Aluminum alloy inner formwork system for cast-in-place box beam with variable cross-section and diaphragm and construction method thereof

Abstract

The present invention discloses an aluminum alloy inner mold system for a variable-section cast-in-place box girder with a transverse diaphragm, which is composed of a template system and a support system installed in the box girder. The template system includes a standard template, a special-shaped template and a first-removal block template, which are respectively installed at the linear straight part, the variable-section part and the center of the top plate template end of the box girder. The support system includes a base beam, a base beam seat and a steel pipe bracket built on the base beam. The front end of the base beam is suspended on the front upper cross beam of the hanging basket through a hanger rod, and the rear end is installed on the base beam seat. The base beam seat is supported on the bottom plate of the cast beam section; the top of the steel pipe bracket is installed with a keel through a top support, and the keel supports the template. The construction steps include: (1) box girder structure analysis; (2) aluminum alloy inner mold design; (3) aluminum alloy inner mold installation; (4) aluminum alloy inner mold removal. The aluminum alloy inner mold system is used in the construction of variable-section cast-in-place box girders with transverse diaphragms, which can solve the problems of the current steel or wooden template assembly and turnover troubles, long construction period, and large material waste.

Description

Technical Field

[0001] The invention relates to the technical field of bridge construction, in particular to an aluminum alloy inner mold system of a cast-in-place box beam with a variable cross-section and a diaphragm and a construction method thereof. Background Art

[0002] Box girder is a type of bridge engineering. It is hollow inside and has flanges on both sides of the upper part, similar to a box, hence the name. Prestressed concrete cast-in-place box girder is the main type of bridge span structure of current beam bridges. It has the advantages of high rigidity, less maintenance and repair after construction, and low noise. It is the preferred main beam structure system for highways, high-speed railways and municipal transportation bridges.

[0003] The main beams of large-span bridges mostly use variable-section box beams. The two-dimensional dimensions of the hollow box chamber inside the box beam and the structural dimensions such as the upper and lower chamfers change continuously with the beam length. At the same time, the internal box chamber of the box beam with a diaphragm can only be turned through the manhole due to the obstruction of the diaphragm. These two factors bring many inconveniences to the template construction. For the variable-section cast-in-place box beam with a diaphragm, wooden templates or steel templates are mostly used as their inner templates. At present, wooden templates are assembled on site and the templates are continuously cut according to the changes in the size of the inner box of the box beam. This practice makes it difficult to control the template installation positioning accuracy and the casting appearance quality is poor. During the construction process, the template needs to be constantly adjusted, and the construction period is long. At the same time, the template has a short service life and cannot be recycled, which increases costs and is not conducive to environmental protection. The use of steel templates as inner templates is heavy and the template turnover needs to pass through the manhole, which makes it difficult to use mechanical assistance. Therefore, the template installation, removal and turnover are extremely inconvenient and easily cause safety problems. Therefore, there is an urgent need to develop an inner mold system that is highly standardized, recyclable, lightweight, easy to use and adaptable to variable-section box girders. Summary of the invention

[0004] The purpose of the present invention is to provide an aluminum alloy inner form system suitable for cast-in-place box girders with variable cross-sections and a construction method thereof, so as to solve the problems of the current steel and wooden formwork assembly and turnover troubles, long construction period, large material waste, etc.

[0005] In order to achieve the purpose of the present invention, the technical solution adopted is:

[0006] A cast-in-place box girder with variable cross-section and a diaphragm, and an aluminum alloy inner mold system, which is composed of a template system installed in the box girder and a support system for supporting and fixing the template; the template system includes three parts: a standard template, a special-shaped template and a first-removal block template; the standard template is made of a rectangular aluminum template of uniform size and is installed on the top plate and web of the box girder and the linear straight parts of the diaphragm; the special-shaped template is installed at the top chamfer and the inner bottom chamfer of the hollow box chamber of the box girder, and is designed separately. Each specification and model of the special-shaped template is only suitable for the construction of the corresponding size of chamfer and cannot be mixed; the first-removal block template is set at the end position of the box girder top plate template, and is composed of two right-angle trapezoidal templates and an isosceles trapezoidal formwork, and when installed, the long side of the isosceles trapezoidal formwork faces the outer end of the formwork; the support system includes a base beam, a base beam seat and a steel pipe bracket built on the base beam, the front end of the base beam is suspended on the front upper cross beam of the hanging basket through a hanger, the rear end is placed on the base beam seat, and is hinged and fixed to the base beam seat through a pin shaft, the base beam seat is supported on the bottom plate of the cast beam section, and the base beams are connected as a whole by means of welded steel beams; a top support is installed on the top of the steel pipe bracket; a keel is installed on the top support, and the keel directly supports the box beam top plate formwork; corner connectors are installed at both ends of the keel, the corner connectors are connected with back ribs, and the box beam web formwork is attached and fixed to the back ribs.

