Swivel structure of rigid frame bridge without junction piers and construction method of swivel structure

Abstract

The invention discloses a swivel structure of a rigid frame bridge without junction piers and a construction method of the swivel structure. Two groups of swivel structures are symmetrically arranged at the lower ends of a left beam body and a right beam body; each single-group swivel structure comprises a spherical hinge pile foundation, a spherical hinge lower bearing platform, a horizontal rotating spherical hinge, a spherical hinge upper bearing platform and a spherical hinge pier column which are located below the junction of the T-shaped bridge and are sequentially arranged from bottom to top, and a balance weight assembly located on a main beam on the short arm side of the T-shaped bridge. The counterweight assembly is used for ensuring the moment balance of the T-shaped bridge short arm side main beam and the T-shaped bridge long arm side main beam on the two sides of the junction of the T-shaped bridge; a plurality of supporting feet for rotation are arranged between the spherical hinge position lower bearing platform and the spherical hinge position upper bearing platform at intervals, and the upper ends of the supporting feet for rotation are fixedly arranged in the spherical hinge position upper bearing platform. On one hand, the balance weight assembly is arranged on the main beam on the short arm side of the T-shaped bridge, so that the balance of torque in the rotating process is ensured, and the investment cost is reduced; and on the other hand, the stability in the rotating process is guaranteed by arranging a plurality of supporting feet for rotating bodies.

Description

Technical Field

[0001] The invention relates to the field of bridge construction, and in particular to a rotation structure of a rigid frame bridge without boundary piers and a construction method thereof. Background Art

[0002] At present, when building bridges over rivers, railways, roads and water channels with special functional protection, the property management units generally require that bridge piers shall not be built within a certain protection range or that construction shall not be carried out for a long time above the clearance of the protection range. There is only the projection of the bridge within the protection range, and it is almost required that the bridge must cross the protection range with one span. At the same time, there are special requirements for construction technology. In the past, bridges that cross the protection range with one span usually adopt the arch bridge scheme. When the construction technology must adopt rotation construction, the bridge type usually adopts a continuous beam bridge with a counterweight span, a continuous rigid frame bridge, a double-tower cable-stayed bridge, or a T-frame bridge and a single-tower cable-stayed bridge structure that are symmetrical about the piers and towers.

[0003] The structure of the existing rotating bridge is as follows Figure 1 As shown, both sides of the horizontally rotating ball joint need to be provided with a connecting pier 1', which results in a large amount of engineering construction and increases the construction cost.

[0004] Therefore, it is urgent to propose a new method to solve the above problems. Summary of the invention

[0005] The present invention provides a swivel structure of a rigid frame bridge without intersection piers and a construction method thereof, so as to solve the problem in the prior art that intersection piers need to be provided on both sides of a horizontally rotating ball joint, resulting in a large amount of engineering construction and high construction costs.

[0006] The present invention provides a swivel structure of a rigid frame bridge without junction piers, wherein two sets of swivel structures are symmetrically arranged at the lower ends of the left and right beam bodies, and a single set of swivel structures comprises a ball joint pile foundation, a lower bearing platform at the ball joint, a horizontal swivel ball joint, an upper bearing platform at the ball joint, and a pier column at the ball joint, which are located below the junction of the T-frame bridge and are arranged in sequence from bottom to top, and a counterweight assembly located on the main beam on the short arm side of the T-frame bridge, wherein the counterweight assembly is used to ensure the moment balance of the main beam on the short arm side of the T-frame bridge and the main beam on the long arm side of the T-frame bridge on both sides of the junction of the T-frame bridge;

[0007] A plurality of swivel support legs are arranged at intervals between the lower support platform at the ball joint and the upper support platform at the ball joint, and the upper ends of the swivel support legs are fixedly arranged in the upper support platform at the ball joint.

[0008] Furthermore, the counterweight assembly includes a beam top counterweight and a beam inner counterweight, wherein the beam top counterweight is arranged on the beam top of the main beam on the short arm side of the T-girder bridge, and the beam inner counterweight is arranged inside the beam of the main beam on the short arm side of the T-girder bridge.

