A large-span steel structure conversion truss system and unloading method thereof

Abstract

The invention relates to a large-span steel structure conversion truss system and an unloading method thereof, belonging to the technical field of building construction. A plurality of supporting columns for supporting the lower truss are arranged at the bottom of the lower truss in the middle, a sand barrel is arranged on the top of the supporting column, a piston column is slidably arranged in the sand barrel, sand is arranged in the sand barrel, the bottom of the piston column is located above the sand and is used to support the piston column; a sand discharge mechanism is arranged on the sand barrel, and is used to control the sand to flow downward during disassembly to reduce the height of the piston column; a sand recovery mechanism is arranged on the sand barrel, and is used to control the sand to flow in the opposite direction before use to increase the height of the piston column; the lifting and lowering of the piston column is controlled by changing the amount of sand in the sand barrel, thereby realizing fine-tuning and unloading of the truss structure, meeting the use requirements in different scenarios, and being easy to install, and realizing automatic discharge of sand through the coordinated work of components such as gears, wedges, and knocking rods.

Description

Technical Field

[0001] The invention belongs to the technical field of building construction, and relates to a large-span steel structure conversion truss system and an unloading method thereof. Background Art

[0002] In high-rise buildings, the upper floors often need to meet the needs of residential and office work, while the lower floors need to meet the needs of supporting facilities such as shops and parking lots. Therefore, when the vertical structural system or form of the lower floors is quite different from that of the upper floors, or the vertical axes of the upper and lower floors are misaligned, it is necessary to arrange a transfer layer on the floor where the structure changes, so as to meet the needs of different building functions through the transfer layer. The structural transfer layer plays a role of "connecting the upper and lower parts" in the building. It is both the "top plate" of the lower structure and the "foundation" of the upper structure. It plays a vital connecting role in the entire building structure system. The transfer truss has a wide range of application prospects due to its advantages such as clearer and more reasonable force characteristics, lighter structural form, more economical material consumption and larger span.

[0003] In the existing steel structure truss construction, the steel structure conversion truss supports a large number of upper structure layers. In the existing construction, the upper and lower floor steel concrete beams are often used as the upper and lower chords of the conversion truss, and together with the steel web bars, form an integral cross-layer conversion truss. The conversion truss has good vertical stiffness and bearing capacity, simple structure, and convenient construction. However, due to the rigid connection between the conversion truss and the main structure, the main structure will form a serious weak layer and soft layer under the truss layer, and the seismic resistance is poor.

[0004] In addition, large-span conversion trusses are mostly made of steel to form segmented truss segments. The truss segments of the steel structure are hoisted in segments and spliced ​​in the air. Due to the large size and weight of the truss segments, the workpiece may swing or misalign during installation, and the high-altitude operation safety risk is high. It is difficult to dock and operate during installation. The installation accuracy of the conversion truss cannot be guaranteed, which brings great troubles to construction safety and quality management. The existing large-span steel structure conversion truss system temporary support also has the following disadvantages during use: the sand box used for temporary support needs to release the sand during the disassembly process so that the piston column can be lowered, and the discharged sand flows out directly, which is inconvenient to reuse and causes waste of resources; the sand box needs to be refilled with sand in the sleeve when it is reused, which is very inconvenient to fill. Summary of the invention

[0005] In view of this, the present invention provides a large-span steel structure conversion truss system and an unloading method thereof in order to solve the problem that the sand boxes used for temporary support of the existing large-span steel structure conversion truss system are inconvenient to reuse and fill.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A large-span steel structure conversion truss system includes a plurality of building columns, each of which is provided with a lower concrete beam on the inner side, a lower truss on the lower concrete beam, a plurality of first steel webs fixedly provided on the top of the lower truss, a same upper truss fixedly provided on the top of the plurality of first steel webs, and a plurality of second steel webs fixedly provided between two adjacent lower trusses and two upper trusses for connecting them into one;