[0007] Further preferred: the base beam is made of steel section, the base of the base beam includes a column formed by two channel steels, a cylindrical bearing is installed between the channel steels for supporting the base beam, a steel base plate is welded to the bottom of the column, the structure is strengthened by welding steel tie plates between the column and the base plate, bolt holes are arranged on the base plate, and the base plate is connected and fixed with the cast box beam base plate by bolts; the column is provided with a hinge hole for hingedly fixing with the base beam through a pin shaft.

[0008] Further preferably, the standard formwork, the special-shaped formwork and the first-dismantled block formwork are connected by a combination of bolts and tapered pins.

[0009] Further preferably, the formwork system is provided with a plurality of tension screws on the box beam web formwork, and both ends of the tension screws are fastened to the back ribs via nuts.

[0010] Further preferred: the keel, corner connectors and back ribs are all made of steel sections, and the keel and back ribs are manufactured in sections according to construction convenience, and the sections are connected by flange bolts.

[0011] Further preferred: the keel and the corner connector are connected by a pin, the corner connector and the back rib are connected by bolts, and the back rib and the formwork system are connected by a connecting buckle.

[0012] The construction process of the aluminum alloy inner formwork system for the variable-section cast-in-place box beam with transverse diaphragm comprises the following steps:

[0013] 1) Box girder structure analysis: According to the cast-in-place continuous box girder drawings, analyze the changes in the box section inside the box girder and the design parameters and similarities and differences of the structural parts of the web, diaphragm, top plate, chamfer, manhole, and tooth block. Determine the combination method and quantity of aluminum alloy inner molds based on the changes in the section of the box girder segments of the entire bridge.

[0014] 2) Aluminum alloy inner mold design: The box girder inner mold is modeled as a whole and grid-divided and divided into mold designs. The plane structures of the web, diaphragm and top plate adopt standard templates, and the spatial structures of manholes, chamfers and tooth blocks adopt special-shaped template combinations. Each type of template is designed according to the size that is easy to combine, assemble, disassemble and transfer. The tie rod holes of the standard templates of the top plate and web are arranged in a matrix. The combination of standard templates in all directions can achieve horizontal and vertical alignment of the tie rod holes. The template at the middle end of the top plate adopts the first-dismantled block template structure design to facilitate template removal and transfer.

[0015] 3) Aluminum alloy inner mold installation:

[0016] a. Install the bottom plate and web reinforcement, prestressed pipes, embedded parts, and base beam of the box beam segment and hoist the base beam;

[0017] b. Measure and lay out, and locate the center line of the side mold of the diaphragm;

[0018] c. Install the diaphragm and web templates, assemble them piece by piece from the middle of the diaphragm to the webs on both sides according to the designed block template combination method, and the assembly height of each cycle is about m-.m;

[0019] d. Install the back ribs and insert the tension screws to fix the template;

[0020] e. Build a layer of steel pipe support from the base beam and lay a working platform on the support. The building height should be consistent with the formwork height for subsequent formwork installation work;

[0021] f. Repeat steps c to e until the diaphragm and web templates are installed to the chamfer of the inner top mold;

[0022] g. Install the top support on the top of the bracket and place the keel on the top support;

[0023] h. Install the top mold template and the upper chamfer template. The template is assembled from the top chamfer of the web plates on both sides to the middle of the top plate. The first dismantled template is used for mold closing in the middle;

[0024] i. Adjust the top support to make the overlapping part of the top mold close to the top plate of the upper segment, and at the same time measure and adjust the elevation of the front end of the top mold to meet the design requirements;

[0025] j. Install the connectors to connect the keel with the back rib, so that the inner top formwork, side formwork and diaphragm formwork are connected as a whole;

[0026] k. Install the box girder top plate steel bars, prestressed pipes and embedded parts, pour the beam section concrete, complete the beam section construction, and start removing the inner formwork after the concrete strength of the beam section reaches the requirements for formwork removal.

