), the first crossbeam 6 is located above the original main bridge 100, and after the first crossbeam 6 is installed, the net height of the original main bridge 100 is not less than 3.5m, which can meet the passage of passenger cars. Oversized vehicles need to detour, without interrupting the traffic of the old bridge. Thus, the crossbeam is set in the space above the old bridge in a staggered manner to connect the main beams of the newly built separated double main bridge located on both sides of the old bridge.

[0053] In the above, the inner side of the main beam 3 of the main bridge is reserved with several steel structural components (not shown in the figure) for connection along the road extension direction during the manufacturing process, and the two ends of the first crossbeam 6 are fixed to the steel structural components on the two main beams respectively.

[0054] In the above, the height of the second crossbeam 2 corresponds to the height of the main beam 3 of the main bridge.

[0055] Several stay cables 4 (such as...) are installed on the inner side of the main girder 3 on both sides of the bridge and between the bridge tower 1. Figure 1 and 2 As shown in the figure, the cable 4 was initially tensioned.

[0056] In the above, the stay cable 4 uses hot-dip galvanized steel wire with a standard strength of 1670MPa and a diameter of 7mm.

[0057] In the above, the stay cables 4 are tensioned only between the inner surface of the main girder 3 of the main bridge and the bridge tower 1. Each main girder 3 of the main bridge is tensioned with ten pairs of stay cables 4, which are distributed on both sides of the front and rear end faces of the bridge tower 1. Therefore, a total of twenty pairs of stay cables 4 are set between the two main girder 3 of the main bridge and the bridge tower 1.

[0058] Then, on both sides of the approach bridge 101 of the old bridge, hoist the corresponding approach bridge main beams 5 of the new bridge (e.g., Figure 2 As shown in the figure, the main beams 3 on both sides of the main bridge and the main beams 5 of the approach bridge on the corresponding sides are joined together to form a bridge.

[0059] In the above, both the main girder 3 of the main bridge and the main girder 5 of the approach bridge adopt a streamlined flat steel box girder structure and are made of Q370qD steel.

[0060] Preferably, the steel box girder of the main bridge main girder 3 and the approach bridge main girder 5 has a top plate thickness of 20~36mm, a bottom plate thickness of 24~32mm, and a web plate thickness of 20mm. The top plate adopts U-shaped stiffening ribs, and the bottom plate and web plate adopt plate stiffening ribs with a lateral spacing of 550mm. A solid web strong transverse diaphragm is set every 6m in the box girder, and a frame weak transverse diaphragm is set every 2m between the strong transverse diaphragms.

[0061] In the above, the inner side of the main beam 5 of the approach bridge also has several steel structural components reserved for connection along the road extension direction during the manufacturing process (not shown in the figure).

[0062] Construction of the new bridge's ancillary facilities was carried out, followed by secondary tensioning of cable-stayed bridge 4, adjustment of the overall bridge alignment and internal forces, and completion of the new bridge construction, forming a single-cable-stayed bridge with left and right separation.

[0063] The construction of ancillary facilities mentioned above includes: installation of railings, lighting facilities, paved roads, and sunshades 7, specifically, the installation of sunshades 7 between two adjacent first crossbeams 6 and between the first crossbeam 6 and the second crossbeam 2 (e.g., Figure 2 As shown in the image, this enhances the comfort of slow-moving pedestrians and improves the landscape.

[0064] In one embodiment, the sunshade is made of perforated steel plate.

[0065] In one embodiment, the construction of the ancillary facilities also includes: installing the viewing platform 8 (such as...). Figure 1-3As shown in the figure, specifically, viewing platforms 8 are installed between the bottom of the two main bridge beams 3 at the corresponding bridge tower 1 position and the top of the original main bridge 100.

[0066] Preferably, the viewing platform 8 adopts a truss structure and the outer wall is made of three layers of laminated tempered glass.

[0067] In another embodiment, when the existing old bridge reaches the end of its service life in the future, it needs to be demolished. After the old bridge is demolished, at least a non-motorized vehicle lane 9 will be laid between the main beams 3 of the main bridge and the main beams 5 of the approach bridges on both sides. Figure 6 The bridge deck system (as shown) is such that the non-motorized vehicle lane 9 is laid on the first crossbeam 6 and the second crossbeam 2. The first crossbeam 6 and the second crossbeam 2 are used to support the non-motorized vehicle lane 9. Of course, before laying, a crossbeam connecting the two is installed between the main beams of the approach bridge on both sides to support the non-motorized vehicle lane in the approach bridge section.

[0068] Preferably, the top surfaces of the first crossbeam 6 and the second crossbeam 2 are both lower than the top surface of the main beam 3 of the main bridge, that is, the height for laying the non-motorized vehicle lane 9 is reserved so that the surface of the laid non-motorized vehicle lane 9 is flush with the surface of the main beams on both sides.

[0069] In the above, the non-motorized vehicle lane is made of steel plate.

[0070] The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the embodiments of the present invention. The descriptions of the embodiments above are only for helping to understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for widening an existing bridge by staggered levels, the existing bridge comprising a main bridge in the middle and approach bridges at both ends, characterized in that, Includes the following steps: S1. Construct at least one new bridge tower spanning above the old bridge; the bridge tower spanning above the main span of the old bridge; a second crossbeam is provided on the inner side of the bridge tower at the position corresponding to the main beam of the main bridge, the second crossbeam being located above the main span of the old bridge; S2. First, hoist the main bridge beams of the corresponding main bridge sections of the new bridge on both sides of the bridge tower. The height of the main bridge beams is higher than that of the main bridge of the old bridge. Then, install several first crossbeams connecting the two main bridge beams on both sides, so that crossbeams are set in the space above the old bridge in a staggered manner to connect the newly built separate double main bridge beams located on both sides of the old bridge. S3. Install several stay cables between the main girder and the bridge tower on both sides of the main bridge, and perform initial tensioning on the stay cables; S31. Hoist the main beams of the approach bridges of the new bridge to the corresponding approach bridge sections on both sides of the approach bridge of the old bridge. The main beams of the main bridge and the main beams of the approach bridges are then joined together to form the bridge. S4. Carry out the construction of the ancillary facilities of the new bridge, and then perform secondary tensioning of the stay cables to complete the construction of the new bridge; S5. After the old bridge is demolished, a bridge deck system is laid between the main beams of the main bridge and the main beams of the approach bridge on both sides, and the laid bridge deck system is located on the first crossbeam and the second crossbeam.

2. The method for widening an old bridge by staggered levels as described in claim 1, characterized in that, The bridge tower has a herringbone structure.

3. The method for widening an old bridge by staggered levels as described in claim 1 or 2, characterized in that, In step S4, the construction of ancillary facilities also includes: installing a viewing platform between the bottom of the main beam of the main bridge at the corresponding bridge tower location and the top of the main bridge of the old bridge.

4. The method for widening an old bridge by staggered levels as described in claim 3, characterized in that, The top surfaces of the first and second crossbeams are both lower than the top surface of the main beam of the main bridge, so that the surface of the laid bridge deck system is flush with the surface of the main beams on both sides.

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