[0008] A plurality of support columns for supporting the lower truss are arranged at the bottom of the lower truss in the middle, and a sand cylinder is arranged on the top of the support column, a piston column is slidably arranged in the sand cylinder, and sand is arranged in the sand cylinder, and the bottom of the piston column is located above the sand for supporting the piston column;

[0009] The sand discharge mechanism is arranged on the sand barrel, and controls the sand to flow downward when disassembling, and lowers the height of the piston column. The sand discharge mechanism comprises a first fixed plate fixedly arranged in the sand barrel, and is used for dividing the sand barrel into two sand storage spaces. A first rotating ring for sealing the sand barrel is rotatably provided at the bottom of the sand barrel, and a plurality of discharge barrels are fixedly provided through the top of the first fixed plate, and a rotating plate is fixedly provided on the inner wall of the discharge barrel, and a second fixed plate located below the rotating plate is rotatably provided on the inner wall of the discharge barrel, and a rotating rod is fixedly provided through the top of the second fixed plate, and a plurality of through holes are provided on the tops of the second fixed plate and the rotating plate. When the through holes on the second fixed plate and the rotating plate coincide, the sand will flow downward, and a connecting rod is rotatably provided through the top of the first fixed plate, and the bottom of the connecting rod is fixedly connected to the first rotating ring, and the rotating rod is transmission-connected to the connecting rod, and is used for driving the second fixed plate to rotate, and controlling the flow of sand, and a limiting ring for limiting the piston column is fixedly provided on the top of the first fixed plate;

[0010] The sand-replenishing mechanism is arranged on the sand barrel and is used to control the reverse flow of sand before use and increase the height of the piston column.

[0011] Furthermore, a groove is provided at the top of the lower concrete beam, and the lower truss is arranged in the groove, with a gap left between the lower truss and the groove to reduce the collision between the lower truss and the lower concrete beam during installation. A polytetrafluoroethylene slide plate is fixed to the bottom of the lower truss and the bottom wall of the groove, and a steel plate is provided between the two polytetrafluoroethylene slide plates to increase the resistance between the lower truss and the lower concrete beam.

[0012] Furthermore, a gear is provided on the outer wall rotating sleeve of the discharge barrel, a second rotating ring located below the discharge barrel is fixedly provided on the inner wall of the gear, a plurality of connecting strips are fixedly provided between the second rotating ring and the rotating rod, and a toothed disk meshing with a plurality of gears is provided on the outer wall fixed sleeve of the connecting rod for driving a plurality of second fixed disks to rotate at the same time.

[0013] Furthermore, a plurality of fixing seats corresponding to the discharge barrel are fixedly provided at the bottom of the first fixed plate, a knocking rod is slidably provided through one side of the fixed seat, a fixing strip is fixedly provided at one end of the knocking rod, a tension spring is provided on the outer wall of the knocking rod, and the two ends of the tension spring are respectively fixedly connected to the sides of the fixed seat and the fixing strip close to each other, a wedge strip used in conjunction with the gear is slidably provided through one side of the fixed seat, and the fixing strip is fixedly provided at the top of one end of the wedge strip, so as to drive the knocking rod to knock on the discharge barrel to accelerate the flow of sand.

[0014] Furthermore, the top of the rotating rod extends to the top of the rotating disk, and a scraper is fixedly provided thereon, and the length of the scraper is adapted to the diameter of the discharge barrel, and is used to scrape off the sand on the rotating disk to prevent the sand from clumping.

[0015] Furthermore, the sand recovery mechanism includes a sliding tube slidably arranged in the connecting rod, and the outer walls of the sliding tube and the connecting rod are provided with a plurality of discharge holes for cooperation. A blocking plate located above the first fixed disk is fixedly arranged on the top of the sliding tube. When in use, the blocking plate seals the top of the connecting rod under gravity. When inverted, sand enters the sliding tube through the corresponding two discharge holes, and drives the blocking plate away from the first fixed disk, and the sand enters the top space of the first fixed disk, thereby realizing sand recovery.

