A method for constructing the main girder of a π-shaped prestressed concrete cable-stayed bridge using a formwork system.

Abstract

This invention relates to the technical field of bridge construction, specifically to a method for constructing a hanging basket for the main girder of a π-shaped section prestressed concrete cable-stayed bridge. The method includes: a full-span scaffolding construction process for the main bridge, a cable-hanging process, a hanging basket assembly process, and a hanging basket pre-stressing process. The hanging basket consists of a bearing platform, a cable-stayed system, a traveling system, a positioning system, an anchoring system, an operating platform, and an embedded parts system. The tensioning mechanism is configured as a combination of tension rods, adjusting components, pads, screw seats, and auxiliary disassembly components. A locking groove is provided on the side wall of the tension rod. The adjusting component is configured as a combination of a threaded pipe and a support seat. A locking assembly consisting of a moving block, a locking block, and a support spring is installed in the mounting groove on the support seat. Through the supporting action of the support spring, the locking block is pressed against the locking groove, effectively ensuring the positioning stability of the adjusting component.

Description

Technical Field

[0001] This invention relates to the technical field of bridge construction, specifically to a method for constructing the main beam of a π-shaped prestressed concrete cable-stayed bridge using a formwork system. Background Technology

[0002] A bridge generally refers to a structure erected over rivers, lakes, or seas to allow vehicles and pedestrians to pass smoothly. To adapt to the rapidly developing modern transportation industry, the term "bridge" has also come to refer to structures built across mountains, streams, challenging geological conditions, or to meet other transportation needs, making travel more convenient. A bridge typically consists of a superstructure, substructure, supports, and ancillary structures. The superstructure, also known as the bridge span structure, is the main structure that crosses obstacles; the substructure includes abutments, piers, and foundations; supports are force-transmitting devices installed at the points where the bridge span structure supports the piers or abutments; and ancillary structures include approach slabs, tapered slopes, revetments, and diversion works.

[0003] Traditionally, the tensioning mechanism on the main girder formwork of cable-stayed bridges is adjusted and positioned using a nut structure. However, during the concrete pouring process, the nuts may shift at a certain angle due to the vibration of the concrete vibrating device, resulting in lower positioning accuracy and affecting subsequent construction. To address this issue, this invention proposes a π-section prestressed concrete cable-stayed bridge main girder formwork construction method. Summary of the Invention

[0004] The purpose of this invention is to provide a method for constructing the main beam of a prestressed concrete cable-stayed bridge with a π-shaped cross section using a formwork system, in order to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for constructing the main girder of a π-shaped section prestressed concrete cable-stayed bridge using a formwork system, the method comprising the following steps:

[0006] Step 1: Construction process of cast-in-place concrete using full-span scaffolding for the main bridge;

[0007] Step Two: Cable Hanging Construction Process. The cable hanging construction process includes: construction preparation process, inspection and installation of upper and lower anchorages, installation of HDPE round pipes, tensioning of single steel strand cables, first overall tensioning process, first pouring of segmental beam concrete, second overall tensioning process, second pouring of segmental beam concrete, third tensioning process, installation of cable clamps and shock absorbers, cyclic cable adjustment process, installation of shock absorbers and anchor head cover plates, and anchorage protection process.

[0008] Step 3: The assembly process of the hanging basket, which consists of a load-bearing platform, a cable system, a walking system, a positioning system, an anchoring system, an operating platform, and a pre-embedded parts system;

[0009] Step 4: Pre-compression process of the hanging basket;

[0010] The load-bearing platform consists of a planar rigid frame and hanging legs that support the suspended load and formwork system. The planar rigid frame is composed of a front crossbeam, a middle crossbeam, and two main longitudinal beams. To reduce the structural weight, the load-bearing platform is made of carbon structural steel. The front ends of the main longitudinal beams on both sides are slotted, with the arc angle consistent with the cable surface. A load-bearing surface is set at the front end of the main longitudinal beams to accommodate the different angles of the stay cables in each segment.

[0011] The cable system consists of a tensioning mechanism and a cold-cast anchor for the stay cables. The tensioning jack in the tensioning mechanism is fixed to the pad assembly by the support feet. The pad assembly can slide up and down and lock along the inner guide rail of the curved beam at the head of the main longitudinal beam. Therefore, the spatial position of the front support point can be adjusted to adapt to the changes in the angle of each segment of the stay cable.

