Construction method of steel box girder of pedestrian cable-stayed bridge
By using temporary piers on land and water and irregular structural design in pedestrian cable-stayed bridges, combined with segmented hoisting and reverse assembly methods, the problems of large weight of steel box girders and numerous piers in river crossing construction were solved, achieving safe and economical construction results.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CCCC FOURTH HARBOR ENG CO LTD
- Filing Date
- 2026-05-07
- Publication Date
- 2026-06-09
AI Technical Summary
In pedestrian cable-stayed bridges constructed across rivers, traditional steel box girder structures are heavy and have long spans, resulting in a large number of piers that affect aesthetics and river operation. The key is to install steel box girders and reduce their weight when the number of piers is limited.
The construction method employs temporary supports on land and water, combined with irregular structural design and segmented hoisting. It utilizes a combination of factory prefabrication and on-site assembly, employing an irregular structural design with varying sizes to reduce the self-weight of the steel box girder, and improves manufacturing precision and safety through reverse assembly.
The number of permanent piers was reduced, the self-weight of the steel box girder was lowered, construction safety and progress were improved, the needs of segmented construction were met, and the view and construction quality were optimized.
Smart Images
Figure CN122169443A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of bridge construction technology, and in particular to a construction method for a steel box girder of a pedestrian cable-stayed bridge. Background Technology
[0002] Pedestrian cable-stayed bridges are a type of bridge designed for pedestrian use. Compared to highway bridges for vehicles, they place greater emphasis on lightweight design, aesthetics, and pedestrian comfort. To meet the lightweight design requirements of pedestrian cable-stayed bridges, traditional concrete structures are no longer the first choice, and steel box girder structures have become the mainstream option. However, the construction of steel box girder pedestrian cable-stayed bridges typically faces the following challenges: I. For pedestrian cable-stayed bridges constructed across river channels, when the span is relatively long, especially when the main span is greater than 100m, building permanent piers in the river channel not only affects the aesthetics of the pedestrian cable-stayed bridge, but also affects the operation of the river channel. Second, although the steel box girder structure generally reduces the weight of the pedestrian cable-stayed bridge compared with the traditional concrete structure, the traditional steel box girder is relatively square (the left and right structure is relatively symmetrical). In order to meet the needs of pedestrians for passage and sightseeing, the width of the top plate of the steel box girder is generally 4m-10m, which makes the traditional steel box girder itself quite heavy. Therefore, how to install steel box girders with a limited number of piers, and how to further reduce their weight under the traditional steel box girder structure, have become the key to the construction of pedestrian cable-stayed bridges. Summary of the Invention
[0003] One of the objectives of this invention is, at least, to provide a construction method for a steel box girder of a pedestrian cable-stayed bridge, addressing the problems existing in the prior art. This method satisfies the need for segmented construction of the steel box girder by erecting temporary land and water supports, and reduces the self-weight of the steel box girder by optimizing its structure and adopting an irregularly shaped structure with large and small ends.
[0004] To achieve the above objectives, the technical solution adopted by the present invention includes the following aspects.
[0005] A construction method for a steel box girder of a pedestrian cable-stayed bridge includes a main bridge and approach bridges located near one end of the main bridge. The main bridge is assembled from multiple steel box girder segments, and the approach bridges are assembled from multiple steel box girder segments. After the main bridge steel box girder construction is completed, the girder is sequentially lowered from north to south onto abutments P1, P2, P3, P4, and P5. After the approach bridge steel box girder construction is completed, the girder is sequentially lowered from east to west onto abutments P7, P6, and P3. Preparatory work has been completed before the steel box girder construction. The steel box girder is constructed using a combination of factory prefabrication and on-site assembly. The method is characterized by the following steps: Step A: Fabricate steel box girders. The main bridge steel box girders include two forms: standard cross-section and variable cross-section. The standard cross-section is the standard section, and the variable cross-section is the widened section. Both the standard section and the widened section include multiple independently hoisted beam segments. Step B involves erecting multiple sets of temporary supports, including land-based and water-based temporary supports. Each set of temporary supports includes steel pipe piles, horizontal bracing between pipe piles, scissor bracing, pile top beams, and load-adjusting short columns. Step C: The steel box girders are hoisted in sections, with the main bridge steel box girders and approach bridge steel box girders being hoisted in sequence. Step D: The steel box girder is precisely positioned and welded to the supports arranged on the cap beam of the pier. Step E: Inspect the welds and apply the anti-corrosion coating; Step F: Inspect and accept the work, and remove the temporary supports after the overall bridge construction is completed.
[0006] Preferably, in step A, the steel box girder is assembled using the reverse assembly method. The main bridge uses seventeen main bridge steel box girder segments as beam segments, from north to south, namely beam segments Y1 to Y17. Among them, beam segments Y1 to Y5 and beam segments Y11 to Y17 are standard segments, each consisting of three independently hoisted beam segments, including beam segment A, beam segment B1, and beam segment B2. Among them, beam segments Y6 to Y10 are widening segments, each consisting of four independently hoisted beam segments, including beam segment A, beam segment B1, beam segment B2, and beam segment C. The approach bridge uses three approach bridge steel box girder segments as beam segments, from east to west, namely beam segment Z1, beam segment Z2, and beam segment Z3.
