CN116181112A - Method for dismantling and installing large-span roof and grid steel structure - Google Patents

Abstract

The invention belongs to the technical field of building construction, and discloses a method for dismantling and installing a large-span roof and a grid steel structure, which comprises the following steps: obtaining a reconstruction area of the old steel structure roof, and dividing the reconstruction area into a plurality of reconstruction areas; setting up a dismantling support scaffold and setting up a conversion support; removing the old steel structure roof along the first direction; dismantling support scaffolds corresponding to the two stand areas, and reforming old concrete structures corresponding to the stand areas to form two reformed concrete structures; setting up installation support scaffolds on the two reconstructed concrete structures respectively, and setting up conversion supports respectively; adjusting the conversion support, and hoisting and installing the newly built steel structure roof in the opposite direction of the first direction; unloading the newly built steel structure roof; and (5) removing the scaffold. The method can effectively remove the old roof and the structure thereof, effectively reduce the influence on the concrete structure, and has high safety, fast construction progress and high efficiency during construction.

Description

Method for dismantling and installing large-span roof and grid steel structure

Technical Field

The invention relates to the technical field of building construction, in particular to a method for dismantling and installing a large-span roof and a grid steel structure.

Background

The steel structure net rack is a common structural form in constructional engineering, has the advantages of light dead weight, high rigidity, industrial processing and the like, and is commonly used as a roof structure of stadiums, science and technology museums, exhibition halls and the like.

When a steel structure roof of a large-scale stadium is transformed, the traditional reconstruction often adopts a mode of 'integrally dismantling + concrete cast-in-situ stand structure + steel structure roof + roof system', and the construction method is as follows: firstly, dismantling a roof from one side to the other side, simultaneously erecting a full scaffold, dismantling a grid structure, and dismantling a concrete structure; secondly, erecting a bent frame, and constructing a cast-in-place concrete stand structure; thirdly, erecting a support and installing a roof steel structure; fourthly, installing a roof system; and fifthly, unloading the temporary support system and forming the overground structure.

The construction method needs to set temporary support after the stand concrete structure is maintained to reach a certain strength, and then the construction of the upper roof structure and the subsequent roof system is carried out. The construction period is greatly prolonged, and the construction error of the cast-in-place concrete structure of the stand is larger, so that the installation of a follow-up roof system is influenced, and the method is only suitable for projects with small total deformation of the roof and original construction.

Disclosure of Invention

The invention aims to provide a method for dismantling and installing a large-span roof and a grid steel structure, which can efficiently dismantle old roofs and structures thereof and can effectively reduce the influence on a concrete structure; meanwhile, the safety during construction is high, the construction progress is fast, and the efficiency is high.

To achieve the purpose, the invention adopts the following technical scheme:

the method for dismantling and installing the large-span roof and the grid steel structure is used for dismantling and rebuilding the old steel structure roof and comprises the following steps of:

s1, obtaining a reconstruction area of a legacy steel structure roof, dividing the reconstruction area into a plurality of reconstruction subareas according to reconstruction requirements of the legacy steel structure roof and a concrete structure, wherein the reconstruction subareas comprise a middle area corresponding to the middle part of a field and two stand areas respectively corresponding to stands at two sides;

s2, erecting a dismantling support scaffold, and arranging a conversion support on the dismantling support scaffold;

s3, dismantling the old steel structure roof along the first direction;

s4, dismantling the dismantling support scaffold corresponding to the two stand areas, and respectively reforming old concrete structures corresponding to the two stand areas to form two reformed concrete structures;

s5, respectively erecting installation support scaffolds on the two reconstructed concrete structures, and respectively arranging conversion supports on the installation support scaffolds;

s6, adjusting the conversion support corresponding to the middle area and the conversion support on the installation support scaffold, and hoisting and installing the newly built steel structure roof in the opposite direction of the first direction;

s7, unloading the newly built steel structure roof;

and S8, dismantling the dismantling support scaffold corresponding to the middle area and installing the support scaffold.

Optionally, in step S2, each lower chord ball of the legacy steel structure roof corresponds to a conversion support.

Optionally, the conversion support includes H type support piece and jack-up piece, and H type support piece includes supporting part and two installation department, and two installation department are parallel and the interval sets up, and the both ends of supporting part are connected respectively on two installation departments, and the upper surface of supporting part is used for supporting the lower string ball of old steel construction roofing, and jack-up piece is connected in the tip of every installation department and demolishs between the support scaffold, and jack-up piece can adjust the tip of installation department and demolishs the distance between the support scaffold.

