A hoisting construction method for steel bridge piers under existing bridges

Abstract

The present invention discloses a construction method for hoisting steel bridge piers under an existing bridge, which relates to the technical field of bridge construction and includes the following steps: surveying the existing bridge, constructing the bearing platform, manufacturing the steel bridge piers in sections, hoisting the steel columns, hoisting the steel cantilevers, grouting the steel bridge piers, and installing the bridge deck accessory structures. Compared with the prior art, by reasonably segmenting the steel bridge piers and setting counterweights on the outer side of the steel cantilevers, the center of gravity of the present method is shifted outside the existing bridge, and the construction of the steel bridge piers of the widened bridge under the existing bridge is successfully realized. It has the remarkable advantages of convenient construction, low cost, safety and effectiveness, and solves the problem that the existing widened bridge can only build the bridge piers outside the projection of the existing bridge.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge construction, and further relates to a method for hoisting and constructing a steel bridge pier under an existing bridge. Background Art

[0002] With the increasingly congested urban traffic, widening and reconstructing existing bridges or roads is one of the ways to solve road congestion. The conventional widening and reconstruction plan is to build new bridge piers outside the existing bridge, and then construct the upper structure main beam and bridge deck system. For example, the Chinese patent "Combined Device of Widened Girder Bridge and Existing Girder Bridge" with the application number 201920904301.5 discloses a technical solution for building new bridge piers and bridge decks on the side of the original bridge. However, due to factors such as urban construction land red line restrictions during the reconstruction and expansion of some bridges or existing pipelines at the proposed location of the new bridge piers, the existing widening and reconstruction plans cannot be implemented. Therefore, a new widening and reconstruction plan is needed to place the new bridge piers under the projection of the original bridge deck, perfectly solving the problems of conflicts between construction land and existing pipelines.

[0003] However, building new bridge piers under the projection of the original bridge deck has caused a series of new problems. The main reason is that the construction clearance under the existing bridge is low, and most conventional bridge pier construction methods cannot be implemented, greatly increasing the overall construction difficulty. Therefore, before this application, there were no similar construction cases in China. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention provides a method for hoisting and constructing a steel bridge pier under an existing bridge. By reasonably segmenting the steel bridge pier and setting counterweights outside the steel cantilever, the center of gravity is shifted outside the existing bridge, successfully realizing the construction of the steel bridge pier of the widened bridge under the existing bridge. It has the remarkable advantages of convenient construction, low cost, safety and effectiveness, and solves the problem that the existing widened bridge can only build bridge piers outside the projection of the existing bridge.

[0005] To solve the above technical problems, the present invention is solved by the following technical solutions: A construction method for hoisting a steel bridge pier under an existing bridge, comprising the following steps: Step A: Survey the existing bridge to determine the projection position of the widened section steel bridge pier on the original bridge deck; Step B: Conduct the construction of the bearing platform at the position where the widened section steel bridge pier is located. During the construction of the bearing platform, embed the anchoring frame, anchor bolts and the external column base; Step C: Divide the steel bridge pier into a steel column and a steel cantilever from bottom to top. The steel column and the steel cantilever are fabricated in sections at the factory and hoisted in sections on site; Step D: When the concrete of the bearing platform reaches the design strength, chisel the concrete in the grouting layer range on the top surface of the bearing platform to expose the fresh aggregate. After cleaning the concrete surface, install the steel column bearing plate; Step E: Lay adjusting pads under the steel column bearing plate of the bearing platform to make its surface horizontal, and install leveling nuts at the bottom of the steel column bearing plate; Step F: Slowly hoist the steel column to the design position by a truck crane. Fine-tune the leveling nuts under the steel column bearing plate to make the elevation and verticality of the column accurate. Then install the anchor bolt support bracket on the anchor bolt and initially tighten it with the anchoring nut. Subsequently, pour the grouting layer under the steel column bearing plate; Step G: After the grouting layer under the steel column bearing plate reaches the design strength and cures to the specified age, tighten the anchoring nut for the second time; Step H: Prepare for the installation of the steel cantilever. Before installing the steel cantilever, a counterweight must be installed at its top to move the center of the steel cantilever to outside the original bridge deck when it is in the design position. Then lift the steel cantilever by a truck crane and slowly move it onto the steel column. During the entire hoisting process, the lifting tool of the truck crane is always outside the original bridge deck; Step I: Weld the steel cantilever and the steel column. After the welding is completed, detect all the welds. After the detection is qualified, slowly pour the core filling concrete through the reserved hole at the top of the steel cantilever. Then tie the column base steel bars and formwork to pour the external column base concrete; Step J: Seal the exposed over-welding holes and temporary construction holes of the steel bridge pier to ensure the airtightness inside the steel structure. Then install the main beam of the superstructure, construct the widened joint and the bridge deck accessory structure to complete the widened bridge.

