Installation method of large-diameter ring truss and cable-net grid combined roof

Abstract

This invention discloses an installation method for a large-diameter ring truss and tensioned mesh combined roof, relating to the field of building steel structure technology. The method includes the following steps: S1, establishing an installation model of the combined roof using finite element analysis software and calculating the cable force value A of the cable system; S2, configuring reinforcing bars at the corresponding lifting system locations on the basement roof slab; S3, arranging a jig on the basement roof slab to connect the ring truss and the mesh shell; S4, arranging a lifting system connected to the support nodes on the basement roof slab, lifting the ring truss and mesh shell until they are detached from the jig and suspended, installing the cable system and tensioning it to the cable force value A; S5, continuing to lift the ring truss to the designed position, and re-tensioning the cable system until the deflection of the mesh shell is within 10mm; S6, installing the support system. This invention solves the problems of irreversible damage to the basement roof slab caused by excessive concentrated loads and large shape and position deviations of the combined roof.

Description

Technical Field

[0001] This invention relates to the field of building steel structure technology, and in particular to an installation method for a roof combining a large-diameter ring truss and a tensioned grid. Background Technology

[0002] With the application, development, and innovation of spatial steel structure roofs, some new hybrid structural systems have gradually evolved from traditional structural systems. In these hybrid systems, a high-stiffness ring truss is typically used as the main load-bearing boundary, bearing the thrust and deformation constraints from the internal structure. The internal structure employs a tensioned grid consisting of a cable system and a reticulated shell. The cable system provides elastic support to the reticulated shell, thereby improving its internal force distribution. The ring truss and the reticulated shell are usually connected by pins using circumferentially arranged corbels, and a support system is installed at the lower part of the ring truss. The connection point between the support system and the ring truss is the support node. This structural system has been used in roof systems for large stadiums, central skylights for airport terminals, and skylights for various large shopping malls, forming a combined roof system of large-diameter ring trusses and tensioned grids.

[0003] Large-diameter ring truss and tensioned mesh roofs are typically installed using ground assembly and overall lifting methods. However, this presents several technical challenges: First, the roof structures are often located on the basement roofs of large public buildings, posing a risk of concentrated local loads during on-site installation. Second, the structure is prone to deformation during lifting, and the cable tension values ​​also change, leading to significant structural deviations after lifting. Third, the tensioned mesh deforms after the cable system is tensioned, making it impossible to connect with the ring truss. These construction difficulties result in inaccurate connections between the ring truss and the tensioned mesh during roof installation, and significant structural deviations after installation, impacting the long-term performance of the structure.

[0004] In view of this, it is necessary to design an installation method for a roof combining a large-diameter ring truss and a tensioned grid to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide an installation method for a roof combining a large-diameter ring truss and a tensioned grid, in order to solve the problems of irreversible damage to the basement roof caused by excessive concentrated loads and large deviations in the shape and position of the combined roof.

[0006] To achieve the above-mentioned objectives, this invention provides a method for installing a roof combining a large-diameter ring truss and a tensioned grid, comprising the following steps: S1. Using finite element analysis software, a combined roof installation model including a ring truss, a tensioned mesh, a support system, and a lifting system is established on the top slab of the basement. The tensioned mesh includes a mesh shell connected to the ring truss and a cable system that provides elastic support to the mesh shell. The lifting system is arranged circumferentially along the ring truss and corresponds to the support nodes of the ring truss. Based on the fact that the form and position deviation of the grid shell is ≤10mm and the stress ratio at the connection node between the ring truss and the grid shell is ≤0.8 when the roof is in a suspended state under construction conditions, the cable force value A of the cable system is calculated. S2. Reinforcing bars are installed at the corresponding lifting system locations on the basement roof slab to improve the load-bearing capacity of the basement roof slab; S3. Install a frame on the basement roof slab to connect the ring truss and the grid shell; S4. Arrange a lifting system connected to the support nodes on the basement roof slab. Use the lifting system to lift the ring truss and grid shell until they are freed from the jig and suspended. Install the cable system and tension it to the cable force value A. S5. Continue to lift the ring truss to the design position and re-tension the cable system until the deflection of the grid shell is within 10mm; S6. Install the support system.

[0007] As a further improvement of the present invention, in step S1, finite element analysis software is also used to calculate the support reaction force B at the connection between the lifting system and the basement roof slab during the lifting process of the ring truss and the reticulated shell.