Optionally, the jacking piece comprises a screw rod part and a nut part, one end of the screw rod part is fixedly connected to the mounting part, a screw hole is formed in the dismantling support scaffold, the other end of the screw rod part is in threaded connection with the screw hole, the nut part is in threaded connection with the outside of the screw rod part, and the end face of the nut part is in butt connection with the peripheral edge of the screw hole.

Optionally, the step of removing the old steel structure roof in the step S3 includes:

s301, dismantling the overhanging net rack;

s302, dividing the old steel structure roof into a plurality of modules to be split which are arranged in sequence along a first direction;

s303, detaching the grid structure in each module to be detached along the direction from the middle ridge to the two sides.

Optionally, when the grid structure is removed in step S303, the horizontal link members are removed first, and then the unit block is removed.

Optionally, in step S6, the horizontal and vertical positions of the conversion support on the conversion support and mounting support scaffold corresponding to the intermediate area are adjusted according to the design requirements of the newly built steel structure roof.

Optionally, the step of installing the newly-built steel structure roof in the step S6 includes:

s601, splicing the cantilever net rack on site, and hoisting and installing the cantilever net rack in a split manner;

s602, constructing a roof support and a suspended ceiling membrane steel structure support.

Optionally, the unloading step of the newly built steel structure roof in step S7 includes:

s701, dividing the newly built steel structure roof into a plurality of unloading areas sequentially outwards by taking the geometric center of the newly built steel structure roof as a midpoint;

s702, sequentially cutting the net rack lower chord ball steel pipes from the middle to the periphery according to the unloading area, so that the net rack lower chord balls fall on the supporting surface of the conversion support.

Optionally, before step S8, the method further includes the following steps:

and (5) sequentially installing the roof primary purline, the roof system and the membrane structure.

The invention has the beneficial effects that:

the invention provides a method for dismantling and installing a large-span roof and a grid steel structure, which is used for dismantling and rebuilding the old steel structure roof and specifically comprises the following steps: s1, obtaining a reconstruction area of a traditional steel structure roof, and dividing the reconstruction area into a plurality of reconstruction subareas according to reconstruction requirements of the traditional steel structure roof and a concrete structure. The reconstruction sub-area comprises a middle area corresponding to the middle part of the field and two stand areas corresponding to the stands on two sides respectively. By dividing the reconstruction areas, the stress characteristics of the existing structure can be effectively utilized to reconstruct the structure to different degrees, and the construction is performed in the areas, so that the construction efficiency is improved. S2, erecting a dismantling support scaffold, and arranging a conversion support on the dismantling support scaffold; s3, dismantling the old steel structure roof along the first direction; s4, dismantling the dismantling support scaffold corresponding to the two stand areas, and respectively reforming old concrete structures corresponding to the two stand areas to form two reformed concrete structures; s5, respectively erecting installation support scaffolds on the two reconstructed concrete structures, and respectively arranging conversion supports on the installation support scaffolds; s6, adjusting the conversion support corresponding to the middle area and the conversion support on the installation support scaffold, and hoisting and installing the newly built steel structure roof in the opposite direction of the first direction; s7, unloading the newly built steel structure roof; and S8, dismantling the dismantling support scaffold corresponding to the middle area and installing the support scaffold. The full scaffold is used for removing the old steel structure roof and installing the newly built steel structure roof, so that the influence on a concrete structure can be effectively reduced; meanwhile, the overall stability of the structure after the grid frame is dismantled can be improved, so that the newly-built grid frame structure can be better positioned by utilizing conversion support. And during construction, the operation environment is relatively safe, so that the simplicity and safety of workers during operation can be improved while the structural safety is ensured, and the construction efficiency and the construction speed are improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following description will briefly explain the drawings needed in the description of the embodiments of the present invention, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the contents of the embodiments of the present invention and these drawings without inventive effort for those skilled in the art.

