Segmented assembled variable-section box girder structure and construction method

Abstract

The present invention provides a piece-by-piece assembled variable-section box girder structure and a construction method. Each box girder segment box girder includes a top plate unit, two web plate units and a bottom plate unit. A plurality of web vertical ribs are embedded in the web plate unit. A threaded sleeve is connected to each web vertical rib at both ends. Vertical rib holes are provided in the top plate unit and the bottom plate unit. Vertical ribs are inserted into the top plate and bottom plate vertical rib holes and are respectively screwed to the threaded sleeves at both ends of the web vertical ribs. When the box girder is hoisted for construction, the plate units of each segment are hoisted separately and connected to form a segment as a whole through the vertical ribs. The present invention can reduce the use of large equipment and reduce the difficulty and cost of prefabrication construction.

Description

Technical Field

[0001] The invention belongs to the technical field of bridge construction, and relates to the construction of a variable-section concrete box girder bridge, and specifically to a segmented assembled variable-section box girder structure and a construction method. Background Art

[0002] The cross section of a variable cross-section box girder bridge changes along the axis of the bridge, with a larger cross section used where the bending moment is larger and a smaller cross section used where the bending moment is smaller. The construction methods of variable cross-section box girders usually include cast-in-place method, cantilever casting method, and segmental prefabrication cantilever assembly method. The segmental cantilever assembly method is a construction method that prefabricates the concrete beam body in sections, and then assembles the concrete beam body prefabricated parts in a balanced manner towards the mid-span section by section, and applies prestressing in sections. It has been increasingly widely used due to its advantages of shorter construction period and higher quality.

[0003] Conventional prefabricated variable-section box girders use a single-box single-chamber cross-section when the bridge deck is narrow. When the bridge deck is wide, in order to reduce the segment size and lifting weight, a separated multi-box cross-section is often used. The segments are mostly prefabricated using the short-line method, with one segment used as the end mold to match the next prefabricated segment. Since the segments need to be shifted repeatedly and the volume and weight of each segment are still large, large-scale equipment is required for shifting, storage, transportation, and lifting. A large number of sets of engineering equipment are invested, and the construction period is long. In addition, each time a segment is shifted to match the next segment, measurement, positioning, and fine-tuning are required, resulting in low efficiency and high cost. Summary of the invention

[0004] The purpose of the present invention is to solve the problems of prefabrication, storage, transportation and installation of cantilevered sections of large-width variable-section box girders, and to provide a segmented assembled variable-section box girder structure and a construction method, in which the top plate, bottom plate and web plate of the box girder are prefabricated in plate units and installed in segmented cantilevers to reduce the difficulty of prefabrication and the investment in large equipment, thereby reducing construction costs while ensuring project quality.

[0005] The present invention provides a piece-by-piece assembled variable-section box girder structure, which is characterized in that it comprises a top plate unit, two web plate units and a bottom plate unit, the bottom surface of the top plate unit is respectively butted against the top surfaces of the two web plate units, and the top surface of the bottom plate unit is respectively butted against the bottom surfaces of the two web plate units; a longitudinal prestressed channel is provided in the web plate unit along the longitudinal direction of the bridge, and a plurality of web plate vertical ribs are pre-embedded, and the upper and lower ends of each web plate vertical rib are respectively connected to a threaded sleeve, and half of each threaded sleeve is connected to the web plate. The plate vertical ribs are screwed, and the top plate unit is provided with top plate vertical rib holes corresponding to the web vertical ribs, and a top plate vertical rib is passed through each top plate vertical rib hole, and the lower end of each top plate vertical rib is screwed to the other half of a threaded sleeve screwed to the upper end of a web vertical rib, and the bottom plate unit is provided with bottom plate vertical rib holes corresponding to the web vertical ribs, and a bottom plate vertical rib is passed through each bottom plate vertical rib hole, and the upper end of each bottom plate vertical rib is screwed to the other half of a threaded sleeve screwed to the lower end of a web vertical rib.

[0006] Furthermore, in the above-mentioned segmented assembled variable-section box girder structure, the front end faces of the top plate unit, the web plate unit and the bottom plate unit are respectively provided with a plurality of shear keys, and the rear end faces are provided with shear key slots corresponding to each shear key.