[0008] As a further improvement of the present invention, the reinforcement configuration in step S2 is specifically as follows: the bearing capacity of the basement roof slab corresponding to the lifting system is 1.2-1.3 times that of B.

[0009] As a further improvement of the present invention, the positions of the lifting system, the formwork, and the reinforcing bars on the basement roof slab are obtained through modeling, which facilitates the positioning and installation of the lifting system, the formwork, and the reinforcing bars.

[0010] As a further improvement of the present invention, in step S5, after the ring truss is further lifted to the design position, the elevation of three support nodes is randomly measured, and the position of the ring truss is adjusted using the lifting system so that the elevation difference of the three support nodes is ≤5mm.

[0011] As a further improvement of the present invention, in step S3, the connection between the ring truss and the grid shell is specifically as follows: the ring truss and the grid shell are connected by corbel pins distributed along the circumference of the ring truss.

[0012] As a further improvement of the present invention, the lifting system includes a portal frame and a lifting device for lifting the ring truss, which is disposed at the top center of the portal frame and is connected to a support node.

[0013] As a further improvement of the present invention, the support system consists of multiple sets of V-shaped columns arranged circumferentially along the ring truss, with the top of each set of V-shaped columns connected to the ring truss to form two support nodes.

[0014] As a further improvement of the present invention, in step S3, when arranging the jig, a roadbed box is set at the bottom of the jig, and the roadbed box is connected by steel sections.

[0015] As a further improvement of the present invention, in step S6, when connecting the support system and the ring truss, guy ropes are used to fix the ring truss.

[0016] The beneficial effects of this invention are: 1. Based on finite element analysis, this invention specifically increases the reinforcement of the basement roof slab, which can effectively improve the strength and stiffness of the basement roof slab and solve the problem of irreversible damage to the basement roof slab caused by excessive concentrated loads.

[0017] 2. This invention solves the problem of precise connection between the inner and outer roofs by connecting the inner and outer roofs, i.e., the ring truss and the tensioned grid, and performing suspension tensioning; it also solves the problem of large shape and position deviations of the composite roof by bidirectionally coupling the structural shape and position deviations and cable force deviations through secondary tensioning. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a roof structure combining a large-diameter ring truss and a tensioned grid.

[0019] Figure 2 This is a schematic diagram showing the connection between the support system and the ring truss.

[0020] Figure 3 This is a schematic diagram showing the layout of the frame, lifting system, and roadbed box on the basement roof slab.

[0021] Figure 4 This is a schematic diagram of the lifting process of the ring truss and tensioned grid.

[0022] Figure Labels 10. Ring truss; 21. Grid shell; 22. Cable system; 30. Support system; 31. Support node; 40. Lifting system; 41. Portal frame; 42. Lifter; 50. Frame; 60. Roadbed box; 70. Basement roof slab. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0025] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0026] like Figures 1-4 As shown, the present invention provides an installation method for a roof combining a large-diameter ring truss and a tensioned grid, comprising the following steps: S1. Using finite element analysis software, a combined roof installation model is established on the basement roof slab 70, including a ring truss 10, a tensioned mesh, a support system 30, and a lifting system 40. The tensioned mesh includes a mesh shell 21 connected to the ring truss 10 and a cable system 22 that provides elastic support to the mesh shell 21. The lifting system 40 is arranged circumferentially along the ring truss 10 and corresponds to the support nodes 31 of the ring truss 10. Based on the fact that the form and position deviation of the grid shell 21 is ≤10mm and the stress ratio at the connection node between the ring truss 10 and the grid shell 21 is ≤0.8 when the roof is in a suspended state under construction conditions, the cable force value A of the cable system 22 is calculated. S2. Reinforcing bars are installed at the corresponding lifting system 40 locations on the basement roof slab 70 to improve the load-bearing capacity of the basement roof slab 70; S3. A frame 50 is arranged on the basement roof slab 70 to connect the ring truss 10 and the grid shell 21. S4. Arrange a lifting system 40 connected to the support node 31 on the basement roof slab 70. Use the lifting system 40 to lift the ring truss 10 and the grid shell 21 to the point of being free from the jig 50 and suspended. Install the cable system 22 and tension it to the cable force value A. S5. Continue to lift the ring truss 10 to the design position, and tension the cable system 22 to the grid shell 21 again so that the deflection value is within 10mm; S6, Install support system 30.