[0006] For the above technical method, preferably, in Step C, the steel column is divided into multiple sections. In Step F, the steel columns of multiple sections are hoisted separately and welded between the steel columns.

[0007] For the above technical method, preferably, there shall be no weld seams within the range of one-fourth from the top down of the steel column, and no weld seams within the range of one-eighth from the bottom up of the steel column root.

[0008] For the above technical method, preferably, in Step H, the sum of the moments of the steel cantilever and the counterweight on the left side of the center line of gravity shall be equal to the moment of the steel cantilever on the right side of the center line of gravity.

[0009] For the above technical method, preferably, in Step H, the counterweight and the steel cantilever must be fixed by high-strength bolt connection, welding connection or bundling connection. After the steel cantilever is fixed to the steel column, the counterweight needs to be removed.

[0010] For the above technical method, preferably, in step I, equipment such as a tremie pipe or a chute is used for pouring concrete to prevent excessive height difference during placement, which may cause concrete segregation. At the same time, self-compacting concrete is used for the core filling concrete to ensure the compactness of the concrete.

[0011] For the above technical method, preferably, in step F, the steel columns are transported horizontally to the bridge location. After being lifted by a truck crane and turned over to the vertical position, they are slowly hoisted to the designed installation position.

[0012] For the above technical method, preferably, in step F, the root steel columns are hoisted first, and then the grouting layer under the bearing plate of the steel columns is poured. After the grouting layer reaches the designed strength and is cured to the specified age, the remaining steel columns except the root steel columns are hoisted.

[0013] For the above technical method, preferably, the steel columns are welded using the carbon dioxide gas shielded welding process.

[0014] The technical features of the present invention are to reasonably segment the steel bridge pier, dividing the steel bridge pier into steel columns and steel cantilevers. After separate hoisting, the weight of each individual hoisting is reduced, making it possible to hoist in a narrow space. When hoisting the steel cantilever, by adding counterweights, the center of gravity is shifted outside the existing bridge, enabling the crane to lift it without interfering with the space of the original bridge during the hoisting process, thus solving the problem of impossible hoisting construction under the bridge.

[0015] Compared with the prior art, this method reasonably segments the steel bridge pier and sets counterweights outside the steel cantilever, shifting the center of gravity outside the existing bridge, thus successfully realizing the construction of the steel bridge pier of the widened bridge under the existing bridge. It has significant advantages such as convenient construction, low cost, safety and effectiveness, and solves the problem that existing widened bridges can only build piers outside the projection of the existing bridge. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will discuss the drawings required for the description of the embodiments or the prior art. Obviously, the technical solutions described in conjunction with the drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other embodiments and their drawings can be obtained based on these embodiments shown in the drawings.

[0017] Figure 1 It is a schematic diagram of the construction steps of the bearing platform of the present invention.

[0018] Figure 2 It is a schematic diagram of step 1 of the steel column hoisting of the present invention.

[0019] Figure 3 It is a schematic diagram of step 2 of the steel column hoisting of the present invention.

[0020] Figure 4 It is a schematic diagram of the hoisting steps of the steel cantilever of the present invention.

[0021] Figure 5 It is a schematic diagram of the pouring and hoisting steps of the steel bridge pier of the present invention.