FIG. 1 is a flow chart of steps of a method for removing and installing a large-span roof and grid steel structure provided by an embodiment of the invention;

FIG. 2 is a construction structure diagram of step S1 of a method for removing and installing a large-span roof and grid steel structure provided by an embodiment of the present invention;

fig. 3 is a construction structure diagram of a demolition support scaffold provided by an embodiment of the present invention;

fig. 4 is a top view of a scaffold for demolition support provided with a conversion support according to an embodiment of the present invention;

FIG. 5 is a top view of a transition support provided by an embodiment of the present invention;

FIG. 6 is a side view of a transition support provided by an embodiment of the present invention;

fig. 7 is an enlarged view of the structure at a in fig. 6;

fig. 8 is a schematic diagram of division of modules to be split of a legacy steel structure roof provided by an embodiment of the invention;

fig. 9 is a mounting structure diagram of a mounting support scaffold provided by an embodiment of the present invention;

FIG. 10 is a schematic view of an installation step of a newly constructed steel roof provided in an embodiment of the present invention;

FIG. 11 is a schematic diagram of the division of the unloading area of the newly constructed steel roof provided by the embodiment of the invention;

FIG. 12 is a construction block diagram of the standing seam piping step in the method for removing and installing a large span roof and rack steel structure provided by the embodiment of the invention.

In the figure:

100. old steel structure roof; 101. a lower chord ball; 102. overhanging the net rack; 103. scaffold transport channels;

200. newly-built steel structure roof;

1. reconstructing the region; 11. a middle region; 12. a stand area;

2. dismantling the support scaffold;

3. a conversion support; 31. an H-shaped support; 311. a support part; 312. a mounting part; 32. a top support; 321. a screw portion; 322. a nut portion;

4. installing and supporting a scaffold;

51. rolling plate; 52. a support assembly; 53. vertical serging equipment; 54. a slideway; 55. and (5) a inhaul cable.

Detailed Description

The technical scheme of the invention is further described below by the specific embodiments with reference to the accompanying drawings.

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.

In the description of the present invention, it should be noted that, directions or positional relationships indicated by terms such as "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., are directions or positional relationships based on those shown in the drawings, or are directions or positional relationships conventionally put in use of the inventive product, are merely for convenience of describing the present invention and simplifying the description, and are not indicative or implying that the apparatus or element to be referred to must have a specific direction, be configured and operated in a specific direction, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance. In the description of the present invention, unless otherwise indicated, the meaning of "a plurality" is two or more.

In the description of the present invention, it should also be noted that, unless explicitly specified and limited otherwise, the terms "disposed", "connected" and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected or integrally connected; either mechanically or electrically. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.

In the present invention, unless expressly stated or limited otherwise, a first feature "above" or "below" a second feature may include both the first and second features being in direct contact, as well as the first and second features not being in direct contact but being in contact with each other through additional features therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly under and obliquely below the second feature, or simply means that the first feature is less level than the second feature.

Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the invention.

The embodiment provides a method for dismantling and installing a large-span roof and a grid steel structure, which is mainly used for dismantling and rebuilding the old steel structure roof. In this embodiment, the legacy steel structure roof is a gymnasium roof. Of course, the method for dismantling and installing the large-span roof and the grid steel structure can also be suitable for construction and reconstruction of roofs of other large-span grid steel structure buildings, and the embodiment only uses the gymnasium steel structure roof as an example for description, and does not limit construction objects.

Specifically, as shown in fig. 1, the method for dismantling and installing the large-span roof and grid steel structure comprises the following steps:

s1, obtaining a reconstruction area 1 of a traditional steel structure roof 100, dividing the reconstruction area 1 into a plurality of reconstruction subareas according to reconstruction requirements of the traditional steel structure roof 100 and a concrete structure, wherein the reconstruction subareas comprise a middle area corresponding to the middle part of a field and two stand areas 12 respectively corresponding to stands at two sides;

s2, erecting a dismantling support scaffold 2, and arranging a conversion support 3 on the dismantling support scaffold 2;

s3, dismantling the old steel structure roof 100 along the first direction;

s4, dismantling the dismantling support scaffold 2 corresponding to the two stand areas 12, and respectively reforming old concrete structures corresponding to the two stand areas 12 to form two reformed concrete structures;

s5, respectively erecting an installation support scaffold 4 on the two reconstructed concrete structures, and respectively arranging a conversion support 3 on the installation support scaffold 4;

s6, adjusting the conversion support 3 corresponding to the middle area and installing the conversion support 3 on the support scaffold 4, and hoisting and installing the newly built steel structure roof 200 along the reverse direction of the first direction;

s7, unloading the newly built steel structure roof 200;

s8, dismantling the dismantling support scaffold 2 and the mounting support scaffold 4 corresponding to the middle area.