[0009] Furthermore, a plurality of the swivel support legs are arranged at equal angles along the circumferential direction of the flat swivel ball joint.

[0010] Furthermore, the swivel structure also includes a ball joint sealing support platform arranged between the lower support platform at the ball joint and the upper support platform at the ball joint, the lower support platform at the ball joint and the upper support platform at the ball joint are integrally connected through the ball joint sealing support platform, and the swivel support foot and the flat ball joint are buried in the ball joint sealing support platform.

[0011] Furthermore, a protective structure and an isolation structure are provided on the side of the upper support platform at the ball joint close to the spanned structure.

[0012] Furthermore, the main beam on the long arm side of the T-shaped bridge includes at least one cavity, and the counterweights in the beam are evenly arranged in the cavity.

[0013] Furthermore, a traction mechanism for providing power for the rotation of the T-bridge is provided on the flat-rotating ball joint.

[0014] Furthermore, the lower end of the swivel support leg is 2 to 3 cm away from the upper surface of the lower support platform at the ball joint.

[0015] The present invention also provides a construction method for a swivel structure of a rigid frame bridge without boundary piers, comprising the following steps:

[0016] Measure the self-weight G11 of the main beam on the short arm side of the T-frame bridge and the self-weight G2 of the main beam on the long arm side of the T-frame bridge, and calculate the distance from the center of gravity of the main beam on the short arm side of the T-frame bridge to the center of the pier column at the ball joint as A11 and the distance from the center of gravity of the main beam on the long arm side of the T-frame bridge to the center of the pier column at the ball joint as A2;

[0017] Use the balance formula G11×A11+G12×A12+G13×A13=G2×A2 to calculate the total moment value of the counterweight G12×A12+G13×A13, where Gl2 is the weight of the counterweight in the beam, Al2 is the distance from the center of gravity of the counterweight in the beam to the center of the pier at the spherical joint, Gl3 is the weight of the counterweight on the top of the beam, and Al3 is the distance from the center of gravity of the counterweight on the top of the beam to the center of the pier at the spherical joint;

[0018] According to the construction space and volume of the main beam on the short arm side of the T-shaped bridge, adjust the weight of the beam top counterweight and the beam internal counterweight until the above balance formula is satisfied;

[0019] Set up isolation structures and enclosure structures at the crossed structures to physically isolate and protect the affected structures;

[0020] According to conventional construction methods, symmetrically construct the ball joint pile foundation and the lower bearing platform at the ball joint on the outer side of the isolation structure of the spanned structure protection zone, install the horizontal ball joint, the upper bearing platform at the ball joint and the pier at the ball joint on the lower bearing platform at the ball joint, and install a plurality of rotating support feet on the upper bearing platform at the ball joint, and the lower end of the rotating support feet is 2 to 3 cm away from the upper surface of the lower bearing platform at the ball joint;

[0021] Level the site and do foundation treatment on the open space outside the isolation structure of the protected area of ​​the spanned structure to prepare for the main beam construction;

[0022] Set up a support on the ground and pre-press the support, support the formwork and tie the steel bars on the pre-pressed support, and cast the main beam on the long arm side of the T-frame bridge and the main beam on the short arm side of the T-frame bridge;

[0023] After the concrete strength and prestressing of the T-shaped bridge are completed, the top weight and the inner weight of the beam are respectively applied to the main beam on the short arm side of the T-shaped bridge, so that G11×A11+G12×A12+G13×A13=G2×A2;

[0024] Remove the cast-in-place bracket of the T-structure bridge, arrange the traction mechanism on the horizontal rotation ball joint, and make the left and right T-structure bridges rotate around the horizontal rotation ball joint at the same time until both T-structure bridges rotate to the joint position;

[0025] Complete the construction of the ball joint sealing platform, which connects the lower platform at the ball joint and the upper platform at the ball joint into a whole, and buries the flat ball joint and the swivel in the ball joint sealing platform with the support feet to complete the T-structure swivel construction;