[0022] Figure 6 It is a schematic diagram of the construction steps of the superstructure of the present invention. Specific embodiments

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments described in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0024] As Figures 1 to 6 shown, a construction method for hoisting a steel bridge pier under an existing bridge includes the following steps: The steel bridge pier is divided into three segments from bottom to top, namely the bottom steel column, the middle steel column, and the steel cantilever, and the factory segmented manufacturing, on-site segmented hoisting and welding construction processes are adopted. The segment division plan needs to consider technical parameters such as the hoisting construction space and hoisting weight under the existing bridge. There shall be no weld seams on the top and bottom plates within 1 / 4 of the steel column top, and no weld seams on the top and bottom and web plates within 1 / 8 of the root, and it shall be reported to the design for confirmation before cutting and construction. The overall construction of the steel bridge pier is divided into the plate unit manufacturing segment, the segment manufacturing and pre-assembly stage, and the bridge position hoisting and welding stage. The plate unit and segment manufacturing are completed on special tooling equipment and jigs in the workshop. When processing the steel cantilever, the pre-camber needs to be considered, and the pre-camber is set according to a quadratic parabola.

[0025] When constructing the bearing platform at the bridge position, embed the anchor frame, anchor bolts and the steel bars for the concrete outside the column foot. To prevent the anchor frame and anchor bolts from loosening during concrete pouring, reliable welding fixation measures must be taken for them. After the bearing platform concrete reaches the design strength, chisel the concrete in the post-grouting layer range on the top surface of the bearing platform to expose the fresh aggregate, and clean the concrete surface. Before hoisting construction, lay adjusting pads under the bearing plate of the steel column to make its surface horizontal, which is convenient for controlling the verticality of the column.

[0026] The bottom steel column is transported to the bridge position in a horizontal posture. After being lifted by a truck crane and turned over to an upright posture, it is slowly hoisted to the designed position. Fine-tune the leveling nuts under the bearing plate to make the elevation and verticality of the column accurate, and then preliminarily tighten the anchoring nuts, and pour the grouting layer under the bearing plate. When constructing the concrete under the bearing plate, pressure grouting should be adopted. It is strictly prohibited to install the remaining steel segments except the root segment of the column before the post-grouting layer under the bearing plate is implemented. After the grouting layer under the bearing plate reaches the designed strength and cures to the specified age, tighten the column foot anchoring nuts for the second time. Install the middle steel column with a truck crane. After checking that the verticality and elevation are accurately in line with the requirements by using inspection equipment such as a spirit level and a level gauge, temporarily position the middle steel column with a spacer plate, and then weld it to the bottom steel column by using the carbon dioxide gas shielded welding process.

[0027] Before installing the steel cantilever, a counterweight block must be installed at its top to move the center of gravity of the steel cantilever outside the existing bridge. Then, the steel cantilever is installed with a truck crane and welded to the middle steel column after the elevation and verticality are accurately corrected. The counterweight block is preferably the body counterweight and turntable counterweight of a truck crane or a crawler crane. Reliable temporary fixing measures such as high-strength bolt connection, welding, or bundling must be adopted between the counterweight block and the steel cantilever to prevent it from falling during hoisting, and the safety of the components during the hoisting process must be ensured. The weight of the counterweight block should be determined according to calculations. The sum of the moments of the steel cantilever and the counterweight block on the left side of the center of gravity line should be equal to the moment of the steel cantilever on the right side of the center of gravity line to meet the requirement of stable hoisting. The technical parameters of the truck crane such as the model, working radius, boom extension length, and boom elevation angle need to be calculated and confirmed according to the actual working conditions on site.

[0028] After the installation of the steel bridge pier is completed, all welds should be inspected. After passing the inspection, the core filling concrete can be slowly poured from the reserved hole at the top of the steel column. To avoid concrete segregation caused by too large a height difference, equipment such as a tremie pipe or a chute can be used for pouring. Considering the limited construction space inside the steel column, self-compacting concrete should be used for the core filling concrete, which can eliminate manual vibration and ensure the compactness of the concrete. Thereafter, tie the steel bars at the column foot, set up the formwork and pour the concrete for the external wrapping of the column foot. After the installation of the steel bridge pier is completed, the exposed over-welding holes and temporary construction manholes should be sealed to ensure the airtightness inside the steel structure and enhance the anti-corrosion performance. Then install the main beam of the superstructure, construct the widened joint and the bridge deck accessory structure, and complete the reconstruction construction of the widened bridge.