[0016] Furthermore, an extension tube is fixedly provided at the bottom of the gear, and the outer wall rotating sleeves of multiple extension tubes and connecting rods are provided with the same conical ring, and the toothed disc is located between the conical ring and the first fixed disc to prevent sand from affecting the rotation of the toothed disc, and the conical ring is in an inverted cone shape for guiding sand.

[0017] Furthermore, a plurality of rectangular holes are provided on the outer wall of the connecting rod, and a limit block is slidably provided in the rectangular hole. The limit block is fixed on the outer wall of the sliding tube and is used for guiding the sliding tube.

[0018] Furthermore, the supporting column is composed of a plurality of connecting columns spliced ​​in sequence, a connecting cylinder is fixedly provided on the top of the top connecting column, a limiting cylinder is inserted in the connecting cylinder, and the limiting cylinder is rotatably arranged at the bottom of the first rotating ring for positioning the sand cylinder.

[0019] A method for unloading a large-span steel structure conversion truss system comprises the following steps:

[0020] S1. Rotate the first rotating ring to drive the second fixed disk to rotate. When the through holes on the second fixed disk and the rotating disk overlap, the sand at the bottom of the piston column will be squeezed onto the first rotating ring, and the piston column will drop at the same time;

[0021] S2. Take out the sand cylinder from the connecting cylinder one by one, and remove the connecting columns one by one;

[0022] S3, dismantling the lower truss, the first steel web member, the upper truss and the second steel web member in sequence;

[0023] S4. Invert the removed sand cylinder. At this time, the sand on the first rotating ring will flow to the top of the piston column to reset the piston column.

[0024] The beneficial effects of the present invention are:

[0025] 1. A large-span steel structure conversion truss system disclosed in the present invention controls the lifting and lowering of the piston column by changing the amount of sand in the sand barrel, thereby achieving fine-tuning and unloading of the truss structure, meeting the use requirements in different scenarios, and is easy to install and fill.

[0026] 2. The large-span steel structure conversion truss system disclosed in the present invention realizes the automatic discharge of sand through the design of mechanical structure, such as the coordinated work of components such as gears, wedges, and knocking rods, and can also collect the discharged sand, reducing manual operations and improving work accuracy and efficiency. At the same time, this design is also convenient for maintenance and inspection.

[0027] 3. The large-span steel structure conversion truss system disclosed in the present invention can invert the sand barrel after use. During the inversion process, the sand can be guided by the conical ring, and the sand can be refluxed through the coordinated use of the connecting rod and the sliding tube, and the piston column can be automatically reset, which is more convenient to use.

[0028] 4. The present invention discloses a large-span steel structure conversion truss system, in which the sliding connection between the lower truss and the lower concrete beam can release its horizontal lateral resistance while retaining the vertical bearing capacity of the truss, solving the problem of excessive rigidity of the conversion truss in the traditional rigid connection between the lower truss and the lower concrete beam.

[0029] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0031] Figure 1 It is a three-dimensional structural schematic diagram of a large-span steel structure conversion truss system of the present invention;

[0032] Figure 2 This is a schematic diagram of the support column structure in a large-span steel structure conversion truss system of the present invention;

[0033] Figure 3This is a cross-sectional view of a lower concrete beam in a large-span steel structure conversion truss system of the present invention;

[0034] Figure 4 This is a schematic diagram of the support column and sand barrel structure in a large-span steel structure conversion truss system of the present invention;

[0035] Figure 5 This is a schematic diagram of the internal structure of a sand tube in a large-span steel structure conversion truss system of the present invention;

[0036] Figure 6 It is a schematic diagram of the internal structure of a discharge barrel in a large-span steel structure conversion truss system of the present invention;

[0037] Figure 7 The present invention is a schematic diagram of a connecting rod structure in a large-span steel structure conversion truss system.