[0027] 4) Removal of aluminum alloy inner mold:

[0028] a. Use the original steel pipe support and working platform to dismantle the tension screws and back ribs;

[0029] b. Remove the web and diaphragm formwork layer by layer from bottom to top;

[0030] c. Remove the first block of the top plate formwork, and then remove the remaining block formworks of the top plate in sequence;

[0031] d. Remove the keel, and then remove the steel pipe support from top to bottom;

[0032] e. Transfer the workpiece through the manhole of the cross partition to the construction location of the next beam section for installation.

[0033] The technology of this application has the following characteristics and advantages over the prior art:

[0034] 1. The aluminum alloy formwork is designed in advance. By deepening the formwork matching, the proportion of special-shaped formwork is reduced to a minimum. About 80% of the formwork is reusable general standard model formwork, which maximizes the turnover rate of the aluminum formwork. At the same time, the formwork adopts a first-disassembly fast design. After the first-disassembly fast formwork is removed from the connecting nut, it can be easily removed by applying a pulling force to the outside, avoiding the problem of the formwork being too tightly connected and being unable to be disassembled or being easily damaged after disassembly after concrete pouring. This reduces construction time and saves formwork maintenance costs.

[0035] 2. The steel pipe support is erected on the base beam and does not touch the bottom plate of the box beam. The construction of various parts of the box beam can be carried out simultaneously, eliminating the trouble of the traditional support method of pouring the bottom plate concrete first and then setting up the support to construct the web and top plate after it solidifies, thus saving construction time.

[0036] 3. Compared with wooden formwork, this aluminum alloy inner formwork system has high installation flatness and good appearance quality of concrete pouring; aluminum alloy formwork can be recycled and reused repeatedly, with a long service life, less material waste, and is beneficial to environmental protection; special-shaped formwork is designed and produced in advance, and there is no need to constantly adjust the formwork during construction, and the construction period is short.

[0037] 4. Compared with steel formwork, this aluminum alloy inner formwork adopts a small piece design, light weight, easy installation, dismantling and transportation, and does not require reliance on large-scale mechanical equipment; at the same time, the aluminum alloy formwork does not rust, and compared with steel formwork, it can reduce maintenance costs during construction and shorten formwork maintenance time. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1This is a schematic diagram of the installation structure of the aluminum alloy inner mold system;

[0039] Figure 2 for Figure 1 A right side schematic diagram of

[0040] Figure 3 The schematic diagram of the arrangement of the base beam is shown in FIG.

[0041] Figure 4 This is a schematic diagram of the installation and connection of the base beam, steel pipe support and base beam base;

[0042] Figure 5 This is a schematic diagram of the installation and connection between the aluminum alloy inner mold system and the support system;

[0043] Figure 6 It is a schematic diagram of the connection structure between the standard template and the back rib;

[0044] Figure 7 for Figure 6 AA direction schematic diagram;

[0045] Figure 8 This is the installation diagram of the first dismantling template;

[0046] Fig. 9 It is a structural schematic diagram of the base beam;

[0047] Fig.10 for Fig. 9 Schematic diagram of the left side;

[0048] Fig.11 for Fig. 9 A top view schematic diagram of

[0049] Fig.12 is a structural schematic diagram of a connecting piece;

[0050] Fig.13 It is a structural schematic diagram of a special-shaped template;

[0051] The names corresponding to the numbers in the figure are:

[0052] 1. Standard formwork; 2. Special-shaped formwork; 3. Right-angle trapezoidal formwork; 4. Isosceles trapezoidal formwork; 5. Base beam; 6. Steel pipe support; 7. Hanger; 8. Front upper beam; 9. Base beam base; 10. Top support; 11. Keel; 12. Corner connector; 13. Back rib; 14. Column; 15. Cylindrical bearing; 16. Bottom plate; 17. Steel tie plate; 18. Tension screw; 19. Steel beam. DETAILED DESCRIPTION

[0053] In order to describe the present technology more clearly, the present technology is further described in detail below with reference to the accompanying drawings and embodiments. Example