Claims

1. A construction method for hoisting steel bridge piers under existing bridges, characterized in that it includes the following steps: Step A: Survey the existing bridge to determine the projection position of the widened-section steel bridge pier on the original bridge deck; Step B: Construct the bearing platform at the position of the widened-section steel bridge pier. During the construction of the bearing platform, embed the anchoring frame, anchor bolts and the outer-wrapped column foot; Step C: Divide the steel bridge pier into steel columns and steel cantilevers from bottom to top. The steel columns and steel cantilevers are fabricated in sections at the factory and hoisted in sections on site; Step D: After the bearing platform concrete reaches the design strength, chisel the concrete in the grouting layer range on the top surface of the bearing platform to expose the fresh aggregate. After cleaning the concrete surface, install the steel column bearing plate; Step E: Lay adjusting pads under the steel column bearing plate of the bearing platform to make its surface horizontal, and install leveling nuts at the bottom of the steel column bearing plate; Step F: Slowly hoist the steel column to the design position by a truck crane. Fine-tune the leveling nuts under the steel column bearing plate to make the elevation and verticality of the column accurate. Then install the anchor bolt support bracket on the anchor bolt and preliminarily tighten it with the anchor nut. Subsequently, pour the grouting layer under the steel column bearing plate; Step G: After the grouting layer under the steel column bearing plate reaches the design strength and cures to the specified age, tighten the anchor nut for the second time; Step H: Prepare for the installation of the steel cantilever. Before installing the steel cantilever, a counterweight block must be installed at its top to move the center of the steel cantilever to the outside of the original bridge deck when it is in the design position. Then lift the steel cantilever by a truck crane and slowly move it onto the steel column. During the entire hoisting process, the lifting tool of the truck crane is always outside the original bridge deck; Step I: Weld the steel cantilever and the steel column. After welding is completed, detect all welds. After passing the detection, slowly pour the core filling concrete through the reserved hole at the top of the steel cantilever. Then tie the column foot steel bars and formwork to pour the column foot outer-wrapped concrete; Step J: Seal the exposed over-welding holes and temporary construction holes of the steel bridge pier to ensure the airtightness inside the steel structure. Then install the main beam of the superstructure, construct the widened joint and the bridge deck accessory structure to complete the widened bridge.

2. A construction method for hoisting steel bridge piers under existing bridges according to claim 1, characterized in that, in Step C, the steel columns are divided into multiple sections. In Step F, the steel columns of multiple sections are hoisted separately and welded between the steel columns.

3. A construction method for hoisting steel bridge piers under existing bridges according to claim 2, characterized in that there shall be no weld seams within a quarter range from the top down of the steel column, and there shall be no weld seams within an eighth range from the root up of the steel column.

4. A construction method for hoisting steel bridge piers under existing bridges according to claim 1, characterized in that, in Step H, the sum of the moments of the steel cantilever and the counterweight block on the left side of the center line shall be equal to the moment of the steel cantilever on the right side of the center line.

5. A construction method for hoisting steel bridge piers under existing bridges according to claim 1, characterized in that, in Step H, fixed measures such as high-strength bolt connection, welding connection or bundling connection must be adopted between the counterweight block and the steel cantilever. After the steel cantilever is fixed to the steel column, the counterweight block needs to be removed.

6. A construction method for hoisting steel bridge piers under existing bridges according to claim 1, characterized in that, in In Step I, equipment such as a string bucket or a chute is used for concrete pouring to prevent concrete segregation caused by excessive height difference. At the same time, self-compacting concrete is used for the core filling concrete to ensure the compactness of the concrete.

7. A method for hoisting a steel bridge pier under an existing bridge according to claim 3, characterized in that, in Step F, the steel column is transported to the bridge position in a horizontal posture, lifted by a truck crane and turned over to an upright posture, and then slowly hoisted to the designed installation position.

8. A method for hoisting a steel bridge pier under an existing bridge according to claim 2, characterized in that, in Step F, the root steel column is hoisted first, and then the grouting layer under the steel column bearing plate is poured. After the grouting layer reaches the designed strength and is cured to the specified age, the remaining steel columns except the root steel column are hoisted.

9. A method for hoisting a steel bridge pier under an existing bridge according to claim 3, characterized in that the steel columns are welded using the carbon dioxide gas shielded welding process.

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