[0007] The construction method of the above-mentioned segmented assembled variable-section box girder is characterized by comprising the following steps:

[0008] (1) Each box girder segment is divided into a top plate unit, two web plate units and a bottom plate unit, and the division position of the top plate unit, the web plate unit and the bottom plate unit is located at the chamfered edge of the box chamber;

[0009] The top plate unit, web plate unit and bottom plate unit are processed in the prefabrication yard. A longitudinal prestressed channel is provided in each web plate unit along the longitudinal direction of the bridge, and multiple web plate vertical ribs are embedded in accordance with the vertical rib layout of the box girder. A threaded sleeve is screwed to the upper and lower ends of each web plate vertical rib, and half of each threaded sleeve is screwed to the web plate vertical rib. A top plate vertical rib channel is provided in each top plate unit corresponding to each web plate vertical rib of the two web plate units, and a bottom plate vertical rib channel is reserved in each bottom plate unit corresponding to each vertical rib of the two web plate units. Multiple shear keys are preset on the front end face of each top plate unit, web plate unit and bottom plate unit, and corresponding shear key slots are preset on the rear end face.

[0010] After all the top plate units, web plate units and bottom plate units are prefabricated, they are transported to the bridge construction site;

[0011] (2) Hoisting of the 0# block of the box girder: First, hoist the 0# block of the bottom plate onto the pier column, and insert the bottom plate vertical reinforcement into each bottom plate vertical reinforcement hole; then hoist the two 0# web plates above the bottom plate, screw the upper end of each bottom plate vertical reinforcement to the lower half of the threaded sleeve at the lower end of a web plate vertical reinforcement, lower the two web plates onto the bottom plate, and grout the bottom plate vertical reinforcement holes at the same time, and install the middle partition plate between the two web plates; then hoist the 0# block of the top plate onto the two web plates, insert the top plate vertical reinforcement into each top plate vertical reinforcement hole, screw the lower end of each top plate vertical reinforcement to the upper half of the threaded sleeve screwed to the upper end of the web plate vertical reinforcement, and grout the top plate vertical reinforcement holes; finally, insert the prestressed reinforcement into the longitudinal prestressed holes of the web plate unit and perform the first tensioning, and complete the installation of the 0# block of the box girder;

[0012] (3) Install two bridge cranes at both ends of the top surface of block 0#;

[0013] (4) Use a bridge crane to symmetrically hoist the two 1# segments: First, hoist the two web units of the 1# segment, butt the 1# segment web with the 0# web through shear keys and shear key slots, and at the same time insert the longitudinal prestressed tendons into the prestressed holes of the 1# segment web, and preliminarily tension the 1# segment prestressed tendons;

[0014] The bottom plate unit of the hoisted 1# segment is butted with the two webs of the 1# segment and the shear keys on the 0# bottom plate at the same time. The vertical reinforcements of the bottom plate are inserted into the vertical reinforcement holes of the bottom plate unit. The upper end of each vertical reinforcement of the bottom plate is screwed with the lower half of the threaded sleeve at the lower end of the vertical reinforcement of the web. The vertical reinforcement holes of the bottom plate are grouted to connect the bottom plate unit and the web unit as a whole.

[0015] The top plate unit of the hoisted 1# segment is butted with the two webs of the 1# segment and the shear keys on the 0# top plate at the same time; the top plate vertical reinforcement is inserted into the vertical reinforcement hole of the top plate unit, the lower end of each top plate vertical reinforcement is screwed with the upper half of the threaded sleeve at the upper end of the web vertical reinforcement, and the top plate vertical reinforcement hole is grouted to connect the top plate unit and the web unit as a whole;

[0016] Perform secondary tensioning on the longitudinal prestressed tendons of the 1# segment and grouting on the prestressed pipes to complete the installation of the 1# segment;

[0017] (5) Move the two bridge cranes forward and hoist the subsequent segments in sequence according to the method in step (4) until the bridge is closed.