[0054] A cast-in-place box girder aluminum alloy inner formwork system with a variable cross-section and a diaphragm, which consists of a formwork system installed in the box girder and a support system for supporting and fixing the formwork; the formwork system comprises three parts: a standard formwork 1, a special-shaped formwork 2 and a first-dismantled block formwork; the standard formwork 1, the special-shaped formwork 2 and the first-dismantled block formwork are connected by a combination of bolts and tapered pins. The standard formwork 1 is made of rectangular aluminum formwork of uniform size and is installed on the linear and straight parts of the box girder top plate, web plate and diaphragm; the special-shaped formwork 2 is installed on the top chamfer and inner bottom chamfer of the hollow box chamber of the box girder and is designed separately. Each specification and model of special-shaped formwork is only suitable for the construction of chamfers of corresponding size and cannot be mixed; the first-dismantled block formwork is arranged at the end position of the box girder top plate formwork and is composed of two right-angled trapezoidal formworks 3 and an isosceles trapezoidal formwork 4. When installed, the long side of the isosceles trapezoidal formwork faces the outer end of the formwork; the support system includes a base beam 5, a base beam base 9 and a steel pipe bracket 6 built on the base beam 5. The front end of the base beam 5 is suspended on the front upper cross beam 8 of the hanging basket through a hanger 7, and the rear end is placed on the base beam base 9 and is hinged and fixed to the base beam base 9 through a pin. The base beam 5 is made of section steel, and the base beam base 9 includes A column 14 is formed by two channel steels, and a cylindrical bearing 15 is installed between the channel steels for supporting the base beam 5. A steel base plate 16 is welded to the bottom of the column 14, and a steel tie plate 17 is welded between the column 14 and the base plate 16 for structural reinforcement. Bolt holes are arranged on the base plate 16, and the base plate 16 is connected and fixed to the bottom plate of the cast box beam by driving bolts; a hinge hole for hingedly fixing with the base beam 5 through a pin shaft is arranged on the column 14; the base beam base 9 is supported on the bottom plate of the cast beam section, and the base beams 5 are connected as a whole by means of a welded steel cross beam 19; a top support 10 is installed on the top of the steel pipe bracket 6; a keel 11 is installed on the top support 10, and the keel directly supports the box beam top plate template; corner connectors 12 are installed at both ends of the keel 11, and the corner connector 12 is connected to the back rib 13, and the box beam web template is attached and fixed to the back rib 13. The keel 11, corner connector 12, and back rib 13 are all made of steel. The keel 11 and back rib 13 are manufactured in sections according to the construction convenience, and the sections are connected by flange bolts. The keel 11 and corner connector 12 are connected by pins, the corner connector 12 and back rib 13 are connected by bolts, and the back rib 13 and the formwork system are connected by connecting buckles.

[0055] The template system is provided with a plurality of tension screws 18 on the box beam web template, and both ends of the tension screws 18 are fastened to the back ribs 13 via nuts.

[0056] The construction process of the aluminum alloy inner formwork system for the variable-section cast-in-place box beam with transverse diaphragm comprises the following steps:

[0057] 1) Box girder structure analysis: According to the cast-in-place continuous box girder drawings, analyze the changes in the box section inside the box girder and the design parameters and similarities and differences of the structural parts of the web, diaphragm, top plate, chamfer, manhole, and tooth block. Determine the combination method and quantity of aluminum alloy inner molds based on the changes in the section of the box girder segments of the entire bridge.

[0058] 2) Aluminum alloy inner mold design: The box girder inner mold is modeled as a whole and grid-divided to design the mold. The plane structure of the web, diaphragm and top plate adopts standard template 1, and the spatial structure of the manhole, chamfer and tooth block adopts a combination of special-shaped templates 2. Each type of template is designed according to the size that is easy to combine, assemble, disassemble and transfer. The tie rod holes of the standard templates of the top plate and web are arranged in a matrix. The combination of standard templates in all directions can achieve horizontal and vertical alignment of the tie rod holes. The template at the middle end of the top plate adopts the first-dismantled block template structure design to facilitate template removal and transfer.

[0059] 3) Aluminum alloy inner mold installation:

[0060] a. Install the bottom plate and web steel bars, prestressed pipes, embedded parts, base beam base 9 of the box beam segment and hoist the base beam 5;

[0061] b. Measure and lay out, and locate the center line of the side mold of the diaphragm;

[0062] c. Install the diaphragm and web templates, assemble them piece by piece from the middle of the diaphragm to the webs on both sides according to the designed block template combination method, and the assembly height of each cycle is about 1m-1.5m;

[0063] d. Install the back rib 13 and insert the tension screw 18 to fix the template;

[0064] e. Build a layer of steel pipe bracket 6 from the base beam 5 and lay a working platform on the bracket. The building height is consistent with the template height for subsequent template installation operations;