[0026] A jack is horizontally arranged at one end of the main beam on the long arm side of the T-frame bridge near the middle connection part, and the main beam on the long arm side of the T-frame bridge on the opposite side is horizontally pushed by the jack so that the pier column at the ball joint obtains a bending moment toward the main beam on the short arm side of the T-frame bridge. The bending moment is used to balance the bending moment of the later rigid frame system toward the long cantilever. Here, the later rigid frame system is a rigid frame bridge after two sets of rotating structures are combined into an integral whole. The magnitude of the main beam force pushed by the jack is the smaller value between the bending moment that the bridge pier can withstand and the bending moment of the later rigid frame toward the long cantilever side.

[0027] Carry out docking construction on the middle connection part. After the joint is completed, remove the jack, the counterweight on the top of the beam and the counterweight inside the beam.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The swivel structure of the rigid frame bridge without intersection piers of the present invention, on the one hand, by setting a counterweight assembly on the main beam on the short arm side of the T-frame bridge, the moment balance during the rotation process is ensured, and the counterweight assembly can be recycled and reused after being disassembled, and there is no need to set an intersection pier and an auxiliary support device, thereby reducing the investment cost and saving the construction period; on the other hand, by setting a plurality of swivel support feet, the stability during the rotation process is ensured;

[0030] 2. The rotation method of the rigid frame bridge without intersection piers of the present invention saves costs by burying the horizontal rotation ball joint in the upper pedestal and the lower pedestal at the ball joint at a later stage. In addition, by setting the counterweight on the top of the beam and the counterweight inside the beam, the setting of the intersection pier can be eliminated, further saving the project cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the rotating structure of the existing T-shaped bridge;

[0032] Figure 2 It is a front view of the rotating structure of the rigid frame bridge without boundary piers of the present invention without the counterweight assembly;

[0033] Figure 3 for Figure 2 The enlarged schematic diagram at A in the middle;

[0034] Figure 4 This is a front view of the present invention in the initial state of the swivel;

[0035] Figure 5 It is a top view of the swivel of the present invention in the initial state;

[0036] Figure 6 This is a front view of the present invention when the rotation is completed;

[0037] Figure 7 It is a top view of the present invention in the final state of rotation;

[0038] Figure 8 A schematic diagram of moment balance of the rotating structure of the rigid frame bridge without boundary piers of the present invention;

[0039] Fig. 9 The cross-section form of the single-box double-chamber main beam of the rotating structure of the rigid frame bridge without boundary piers of the present invention;

[0040] Fig.10 It is a double-box double-chamber main beam cross-section form of the rotation structure of the rigid frame bridge without boundary piers of the present invention;

[0041] Fig.11 The cross-section form of the single-box three-chamber main beam of the rotating structure of the rigid frame bridge without boundary piers of the present invention;

[0042] Figure numerals: 1', junction pier; 11, pile foundation at ball joint; 12, lower pedestal at ball joint; 13, horizontal ball joint; 14, upper pedestal at ball joint; 15, pier at ball joint; 16, support foot for rotation; 17, traction mechanism; 18, ball joint sealing pedestal; 2, middle connecting part; 31, junction of T-beam bridge; 32, main beam on the long arm side of T-beam bridge; 33, main beam on the short arm side of T-beam bridge; 4, counterweight assembly; 41, counterweight on top of beam; 42, counterweight inside beam; 51, enclosure structure; 52, isolation structure;. DETAILED DESCRIPTION

[0043] In order to further understand the content, features and effects of the present invention, the following embodiments are given together with the attached Figures 2 to 11 The detailed instructions are as follows.