[0007] Preferably, in step B, sixteen sets of temporary supports are erected at the main bridge, namely temporary supports YD1~YD16 from north to south. Temporary supports YD1~YD6 and temporary supports YD11~YD16 are all land-based temporary supports, and temporary supports YD7~YD10 are all water-based temporary supports. Two sets of land-based temporary supports are erected at the approach bridge, namely temporary supports ZD1 and temporary supports ZD2 from east to west.
[0008] Preferably, in step B, the four steel pipe piles are respectively arranged at the four corners of the rectangle; multiple sets of horizontal bracing between the pipe piles are arranged side by side along the length of the steel pipe piles, with each horizontal bracing between two adjacent steel pipe piles; the scissor bracing is arranged between two sets of horizontal bracing near the top of the steel pipe piles; two pile top beams are arranged on the top of the steel pipe piles, with each pile top beam arranged on top of two steel pipe piles arranged side by side along the width of the bridge; multiple load-adjusting short columns are arranged on the top of each pile top beam, the height of which is adjusted according to the slope of the bridge, and each load-adjusting short column is provided with diagonal bracing.
[0009] Preferably, in step B, the temporary land support is erected on the soil foundation on both the north and south banks using strip foundations. The strip foundations are reinforced concrete structures, and the ground was treated before pouring. The steel pipe piles of the temporary land support are connected to the strip foundations using expansion bolts. The temporary water support is located in the river channel. When erecting the temporary water support, depending on the location of the original steel trestle bridge and the type of pile foundation, a crawler crane and a vibratory hammer are used to drive steel pipe piles. When the effective depth h of the steel pipe pile is less than 5m, a pilot hole method is adopted, and the pilot hole depth h' is not less than 4m. When the effective depth h of the steel pipe pile is greater than 5m, a vibratory pile driving method is adopted.
[0010] Preferably, in step B, when the steel pipe piles are extended, the upper and lower sections of the steel pipe piles are precisely aligned and then welded together. Four stiffening steel plates are symmetrically welded at the connection between the upper and lower sections of the steel pipe piles. During welding, the stiffening steel plates are made to fit tightly against the outer wall of the steel pipe pile. The pile driving continues only after the welding quality between the upper and lower sections of the steel pipe piles has been inspected and found to be qualified.
[0011] Preferably, in step C, when hoisting the main bridge steel box girder, girder segments Y1 to Y13 are hoisted sequentially from north to south, and girder segments Y17 to Y14 are hoisted sequentially from south to north. After girder segment Y2 is hoisted into place, it is assembled using girder segment Y1 as a reference and welded to girder segment Y1. After girder segment Y3 is hoisted into place, it is not welded to girder segment Y2. After girder segment Y4 is hoisted into place, it is assembled using girder segment Y3 as a reference and welded to girder segment Y3. After beam segments Y5 to Y13 are hoisted into place, they are welded to the previous beam segments that have already been welded. After beam segment Y16 is hoisted into place, it is assembled with beam segment Y17 as the reference and welded to beam segment Y17. After beam segments Y15 and Y14 are hoisted into place, they are welded to the previous beam segments that have already been welded. When hoisting the steel box girder of the approach bridge, beam segments Z1 to Z3 are assembled and welded from east to west.
[0012] Preferably, in step C, when hoisting each segment of the main bridge steel box girder, traction ropes are fixed at both ends of each segment before hoisting. After the front and rear segments of each segment are hoisted into place, temporary fixing is performed using a support plate. The hoisting process of segment Y1 includes: Step C1: Hoist beam A so that one end of beam A is fixed to a support structure of bridge abutment P1, and the other end of beam A is located on the two adjustable load short columns corresponding to temporary pier YD1. Step C2: Hoist beam B1 so that one end of beam B1 is fixed to another support structure of bridge abutment P1, and the other end of beam B1 is located on a short adjustable load column corresponding to temporary pier YD1. Step C3: Temporarily fix beam A and beam B1 using a support plate. The support plate is located on top of beam A and beam B1 and is set up side by side along the length of the main bridge. Step C4: Hoist beam B2. Beams B1 and B2 are also temporarily fixed using a support plate. Step C5: Weld beam A, beam B1, and beam B2 to form a whole; When hoisting the widened section, after beam A and beam B1 are hoisted into place, the bottom of the steel box girder is welded to the short column for adjusting the load. When beam C is installed, the crane hook is kept in place. After the welding plate is fixed and cooled for no less than 1 hour, the longitudinal and transverse welds of the top plate of the steel box girder are welded.
[0013] Preferably, in step D, two anti-pull points and two limiting plates are arranged on the top surface of the cap beam of the pier, and jacks and hand-operated hoists are used for precise lateral and longitudinal positioning. The anti-pull points are pre-reserved steel bars, and the limiting plates are triangular bracket components welded to pre-embedded steel plates on the cap beam. The limiting plates include lateral limiting plates and longitudinal limiting plates. The top of the jack is equipped with sliders and pads, and the pads are fixed to the jacks. A steel plate for installing hand-operated hoists is provided at the bottom of the steel box girder. One end of each of the two hand-operated hoists is connected to the two anti-pull points, and the other end is connected to the corresponding steel plate. Two limiting baffles for precise lateral and longitudinal positioning are also provided at the bottom of the steel box girder.