[0065] f. Repeat steps c to e until the diaphragm and web templates are installed to the chamfer of the inner top mold;

[0066] g. Install a top support 10 on the top of the bracket 6, and place a keel 11 on the top support;

[0067] h. Install the top mold template and the upper chamfer template. The template is assembled from the top chamfer of the web plates on both sides to the middle of the top plate. The first dismantled template is used for mold closing in the middle;

[0068] i. Adjust the top support 10 to make the overlapping part of the top mold close to the top plate of the upper segment, and at the same time measure and adjust the elevation of the front end of the top mold to meet the design requirements;

[0069] j. Install the connector 12 to connect the keel 11 with the back rib 13, so that the inner top formwork, the side formwork and the diaphragm formwork are connected as a whole;

[0070] k. Install the box girder top plate steel bars, prestressed pipes and embedded parts, pour the beam section concrete, complete the beam section construction, and start removing the inner formwork after the concrete strength of the beam section reaches the requirements for formwork removal.

[0071] 4) Removal of aluminum alloy inner mold:

[0072] a. Use the original steel pipe support 6 and work platform to dismantle the tension screw 18 and back rib 13;

[0073] b. Remove the web and diaphragm formwork layer by layer from bottom to top;

[0074] c. Remove the first block of the top plate formwork, and then remove the remaining block formworks of the top plate in sequence;

[0075] d. Remove the keel 11, and then remove the steel pipe support 6 from top to bottom;

[0076] e. Transfer the workpiece through the manhole of the cross partition to the construction location of the next beam section for installation.

[0077] The above description is not a limitation of the present application, and the present application is not limited to the above examples. Any changes, modifications, additions or substitutions made by technicians in this field within the essential scope of the present application should fall within the scope of protection of the present application.

Claims

1. A construction method for an aluminum alloy inner mold system of a cast-in-place box beam with a variable cross-section and a diaphragm, characterized in that: The aluminum alloy inner formwork system of a cast-in-place box girder with a variable cross-section and a transverse diaphragm comprises a formwork system installed in the box girder and a support system for supporting a fixed formwork; the formwork system comprises three parts: a standard formwork (1), a special-shaped formwork (2) and a first-removal block formwork; the standard formwork (1) is made of a rectangular aluminum formwork of uniform size and is installed on the top plate and web of the box girder and the linear and straight parts of the transverse diaphragm; the special-shaped formwork (2) is installed on the top chamfer and the inner bottom chamfer of the hollow box chamber of the box girder and is designed separately. Each specification and model of the special-shaped formwork is only suitable for the construction of the corresponding chamfer and cannot be mixed; the first-removal block formwork is arranged at the end position of the box girder top plate formwork and is composed of two right-angled trapezoidal formworks (3) and an isosceles trapezoidal formwork (4). When installed, the long side of the isosceles trapezoidal formwork faces the outside of the formwork. end; the support system comprises a base beam (5), a base beam base (9) and a steel pipe support (6) built on the base beam (5); the front end of the base beam (5) is suspended on the front upper cross beam (8) of the hanging basket via a suspension rod (7); the rear end is placed on the base beam base (9) and is hingedly fixed to the base beam base (9) via a pin shaft; the base beam base (9) is supported on the bottom plate of the cast beam section; the base beams (5) are connected as a whole by means of a welded steel cross beam (19); a top support (10) is installed on the top of the steel pipe support (6); a keel (11) is installed on the top support (10), and the keel directly supports the box beam top plate template; corner connectors (12) are installed at both ends of the keel (11), and the corner connector (12) is connected to a back rib (13), and the box beam web template is attached and fixed to the back rib (13); The construction process of the aluminum alloy inner formwork system for cast-in-place box beams with variable cross-sections including diaphragms includes the following steps: 1) Box girder structure analysis: According to the cast-in-place continuous box girder drawings, analyze the changes in the box section inside the box girder and the design parameters and similarities and differences of the structural parts of the web, diaphragm, top plate, chamfer, manhole, and tooth block, and determine the combination method and quantity of the aluminum alloy inner mold based on the changes in the section of the box girder segments of the entire bridge; 2) Aluminum alloy inner mold design: The box girder inner mold is modeled as a whole and grid-divided to design the mold. The plane structure of the web, diaphragm and top plate adopts standard templates (1), and the spatial structure of the manhole, chamfer and tooth block adopts a combination of special-shaped templates (2). Each type of template is designed according to the size that is easy to assemble, disassemble and transfer. The tie rod holes of the standard templates of the top plate and web plate adopt a matrix hole arrangement. The combination of standard templates in all directions can achieve the horizontal and vertical alignment of the tie rod holes. The template at the middle end of the top plate adopts the first-dismantling block template structure design to facilitate the removal and transfer of the template. 3) Aluminum alloy inner mold installation: a. Install the bottom plate and web reinforcement, prestressed pipes, embedded parts, and base beam base (9) of the box beam segment and hoist the base beam (5); b. Measure and lay out, and locate the center line of the side mold of the diaphragm; c. Install the diaphragm and web templates, assemble them piece by piece from the middle of the diaphragm to the webs on both sides according to the designed block template combination method, and the assembly height of each cycle is about 1m-1.5m; d. Install the back rib (13) and insert the tension screws (18) to fix the template; e. Build a layer of steel pipe brackets (6) from the base beam (5) and lay a working platform on the brackets. The height of the brackets should be consistent with the height of the template for subsequent template installation operations; f. Repeat steps c to e until the diaphragm and web templates are installed to the chamfer of the inner top mold; g. Install a top support (10) on the top of the bracket (6), and place a keel (11) on the top support; h. Install the top mold template and the upper chamfer template. The template is assembled from the top chamfer of the web plates on both sides to the middle of the top plate. The first dismantled template is used for mold closing in the middle; i. Adjust the top support (10) so that the overlapping part of the top mold is in close contact with the top plate of the upper segment. At the same time, measure and set out to adjust the elevation of the front end of the top mold to meet the design requirements; j. Install the connector (12) to connect the keel (11) with the back rib (13), so that the inner top formwork, the side formwork and the diaphragm formwork are connected as a whole; k. Install the steel bars, prestressed pipes and embedded parts of the box beam top plate, pour the beam section concrete, complete the beam section construction, and start to remove the inner formwork after the concrete strength of the beam section reaches the requirements for formwork removal; 4) Removal of aluminum alloy inner mold: a. Using the original steel pipe support (6) and the working platform, remove the tension screws (18) and the back ribs (13); b. Remove the web and diaphragm formwork layer by layer from bottom to top; c. Remove the first block of the top plate formwork, and then remove the remaining block formworks of the top plate in sequence; d. Remove the keel (11), and then remove the steel pipe support (6) from top to bottom; e. Transfer the workpiece through the manhole of the cross partition to the construction location of the next beam section for installation.