[0038] Figure numerals: 1, building column; 2, lower concrete beam; 3, lower truss; 4, first steel web; 5, upper truss; 6, second steel web; 7, support column; 8, sand cylinder; 9, connecting column; 10, connecting cylinder; 11, first rotating ring; 12, piston column; 13, polytetrafluoroethylene slide plate; 14, steel plate; 15, groove; 16, limit cylinder; 17, first fixed plate; 18, limit ring; 19, discharge cylinder; 20, connecting Connecting rod; 21. Sliding tube; 22. Toothed disc; 23. Discharge hole; 24. Blocking plate; 25. Extension tube; 26. Conical ring; 27. Rotating rod; 28. Second rotating ring; 29. ​​Gear; 30. Connecting strip; 31. Second fixed disc; 32. Rotating disc; 33. Through hole; 34. Scraper; 35. Fixed seat; 36. Wedge strip; 37. Fixed strip; 38. Knocking rod; 39. Tension spring; 40. Limit block; 41. Rectangular hole. DETAILED DESCRIPTION

[0039] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0040] like Figure 1-Figure 7 A large-span steel structure conversion truss system is shown: multiple building columns 1 are used to support the steel structure truss, and the inner side of each building column 1 is pre-cast with a lower concrete beam 2. A groove 15 is designed and opened on the top of the lower concrete beam 2, which is used to accommodate the lower truss 3 and ensure that there is a certain gap between the lower truss 3 and the groove 15 to avoid unnecessary bumps during installation.

[0041] Next, the lower truss 3 is precisely placed in the groove 15, and polytetrafluoroethylene slide plates 13 are respectively fixedly installed on the bottom of the lower truss 3 and the bottom wall of the groove 15. A layer of steel plate 14 is laid between the two polytetrafluoroethylene slide plates 13, the purpose of which is to provide a certain friction between the lower truss 3 and the lower concrete beam 2 to increase the structural stability.

[0042] Subsequently, a plurality of first steel web members 4 are fixedly installed on the top of the lower truss 3, and these first steel web members 4 jointly support the upper truss 5. The upper truss 5 is closely connected to the lower truss 3 through the first steel web members 4, forming a stable truss structure. At the same time, the two adjacent lower trusses 3 and the two upper trusses 5 are integrally connected by fixing a plurality of second steel web members 6, forming a complete conversion truss system.

[0043] In order to further enhance the supporting capacity of the lower truss 3, a plurality of supporting columns 7 are arranged at the bottom of the lower truss 3 located in the middle. A sand barrel 8 is installed on the top of each supporting column 7. The sand barrel 8 is filled with sand, and a piston column 12 is arranged above the sand. The bottom of the piston column 12 is supported by the sand, thereby achieving effective support for the lower truss 3.

[0044] The supporting column 7 adopts a modular design and is composed of a plurality of connecting columns 9 that are spliced ​​in sequence. A connecting cylinder 10 is fixedly installed on the top of the connecting column 9 at the top, and the connecting cylinder 10 is used to insert the limiting cylinder 16. The limiting cylinder 16 is rotatably installed at the bottom of the first rotating ring 11, in this way, the sand cylinder 8 is accurately positioned and firmly supported. This design not only facilitates the installation and removal of the supporting column 7, but also improves the flexibility and maintainability of the entire truss system.