Through step S1, the reconstruction area 1 is divided, the stress characteristics of the existing structure can be effectively utilized to reconstruct the structure to different degrees, and the construction is performed in the divided areas, so that the construction efficiency is improved. S2-S8, setting up a full scaffold, and removing the old steel structure roof 100 and installing the newly built steel structure roof 200 by using the full scaffold, so that the influence on a concrete structure can be effectively reduced; meanwhile, the overall stability of the structure after the grid frame is dismantled can be improved, so that the newly-built grid frame structure can be positioned by utilizing the conversion support 3 better. In steps S3-S6, the old steel structure roof 100 is removed along the first direction, the newly-built steel structure roof 200 is installed along the opposite direction of the first direction, and the steel structure roof can be removed and installed integrally by adjusting the conversion support 3.

More specifically, in this embodiment, the first direction is from north to south. That is, the gymnasium roof is dismantled from the north to the south, and the gymnasium roof is installed from the north to the south.

As shown in fig. 2, in step S1, after the division of the reconstruction area 1 is completed, preparation work before construction is performed, specifically: the construction road and the tower crane are arranged on the outer side of the venue building, and the scaffold transport channel 103 is arranged on the dismantled part of the roof, so that the scaffold can be conveniently installed or dismantled at a later stage.

As shown in fig. 3 to 7, in step S2, the demolition support scaffold 2 is a full scaffold structure, and each lower chord ball 101 of the old steel structure roof 100 corresponds to one conversion support 3, so that the demolition support scaffold 2 performs omnibearing stable support on the old steel structure roof 100.

Specifically, referring to fig. 5 and 6, the conversion support 3 includes an H-shaped support 31 and a top support 32. The H-shaped supporting member 31 includes a supporting portion 311 and two mounting portions 312, the two mounting portions 312 are parallel and spaced apart, and two ends of the supporting portion 311 are respectively connected to the two mounting portions 312. The upper surface of the support portion 311 is used to support the lower chord ball 101 of the old steel structure roofing 100, and the jacking piece 32 is connected between the end of each mounting portion 312 and the removal support scaffold 2. The jacking members 32 are able to adjust the distance between the end of the mounting portion 312 and the removal support scaffold 2. In this embodiment, the supporting portion 311 and the mounting portion 312 are both i-steel, so that the supporting strength is high, the use safety is good, and the cost is low.

Referring to fig. 7, the jack 32 includes a screw portion 321 and a nut portion 322. One end of the screw portion 321 is fixedly connected to the mounting portion 312, a screw hole is formed in the dismantling support scaffold 2, the other end of the screw portion 321 is connected to the screw hole in a screwed mode, the nut portion 322 is connected to the outside of the screw portion 321 in a screwed mode, and the end face of the nut portion 322 abuts against the peripheral edge of the screw hole. The top support 32 has a screw-nut structure, and the screw portion 321 is moved in the axial direction thereof by rotating the nut portion 322, thereby adjusting the distance between the mounting portion 312 and the dismounting support scaffold 2.

As shown in fig. 8, in step S3, the step of removing the old steel structure roofing 100 specifically includes:

s301, dismantling the cantilever net frame 102;

s302, dividing the old steel structure roof 100 into a plurality of modules to be split which are arranged in sequence along a first direction;

s303, detaching the grid structure in each module to be detached along the direction from the middle ridge to the two sides.

Before step S301, roof demolishing protection arrangement should be performed, that is, a protective safety net is bound at the grid node position, and a protective fence is set at the gutter to ensure demolishing safety.

Specifically, as shown in fig. 8, in this embodiment, the old steel structure roof 100 is divided into C1, C2, C3 … … C22, and a total of 22 modules to be split, and the C1, C2, C3 … … C22 are sequentially removed along the first direction, and the total of 22 modules to be split is removed. The number of modules to be split is specifically determined according to the construction condition, and the embodiment is not limited herein.

Specifically, when the grid structure is removed in step S303, the horizontal link members are removed first, and then the unit blocks are removed. In this embodiment, each small net rack triangle is taken as one unit block. And (3) removing each unit block layer by layer from the position of the middle ridge to the directions of two sides, wherein the roofing metal frame is removed by using a tower crane.