[0012] The walking system is used to realize the unloaded forward movement of the hanging basket. It consists of a propulsion mechanism, guide rails and walking anti-roll wheels. Its traction mechanism is composed of two 500kN jacks that push the hanging legs synchronously to drive the hanging basket forward. The hanging leg support slides on the steel rail slide provided on the top surface of the main beam. When the hanging basket moves, the anti-roll wheels balance the forward tilting force, and the steel rails need to be connected and fixed with the precision-rolled threaded steel bars between the main beam.

[0013] The positioning system is used to achieve the initial positioning and fine-tuning positioning functions before the hanging basket is poured. It consists of a lifting mechanism, front and rear anchor bolt groups, thrust mechanism, etc. The hanging basket is lifted into place by the front anchor bolt group, the lifting mechanism is placed at the tail of the main longitudinal beam, and the thrust mechanism bears the horizontal component of the tension force of the cable. When the hanging basket is positioned, the vertical elevation of the front end of the hanging basket is adjusted.

[0014] The anchoring system includes a front anchor group and a rear anchor group. The front anchor group is located in the middle of the main longitudinal beam and on the rear transverse beam. Its function is to transfer the construction load borne by the bearing platform to the cast beam segment. The rear anchor group is located at the tail of the main longitudinal beam. Its function is to balance the overturning force generated when the hanging basket cable is initially tensioned. At the same time, the two anchor groups also serve as wind-resistant safety anchor points.

[0015] The formwork system is designed according to the main beam segment casting of the beam segment, and the formwork system is composed of bottom formwork and side formwork, bottom formwork and side formwork of transverse diaphragm, and inner formwork. When the main beam is demolded, the tie bolts are loosened first, the outer formwork is placed on the bearing platform, the hanging basket is moved forward and positioned, the formwork is erected, and the next segment is cast.

[0016] Preferably, the tensioning mechanism includes:

[0017] The tension rod has a first external thread structure on the outer wall of its lower end, and a cut surface is formed on the outer wall of its lower end by cutting, and a locking groove is formed on the cut surface.

[0018] An adjusting component is installed at the external thread position on the tension rod, and the adjusting component is composed of a threaded tube and a support base. The outer wall of the threaded tube is provided with a secondary external thread.

[0019] The pad is fitted onto the tension rod and placed on the support base. The base of the main beam hanging basket is placed on the pad, and the tension rod is installed by passing through the reserved hole on the base of the main beam hanging basket.

[0020] A screw-on seat, which is screwed onto the secondary external thread on the outer wall of the threaded pipe;

[0021] An auxiliary disassembly component is sleeved and installed on a threaded pipe, and the auxiliary disassembly component is limited by a screw seat.

[0022] Preferably, the support base has an installation groove, the installation groove is circumferentially arranged in a circle, and the inner side of the installation groove is provided with a locking block groove, and the bottom surface of the installation groove is provided with a movable groove, and a locking component is movably arranged in the installation groove.

[0023] Preferably, the engaging assembly is composed of a moving block, an engaging block, and a supporting spring. The moving block and the engaging block are integrally formed. The moving block is movably disposed in the mounting groove, and the engaging block is movably disposed in the engaging block groove. A spring hole is provided on the inner side of the moving block, and the supporting spring is fixedly glued to the bottom of the spring hole. Wedge-shaped grooves are provided on both sides of the moving block.

[0024] Preferably, when the support spring is in the reset state, the end of its engaging block is embedded in the engaging groove.

[0025] Preferably, the auxiliary disassembly component is composed of an annular seat, a movable block, and a push plate, with the annular seat sleeved and connected to the threaded pipe.

[0026] Preferably, the movable block is fixedly welded to the annular seat, and the movable block is provided with a circle of equal circumference. The push plate is integrally formed with the movable block, and a pair of push plates are symmetrically arranged on a single movable block, and the cross-section of the push plate is a right trapezoid.

[0027] Preferably, the cross-sectional dimensions of the movable block match the cross-sectional dimensions of the movable groove, and when the movable block is inserted into the movable groove, its push plate is correspondingly set with the wedge groove on the movable block.

[0028] Preferably, when the push plate is fully inserted into the wedge groove, its moving block is moved outward by force, and at this time, the locking block is fully retracted into the locking block groove.

