Assembly type segmental prefabricated cover beam non-support installation method

Abstract

The invention relates to the technical field of bridge engineering construction, in particular to an assembly type segmental prefabricated cover beam non-support installation method. Comprising the following steps that quality inspection is conducted on two prefabricated bent cap stand column embedded parts, and construction equipment and materials are prepared; the bent cap is hoisted to the position above the installation position through large hoisting equipment; the position and the angle of the cover beam are adjusted through the positioning device, and accurate alignment between the cover beam and the stand column and between the cover beam and the stand column is ensured; the bent cap A is connected with a pier top steel bar pre-buried in the stand column through a grouting corrugated pipe; the bent cap A and the bent cap B are preliminarily connected through a joint formed by the bracket structure and the tooth key structure and coated with an adhesive; after the bent cap B is installed and positioned, a full-length steel bar is inserted to be connected with the bent cap A, and grouting is conducted on the grouting corrugated pipe and the grouting sleeve; the overall position, elevation and perpendicularity of the bent cap are measured, and appearance and mechanical property detection is conducted on the connecting part. The method can obviously shorten the construction period and reduce the construction cost.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge engineering construction, and particularly to a method for installing precast segmental pier caps without supports. Background Art

[0002] In the field of bridge engineering, the assembly construction of precast segmental pier caps is a key link in the construction of the upper structure of bridges. Traditional construction methods usually rely on setting up temporary support frames to assist in the positioning and fixing of pier cap segments, and cast-in-place joints (i.e., wet joints) are provided between two segments for connection. The main processes of the existing technology include: setting up a support frame at the construction site as the temporary load-bearing structure of the pier cap, hoisting the precast pier cap segments onto the support, and completing the connection of the two segments through the wet joint process after adjusting the position.

[0003] However, the above traditional methods have the following defects: low construction efficiency: The erection of the support frame usually takes 2 - 3 days, and the wet joint construction involves many processes such as steel bar connection, concrete pouring and curing, with a total cycle of up to 7 - 10 days, seriously restricting the overall construction progress. High cost: A large amount of steel and labor are required for the erection of the support frame, and the wet joint construction also consumes formwork, steel bars and concrete materials, resulting in a relatively high comprehensive cost. In addition, in the existing technology, the connection between pier cap segments relies on cast-in-place concrete joints, and it is difficult to guarantee the construction accuracy and connection reliability. Therefore, there is an urgent need for an efficient, economical and adaptable support-free installation method to overcome the inherent defects of traditional technologies. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a method for installing precast segmental pier caps without supports, which overcomes the drawbacks of the need to set up support frames and carry out wet joint construction in the assembly construction of traditional two-segment pier caps, realizes rapid, efficient and safe installation of pier caps, reduces construction costs, and improves construction quality.

[0005] In order to achieve the above objectives, the present invention specifically adopts the following technical means:

[0006] A method for installing precast segmental pier caps without supports includes the following steps:

[0007] a. Construction preparation: Conduct quality inspections on the precast two-segment pier caps, pier cap A and pier cap B, and column embedded parts, and prepare construction equipment and materials;

[0008] b. Segment hoisting: Use a large lifting device to hoist pier cap A and pier cap B above the installation position;

[0009] c. Segment positioning: Adjust the positions and angles of pier cap A and pier cap B through a positioning device to ensure accurate alignment with the columns and with each other;

[0010] d. Segment connection: The capping beam A is connected to the pier top steel bars embedded in the column through grouting bellows; the capping beam A and the capping beam B are preliminarily connected through the joints formed by the corbel structure and the keyway structure and coated with adhesive; after the capping beam B is installed and positioned, the full-length steel bars are inserted and connected to the capping beam A, and the grouting bellows and grouting sleeves are grouted.

[0011] e. Overall inspection: Measure the overall position, elevation and verticality of the capping beam, and conduct appearance and mechanical property tests on the connection parts.

[0012] Furthermore, the corbel structure is made of C reinforced concrete with dimensions of length × width × height = 800 × 300 × 200 mm; the depth of the keyway structure is 50 mm, the width is 80 mm, and the spacing is 150 mm; the elevation deviation of the corbel top surface ≤ 1 mm, and the alignment error of the keyway ≤ 0.5 mm.