[0014] Preferably, in step D, the support is an adjustable support. When the distance between the top surface of the support and the bottom of the steel box girder is 2-5cm, precise positioning is performed. After positioning, the height of the support is adjusted so that the top surface of the support is welded to the bottom of the steel box girder, and the adjustment jack and hand-operated hoist are unloaded.
[0015] In summary, by adopting the above technical solution, the present invention has at least the following beneficial effects: 1. The construction method of the steel box girder of this pedestrian cable-stayed bridge meets the needs of segmented construction of the steel box girder by erecting temporary piers on land and water. Finally, the girder is lowered onto piers not on the river channel, which ensures construction safety and quality while reducing the number of permanent piers and saving construction costs. By optimizing the structure of the steel box girder and adopting an irregular structure design with large and small ends, the self-weight of the steel box girder is reduced. The design of combining standard and widened sections improves the view while further reducing the self-weight of the steel box girder. 2. The irregularly shaped steel box girder uses multiple independently hoisted beam segments, which are installed sequentially, thus improving construction safety compared to the monolithic structural design. 3. By adapting to local conditions, the original steel trestle bridge was used as part of the transportation road and as part of the hoisting area, which reduced the difficulty of construction and accelerated the construction progress. 4. The steel box girder is assembled using the reverse assembly method. The reverse assembly method can control the lateral assembly accuracy and reduce the construction difficulty. The bottom plate of the steel box girder is curved and needs to be rolled by a plate rolling machine. The amount of butt joints is large. The reverse assembly method can not only change the welding position, thereby greatly reducing the welding difficulty, but also greatly improve the manufacturing progress and manufacturing accuracy. Attached Figure Description
[0016] Figure 1 This is a construction plan layout diagram of the pedestrian cable-stayed bridge of the present invention.
[0017] Figure 2 This is an elevation layout diagram of the main bridge of the pedestrian cable-stayed bridge of the present invention.
[0018] Figure 3 This is a plan view of the approach bridge of the pedestrian cable-stayed bridge of the present invention.
[0019] Figure 4 This invention relates to a construction flowchart for the steel box girder of a pedestrian cable-stayed bridge.
[0020] Figure 5 This is a transverse segmentation diagram of the standard section of the main bridge's steel box girder.
[0021] Figure 6 This is a transverse segmentation diagram of the widened section of the main bridge's steel box girder.
[0022] Figure 7 This is a detailed drawing of the longitudinal interface of the land-based beams of the main bridge.
[0023] Figure 8 This is a detailed drawing of the longitudinal interface of the main bridge's underwater beams.
[0024] Figure 9 This is a cross-sectional view of the temporary land-based support pier for the main bridge.
[0025] Figure 10 This is a cross-sectional view of the temporary underwater support pier for the main bridge.
[0026] Figure 11 This is a cross-sectional view of the temporary support pier for the widened section.
[0027] Figure 12 This is a cross-sectional view of the temporary land support pier for the approach bridge.
[0028] Figure 13 This is a schematic diagram of steel pipe pile extension.
[0029] Figure 14 This is a schematic diagram of the pier adjustment points for a steel box girder bridge.
[0030] Figure 15 This is a schematic diagram of the longitudinal adjustment of a steel box girder bridge.
[0031] Figure 16 This is a schematic diagram of the lateral adjustment of a steel box girder bridge.
[0032] Figure 17 This is a schematic diagram of the hoisting of beam segment A.
[0033] Figure 18 This is a schematic diagram of the hoisting of beam segment B1.
[0034] Figure 19 This is a schematic diagram of the hoisting of beam segment B2.
[0035] Figure 20 This is a schematic diagram of the hoisting of beam segment C.
[0036] Figure 21 This is a cross-sectional view of the main bridge's steel box girder pier.
[0037] The markings in the diagram are: 1-Steel pipe pile, 2-Horizontal bracing between pipe piles, 3-Scissors brace, 4-Pile top beam, 5-Short column for adjusting load, 6-Diagonal brace, 7-Strip foundation, 8-Stiffening steel plate, 9-Cap beam, 10-Support, 11-Tension point, 12-Limiting plate, 13-Hand chain hoist, 14-Steel plate, 15-Jack, 16-Platelet, 17-Limiting baffle. Detailed Implementation
[0038] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, so that the objectives, technical solutions, and advantages of the present invention will be clearer. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.
[0039] In the description of this invention, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the accompanying drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances. Example
[0040] This embodiment provides a construction method for a steel box girder of a pedestrian cable-stayed bridge. Taking an ongoing pedestrian cable-stayed bridge project as an example, the bridge is 249.9m long, including a main bridge and approach bridges near one end of the main bridge. The main bridge is 182.5m long, with a span arrangement of (24+102+2*24)m, a bridge deck width of 6-9m, and a single-column, single-tower spatial cable-stayed structure. The highest point of the bridge deck is at an elevation of 181.8m, and the vertical curve radius is 600m. The bridge adopts a variable longitudinal slope with a gradient of -8.0% to 3.3%. In plan view, the entire bridge is arranged in a circular curve with a curve radius of 340m. The approach bridge is 67.4m long with a span arrangement of (2*32)m. The bridge deck is 3.5m wide and the structural form is a continuous steel box girder bridge. The highest point of the bridge deck is located at the starting point with an elevation of 181.385m and a vertical curve radius of 50m. It adopts a single longitudinal slope with a gradient of 8.0%. In plan view, the entire bridge is arranged in a circular curve with a curve radius of 80m.