[0044] like Figures 2 to 11As shown, the present invention provides a swivel structure of a rigid frame bridge without junction piers, wherein two groups of swivel structures are symmetrically arranged at the lower ends of the left and right beam bodies, wherein the beam bodies include a main beam 33 on the short arm side of a T-frame bridge and a main beam 32 on the long arm side of a T-frame bridge, and a single group of swivel structures includes a ball joint pile foundation 11, a lower bearing platform 12 on the ball joint, a horizontal swivel ball joint 13, an upper bearing platform 14 on the ball joint, and a pier column 15 on the ball joint, which are located below the junction 31 of the T-frame bridge and are arranged in sequence from bottom to top, and a counterweight assembly 4 on the main beam 33 on the short arm side of the T-frame bridge, wherein the counterweight assembly 4 is used to ensure the moment balance of the main beam 33 on the short arm side of the T-frame bridge and the main beam 32 on the long arm side of the T-frame bridge on both sides of the junction 31 of the T-frame bridge;

[0045] The weight of the main beam 32 on the long arm side of the T-bridge is greater than the weight of the main beam 33 on the short arm side of the T-bridge. The side projection shape of the main beam 32 on the long arm side of the T-bridge is approximately a right-angled trapezoid, and the side projection shape of the main beam 33 on the short arm side of the T-bridge is a rectangle. The height of the intersection of the two is the same. The T-bridge intersection 31 is located at the bottom end of the short arm side main beam 33 of the T-bridge close to the long arm side main beam 32 of the T-bridge.

[0046] A plurality of swivel support legs 16 are arranged at intervals between the lower support platform 12 at the ball joint and the upper support platform 14 at the ball joint, and the upper ends of the swivel support legs 16 are fixedly arranged in the upper support platform 14 at the ball joint.

[0047] On the one hand, the present invention ensures the balance of torque during rotation by arranging a counterweight assembly on the main beam on the short arm side of the T-shaped bridge. The counterweight assembly can be recycled and reused after being disassembled, and there is no need to set up transfer piers and auxiliary support devices, thereby reducing investment costs and saving construction time. On the other hand, stability during rotation is ensured by setting up multiple swivel supports.

[0048] In this embodiment, Figures 9-11 As shown, the counterweight assembly 4 includes a beam top counterweight 41 and a beam inner counterweight 42 . The beam top counterweight 41 is arranged on the beam top of the short arm side main beam 33 of the T-structured bridge, and the beam inner counterweight 42 is arranged inside the beam of the short arm side main beam 33 of the T-structured bridge.

[0049] In this embodiment, Figures 9-11 As shown, a plurality of the swivel legs 16 are arranged at equal angles along the circumferential direction of the flat swivel joint 13 .

[0050] In this embodiment, Figures 9-11 As shown, the swivel structure also includes a ball joint sealing platform 18 arranged between the lower platform 12 at the ball joint and the upper platform 14 at the ball joint. The ball joint sealing platform 18 is made of concrete and is used to cast the lower platform 12 at the ball joint and the upper platform 14 at the ball joint as a whole after the rigid frame bridge is rotated into place. The swivel support leg 16 and the flat ball joint 13 are buried in the ball joint sealing platform 18.

[0051] In this embodiment, Figures 9-11 As shown, a protective structure 51 and an isolation structure 52 are provided on the side of the upper support platform 14 at the ball joint close to the spanned structure, thereby protecting the spanned structure.

[0052] In this embodiment, Figures 9-11 As shown, the flat-rotating ball joint 13 is provided with a traction mechanism 17 for providing power for the rotation of the T-beam bridge. The traction mechanism 17 can be a hydraulic traction machine to realize the rotation of the main beam 32 on the long arm side of the T-beam bridge and the main beam 33 on the short arm side of the T-beam bridge.

[0053] In this embodiment, Figures 9-11 As shown, the cross-sectional forms of a single box with two chambers, a double box with two chambers and a single box with three chambers are respectively given, and the counterweights 42 in the beam are evenly arranged in the cavern, so that it can adapt to T-structured bridges of different shapes.

[0054] In this embodiment, Figures 9-11 As shown, the lower end of the swivel support leg 16 is 2 to 3 cm away from the upper surface of the lower support platform 12 at the ball joint, so that when an unbalanced load occurs during rotation, the upper support platform 14 at the ball joint tilts, causing the swivel support leg 16 to abut against the lower support platform 12 at the ball joint, causing it to stop rotating; after the unbalanced load is eliminated, it continues to rotate.