2. The construction method of the aluminum alloy inner mold system for the variable-section cast-in-place box beam with diaphragm according to claim 1 is characterized by: The base beam (5) is made of steel, and the base beam base (9) includes a column (14) formed by two channel steels, a cylindrical bearing (15) is installed between the channel steels for supporting the base beam (5), a steel bottom plate (16) is welded to the bottom of the column (14), and a steel tie plate (17) is welded between the column (14) and the bottom plate (16) for structural reinforcement, and bolt holes are provided on the bottom plate (16) for connecting and fixing with the cast box beam bottom plate by bolting; and a hinge hole for hingedly connecting and fixing with the base beam (5) by a pin is provided on the column (14).

3. The construction method of the aluminum alloy inner mold system for the variable-section cast-in-place box beam with diaphragm according to claim 1 is characterized by: The connection between the standard template (1), the special-shaped template (2) and the first-dismantled template is achieved by a combination of bolts and tapered pins.

4. The construction method of the aluminum alloy inner mold system for the variable-section cast-in-place box beam with diaphragm according to claim 1 is characterized in that: The template system is provided with a plurality of tension screws (18) on the box beam web template, and both ends of the tension screws (18) are fastened to the back ribs (13) via nuts.

5. The construction method of the aluminum alloy inner mold system for the variable-section cast-in-place box beam with diaphragm according to claim 1 is characterized by: The keel (11), the corner connector (12), and the back rib (13) are all made of steel. The keel (11) and the back rib (13) are manufactured in sections, and the sections are connected by flange bolts.

6. The construction method of the aluminum alloy inner mold system for the variable cross-section cast-in-place box beam with diaphragm according to claim 1 is characterized by: The keel (11) and the corner connector (12) are connected by a pin, the corner connector (12) and the back rib (13) are connected by bolts, and the back rib (13) and the formwork system are connected by a connecting buckle.

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