[0041] The project mainly includes the construction of steel box girders, inclined tower columns, and cable stays. This embodiment focuses on the construction of the steel box girders, where the main bridge is assembled from multiple main bridge steel box girder segments, and the approach bridges are assembled from multiple approach bridge steel box girder segments. (Refer to...) Figures 1-3 After the main bridge steel box girder is constructed, it is placed on two abutments and three piers. The two abutments are located at both ends of the main bridge, and the three piers are located between the two abutments. From north to south, they are abutment P1, pier P2, pier P3, pier P4, and abutment P5. After the approach bridge steel box girder is constructed, it is placed on piers P3, P6, and P7. Piers P3 and P7 are located at both ends of the approach bridge, and pier P6 is located between piers P3 and P7. From east to west, they are abutment P7, pier P6, and pier P3.
[0042] Before the construction of the steel box girder, preliminary preparations were completed, such as the construction of bridge abutments and piers, the leveling of the construction site, the preparation of the hoisting area and the preparation of the transportation roads. The hoisting area includes the island platforms on the north and south banks and the steel trestle bridges (the island platforms are temporary concrete roads, and the steel trestle bridges are passageways built on the original river channel). The hoisting area for the main bridge steel box girder consists of the island platforms on the north and south banks and the steel trestle bridges, while the hoisting area for the approach bridge steel box girder is the island platform on the south bank. The transportation roads include earth-filled access roads and steel trestle bridges.
[0043] The steel box girders are constructed using a combination of factory prefabrication and on-site assembly. Figure 4 The diagram illustrates the construction process of a steel box girder for a pedestrian cable-stayed bridge. The construction method for the steel box girder of a pedestrian cable-stayed bridge includes the following steps: Step A: Fabricate the steel box girder. The main bridge steel box girder includes two forms: standard cross-section and variable cross-section. The standard cross-section is the standard segment, and the variable cross-section is the widened segment. Both the standard segment and the widened segment consist of multiple independently hoisted beam segments; (Refer to...) Figure 1 , Figure 2 , Figure 5 and Figure 6 The main bridge is divided into seventeen spans, assembled from seventeen steel box girders, numbered Y1 to Y17 from north to south. Segments Y1 to Y5 and Y11 to Y17 are standard sections with a cross-sectional width of 6m, each consisting of three independently hoisted beams: beam A, beam B1, and beam B2. Segments Y6 to Y10 are widened sections with variable cross-sections, ranging from 6m to 9m in width (changing in the order of 6m-9m-6m). These widened sections consist of four independently hoisted beams: beam A, beam B1, beam B2, and beam C. (Reference) Figure 1 and Figure 3 The approach bridge is divided into three spans, which are assembled from three steel box girders, namely Z1, Z2 and Z3 from east to west. Each steel box girder is assembled using the reverse assembly method (i.e., the bottom is facing up). The reverse assembly method can control the lateral assembly accuracy and reduce the construction difficulty. The bottom plate of the steel box girder is curved and needs to be rolled by a plate rolling machine. The amount of butt joints is large. The reverse assembly method can not only change the welding position to greatly reduce the welding difficulty, but also greatly improve the manufacturing progress and manufacturing accuracy. Step B involves erecting multiple sets of temporary supports, including land-based and water-based temporary supports. Each set of temporary supports includes steel pipe piles 1, horizontal bracing between pipe piles 2, scissor bracing 3, pile top beams 4, and load-adjusting short columns 5; (Refer to...) Figures 1-3 In this embodiment, a total of eighteen sets of temporary supports are erected. Sixteen sets of temporary supports are erected at the main bridge, from north to south: temporary supports YD1 to YD16. Temporary supports YD1 to YD6 and temporary supports YD11 to YD16 are all land-based temporary supports (12 sets in total), while temporary supports YD7 to YD10 are all water-based temporary supports (4 sets in total). Two sets of temporary supports are erected at the approach bridge, from east to west: temporary supports ZD1 and temporary supports ZD2. Temporary supports ZD1 and temporary supports ZD2 are both land-based temporary supports. refer to Figures 7-12The steel pipe pile 1 is made of spiral welded pipe. The horizontal bracing 2 between pipe piles, the scissor bracing 3, the pile top beam 4, and the load-adjusting short column 5 are all made of I-beams. The four steel pipe piles 1 are respectively arranged at the four corners of the rectangle. Multiple sets of horizontal bracing 2 between pipe piles are arranged side by side along the length of the steel pipe pile 1 (the number of sets of horizontal bracing 2 between pipe piles on the steel pipe pile 1 can be selected according to the height of the steel pipe pile 1). The length of the horizontal bracing 2 between pipe piles is adapted to the distance between two adjacent steel pipe piles 1. Each horizontal bracing 2 between pipe piles is arranged between two adjacent steel pipe piles 1, so that the two ends of the horizontal bracing 2 between pipe piles are fixedly connected to the two adjacent steel pipe piles 1 respectively. The scissor bracing 3 is arranged between the two sets of horizontal couplings 2 near the top of the steel pipe pile 1; the two pile top beams 4 are arranged on the top of the steel pipe pile 1, each pile top beam 4 is arranged on the top of two steel pipe piles 1 arranged side by side along the width direction of the bridge, and