[0013] Furthermore, the large-scale lifting equipment is a 250t crawler crane with a maximum lifting capacity of 250t and a main boom length of 60m

[0014] Furthermore, the grouting material is C60 slightly expanded grouting material with a fluidity ≥ 300 mm and a 1-day strength ≥ 40 MPa; the grouting pressure is controlled at 0.6 - 0.8 MPa, and the pressure maintaining time is 3 minutes.

[0015] Furthermore, the full-length steel bars are HRB500E Φ28mm steel bars, and the anchorage length of the steel bars in the capping beam A inserted into the pier top steel bars embedded in the column ≥ 800 mm.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects:

[0017] Traditional wet joints require on-site steel bar binding, formwork support, pouring and curing, which are easily affected by environmental temperature and humidity, resulting in problems such as concrete shrinkage cracking and uneven strength. The corbel-keyway joint is prefabricated in the factory, avoiding the uncertainty of on-site pouring. By adopting the hybrid connection process of the corbel-keyway joint structure and full-length steel bars, a self-stabilizing system for two-section capping beams is realized, eliminating the traditional support frame erection and wet joint construction. Combined with rapid hoisting and positioning, the installation process does not rely on the curing of cast-in-place concrete, and the construction period is shortened from the traditional 9 - 13 days to within 1 day. This effect directly addresses the problems of difficult support frame erection in complex terrain areas and long wet joint cycles in the traditional method, greatly improving the construction efficiency and terrain adaptability.

[0018] The scaffold-free installation process reduces the material and labor costs for support frame erection. At the same time, it eliminates the processes of wet joint steel bar binding, formwork installation and concrete curing, saving about 40% - 50% of material losses. Through the high-precision control of prefabricated capping beams and standardized construction processes, the rework rate and resource waste are further reduced.

[0019] The bracket-toothed key joint forms a mechanical interlocking effect through multi-tooth meshing, significantly improving the shear resistance of the joint. Compared with traditional planar joints or simple mortise and tenon joints, it has a larger contact area, a more uniform load transfer path, can withstand greater lateral shear forces, reduce stress concentration, and avoid joint slip or cracking. Brief Description of the Drawings

[0020] Figure 1 Schematic diagram of the bracket-toothed key joint structure of the two-section bent cap in an embodiment of the present invention;

[0021] Figure 2 Connection structure diagram of bent cap A and column in an embodiment of the present invention;

[0022] Figure 3 Connection structure diagram of bent cap B and column in an embodiment of the present invention.

[0023] Numbers in the figure: 1, bracket structure; 2, toothed key structure; 3, bent cap A; 4, bent cap B; 5, full-length reinforcement; 6, grouting sleeve; 7, grouting bellows; 8, column; 9, reserved reinforcement of column. Detailed Embodiment

[0024] The following further describes the present invention in detail with reference to the drawings, but the embodiments of the present invention are not limited thereto. Please refer to Figures 1 to 3 , the specific implementation steps of the method for realizing the scaffold-free installation of the two-section precast bent cap using the bracket-toothed key joint of the present invention are as follows:

[0025] 1. Construction preparation: Conduct quality inspections on the precast bent caps A and B to ensure that their dimensional deviations are ≤ ±1 mm and the concrete strength reaches C50 or above; check the surface cleanliness and position accuracy of the reserved pier top reinforcement 9, grouting bellows 7 and grouting sleeves 6 embedded in the column 8 to ensure that their surfaces are clean, free of oil stains and impurities. Prepare equipment and materials such as a 250t crawler crane (maximum lifting capacity 250t, main boom length 60m), total station, laser centering instrument, C60 slightly expanding grouting material (fluidity ≥ 300 mm, 1-day strength ≥ 40 MPa) and HRB500E Φ28mm full-length reinforcement 5.

[0026] 2. Lifting of segments: Please refer to Figure 1 , use a 250t crawler crane to lift the bent caps A and B to above the installation positions respectively. During hoisting, control the swing of the segments through auxiliary towing ropes to ensure smooth hoisting.

[0027] 3. Positioning of segments: Please refer to Figure 2 , monitor the position of the bent cap A3 in real time through a total station and a laser centering instrument, adjust its horizontal angle and verticality, and accurately align the grouting bellows 7 with the reserved pier top reinforcement 9 embedded in the column 8, with an error ≤ ±1 mm.

[0028] See also Figure 3 , synchronously adjust the position of cap beam B to ensure that its corbel structure 1 is accurately engaged with the tooth key structure 2 of cap beam A3, the elevation deviation of the corbel top surface is ≤1mm, and the tooth key alignment error is ≤0.5mm.