[0055] The present invention also provides a construction method for a swivel structure of a rigid frame bridge without boundary piers, comprising the following steps:

[0056] S1, measure the self-weight G11 of the main beam 33 on the short arm side of the T-frame bridge and the self-weight G2 of the main beam 32 on the long arm side of the T-frame bridge, and calculate the distance from the center of gravity of the main beam 33 on the short arm side of the T-frame bridge to the center of the pier 15 at the ball joint as A11 and the distance from the center of gravity of the main beam 32 on the long arm side of the T-frame bridge to the center of the pier 15 at the ball joint as A2;

[0057] S2, such as Figure 8 As shown, the total moment value G12×A12+G13×A13=G2×A2 of the counterweight is calculated using the balance formula G11×A11+G12×A12+G13×A13=G2×A2, where Gl2 is the weight of the counterweight 42 in the beam, Al2 is the distance from the center of gravity of the counterweight 42 in the beam to the center of the pier 15 at the ball joint, Gl3 is the weight of the counterweight 41 at the top of the beam, and Al3 is the distance from the center of gravity of the counterweight 41 at the top of the beam to the center of the pier 15 at the ball joint;

[0058] S3, adjusting the weight of the beam top counterweight 41 and the beam inner counterweight 42 according to the construction space and volume of the main beam 33 on the short arm side of the T-shaped bridge until the above balance formula is satisfied;

[0059] S4. An isolation structure 52 and a protective structure 51 are set up at the spanned structure to physically isolate and protect the affected structure;

[0060] S5. According to conventional construction methods, symmetrically construct the ball joint pile foundation 11 and the lower bearing platform 12 at the ball joint on the outer side of the isolation structure 52 of the spanned structure protection zone, install the horizontal ball joint 13, the upper bearing platform 14 at the ball joint and the pier 15 at the ball joint on the lower bearing platform 12 at the ball joint, and install a plurality of swivel support legs 16 on the upper bearing platform 14 at the ball joint, and the lower end of the swivel support legs 16 is 2 to 3 cm away from the upper surface of the lower bearing platform 12 at the ball joint;

[0061] S6. Leveling the site and treating the foundation on the open space outside the isolation structure 52 of the spanned structure protection area to prepare for the main beam construction;

[0062] S7, erecting a support on the ground, and pre-pressing the support, supporting a formwork and tying steel bars on the pre-pressed support, and casting the main beam 32 on the long arm side of the T-frame bridge and the main beam 33 on the short arm side of the T-frame bridge;

[0063] S8, after the concrete strength and prestressing of the T-shaped bridge are completed, the top counterweight 41 and the inner counterweight 42 are respectively applied to the main beam 33 on the short arm side of the T-shaped bridge, so that G11×A11+G12×A12+G13×A13=G2×A2;

[0064] S9, dismantle the cast-in-place bracket of the T-structure bridge, arrange the traction mechanism 17 on the horizontal rotation ball joint 13, and make the left and right T-structure bridges rotate around the horizontal rotation ball joint 13 at the same time, until the two T-structure bridges are rotated to the joint position;

[0065] S10, completing the construction of the ball joint sealing platform 18, wherein the ball joint sealing platform 18 connects the lower platform 12 at the ball joint and the upper platform 14 at the ball joint into a whole, and buries the flat ball joint 13 and the swivel support 16 in the ball joint sealing platform 18, completing the T-structure swivel construction;

[0066] S11. A jack is horizontally arranged at one end of the main beam 32 of the long arm side of the T-frame bridge near the middle connecting part 2. The jack is used to horizontally push the main beam 32 of the long arm side of the T-frame bridge on the opposite side so that the pier 15 at the ball joint obtains a bending moment toward the main beam 33 of the short arm side of the T-frame bridge. The bending moment is used to balance the bending moment of the later rigid frame system toward the long cantilever. Here, the later rigid frame system is a rigid frame bridge after two sets of rotating structures are combined into an integral whole. The magnitude of the main beam force pushed by the jack is the smaller value between the bending moment that the bridge pier can withstand and the bending moment of the later rigid frame toward the long cantilever side.