As shown in fig. 9, in steps S4 and S5, the demolition support scaffold 2 corresponding to the two stand areas 12 is demolished, the concrete structure of the areas is reinforced and reformed, and the embedded part installation fixing steel support is placed at the same time, thereby improving the support stability. The scaffold is newly erected on the newly reconstructed concrete structure, namely the mounting support scaffold 4 is arranged, and the conversion support 3 is arranged on the mounting support scaffold 4. That is, the position and structure of the demolition support scaffold 2 corresponding to the middle area are unchanged, the installation support scaffold 4 is newly erected on both sides, and then a new support scaffold system is formed, providing a support foundation for the installation of the subsequent newly built steel structure.

As shown in fig. 10, before the newly-built steel structure roof 200 is installed by being lifted, it is necessary to first adjust the horizontal and vertical positions of the conversion support 3 corresponding to the middle area and the conversion support 3 on the both side installation support scaffolds 4 according to the design requirements of the newly-built steel structure roof 200. Wherein the horizontal position adjustment is performed by the support portion 311 of the H-shaped support member 31, and the vertical position adjustment is performed by the rotation of the nut portion 322 of the top support member 32.

Specifically, in step S6, the step of installing the newly built steel structure roof 200 includes:

s601, splicing the cantilever net racks 102 on site, and hoisting and installing the cantilever net racks in a split manner;

s602, constructing a roof support and a suspended ceiling membrane steel structure support.

In step S601, the split hoisting is mainly to reduce temporary support columns in a narrow space.

Fig. 11 shows a schematic diagram of dividing the unloading area of the newly built steel structure roof provided by the embodiment of the invention. Optionally, the unloading step of the newly built steel structure roof 200 in step S7 includes:

s701, dividing the newly built steel structure roof 200 into a plurality of unloading areas outwards in sequence by taking the geometric center of the newly built steel structure roof as a midpoint;

s702, sequentially cutting steel pipes of the net rack lower chord ball 101 from the middle to the periphery according to an unloading area, so that the net rack lower chord ball 101 falls on a supporting surface of the conversion support 3.

In this embodiment, as shown in fig. 11, the newly built steel structure roof 200 is divided into four unloading areas, X1, X2, X3 and X4, sequentially and outwardly with the geometric center thereof as a midpoint. Because the peripheral supporting condition of the net rack is better, the number of the supports is large, and the nodes of each lower chord ball 101 are supported, the total unloading amount is small, and therefore, the unloading is carried out by adopting a simple method for cutting supporting steel pipes. The D219x8 steel pipe supporting the net rack lower chord ball 101 is cut by about 10mm directly by a cutter, so that the net rack ball falls on the rest steel pipe freely. When the steel pipe is cut off, the steel pipe is cut off from inside to outside according to the partition sequence, and the inner ring is cut firstly and then the outer ring is cut off still according to the circle inside the partition. 2 cutters on each side of the hexagon are symmetrically cut from the middle point to two sides. During each circle of cutting, the interval cutting is needed, the arrangement sequence of the balls is set as ABABABABAB, all the A ball support posts are cut first, and then all the B ball support posts are cut.

That is, the rack unloading process can be divided into the following steps: the method comprises the steps of first step of X1 area, first step of X2 area, second step of X1 area, second step of X2 area, second step of X3 area, third step of X1 area, third step of X2 area, third step of X3 area, fourth step of X1 area, fourth step of X2 area, fourth step of X3 area and fourth step of X1 area. The cutting is carried out for 10mm each time.

Optionally, before step S8, the method further includes the following steps:

and (5) sequentially installing the roof primary purline, the roof system and the membrane structure.

The roofing system includes an upstanding serging installation, as shown in fig. 12, in which upstanding serging equipment 53 is mounted on a support assembly 52, and a rolled sheet 51 is processed by the upstanding serging equipment 53, transported to the newly constructed steel structure roofing 200 via a slideway 54 connected to a guy cable 55 secured to the newly constructed steel structure roofing 200, and completed installation of the upstanding serging structure.

It is to be understood that the above examples of the present invention are provided for clarity of illustration only and are not limiting of the embodiments of the present invention. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.