[0029] 4. Segment connection: Please refer to Figure 2 , slowly lower the cap beam A so that the grouting corrugated pipe 7 is inserted into the pier top steel bar 9 of the column 8, with an insertion depth of ≥800mm. Then use the pressure grouting equipment to inject C60 micro-expansion grouting material, control the grouting pressure to 0.6-0.8MPa, and maintain the pressure for 3 minutes to ensure that the grouting is dense. Figure 1 , achieve the initial self-stabilizing connection between cap beam A and cap beam B through the bracket structure 1 and the tooth key structure 2, and evenly apply high-performance adhesive on the joint surface. Then insert HRB500EΦ28mm full-length steel bar 5, pass through cap beam B and reliably connect with the internal steel bars of cap beam A. Figure 3 The grouting sleeve 6 and the grouting bellows 7 between the cap beam B4 and the column 8 are grouted synchronously, and the process parameters are the same as those of the connection of the cap beam A3.

[0030] 5. Overall inspection: Use a total station to re-measure the overall position, elevation and verticality of the cap beam. The deviation must comply with the design specifications. Perform a visual inspection of the connection parts of the corbel-tooth key joint, the grouting bellows 7 and the full-length steel bar 5, and use an ultrasonic detector to verify the mechanical properties to ensure that the shear strength of the joint is ≥40MPa.

[0031] In the segment connection step, the elevation deviation of the top surface of the corbel is ≤1mm, and the tooth key alignment error is ≤0.5mm, which requires extremely high installation accuracy. If the cap beams A and B are fixed to the columns first, the tooth keys between the two sections of the cap beams may not be accurately aligned due to column position deviation or lifting error, which may require repeated adjustments or even rework. The corbel-tooth key docking of the two sections of the cap beams is completed on the ground or in the air. The relative positions of the cap beams A and B can be adjusted independently to ensure tight engagement of the tooth keys and avoid the influence of the position deviation of the embedded steel bars of the columns on the joints between the cap beams. After calibration, connect the entire structure to the column to reduce the risk of cumulative errors.

[0032] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be regarded as limiting the present invention, and the protection scope of the present invention should be defined by the appended claims.

Claims

1. An installation method for precast segmental capping beams without supports, characterized in that a. Construction preparation: Conduct quality inspections on the precast two-segment capping beams and the embedded parts of the columns (8), and prepare construction equipment and materials. b. Segment hoisting: Use large lifting equipment to hoist capping beam A (3) and capping beam B (4) above the installation position. c. Segment positioning: Adjust the positions and angles of capping beam A (3) and capping beam B (4) through the positioning device to ensure accurate alignment with the columns (8) and with each other. d. Segment connection: Capping beam A (3) is connected to the pier top reinforcement (9) embedded in the column (8) through the grouting bellows (7); the joint formed by the corbel structure (1) and the keyway structure (2) between capping beam A (3) and capping beam B (4) is preliminarily connected and coated with adhesive; after capping beam B (4) is installed and positioned, the full-length reinforcement (5) is inserted and connected to capping beam A (3), and the grouting bellows (7) and grouting sleeves (6) are grouted. e. Overall inspection: Measure the overall position, elevation, and verticality of the capping beam, and conduct appearance and mechanical property tests on the connection parts.

2. The method for installing a precast segmental cast-in-place capping beam without supports according to claim 1, wherein The corbel structure (1) is made of C50 reinforced concrete, with dimensions of length × width × height = 800 × 300 × 200 mm; the keyway depth of the keyway structure (2) is 50 mm, the keyway width is 80 mm, and the keyway spacing is 150 mm; the elevation deviation of the corbel top surface ≤ 1 mm, and the keyway alignment error ≤ 0.5 mm.

3. The method for installing the precast segmental capping beam without support according to claim 1, characterized in that, The grouting material is C60 slightly expanded grouting material, with a fluidity ≥ 300 mm and a 1-day strength ≥ 40 MPa; the grouting pressure is controlled at 0.6 - 0.8 MPa, and the pressure holding time is 3 minutes.

4. The method for installing the precast segmental capping beam without supports according to claim 1, characterized in that, The full-length reinforcement (5) is HRB500E Φ28 mm reinforcement, and the anchorage length of the reinforcement in capping beam A (3) inserted into the pier top reinforcement (9) of the column (8) ≥ 800 mm.

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