the length of the pile top beam 4 is greater than the distance between two adjacent steel pipe piles 1; multiple load-adjusting short columns 5 are arranged on the top of each pile top beam 4, the height of the load-adjusting short columns 5 is adjusted according to the slope of the bridge, and each load-adjusting short column 5 is provided with a diagonal brace 6, which is located at the connection between the load-adjusting short column 5 and the pile top beam 4, and the diagonal brace 6 is made of I-beams; In this embodiment, the steel pipe pile 1 is made of spiral welded pipe with a diameter of 529mm and a wall thickness of 10mm. The spacing between two adjacent steel pipe piles 1 is 2m, and the height of the steel pipe pile 1 is 3-5m (after installation, the verticality deviation of a single section of the steel pipe pile 1 is less than H / 1000 and not greater than 10mm, and the overall verticality deviation of the steel pipe pile 1 is not greater than 35mm, where H is the height of a single section of the steel pipe pile 1). The horizontal bracing 2 between the pipe piles is made of 25B type I-beams. When the height of the steel pipe pile 1 is 3m, only one set of horizontal bracing 2 between the pipe piles can be installed on the steel pipe pile 1, and this horizontal bracing 2 between the pipe piles can be installed close to the top of the steel pipe pile 1 (at this time, the shear bracing 3 is not required). When the height of the steel pipe pile 1 exceeds 3m, in addition to the two sets of horizontal bracing 2 between the pipe piles located at the shear bracing 3, one or more sets of pipe piles can be added below it. The scissor brace 3 and the pile top beam 4 are made of 25B type I-beams; the load-adjusting short column 5 is made of 14 type I-beams; each pile top beam 4 of the temporary support at the main bridge location is provided with three load-adjusting short columns 5, namely the first load-adjusting short column, the second load-adjusting short column and the third load-adjusting short column, wherein the first load-adjusting short column is a group and is used to place beam segment B1, the second load-adjusting short column and the third load-adjusting short column are a group and are used to place beam segment A; each pile top beam 4 of the temporary support at the approach bridge location is provided with two load-adjusting short columns 5, namely the fourth load-adjusting short column and the fifth load-adjusting short column (the fourth load-adjusting short column and the fifth load-adjusting short column are each a group); the diagonal brace 6 is made of 14 type I-beams; refer to Figure 7 , Figure 9 and Figure 12 The temporary land support is erected on the soil foundation on the north and south banks via strip foundations 7. The strip foundations 7 are reinforced concrete structures (in this embodiment, the dimensions of the strip foundations 7 are 3m long * 3m wide * 0.5m thick). The foundation was treated before the strip foundations 7 were poured (by removing the loose planting soil layer and excavating down to the original soil). The steel pipe piles 1 of the temporary land support are connected to the strip foundations 7 by expansion bolts, such as using multiple expansion bolts with a diameter of 14mm and a length of 100mm. The temporary supports are located in the river channel (the bearing capacity of the foundation in the river channel is sufficient to meet the construction requirements). When erecting the temporary supports, depending on the location of the original steel trestle bridge and the type of pile foundation, a crawler crane and a vibratory hammer are used to drive steel pipe piles 1 (e.g., a 75T crawler crane and a DZ90 vibratory hammer are used). After measuring and confirming that the verticality of the pile position meets the requirements, the vibratory hammer is started to vibrate. During the vibration process, the verticality of the pile position is continuously monitored and corrected in time. After the construction of the steel pipe piles 1 of each temporary support is completed, the horizontal bracing 2 between the pipe piles, the shear bracing 3, and the pile top beam 4 are immediately constructed. When constructing the temporary supports, if the effective depth h of the steel pipe pile 1 is less than 5m, a pre-drilling method is adopted (or a pile driving method can be adopted), and the pre-drilling depth h' is not less than 4m. If the effective depth h of the steel pipe pile 1 is greater than 5m, a vibratory pile driving method is adopted (the hammer stopping standard is controlled by the penetration, continuous vibratory driving for 3 minutes, and the penetration in the last minute is not greater than 1cm). Figure 13 When extending the steel pipe pile 1, the upper and lower sections of the steel pipe pile 1 are precisely aligned and then welded together. Four stiffening steel plates 8 are symmetrically welded to the connection between the upper and lower sections of the steel pipe pile 1. During welding, the stiffening steel plates 8 are made of steel plates with dimensions of 200mm in length, 150mm in width, and 10mm in thickness. The pile driving will continue only after the welding quality between the upper and lower sections of the steel pipe pile 1 has been inspected and approved. Step C: Segmented hoisting of the steel box girders. The main bridge steel box girders and approach bridge steel box girders are hoisted sequentially using truck cranes (the rated power of the truck cranes must be greater than the weight of the steel box girders; for example, a truck crane with a rated power of 75T is used to hoist the main bridge steel box girders, and a truck crane with a rated power of 100T is used to hoist the approach bridge steel box girders). Before hoisting, scaffolding and working platforms have been erected at each abutment, pier, and temporary support. Two support structures are set up on each abutment (the two support structures on abutment P1 are used to fix beam segments A and B1 of beam segment Y1 respectively; the two support structures on abutment