[0029] Preferably, when the screw seat is screwed to the lowest side, its push plate completely retracts from the movable groove.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] 1. By setting up a construction method for the main beam of a concrete cable-stayed bridge consisting of the main bridge full-span scaffolding cast-in-place construction process, the hanging basket assembly process, and the hanging basket pre-stressing process, and by setting up the hanging basket to consist of a bearing platform, cable system, walking system, positioning system, anchoring system, operating platform and embedded part system, etc., the risk of excessive unbalanced load caused by cumulative error to the construction of large cantilever hanging basket is prevented.

[0032] 2. The tensioning mechanism is configured to consist of a tension rod, an adjusting component, a pad, a screw seat, and an auxiliary disassembly component. A locking groove is provided on the side wall of the tension rod, and the adjusting component is configured to consist of a threaded tube and a support seat. A locking assembly consisting of a moving block, a locking block, and a support spring is installed in the mounting groove on the support seat. The locking block is then pressed against the locking groove by the support spring, thereby effectively ensuring the positioning stability of the adjusting component. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the present invention;

[0034] Figure 2 This is a longitudinal half-sectional view of the present invention;

[0035] Figure 3 This is a horizontal half-sectional view of the present invention;

[0036] Figure 4 for Figure 3 Enlarged schematic diagram of the structure at point A in the middle;

[0037] Figure 5 This is a schematic diagram of the tension rod structure of the present invention;

[0038] Figure 6 This is a schematic diagram of the adjusting component structure of the present invention;

[0039] Figure 7 This is a half-sectional view of the support base of the present invention;

[0040] Figure 8 This is a schematic diagram of the auxiliary disassembly component structure of the present invention;

[0041] Figure 9 This is a schematic diagram of the snap-fit ​​assembly structure of the present invention;

[0042] Figure 10 This is a schematic diagram of the cable-hanging construction process of the present invention.

[0043] In the diagram: 1. Tensioning rod; 2. Adjusting component; 3. Pad; 4. Tightening seat; 5. Auxiliary disassembly component; 6. Cut surface; 7. Engaging groove; 8. Threaded pipe; 9. Support seat; 10. Mounting groove; 11. Engaging block groove; 12. Movable groove; 13. Engaging assembly; 14. Moving block; 15. Engaging block; 16. Support spring; 17. Wedge groove; 18. Ring seat; 19. Movable block; 20. Push plate. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Please see Figure 1-10 The present invention provides the following three preferred embodiments.

[0046] Example 1

[0047] A method for constructing the main girder of a π-shaped prestressed concrete cable-stayed bridge using a formwork system includes the following steps:

[0048] Step 1: Construction process of cast-in-place concrete using full-span scaffolding for the main bridge;

[0049] Step Two: Cable Hanging Construction Process. The cable hanging construction process includes: construction preparation process, inspection and installation of upper and lower anchorages, installation of HDPE round pipes, tensioning of single steel strand cables, primary overall tensioning process, primary pouring of segmental beam concrete, secondary overall tensioning process, secondary pouring of segmental beam concrete, tertiary tensioning process, installation of cable clamps and shock absorbers, cyclic cable adjustment process, installation of shock absorbers and anchor head cover plates, and anchorage protection process.

[0050] Step 3: The assembly process of the hanging basket, which consists of a load-bearing platform, a cable system, a walking system, a positioning system, an anchoring system, an operating platform, and a pre-embedded parts system;

[0051] Step 4: Pre-compression process of the hanging basket;

[0052] The load-bearing platform consists of a planar rigid frame and hanging legs that support the cantilever load and formwork system. The planar rigid frame is composed of a front crossbeam, a middle crossbeam, and two main longitudinal beams. To reduce the structural weight, the load-bearing platform is made of carbon structural steel. The front ends of the main longitudinal beams on both sides are slotted, and the arc angle is consistent with the cable surface. A load-bearing surface is set at the front end of the main longitudinal beams to accommodate the different angles of the stay cables in each segment.

[0053] The cable system consists of a tensioning mechanism and cold-cast anchors for the stay cables. The tensioning jacks in the tensioning mechanism are fixed to the pad assembly by the support feet. The pad assembly can slide up and down and lock along the inner guide rail of the curved beam at the head of the main longitudinal beam. Therefore, the spatial position of the front support can be adjusted to adapt to the changes in the angle of each section of the stay cable.