[0018] The present invention innovates the prefabrication and assembly form of the box beam, breaking through the limitations of the traditional segment prefabrication and cantilever assembly methods. The box beam structure of the present invention is the same as the segment prefabrication cantilever assembly in terms of force, but has the following advantages compared with the prior art:

[0019] 1. All structural modules are prefabricated in factories and assembled on site, with a factory rate of 100%, which can greatly improve the construction quality and speed;

[0020] 2. It can significantly reduce the size and hoisting weight of prefabricated components. The model and power requirements of prefabrication, storage, transportation and hoisting equipment are low, which can reduce the investment in large equipment and reduce machinery costs;

[0021] 3. By re-dividing and layout the variable-section box girder segments, most units can be designed as universal plate units, reducing the number of templates and facilitating construction quality control;

[0022] 4. The board units can be stored in multi-layer stacking, saving storage pedestals and space;

[0023] 5. When hoisting each segment, prestressed steel bars are tensioned to improve the erection efficiency. There is no need to wait for the joint concrete to reach the required strength before construction can begin, and the construction speed is fast.

[0024] 6. During prefabrication, repeated measurements of the measuring tower and segment resetting are not required, saving measurement costs;

[0025] 7. The number of operators is reduced, which can save labor costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the overall structure of the segmented assembled variable-section box girder of the present invention;

[0027] Figure 2 It is a three-dimensional diagram of the exploded structure of the segmented assembled variable-section box girder;

[0028] Figure 3 It is the decomposed structural cross-section diagram of the segmented assembled variable-section box girder;

[0029] Figure 4 It is the cross-sectional view of the segmented assembled variable-section box girder where the vertical reinforcement is set;

[0030] Figure 5 This is a schematic diagram of the base plate installation structure of block 0;

[0031] Figure 6 This is a schematic diagram of the web installation structure of block 0;

[0032] Figure 7 This is a schematic diagram of the top plate installation structure of block 0;

[0033] Figure 8 It is a schematic diagram of the arrangement of longitudinal prestressed tendons for variable-section box girders;

[0034] Fig. 9 This is a schematic diagram of the installation structure of the 0 bridge deck crane;

[0035] Fig.10 This is a schematic diagram of the web plate hoisting status of block No. 1;

[0036] Fig.11 This is a schematic diagram of the lifting and installation status of block No. 1;

[0037] Fig.12 This is a schematic diagram of the top plate installation status of block 1;

[0038] Fig.13 This is a schematic diagram of the status after the installation of block No. 1 is completed. DETAILED DESCRIPTION

[0039] like Figures 1 to 4 As shown, a piece-by-piece assembled variable-section box girder structure provided by the present invention comprises a top plate unit 1, two web plate units 2 and a bottom plate unit 3, wherein the bottom surface of the top plate unit 1 is respectively butted against the top surfaces of the two web plate units 2, and the top surface of the bottom plate unit 3 is respectively butted against the bottom surfaces of the two web plate units 2; a longitudinal prestressed duct is provided in the web plate unit 2 along the longitudinal direction of the bridge, and a plurality of web plate vertical ribs 21 are pre-embedded, and the upper and lower ends of each web plate vertical rib 21 are respectively connected to a threaded sleeve 22, and half of each threaded sleeve 22 is connected to the web plate vertical rib Screw connection, the top plate unit 1 is provided with a top plate vertical rib channel 11 corresponding to the web vertical rib, each top plate vertical rib channel is penetrated with a top plate vertical rib 12, the lower end of each top plate vertical rib 12 is screwed to the other half of a threaded sleeve 22 screwed to the upper end of a web vertical rib, the bottom plate unit 3 is provided with a bottom plate vertical rib channel 31 corresponding to the web vertical rib, each bottom plate vertical rib channel is penetrated with a bottom plate vertical rib 32, the upper end of each bottom plate vertical rib 32 is screwed to the other half of a threaded sleeve 22 screwed to the lower end of a web vertical rib 21.

[0040] The front end faces of the top plate unit 1, the web plate unit 2 and the bottom plate unit 3 are respectively provided with a plurality of shear keys 4, and the rear end faces are provided with shear key slots corresponding to each shear key. The shear keys are used to bear and transmit shear forces, and to assist in the assembly, inlaying and docking positioning of segments.