P5 are used to fix beam segments A and B1 of beam segment Y17 respectively; the two support structures on abutment P7 are used to fix beam segment Z1). Two support structures for fixing beam segment Z3 are set up on the cap beam of pier P3 near pier P6. When hoisting the main bridge steel box girder, girder segments Y1 to Y13 are hoisted sequentially from north to south, and girder segments Y17 to Y14 are hoisted sequentially from south to north. After girder segment Y2 is hoisted into place, it is assembled using girder segment Y1 as a reference (no further precise repositioning is required) and welded to girder segment Y1. After girder segment Y3 is hoisted into place, it is not welded to girder segment Y2. After girder segment Y4 is hoisted into place, it is assembled using girder segment Y3 as a reference and welded to girder segment Y3. After welding is completed, beam segments Y5 to Y13 are hoisted into place and then welded to the previously welded beam segments. Beam segment Y16 is hoisted into place and then assembled using beam segment Y17 as a reference, and then welded to beam segment Y17. Beam segments Y15 and Y14 are hoisted into place and then welded to the previously welded beam segments. When hoisting the approach bridge steel box girder, beam segments Z1 to Z3 are assembled and welded sequentially from east to west. When hoisting the steel box girder segments of the main bridge, standard segments A, B1, and B2 are hoisted sequentially, while widened segments A, B1, B2, and C are hoisted sequentially. Before hoisting each segment, traction ropes are fixed to both ends of the segment. After the preceding and following segments of each segment are in place, temporary fixation is achieved using a 16-inch support plate (see reference). Figures 17-20 This explanation uses the hoisting beam segment Y1 as an example. Figures 17-19 This includes the following steps: Step C1: Hoist beam A so that one end of beam A is fixed to a support structure of bridge abutment P1, and the other end of beam A is located on the two adjusting load short columns 5 corresponding to temporary pier YD1. The adjusting load short columns 5 are close to bridge abutment P1. Step C2: Hoist beam B1 so that one end of beam B1 is fixed to another support structure of bridge abutment P1, and the other end of beam B1 is located on a short adjustable load column 5 corresponding to temporary pier YD1. The short adjustable load column 5 is close to bridge abutment P1. Step C3: Temporarily fix beam A and beam B1 using mounting plate 16. Mounting plate 16 is located on top of beam A and beam B1 and is set up side by side along the length of the main bridge (the standard spacing between adjacent mounting plates 16 is 40cm). Mounting plate 16 is made of Q355C steel plate with dimensions of 600mm long * 200mm wide * 16mm thick. Step C4: Hoist beam B2. Beams B1 and B2 are also temporarily fixed using the mortise and tenon joint 16. Step C5: Weld beam A, beam B1, and beam B2 to form a whole; Furthermore, to prevent the steel box girder from overturning during the hoisting of the widened section, after beam A and beam B1 are hoisted into place, the bottom of the steel box girder is welded to the short column 5 for adjusting the load. When beam C is installed, the crane hook is kept in place. After the mast plate 16 is welded and fixed and cooled for no less than 1 hour, the longitudinal and transverse welds of the top plate of the steel box girder are welded. Step D involves precisely positioning the steel box girder and welding it to the support 10 located on the cap beam 9 of the pier; (Refer to...) Figures 14-16 and Figure 21 The bridge pier's cap beam 9 is constructed using two anti-pull points 11 and two limiting plates 12 (including a transverse limiting plate and a longitudinal limiting plate) arranged on its top surface. These are combined with a jack 15 and a hand-operated hoist 13 for precise transverse and longitudinal positioning (e.g., using a 2t rated power hand-operated hoist 13). The anti-pull points 11 are pre-reserved reinforcing bars (e.g., 25mm diameter bars). The limiting plates 12 are triangular bracket components made of 25A I-beams. The limiting plates 12 are welded to pre-embedded steel plates embedded in the cap beam 9. The jack 15 has sliders and pads on its top, with the pads fixed to the jack 15. The bottom of the steel box girder is provided with steel plates 14 for installing hand-operated hoists 13. Mounting holes are provided on the steel plates 14. Two steel plates 14 are used for precise lateral adjustment, and the other two are used for precise longitudinal adjustment. One end of each of the two hand-operated hoists 13 is connected to one of the two anti-pull points 11, and the other end of each hand-operated hoist 13 is connected to the corresponding steel plate 14. The bottom of the steel box girder is also provided with two limiting baffles 17 for precise lateral and longitudinal adjustment, respectively. The support 10 is an adjustable support. Precise adjustment is performed when the top surface of the support 10 is 2-5 cm from the bottom of the steel box girder. After adjustment, the height of the support 10 is adjusted so that the top surface of the support 10 is welded to the bottom of the steel box girder, and the adjusting jack 15 and the hand-operated hoist 13 are unloaded. Furthermore, beam segments Y3 to Y13 are precisely positioned using piers P2 and P3, beam segments Y14 to Y17 are precisely positioned using pier P4, and beam segments Z1 to Z3 are precisely positioned using pier P6. After precise positioning and welding connection with support 10, beam segments Y2 are welded to beam segment Y3, beam segments Y13 are welded to beam segment Y14, and beam segments Z3 are welded to beam segment Y13. Step E: Inspect the welds and apply the anti-corrosion coating; Step F involves inspecting and accepting the work, and then removing the temporary supports after the overall bridge construction is completed. The overall bridge construction also includes the subsequent construction of towers and stay cables.