[0045] In order to lower the height of the piston column 12 when necessary, that is, to release the sand in the sand barrel 8, a sand discharge mechanism is designed. The mechanism includes a first fixed disk 17 fixed in the sand barrel 8, which divides the sand barrel 8 into two sand storage spaces. The bottom of the sand barrel 8 is rotatably provided with a first rotating ring 11 for sealing. A plurality of discharge barrels 19 are fixed through the first fixed disk 17, and a rotating disk 32 and a second fixed disk 31 are installed in each discharge barrel 19, and a through hole 33 is opened on the top of both. When the through holes 33 on the second fixed disk 31 and the rotating disk 32 are aligned, sand can flow out through the discharge barrel 19. In addition, a connecting rod 20 is rotatably provided on the first fixed disk 17, and its bottom is fixedly connected to the first rotating ring 11. Through the transmission device, the connecting rod 20 is connected to the rotating rod 27, thereby controlling the rotation of the second fixed disk 31, realizing the alignment and misalignment of the through holes 33, and controlling the flow of sand. At the same time, a limiting ring 18 is also provided on the top of the first fixed plate 17 to limit the piston column 12 to prevent the piston column 12 from damaging the discharge barrel 19.

[0046] In order to simultaneously control the alignment of the through holes 33 of multiple discharge barrels 19, a transmission system of gears 29 and toothed discs 22 is designed. A gear 29 is rotatably sleeved on the outer wall of each discharge barrel 19, and a second rotating ring 28 is provided below the gear 29. The second rotating ring 28 is fixedly connected to the rotating rod 27 through a connecting strip 30. A toothed disc 22 meshing with multiple gears 29 is fixedly sleeved on the outer wall of the connecting rod 20. When the first rotating ring 11 is rotated, the connecting rod 20 will also rotate, and the toothed disc 22 drives all the gears 29 to rotate synchronously, thereby realizing the synchronous rotation of all the second fixed discs 31, and controlling the through holes 33 of all discharge barrels 19 to be aligned or misaligned at the same time.

[0047] In order to speed up the flow of sand, a knocking mechanism is also designed. A plurality of fixed seats 35 corresponding to the discharge barrel 19 are fixed at the bottom of the first fixed plate 17, and a knocking rod 38 and a wedge bar 36 are slidably arranged in each fixed seat 35. A fixed bar 37 is fixed at one end of the knocking rod 38, and the knocking rod 38 is connected to the fixed seat 35 through a tension spring 39. When the wedge bar 36 moves with the rotation of the gear 29, it will cooperate with the tension spring 39 to push the knocking rod 38 to knock the discharge barrel 19, thereby speeding up the flow of sand.

[0048] A scraper 34 is designed and fixed on the top of the rotating rod 27, and the length of the scraper matches the diameter of the discharge barrel 19 to ensure that the top of the rotating disk 32 can be completely covered. When the rotating rod 27 rotates together with the second fixed disk 31, the scraper 34 will slide close to the top surface of the rotating disk 32, effectively scraping off the sand attached to the rotating disk 32, preventing the sand from agglomerating due to long-term accumulation and affecting the sand discharge efficiency.

[0049] Finally, in order to restore the height of the sand in the sand barrel 8 before use, a restoring mechanism is designed. The design of the restoring mechanism includes sliding a sliding tube 21 inside the connecting rod 20. The outer walls of the connecting rod 20 and the sliding tube 21 are provided with a plurality of corresponding discharge holes 23. A plugging plate 24 is fixedly provided on the top of the sliding tube 21, and the plugging plate 24 is located above the first fixed disk 17. Under normal use, the plugging plate 24 seals the top of the connecting rod 20 by its own gravity to prevent sand from entering. When restoring the sand is needed, the entire device is turned upside down, and the sand enters the sliding tube 21 through the two corresponding discharge holes 23. As the sand accumulates, the plugging plate 24 is gradually pushed away from the first fixed disk 17 until the sand can smoothly enter the top space of the first fixed disk 17, thereby completing the restoring process.

[0050] An extension tube 25 is fixedly installed at the bottom of each gear 29, and a conical ring 26 is sleeved on the outer wall of the multiple extension tubes 25 and the connecting rod 20. The conical ring 26 is designed to be an inverted cone, with its top adjacent to the toothed disc 22 and its bottom located below the first fixed disc 17. Such a design can effectively prevent sand from entering the gap between the toothed disc 22 and the gear 29, affecting the normal rotation of the toothed disc 22. At the same time, the inverted cone structure of the conical ring 26 can also guide the sand, allowing the sand to flow more smoothly.