[0041] The specific construction method of the above-mentioned segmented assembled variable-section box girder is as follows:

[0042] (1) Based on Figure 2 , Figure 4 In the structure shown, each box beam segment is divided into a top plate unit 1, two web plate units 2 and a bottom plate unit 3, and the division position of the top plate unit, the web plate unit and the bottom plate unit is located at the chamfered edge of the box chamber;

[0043] The top plate unit, web plate unit and bottom plate unit are processed in the prefabrication yard. A longitudinal prestressed channel is provided in each web plate unit 2 along the longitudinal direction of the bridge, and a plurality of web plate vertical ribs 21 are embedded in advance according to the vertical rib layout of the box girder. A threaded sleeve 22 is screwed to the upper and lower ends of each web plate vertical rib, and half of each threaded sleeve is screwed to the web plate vertical rib. A top plate vertical rib channel 11 is provided in each top plate unit 1 corresponding to each web plate vertical rib of the two web plate units, and a bottom plate vertical rib channel 31 is reserved in each bottom plate unit 3 corresponding to each vertical rib of the two web plate units. A plurality of shear keys 4 are preset on the front end face of each top plate unit, web plate unit and bottom plate unit, and a corresponding shear key slot is preset on the rear end face.

[0044] When the web unit is prefabricated, a notch is set at the lower edge of the web unit to facilitate the installation of the longitudinal prestressed anchor pad and prestressing in the web; the segmented position of the bottom plate unit is aligned with the notch edge of the web.

[0045] After all the top plate units, web plate units and bottom plate units are prefabricated, they are transported to the bridge construction site;

[0046] (2) Hoisting of box beam 0#:

[0047] like Figure 5 As shown, the 0# bottom plate 3 is hoisted onto the pier 7 by a truck crane, and the bottom plate vertical reinforcement is inserted into each bottom plate vertical reinforcement hole 31;

[0048] like Figure 6 As shown, two 0# webs 2 are hoisted above the bottom plate, the upper end of each bottom plate vertical rib is screwed to the lower half of the threaded sleeve at the lower end of a web vertical rib, the two webs are lowered to the bottom plate, grouting is performed in the bottom plate vertical rib holes at the same time, and a middle partition is installed between the two webs;

[0049] like Figure 7 As shown, the 0# top plate 1 is hoisted onto the two webs 2, the top plate vertical reinforcement is inserted into each top plate vertical reinforcement channel, the lower end of each top plate vertical reinforcement is screwed to the upper half of the threaded sleeve that is screwed to the upper end of the web vertical reinforcement, and the top plate vertical reinforcement channels are grouted; finally, the prestressed reinforcement is passed through the longitudinal prestressed channels of the web unit and the first tensioning is carried out to complete the installation of the 0# box girder.

[0050] like Figure 8 As shown, the longitudinal prestressed tendons of the present invention are arranged in the same manner as the ordinary short-line segment prefabricated cantilever assembly method. The longitudinal prestressed tendons 5 are arranged in the web of each segment along the longitudinal direction of the bridge, which will not be described in detail here.

[0051] (3) Fig. 9 As shown, two bridge deck cranes 6 are installed at both ends of the top surface of block 0#;

[0052] (4) Use a bridge crane to symmetrically hoist two 1# segments:

[0053] like Fig.10 As shown, firstly, the two web units 2 of the 1# segment are hoisted, and the web of the 1# segment is butted with the web of the 0# block through the shear key and the shear key slot, and at the same time, the longitudinal prestressed tendons are inserted into the prestressed holes of the web of the 1# segment, and the prestressed tendons of the 1# segment are preliminarily tensioned;

[0054] like Fig.11 As shown in the figure, the bottom plate unit 3 of the hoisted 1# segment is connected to the two webs 2 of the 1# segment and the shear keys on the 0# bottom plate at the same time. Figure 3 , Figure 4 The structure shown is that the bottom plate vertical ribs 32 are inserted into the vertical rib holes 31 of the bottom plate unit, the upper end of each bottom plate vertical rib 32 is screwed to the lower half of the threaded sleeve 22 at the lower end of the web vertical rib 21, and the bottom plate vertical rib holes are grouted to connect the bottom plate unit and the web unit as a whole;

[0055] like Fig.12 As shown, the top plate unit 1 of the hoisted 1# segment is butted against the two web plates 2 of the 1# segment and the shear keys on the 0# top plate at the same time; Figure 3 , Figure 4 The structure shown is that the top plate vertical ribs 12 are inserted into the vertical rib holes 11 of the top plate unit, the lower end of each top plate vertical rib 12 is screwed to the upper half of the threaded sleeve 22 at the upper end of the web vertical rib 21, and the top plate vertical rib holes are grouted to connect the top plate unit and the web unit as a whole;

[0056] Perform secondary tensioning on the longitudinal prestressed tendons of the 1# segment and grouting on the prestressed pipes to complete the installation of the 1# segment;

[0057] (5) Fig.13 As shown, the two bridge cranes 6 are moved forward, and subsequent segments are hoisted in sequence according to the method of step (4) until the bridge is closed.