[0044] The above description is merely a detailed illustration of specific embodiments of the present invention and is not intended to limit the invention. Various substitutions, modifications, and improvements made by those skilled in the art without departing from the principles and scope of the present invention should be included within the protection scope of the present invention.
Claims
1. A construction method for a steel box girder of a pedestrian cable-stayed bridge, comprising a main bridge and approach bridges located near one end of the main bridge. The main bridge is assembled from multiple sections of main bridge steel box girders, and the approach bridges are assembled from multiple sections of approach bridge steel box girders. After the main bridge steel box girders are constructed, they are sequentially lowered from north to south onto abutments P1, P2, P3, P4, and P5. After the approach bridge steel box girders are constructed, they are sequentially lowered from east to west onto abutments P7, P6, and P3. Preparatory work for the steel box girder construction has been completed beforehand. The steel box girders are constructed using a combination of factory prefabrication and on-site assembly. Includes the following steps: Step A: Fabricate steel box girders. The main bridge steel box girders include two forms: standard cross-section and variable cross-section. The standard cross-section is the standard section, and the variable cross-section is the widened section. Both the standard section and the widened section include multiple independently hoisted beam segments. Step B: Erect multiple sets of temporary supports, including land-based temporary supports and water-based temporary supports. Each set of temporary supports includes steel pipe piles (1), horizontal bracing between pipe piles (2), scissor bracing (3), pile top beams (4), and load-adjusting short columns (5). Step C: The steel box girders are hoisted in sections, with the main bridge steel box girders and approach bridge steel box girders being hoisted in sequence. Step D: The steel box girder is precisely positioned and welded to the support (10) arranged on the cap beam (9) of the pier. Step E: Inspect the welds and apply the anti-corrosion coating; Step F: Inspect and accept the work, and remove the temporary supports after the overall bridge construction is completed.
2. The construction method for the steel box girder of a pedestrian cable-stayed bridge according to claim 1, characterized in that, In step A, the steel box girder is assembled using the reverse assembly method. The main bridge uses seventeen main bridge steel box girder segments as beam segments, from north to south, namely beam segments Y1 to Y17. Among them, beam segments Y1 to Y5 and beam segments Y11 to Y17 are standard segments, each consisting of three independently hoisted beam segments, including beam segment A, beam segment B1, and beam segment B2. Among them, beam segments Y6 to Y10 are widening segments, each consisting of four independently hoisted beam segments, including beam segment A, beam segment B1, beam segment B2, and beam segment C. The approach bridge uses three approach bridge steel box girder segments as beam segments, from east to west, namely beam segment Z1, beam segment Z2, and beam segment Z3.
3. The construction method for the steel box girder of a pedestrian cable-stayed bridge according to claim 2, characterized in that, In step B, sixteen sets of temporary supports are erected at the main bridge, namely temporary supports YD1~YD16 from north to south. Temporary supports YD1~YD6 and temporary supports YD11~YD16 are all land-based temporary supports, while temporary supports YD7~YD10 are all water-based temporary supports. Two sets of land-based temporary supports are erected at the approach bridge, namely temporary supports ZD1 and temporary supports ZD2 from east to west.
4. The construction method for the steel box girder of a pedestrian cable-stayed bridge according to claim 3, characterized in that, In step B, the four steel pipe piles (1) of the temporary support are respectively arranged at the four corners of the rectangle; multiple sets of horizontal bracing (2) between the pipe piles are arranged side by side along the length of the steel pipe piles (1), and each horizontal bracing (2) between the pipe piles is arranged between two adjacent steel pipe piles (1); the scissor bracing (3) is arranged between two sets of horizontal bracing (2) between the pipe piles near the top of the steel pipe piles (1); two pile top beams (4) are arranged on the top of the steel pipe piles (1), and each pile top beam (4) is arranged on the top of two steel pipe piles (1) arranged side by side along the width of the bridge; multiple load-adjusting short columns (5) are arranged on the top of each pile top beam (4), and the height of the load-adjusting short columns (5) is adjusted according to the slope of the bridge, and each load-adjusting short column (5) is provided with a diagonal brace (6).