[0054] The walking system is used to realize the unloaded forward movement of the hanging basket. It consists of a propulsion mechanism, guide rails and walking anti-roll wheels. Its traction mechanism is composed of two 500kN jacks that push the hanging legs synchronously to drive the hanging basket forward. The hanging leg support slides on the steel rail slide track laid on the top surface of the main beam. When the hanging basket moves, the anti-roll wheels balance the forward tilting force, and the steel rails need to be connected and fixed with the precision-rolled threaded steel bars between the main beam.

[0055] The positioning system is used to achieve the initial positioning and fine-tuning positioning functions before the hanging basket is poured. It consists of a lifting mechanism, front and rear anchor bolt groups, thrust mechanism, etc. The hanging basket is lifted into place by the front anchor bolt group, the lifting mechanism is placed at the tail of the main longitudinal beam, and the thrust mechanism bears the horizontal component of the tension force of the cable. When the hanging basket is positioned, the vertical elevation of the front end of the hanging basket is adjusted.

[0056] The anchoring system includes a front anchor group and a rear anchor group. The front anchor group is located in the middle of the main longitudinal beam and on the rear transverse beam. Its function is to transfer the construction load borne by the bearing platform to the cast beam segment. The rear anchor group is located at the tail of the main longitudinal beam. Its function is to balance the overturning force generated when the hanging basket cable is initially tensioned. At the same time, the two anchor groups also serve as wind-resistant safety anchor points.

[0057] The formwork system is designed according to the segmental casting of the main beam. The formwork system is composed of bottom formwork and side formwork, bottom formwork and side formwork of the transverse diaphragm, and inner formwork. When demolding the main beam, the tie bolts are loosened first, the outer formwork is placed on the bearing platform, the hanging basket is moved forward and positioned, the formwork is erected, and the next segment is cast. The construction method of the main beam hanging basket of the concrete cable-stayed bridge is set up by combining the main bridge full-span scaffolding in-situ construction process, hanging basket assembly process, and hanging basket pre-stressing process. The hanging basket is set up to be composed of bearing platform, cable system, walking system, positioning system, anchoring system, operating platform and embedded part system, etc., to prevent the risk of excessive unbalanced load caused by cumulative error to the construction of large cantilever hanging basket.

[0058] Example 2

[0059] Based on Embodiment 1, the tensioning mechanism includes a tension rod 1, an adjusting component 2, a pad 3, a screw seat 4, and an auxiliary disassembly component 5. The lower end of the tension rod 1 has a first external thread structure on its outer wall, and a cut surface 6 is formed on the lower end of the outer wall of the tension rod 1 by cutting, and a locking groove 7 is formed on the cut surface 6. The adjusting component 2 is installed on the external thread position of the tension rod 1, and the adjusting component 2 is composed of a threaded tube 8 and a support seat 9. The outer wall of the threaded tube 8 has a secondary external thread. The pad 3 is sleeved on the tension rod 1 and rests on the support seat 9, and the base of the main beam hanging basket is rested on the pad 3. The tension rod 1 is installed by passing through the reserved hole on the base of the main beam hanging basket. The screw seat 4 is screwed and installed on the secondary external thread on the outer wall of the threaded tube 8. The auxiliary disassembly component 5 is sleeved and installed on the threaded tube 8, and the auxiliary disassembly component 5 is limited by the screw seat 4.

[0060] The support base 9 has an installation groove 10, which is arranged in a circle. The inner side of the installation groove 10 is provided with a locking block groove 11, and the bottom surface of the installation groove 10 is provided with a movable groove 12. The locking component 13 is movably arranged in the installation groove 10.

[0061] The engaging assembly 13 is composed of a movable block 14, an engaging block 15, and a support spring 16. The movable block 14 and the engaging block 15 are integrally formed. The movable block 14 is movably disposed in the mounting groove 10, and the engaging block 15 is movably disposed in the engaging block groove 11. A spring hole is provided on the inner side of the movable block 14. The support spring 16 is fixedly glued to the bottom of the spring hole. Wedge-shaped grooves 17 are provided on both sides of the movable block 14.

[0062] When the support spring 16 is in the reset state, the end of its locking block 15 is embedded in the locking groove 7. By setting the tensioning mechanism to be composed of tension rod 1, adjusting component 2, pad 3, screw seat 4 and auxiliary disassembly component 5, and opening the locking groove 7 on the side wall of tension rod 1, and setting the adjusting component 2 to be composed of threaded tube 8 and support seat 9, and setting the locking assembly 13 composed of moving block 14, locking block 15 and support spring 16 in the mounting groove 10 on support seat 9, the locking block 15 is pressed against the locking groove 7 by the supporting action of the support spring 16, thereby effectively ensuring the positioning stability of adjusting component 2.