Claims

1. A construction method for a piecewise assembled variable-section box girder, characterized in that: The following steps are involved: (1) Each box girder segment is divided into a top plate unit, two web plate units and a bottom plate unit, and the division position of the top plate unit, the web plate unit and the bottom plate unit is located at the chamfered edge of the box chamber; The top plate unit, web plate unit and bottom plate unit are processed in the prefabrication yard. A longitudinal prestressed channel is provided in each web plate unit along the longitudinal direction of the bridge, and multiple web plate vertical ribs are embedded in accordance with the vertical rib layout of the box girder. A threaded sleeve is screwed to the upper and lower ends of each web plate vertical rib, and half of each threaded sleeve is screwed to the web plate vertical rib. A top plate vertical rib channel is provided in each top plate unit corresponding to each web plate vertical rib of the two web plate units, and a bottom plate vertical rib channel is reserved in each bottom plate unit corresponding to each vertical rib of the two web plate units. Multiple shear keys are preset on the front end face of each top plate unit, web plate unit and bottom plate unit, and corresponding shear key slots are preset on the rear end face. After all the top plate units, web plate units and bottom plate units are prefabricated, they are transported to the bridge construction site; (2) Hoisting of the 0# block of the box girder: First, hoist the 0# block of the bottom plate onto the pier column, and insert the bottom plate vertical reinforcement into each bottom plate vertical reinforcement hole; then hoist the two 0# web plates above the bottom plate, screw the upper end of each bottom plate vertical reinforcement to the lower half of the threaded sleeve at the lower end of a web plate vertical reinforcement, lower the two web plates onto the bottom plate, and grout the bottom plate vertical reinforcement holes at the same time, and install the middle partition plate between the two web plates; then hoist the 0# block of the top plate onto the two web plates, insert the top plate vertical reinforcement into each top plate vertical reinforcement hole, screw the lower end of each top plate vertical reinforcement to the upper half of the threaded sleeve screwed to the upper end of the web plate vertical reinforcement, and grout the top plate vertical reinforcement holes; finally, insert the prestressed reinforcement into the longitudinal prestressed holes of the web plate unit and perform the first tensioning, and complete the installation of the 0# block of the box girder; (3) Install two bridge cranes at both ends of the top surface of block 0#; (4) Use a bridge crane to symmetrically hoist the two 1# segments: First, hoist the two web units of the 1# segment, butt the 1# segment web with the 0# web through shear keys and shear key slots, and at the same time insert the longitudinal prestressed tendons into the prestressed holes of the 1# segment web, and preliminarily tension the 1# segment prestressed tendons; The bottom plate unit of the hoisted 1# segment is butted with the two webs of the 1# segment and the shear keys on the 0# bottom plate at the same time. The vertical reinforcements of the bottom plate are inserted into the vertical reinforcement holes of the bottom plate unit. The upper end of each vertical reinforcement of the bottom plate is screwed with the lower half of the threaded sleeve at the lower end of the vertical reinforcement of the web. The vertical reinforcement holes of the bottom plate are grouted to connect the bottom plate unit and the web unit as a whole. The top plate unit of the hoisted 1# segment is butted with the two webs of the 1# segment and the shear keys on the 0# top plate at the same time; the top plate vertical reinforcement is inserted into the vertical reinforcement hole of the top plate unit, the lower end of each top plate vertical reinforcement is screwed with the upper half of the threaded sleeve at the upper end of the web vertical reinforcement, and the top plate vertical reinforcement hole is grouted to connect the top plate unit and the web unit as a whole; Perform secondary tensioning on the longitudinal prestressed tendons of the 1# segment and grouting on the prestressed pipes to complete the installation of the 1# segment; (5) Move the two bridge cranes forward and hoist the subsequent segments in sequence according to the method in step (4) until the bridge is closed.

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