5. The construction method for the steel box girder of a pedestrian cable-stayed bridge according to claim 4, characterized in that, In step B, the land temporary support is erected on the soil foundation on the north and south banks by strip foundation (7). The strip foundation (7) is a reinforced concrete structure. The foundation was treated before the strip foundation (7) was poured. The steel pipe pile (1) of the land temporary support is connected to the strip foundation (7) by expansion bolts. The water temporary support is located in the river channel. When erecting the water temporary support, according to the location of the original steel trestle bridge and the type of pile foundation, the steel pipe pile (1) is driven by crawler crane with vibratory hammer. When the effective depth h of the steel pipe pile (1) is less than 5m, the pilot hole construction method is adopted, and the pilot hole depth h´ is not less than 4m. When the effective depth h of the steel pipe pile (1) is greater than 5m, the vibratory pile driving method is adopted.
6. The construction method for the steel box girder of a pedestrian cable-stayed bridge according to claim 5, characterized in that, In step B, when the steel pipe pile (1) is extended, the upper and lower sections of the steel pipe pile (1) are precisely aligned and then welded together. Four stiffening steel plates (8) are symmetrically welded at the connection between the upper and lower sections of the steel pipe pile (1). During welding, the stiffening steel plates (8) are made to fit tightly against the outer wall of the steel pipe pile (1). After the welding quality between the upper and lower sections of the steel pipe pile (1) is inspected and found to be qualified, the pile driving can continue.
7. The construction method for the steel box girder of a pedestrian cable-stayed bridge according to claim 2, characterized in that, In step C, when hoisting the main bridge steel box girder, beam segments Y1 to Y13 are hoisted sequentially from north to south, and beam segments Y17 to Y14 are hoisted sequentially from south to north. After beam segment Y2 is hoisted into place, it is assembled using beam segment Y1 as a reference and welded to beam segment Y1. After beam segment Y3 is hoisted into place, it is not welded to beam segment Y2. After beam segment Y4 is hoisted into place, it is assembled using beam segment Y3 as a reference and welded to beam segment Y3. After beam segments Y5 to Y13 are hoisted into place, they are welded to the previously welded beam segments. After beam segment Y16 is hoisted into place, it is assembled using beam segment Y17 as a reference and welded to beam segment Y17. After beam segments Y15 and Y14 are hoisted into place, they are welded to the previously welded beam segments. When hoisting the approach bridge steel box girder, beam segments Z1 to Z3 are assembled and welded sequentially from east to west.
8. The construction method for the steel box girder of a pedestrian cable-stayed bridge according to claim 4, characterized in that, In step C, when hoisting each segment of the main bridge steel box girder, before hoisting each segment, traction ropes are fixed at both ends of the segment. After the front and rear segments of each segment are hoisted into place, temporary fixing is performed using a support plate (16). The hoisting process of segment Y1 includes: Step C1: Hoist beam A so that one end of beam A is fixed on a support structure of bridge abutment P1, and the other end of beam A is located on the two adjustable load short columns (5) corresponding to temporary pier YD1. Step C2, hoist beam B1, fix one end of beam B1 to another support structure of bridge abutment P1, and place the other end of beam B1 on a short adjustable load column (5) corresponding to temporary pier YD1; Step C3: Use a support plate (16) to temporarily fix beam A and beam B1. The support plate (16) is located on top of beam A and beam B1 and is set up side by side along the length of the main bridge. Step C4, hoist beam B2. Beams B1 and B2 are also temporarily fixed using a support plate (16). Step C5: Weld beam A, beam B1, and beam B2 to form a whole; When hoisting the widened section, after beam A and beam B1 are hoisted into place, the bottom of the steel box girder is welded to the short column (5) for adjusting the load. When beam C is installed, the crane hook is kept in place. The mast plate (16) is welded and fixed. After cooling for no less than 1 hour, the longitudinal and transverse welds of the top plate of the steel box girder are welded.
9. The construction method for the steel box girder of a pedestrian cable-stayed bridge according to any one of claims 1 to 9, characterized in that, In step D, two anti-pull points (11) and two limiting plates (12) are arranged on the top surface of the cap beam (9) of the pier, and the jack (15) and the hand chain hoist (13) are used for precise horizontal and vertical adjustment. The anti-pull point (11) is a reserved steel bar, and the limiting plate (12) is a triangular bracket component that is welded to the pre-embedded steel plate on the cap beam (9). The limiting plate (12) includes a horizontal limiting plate and a vertical limiting plate. The top of the jack (15) is provided with a slider and a pad, and the pad is fixed to the jack (15). The bottom of the steel box beam is provided with a steel plate (14) for installing the hand chain hoist (13). One end of the two hand chain hoists (13) is connected to the two anti-pull points (11) respectively, and the other end is connected to the corresponding steel plate (14) respectively. The bottom of the steel box beam is also provided with two limiting baffles (17) for precise horizontal and vertical adjustment respectively.
10. The construction method for the steel box girder of a pedestrian cable-stayed bridge according to claim 9, characterized in that, In step D, the support (10) is an adjustable support. When the top surface of the support (10) is 2-5cm away from the bottom of the steel box girder, it is precisely adjusted. After the adjustment is completed, the height of the support (10) is adjusted so that the top surface of the support (10) is welded to the bottom of the steel box girder, and the adjustment jack (15) and the hand hoist (13) are unloaded.