[0063] Example 3

[0064] Based on Embodiment 2, the auxiliary disassembly component 5 is composed of an annular seat 18, a movable block 19 and a push plate 20, with the annular seat 18 sleeved and connected to the threaded pipe 8.

[0065] The movable block 19 is fixedly welded to the annular seat 18, and a ring is arranged around the circumference of the movable block 19. The push plate 20 is integrally formed with the movable block 19, and a pair of push plates 20 are symmetrically arranged on a single movable block 19, and the cross section of the push plate 20 is a right trapezoid.

[0066] The cross-sectional dimensions of the movable block 19 match the cross-sectional dimensions of the movable groove 12, and when the movable block 19 is inserted into the movable groove 12, its push plate 20 is correspondingly set with the wedge groove 17 on the movable block 14.

[0067] When the push plate 20 is fully inserted into the wedge groove 17, its moving block 14 is moved outward by force, and at this time, the locking block 15 is fully retracted into the locking block groove 11.

[0068] When the screw seat 4 is screwed to the lowest side, its push plate 20 is completely disengaged from the movable groove 12. By screwing the screw seat 4, the annular seat 18 is pushed, which in turn pushes the movable block 19 and the push plate 20, thereby pushing the moving block 14, so that the locking block 15 is put into the locking block groove 11, thereby unlocking the locking and allowing the adjusting member 2 to be freely adjusted.

[0069] Although the illustrative specific embodiments of this application have been described above to enable those skilled in the art to understand this application, this application is not limited to the scope of the specific embodiments. For those skilled in the art, all applications utilizing the concept of this application are protected as long as various variations are within the spirit and scope of this application as defined and determined by the appended claims.