[0051] In order to enhance the stability of the sliding tube 21 in the connecting rod 20, a plurality of rectangular holes 41 are provided on the outer wall of the connecting rod 20, and a stopper 40 is slidably installed in each rectangular hole 41. The stopper 40 is fixedly arranged on the outer wall of the sliding tube 21, and as the sliding tube 21 moves up and down, the stopper 40 slides in the rectangular hole 41 accordingly, thereby achieving the guiding and limiting effect on the sliding tube 21, and preventing it from deflecting or rotating during the movement.

[0052] When installing the large-span steel structure conversion truss system, multiple connecting columns 9 are spliced ​​in sequence, and the spliced ​​supporting columns 7 are installed on the ground in sequence, and the sand tube 8 is placed in the connecting tube 10, and then the lower truss 3, the first steel web 4 and the upper truss 5 are spliced ​​in sequence on the ground, and then the spliced ​​lower truss 3, the first steel web 4 and the upper truss 5 are placed on the lower concrete beam 2 and multiple piston columns 12 by hoisting equipment, and the lower trusses 3 at both ends are placed in the groove 15, and a gap is left between the lower truss 3 and the lower concrete beam 2 to avoid collision between the lower truss 3 and the lower concrete beam 2. After the splicing is completed, multiple second steel webs 6 are sequentially connected between two adjacent lower trusses 3 and two adjacent upper trusses 5, and finally construction is carried out on the top;

[0053] When unloading is required, first rotate the first rotating ring 11. The rotation of the first rotating ring 11 can drive the connecting rod 20 to rotate. The rotation of the connecting rod 20 can drive the toothed disc 22 to rotate. The rotation of the toothed disc 22 can drive the second rotating ring 28 to rotate through the gear 29. The rotation of the second rotating ring 28 can drive the rotating rod 27 to rotate through a plurality of connecting strips 30. The rotation of the rotating rod 27 can drive the second fixed disk 31 to rotate. When the through holes 33 on the second fixed disk 31 and the rotating disk 32 coincide, the sand at the bottom of the piston column 12 will be squeezed and flowed downward, and discharged downward through the through hole 33, the discharge cylinder 19 and the extension cylinder 25, and discharged onto the first rotating ring 11. At the same time, the rotating rod 2 When the gear 29 rotates, the scraper 34 can be driven to rotate, and the agglomerated sand can be broken up so that the sand can pass through the through hole 33 smoothly. When the gear 29 rotates, the wedge bar 36 can be driven to move outward. The outward movement of the wedge bar 36 can drive the knocking rod 38 away from the discharge barrel 19 through the fixed bar 37. When the teeth of the gear 29 are away from the wedge bar 36, the knocking rod 38 can be reset and moved under the action of the tension spring 39, driving the knocking rod 38 to knock the discharge barrel 19, accelerating the flow of sand, and driving the wedge bar 36 to move into the tooth groove of the gear 29, knocking in turn. During the downward flow of sand, the piston column 12 will drop until the piston column 12 is away from the bottom of the lower truss 3.

[0054] Next, the sand cylinder 8 is removed from the connecting cylinder 10 in sequence, and the connecting columns 9 are removed in sequence;

[0055] Then, the lower truss 3, the first steel web member 4, the upper truss 5 and the second steel web member 6 are removed in sequence;