Claims (10)

1. The method for removing and installing the large-span roof and the grid frame steel structure is used for removing and rebuilding the old steel structure roof (100), and is characterized by comprising the following steps:

s1, obtaining a reconstruction area (1) of a traditional steel structure roof (100), dividing the reconstruction area (1) into a plurality of reconstruction subareas according to reconstruction requirements of the traditional steel structure roof (100) and a concrete structure, wherein the reconstruction subareas comprise a middle area corresponding to the middle part of a field and two stand areas (12) respectively corresponding to stands at two sides;

s2, erecting a dismantling support scaffold (2), and arranging a conversion support (3) on the dismantling support scaffold (2);

s3, dismantling the old steel structure roof (100) along the first direction;

s4, dismantling the dismantling support scaffold (2) corresponding to the two stand areas (12), and respectively reforming old concrete structures corresponding to the two stand areas (12) to form two reformed concrete structures;

s5, respectively erecting an installation support scaffold (4) on the two reconstructed concrete structures, and respectively arranging a conversion support (3) on the installation support scaffold (4);

s6, adjusting the conversion support (3) corresponding to the middle area and installing the conversion support (3) on the support scaffold (4), and hoisting and installing the newly built steel structure roof (200) along the opposite direction of the first direction;

s7, unloading the newly built steel structure roof (200);

s8, dismantling the dismantling support scaffold (2) corresponding to the middle area and installing the support scaffold (4).

2. The method of demolishing and installing large span roof and grid steel structures according to claim 1, characterized in that in step S2, each lower chord ball (101) of the old steel structure roof (100) corresponds to a conversion support (3).

3. The method for dismantling and installing a large-span roof and grid steel structure according to claim 2, wherein the conversion support (3) comprises an H-shaped support (31) and a top support (32), the H-shaped support (31) comprises a support part (311) and two installation parts (312), the two installation parts (312) are arranged in parallel and at intervals, two ends of the support part (311) are respectively connected to the two installation parts (312), the upper surface of the support part (311) is used for supporting a lower chord ball (101) of the old steel structure roof (100), the top support (32) is connected between the end part of each installation part (312) and the dismantling support scaffold (2), and the top support (32) can adjust the distance between the end part of the installation part (312) and the dismantling support scaffold (2).

4. The method for removing and installing the large-span roof and grid steel structure according to claim 3, wherein the top support member (32) comprises a screw rod portion (321) and a nut portion (322), one end of the screw rod portion (321) is fixedly connected to the installation portion (312), a screw hole is formed in the removing support scaffold (2), the other end of the screw rod portion (321) is in threaded connection with the screw hole, the nut portion (322) is in threaded connection with the outside of the screw rod portion (321), and the end face of the nut portion (322) is in abutting connection with the peripheral edge of the screw hole.

5. The method of removing and installing a large span roof and rack steel structure of claim 1, wherein the step of removing the old steel structure roof (100) in step S3 comprises:

s301, dismantling the overhanging net rack (102);

s302, dividing the old steel structure roof (100) into a plurality of modules to be split which are sequentially arranged along a first direction;

s303, detaching the grid structure in each module to be detached along the direction from the middle ridge to the two sides.

6. The method for removing and installing a large span roof and rack steel structure according to claim 5, wherein in step S303, when removing the rack structure, the horizontal link members are removed, and then the unit block is removed.

7. The method for dismantling and installing the large span roof and grid steel structure as claimed in claim 1, wherein in step S6, the horizontal position and the vertical position of the conversion support (3) on the conversion support (3) and the installation support scaffolding (4) corresponding to the middle area are adjusted according to the design requirement of the newly built steel structure roof (200).

8. The method of removing and installing a large span roof and rack steel structure of claim 7, wherein the step of installing a newly constructed steel structure roof (200) in step S6 comprises:

s601, splicing the cantilever net rack (102) on site, and hoisting and installing the cantilever net rack in a split manner;

s602, constructing a roof support and a suspended ceiling membrane steel structure support.

9. The method of removing and installing a large span roof and rack steel structure according to claim 1, wherein the unloading step of the newly constructed steel structure roof (200) in step S7 comprises:

s701, dividing the newly built steel structure roof (200) into a plurality of unloading areas outwards in sequence by taking the geometric center of the newly built steel structure roof as a midpoint;

s702, sequentially cutting steel pipes of the net rack lower chord balls (101) from the middle to the periphery according to an unloading area, so that the net rack lower chord balls (101) fall on a supporting surface of the conversion support (3).

10. The method of demolishing and installing a large span roof and rack steel structure according to any one of claims 1 to 9, further comprising the steps of, before step S8:

and (5) sequentially installing the roof primary purline, the roof system and the membrane structure.

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