Claims

1. A method for constructing the main beam of a prestressed concrete cable-stayed bridge with a π-shaped cross-section using a formwork system, characterized in that: The construction method for the hanging basket of the main girder of the prestressed concrete cable-stayed bridge with a π-shaped cross section includes the following steps: Step 1: Construction process of cast-in-place concrete using full-span scaffolding for the main bridge; Step Two: Cable Hanging Construction Process. The cable hanging construction process includes: construction preparation process, inspection and installation of upper and lower anchorages, installation of HDPE round pipes, tensioning of single steel strand cables, first overall tensioning process, first pouring of segmental beam concrete, second overall tensioning process, second pouring of segmental beam concrete, third tensioning process, installation of cable clamps and shock absorbers, cyclic cable adjustment process, installation of shock absorbers and anchor head cover plates, and anchorage protection process. Step 3: The assembly process of the hanging basket, which consists of a load-bearing platform, a cable system, a walking system, a positioning system, an anchoring system, an operating platform, and a pre-embedded parts system; Step 4: Pre-compression process of the hanging basket; The load-bearing platform consists of a planar rigid frame and hanging legs that support the suspended load and formwork system. The planar rigid frame consists of a front crossbeam, a middle crossbeam and two main longitudinal beams. To reduce the structural weight, the load-bearing platform is made of carbon structural steel. The front ends of the main longitudinal beams on both sides are slotted, and the arc angle is consistent with the cable surface. A load-bearing surface is set at the front end of the main longitudinal beams to adapt to the different angle changes of the stay cables in each segment. The cable system consists of a tensioning mechanism and a cold-cast anchor for the stay cables. The tensioning jack in the tensioning mechanism is fixed to the pad assembly by the support feet. The pad assembly can slide up and down and lock along the inner guide rail of the curved beam at the head of the main longitudinal beam. Therefore, the spatial position of the front support point can be adjusted to adapt to the changes in the angle of each segment of the stay cable. The walking system is used to realize the unloaded forward movement of the hanging basket. It consists of a propulsion mechanism, guide rails and walking anti-roll wheels. Its traction mechanism is composed of two 500kN jacks that push the hanging legs synchronously to drive the hanging basket forward. The hanging leg support slides on the steel rail slide provided on the top surface of the main beam. When the hanging basket moves, the anti-roll wheels balance the forward tilting force, and the steel rails need to be connected and fixed with the precision-rolled threaded steel bars between the main beam. The positioning system is used to achieve the initial positioning and fine-tuning positioning functions before the hanging basket is poured. It consists of a lifting mechanism, front and rear anchor bolt groups, thrust mechanism, etc. The hanging basket is lifted into place by the front anchor bolt group, the lifting mechanism is placed at the tail of the main longitudinal beam, and the thrust mechanism bears the horizontal component of the tension force of the cable. When the hanging basket is positioned, the vertical elevation of the front end of the hanging basket is adjusted. The anchoring system includes a front anchor group and a rear anchor group. The front anchor group is located in the middle of the main longitudinal beam and on the rear transverse beam. Its function is to transfer the construction load borne by the bearing platform to the cast beam segment. The rear anchor group is located at the tail of the main longitudinal beam. Its function is to balance the overturning force generated when the hanging basket cable is initially tensioned. At the same time, the two anchor groups also serve as wind-resistant safety anchor points. The formwork system is designed according to the main beam segment casting of the beam segment, and the formwork system is composed of bottom formwork and side formwork, bottom formwork and side formwork of transverse diaphragm, and inner formwork. When demolding the main beam, the tie bolts are loosened first, the outer formwork is placed on the bearing platform, the hanging basket is moved forward and positioned, the formwork is erected, and the next segment is cast. The tensioning mechanism includes: Tensioning rod (1), the lower end of the tensioning rod (1) is provided with a first external thread structure on the outer wall, and the lower end of the tensioning rod (1) is provided with a cut surface (6) formed by cutting, and a locking groove (7) is provided on the cut surface (6). Adjusting component (2), the adjusting component (2) is installed at the external thread position on the tension rod (1), and the adjusting component (2) is composed of a threaded tube (8) and a support seat (9), and the outer side wall of the threaded tube (8) is provided with a secondary external thread; Pad plate (3), the pad plate (3) is sleeved on the tension rod (1) and erected on the support seat (9), and the base of the main beam hanging basket is erected on the pad plate (3), and the tension rod (1) is installed by passing through the reserved hole on the base of the main beam hanging basket; Screwing seat (4), which is screwed onto the secondary external thread on the outer side wall of the threaded pipe (8); Auxiliary disassembly component (5) is sleeved on the threaded pipe (8) and the auxiliary disassembly component (5) is limited by the screw seat (4); The support base (9) is provided with an installation groove (10), the installation groove (10) is provided with a circle, and the inner side of the installation groove (10) is provided with a locking block groove (11), and the bottom surface of the installation groove (10) is provided with a movable groove (12). A locking component (13) is movably provided in the installation groove (10). The engaging assembly (13) is composed of a moving block (14), an engaging block (15), and a supporting spring (16). The moving block (14) and the engaging block (15) are integrally formed. The moving block (14) is movably disposed in the mounting groove (10), and the engaging block (15) is movably disposed in the engaging block groove (11). A spring hole is provided on the inner side of the moving block (14), and the supporting spring (16) is fixedly glued to the bottom of the spring hole. Wedge-shaped grooves (17) are provided on both sides of the moving block (14). When the support spring (16) is in the reset state, the end of its locking block (15) is embedded in the locking groove (7); The auxiliary disassembly component (5) is composed of an annular seat (18), a movable block (19) and a push plate (20), and the annular seat (18) is sleeved and connected to the threaded pipe (8); The movable block (19) is fixedly welded to the ring seat (18), and the movable block (19) is surrounded by a circle. The push plate (20) is integrally formed with the movable block (19), and a pair of push plates (20) are symmetrically arranged on a single movable block (19), and the cross section of the push plate (20) is a right trapezoid. The cross-sectional dimensions of the movable block (19) match the cross-sectional dimensions of the movable groove (12), and when the movable block (19) is inserted into the movable groove (12), its push plate (20) is correspondingly set with the wedge groove (17) on the movable block (14).

2. The method for constructing the main beam of a prestressed concrete cable-stayed bridge with a π-shaped cross-section using a formwork system according to claim 1, characterized in that: When the push plate (20) is fully inserted into the wedge groove (17), its moving block (14) is moved outward by force, and at this time, the locking block (15) is fully retracted into the locking block groove (11).

3. The method for constructing the main beam of a prestressed concrete cable-stayed bridge with a π-shaped cross-section using a formwork system according to claim 2, characterized in that: When the screw seat (4) is screwed to the lowest side, its push plate (20) completely retracts from the movable groove (12).

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