[0067] S12, perform docking construction on the middle connection part 2. After the joint is completed, remove the jack, the beam top counterweight 41 and the beam inner counterweight 42, and carry out the completion acceptance of the bridge.

[0068] The rotation method of the rigid frame bridge without intersection piers of the present invention saves costs by burying the horizontal rotation ball joint in the upper pedestal and the lower pedestal at the ball joint at a later stage. In addition, by setting the counterweight on the top of the beam and the counterweight inside the beam, the setting of the intersection pier can be eliminated, further saving the project cost.

[0069] The invention described above only expresses the implementation methods of the embodiments of the present invention, and cannot be understood as limiting the scope of the invention patent, nor does it impose any form of limitation on the structure of the embodiments of the present invention. It should be pointed out that for ordinary technicians in this field, several changes and improvements can be made without departing from the concept of the embodiments of the present invention, which all belong to the protection scope of the embodiments of the present invention.

Claims

1. A swivel structure of a rigid frame bridge without boundary piers, wherein two sets of swivel structures are symmetrically arranged at the lower ends of the left and right beam bodies, and characterized in that: The single-group rotating structure comprises a ball joint pile foundation (11), a lower bearing platform (12), a horizontal rotating ball joint (13), an upper bearing platform (14) and a ball joint pier (15) which are arranged in sequence from bottom to top below the junction (31) of the T-shaped bridge, and a counterweight assembly (4) located on the short arm side main beam (33) of the T-shaped bridge, wherein the counterweight assembly (4) is used to ensure the moment balance of the short arm side main beam (33) of the T-shaped bridge and the long arm side main beam (32) of the T-shaped bridge on both sides of the junction (31) of the T-shaped bridge; A plurality of swivel support legs (16) are arranged at intervals between the lower support platform (12) at the ball joint and the upper support platform (14) at the ball joint, and the upper ends of the swivel support legs (16) are fixedly arranged in the upper support platform (14) at the ball joint.

2. The swivel structure of a rigid frame bridge without boundary piers according to claim 1, characterized in that: The counterweight assembly (4) comprises a beam top counterweight (41) and a beam interior counterweight (42), wherein the beam top counterweight (41) is arranged on the beam top of a main beam (33) on the short arm side of a T-shaped bridge, and the beam interior counterweight (42) is arranged inside the beam of the main beam (33) on the short arm side of the T-shaped bridge.

3. The swivel structure of a rigid frame bridge without boundary piers according to claim 1, characterized in that: The plurality of rotating body support legs (16) are arranged at equal angles along the circumferential direction of the flat rotating ball joint (13).

4. The swivel structure of a rigid frame bridge without boundary piers according to claim 3 is characterized in that: The swivel structure also includes a ball joint sealing support (18) arranged between the lower support (12) at the ball joint and the upper support (14) at the ball joint. The lower support (12) at the ball joint and the upper support (14) at the ball joint are integrally connected via the ball joint sealing support (18). The swivel support leg (16) and the parallel swivel ball joint (13) are embedded in the ball joint sealing support (18).

5. The swivel structure of a rigid frame bridge without boundary piers according to claim 1, characterized in that: A protective structure (51) and an isolation structure (52) are provided on the side of the upper support platform (14) at the ball joint close to the spanned structure.

6. The swivel structure of a rigid frame bridge without boundary piers according to claim 2, characterized in that: The long arm side main beam (32) of the T-shaped bridge comprises at least one cavity, and the internal counterweights (42) of the beam are evenly arranged in the cavity.

7. The swivel structure of a rigid frame bridge without boundary piers according to claim 1, characterized in that: The flat-rotating ball joint (13) is provided with a traction mechanism (17) for providing power for the rotation of the T-bridge.

8. The swivel structure of a rigid frame bridge without boundary piers according to claim 1, characterized in that: The lower end of the rotating support leg (16) is 2 to 3 cm away from the upper surface of the lower support platform (12) at the ball joint.