[0056] Finally, the dismantled sand cylinder 8 is inverted. At this time, the sand on the first rotating ring 11 will gather in the conical ring 26, and the piston column 12 can be reset and moved under gravity. At the same time, the blocking plate 24 can drive the toothed disc 22 to move downward under gravity, and the sand in the first rotating ring 11 will flow downward through the sliding tube 21 and the discharge hole 23 on the connecting rod 20, and be guided by the blocking plate 24 to flow to the top of the piston column 12, resetting the piston column 12. When used again, the blocking plate 24 can drive the sliding tube 21 to move downward under gravity to seal the discharge hole 23.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A large-span steel structure transfer truss system, characterized in that: The invention comprises a plurality of building columns (1), wherein a lower concrete beam (2) is provided on the inner side of each of the building columns (1), a lower truss (3) is provided on the lower concrete beam (2), a plurality of first steel web members (4) are fixedly provided on the top of the lower truss (3), a same upper truss (5) is fixedly provided on the top of the plurality of first steel web members (4), and a plurality of second steel web members (6) are fixedly provided between two adjacent lower trusses (3) and two upper trusses (5) for connecting them into one body; A plurality of support columns (7) for supporting the lower truss (3) are provided at the bottom of the lower truss (3) located in the middle, a sand cylinder (8) is provided at the top of the support column (7), a piston column (12) is slidably provided in the sand cylinder (8), sand is provided in the sand cylinder (8), and the bottom of the piston column (12) is located above the sand and is used to support the piston column (12); A sand discharge mechanism is arranged on a sand barrel (8) and controls sand to flow downward when disassembled, thereby lowering the height of a piston column (12). The sand discharge mechanism comprises a first fixed disk (17) fixedly arranged in the sand barrel (8) and used to divide the sand barrel (8) into two sand storage spaces. The bottom of the sand barrel (8) is rotatably provided with a first rotating ring (11) for sealing the sand barrel (8). A plurality of discharge barrels (19) are fixedly arranged on the top of the first fixed disk (17). A rotating disk (32) is fixedly arranged on the inner wall of the discharge barrel (19). A second fixed disk (31) located below the rotating disk (32) is rotatably provided on the inner wall of the discharge barrel (19). The top of the second fixed disk (31) is provided with a plurality of discharge barrels (19). A rotating rod (27) is fixedly provided through the top of the second fixed disk (31) and the rotating disk (32), a plurality of through holes (33) are provided on the top of the second fixed disk (31) and the rotating disk (32), and when the through holes (33) on the second fixed disk (31) and the rotating disk (32) overlap, sand will flow downwards; a connecting rod (20) is rotatably provided through the top of the first fixed disk (17), the bottom of the connecting rod (20) is fixedly connected to the first rotating ring (11), the rotating rod (27) is transmission-connected to the connecting rod (20) and is used to drive the second fixed disk (31) to rotate and control the flow of sand; a limiting ring (18) for limiting the position of the piston column (12) is fixedly provided on the top of the first fixed disk (17); The sand recovery mechanism is arranged on the sand barrel (8) and is used to control the reverse flow of sand before use and to increase the height of the piston rod (12).

2. A large-span steel structure conversion truss system as claimed in claim 1, characterized in that: The support column (7) is composed of a plurality of connection columns (9) connected in sequence, and a connection cylinder (10) is fixedly provided on the top of the connection column (9) at the top end, and a limiting cylinder (16) is inserted into the connection cylinder (10). The limiting cylinder (16) is rotatably arranged at the bottom of the first rotating ring (11) and is used to position the sand cylinder (8).

3. A large-span steel structure conversion truss system as claimed in claim 2, characterized in that: The outer wall of the discharge barrel (19) is rotatably sleeved with a gear (29), the inner wall of the gear (29) is fixedly sleeved with a second rotating ring (28) located below the discharge barrel (19), a plurality of connecting strips (30) are fixedly sleeved between the second rotating ring (28) and the rotating rod (27), and the outer wall of the connecting rod (20) is fixedly sleeved with a toothed disk (22) meshing with the plurality of gears (29) for simultaneously driving the plurality of second fixed disks (31) to rotate.

4. A large-span steel structure conversion truss system as claimed in claim 3, characterized in that: A plurality of fixed seats (35) corresponding to the discharge barrel (19) are fixedly provided at the bottom of the first fixed plate (17); a knocking rod (38) is slidably provided through one side of the fixed seat (35); a fixing strip (37) is fixedly provided at one end of the knocking rod (38); a tension spring (39) is sleeved on the outer wall of the knocking rod (38); two ends of the tension spring (39) are respectively fixedly connected to the fixed seat (35) and the fixing strip (37) on one side close to each other; a wedge strip (36) used in conjunction with a gear (29) is slidably provided through one side of the fixed seat (35); the fixing strip (37) is fixedly provided at the top of one end of the wedge strip (36) and is used to drive the knocking rod (38) to knock the discharge barrel (19) to accelerate the flow of sand.

5. A large-span steel structure conversion truss system as claimed in claim 4, characterized in that: The top of the rotating rod (27) extends to the top of the rotating disk (32) and is fixedly provided with a scraper (34). The length of the scraper (34) is adapted to the diameter of the discharge barrel (19) and is used to scrape sand on the rotating disk (32) to prevent sand from agglomerating.

6. A large-span steel structure conversion truss system as claimed in claim 2, characterized in that: The sand recovery mechanism comprises a sliding tube (21) slidably arranged in the connecting rod (20), the outer walls of the sliding tube (21) and the connecting rod (20) are both provided with a plurality of discharge holes (23) for use in conjunction with each other, a blocking plate (24) located above the first fixed plate (17) is fixedly arranged at the top of the sliding tube (21), when in use, the blocking plate (24) seals the top of the connecting rod (20) under gravity, when inverted, sand enters the sliding tube (21) through the two corresponding discharge holes (23), and drives the blocking plate (24) away from the first fixed plate (17), and the sand enters the top space of the first fixed plate (17), thereby achieving sand recovery.

7. A large-span steel structure transfer truss system as claimed in claim 3, characterized in that: An extension tube (25) is fixedly provided at the bottom of the gear (29), and a plurality of the extension tubes (25) and the outer wall of the connecting rod (20) are rotatably sleeved with a same conical ring (26), and the toothed disc (22) is located between the conical ring (26) and the first fixed disc (17) to prevent sand from affecting the rotation of the toothed disc (22), and the conical ring (26) is in an inverted cone shape for guiding sand.

8. A large-span steel structure transfer truss system as claimed in claim 6, characterized in that: The outer wall of the connecting rod (20) is provided with a plurality of rectangular holes (41), and a limit block (40) is slidably provided in the rectangular hole (41). The limit block (40) is fixedly provided on the outer wall of the sliding tube (21) and is used to guide the sliding tube (21).

9. A large-span steel structure transfer truss system as claimed in claim 2, characterized in that: A groove (15) is provided at the top of the lower concrete beam (2), and the lower truss (3) is slidably arranged in the groove (15), and a gap is left between the lower truss (3) and the groove (15) to reduce the collision between the lower truss (3) and the lower concrete beam (2) during installation. A polytetrafluoroethylene slide plate (13) is fixedly provided at the bottom of the lower truss (3) and the bottom wall of the groove (15), and a steel plate (14) is provided between the two polytetrafluoroethylene slide plates (13) to increase the resistance between the lower truss (3) and the lower concrete beam (2).

10. A method for unloading a large-span steel structure conversion truss system according to any one of claims 2 to 9, characterized in that: The following steps are involved: S1, rotating the first rotating ring (11) to drive the second fixed disk (31) to rotate, and when the through holes (33) on the second fixed disk (31) and the rotating disk (32) overlap, the sand at the bottom of the piston column (12) will be squeezed onto the first rotating ring (11), and the piston column (12) will descend; S2, sequentially removing the sand cylinder (8) from the connecting cylinder (10), and sequentially removing the connecting column (9); S3, dismantling the lower truss (3), the first steel web member (4), the upper truss (5) and the second steel web member (6) in sequence; S4. Invert the removed sand cylinder (8), and the sand on the first rotating ring (11) will flow to the top of the piston column (12), thereby resetting the piston column (12).

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