9. A construction method for a rotating structure of a rigid frame bridge without boundary piers, characterized in that: The following steps are involved: The self-weight G11 of the main beam (33) on the short arm side of the T-frame bridge and the self-weight G2 of the main beam (32) on the long arm side of the T-frame bridge are measured, and at the same time, the distance from the center of gravity of the main beam (33) on the short arm side of the T-frame bridge to the center of the pier (15) at the ball joint is calculated as A11 and the distance from the center of gravity of the main beam (32) on the long arm side of the T-frame bridge to the center of the pier (15) at the ball joint is calculated as A2; The total moment value G12×A12+G13×A13=G2×A2 of the counterweight is calculated, wherein G12×A12+G13×A13 is the weight of the counterweight (42) in the beam, A12 is the distance from the center of gravity of the counterweight (42) in the beam to the center of the pier (15) at the spherical joint, G13 is the weight of the counterweight (41) at the top of the beam, and A13 is the distance from the center of gravity of the counterweight (41) at the top of the beam to the center of the pier (15) at the spherical joint; The weight of the beam top counterweight (41) and the beam inner counterweight (42) are adjusted according to the construction space and volume of the main beam (33) on the short arm side of the T-shaped bridge until the above balance formula is satisfied; An isolation structure (52) and a protective structure (51) are set up at the spanned structure to physically isolate and protect the affected structure; According to conventional construction methods, a ball joint pile foundation (11) and a lower bearing platform (12) at the ball joint are symmetrically constructed on the outer side of the isolation structure (52) of the spanned structure protection zone, a horizontal spherical joint (13), an upper bearing platform (14) at the ball joint and a pier column (15) at the ball joint are installed on the lower bearing platform (12) at the ball joint, and a plurality of swivel support feet (16) are installed on the upper bearing platform (14) at the ball joint, and the lower end of the swivel support foot (16) is spaced 2 to 3 cm from the upper surface of the lower bearing platform (12) at the ball joint; Leveling the site and treating the foundation along the open space outside the isolation structure (52) of the protected area of ​​the spanned structure to prepare for the main beam construction; Setting up a support on the ground and pre-pressing the support, supporting a formwork and tying steel bars on the pre-pressed support, and casting a main beam (32) on the long arm side of the T-shaped bridge and a main beam (33) on the short arm side of the T-shaped bridge; After the concrete strength and prestressing of the T-shaped bridge are completed, a top counterweight (41) and an inner counterweight (42) are respectively applied to the main beam (33) on the short arm side of the T-shaped bridge, so that G11×A11+G12×A12+G13×A13=G2×A2; The cast-in-place bracket of the T-structure bridge is removed, and a traction mechanism (17) is arranged on the horizontally rotating ball joint (13), so that the two T-structure bridges on the left and right sides are rotated in a plane around the horizontally rotating ball joint (13) as a whole, until both T-structure bridges are rotated to the joint position; The construction of the ball joint sealing hinge support platform (18) is completed. The ball joint sealing hinge support platform (18) connects the lower support platform (12) at the ball joint and the upper support platform (14) at the ball joint into a whole, and the horizontal ball joint (13) and the support legs (16) for the swivel are buried in the ball joint sealing hinge support platform (18), thereby completing the construction of the T-structure swivel; A jack is horizontally arranged at one end of the long arm side main beam (32) of the T-frame bridge near the middle connecting portion (2), and the jack is used to horizontally push the long arm side main beam (32) of the T-frame bridge on the opposite side so that the pier column (15) at the ball joint obtains a bending moment toward the short arm side main beam (33) of the T-frame bridge. The magnitude of the force of the jack pushing the main beam is the smaller value between the bending moment that the bridge pier can withstand and the bending moment of the later rigid frame toward the long cantilever side; The middle connecting part (2) is butt-jointed, and after the jointing is completed, the jack, the beam top counterweight (41) and the beam inner counterweight (42) are disassembled.

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