[0027] For example, finite element analysis software was also used to calculate the support reaction force B at the connection between the lifting system 40 and the basement roof slab 70 during the lifting process of the ring truss 10 and the reticulated shell 21.

[0028] The specific configuration of the reinforcing bars in step S2 is as follows: the bearing capacity at the lifting system 40 corresponding to the basement roof slab 70 is 1.2-1.3 times that of B.

[0029] When lifting the combined roof structure onto the basement roof slab 70, the contact point between the basement roof slab 70 and the lifting system 40 will bear a very large concentrated load, potentially causing irreversible damage such as cracks, deformation, and collapse of the basement roof slab 70. Existing technologies typically employ a backfilling method to address this, which involves placing steel sections at the bottom of the basement roof slab 70 corresponding to the lifting system 40 to support it. However, this requires a large amount of material, and placing the steel sections at the bottom of the basement roof slab 70 is labor-intensive and inefficient. This invention uses finite element analysis to calculate the load borne by the basement roof slab 70 and analyze whether the deformation and stress of the basement roof slab 70 under this load meet the design requirements. If the requirements are not met, the reinforcement configuration of the basement roof slab 70 can be specifically increased to increase its strength and stiffness until the deformation and stress of the basement roof slab 70 under this load meet the design requirements.

[0030] Furthermore, since the composite roof will produce asynchronous phenomena during the lifting process, the load borne by the basement roof slab 70 corresponding to each lifting system 40 position is uneven. Therefore, the support reaction force at the connection node between the lifting system 40 and the basement roof slab 70 is multiplied by 1.2~1.3 (asynchronous lifting safety factor) as the load borne by the basement roof slab 70, which is 1.2-1.3 times B.

[0031] For example, in step S3, in order to avoid the basement roof slab 70 bearing concentrated loads during the assembly of the combined roof, when arranging the frame 50, a roadbed box 60 is set at the bottom of the frame 50 to distribute the self-weight load. At the same time, in order to improve the uniformity of the load borne by the basement roof slab 70, the roadbed box 60 is connected by steel sections.

[0032] For example, in step S3, the connection between the ring truss 10 and the grid shell 21 is specifically as follows: the ring truss 10 and the grid shell 21 are connected by bracket pins distributed circumferentially along the ring truss 10. Since the brackets will bear a large load during the initial tensioning in the suspended state, in this example, the stress ratio of the brackets is less than or equal to 0.8 to ensure the safety of the structure.

[0033] For example, the positions of the lifting system 40, the formwork 50, and the reinforcing bars on the basement roof slab 70 are also obtained through modeling to facilitate the positioning and installation of the lifting system 40, the formwork 50, and the reinforcing bars.

[0034] For example, the lifting system 40 is arranged circumferentially along the ring truss 10, and the number of lifting systems 40 is the same as the number of support nodes 31. In this example, the lifting system 40 includes a portal frame 41 and a lifting device 42 for lifting the ring truss 10, which is disposed at the top center of the portal frame 41. Figure 3The lifting device 42 is connected to the support node 31, meaning that the lifting device 42 is located on top of the support node 31 and has a one-to-one positional relationship with the support node 31. The lifting device 42 can be any existing device that can realize the lifting and lowering of the ring truss 10, and will not be described in detail here.

[0035] For example, the support system 30 consists of 5 sets of V-shaped columns, each set of V-shaped columns being connected at the top to the ring truss 10 to form two support nodes 31. Figure 2 ).

[0036] In step S5, the deflection of the cable system 22 to the mesh shell 21 is reduced to within 10 mm to ensure the final shape and position accuracy of the tensioned mesh.

[0037] In this invention, the cable system 22 is designed with reference to existing technology, which can achieve elastic support for the mesh shell 21. For example, the suspension mechanism in a large-diameter ring truss and tensioned mesh combined structure system disclosed in CN 120844698 A can be referred to, which will not be described in detail here.

[0038] For example, in step S5, after the ring truss 10 is raised to the design position, the elevation of three support nodes 31 is randomly measured, and the position of the ring truss 10 is adjusted using the lifting system 40 so that the elevation difference of the three support nodes 31 is ≤5mm.

[0039] In existing technology, after the tensioned mesh is assembled, it is tensioned according to the designed cable force value, and then the tensioned mesh is connected to the ring truss 10. The tensioned mesh deforms after tensioning, and the pin connection clearance between the tensioned mesh and the ring truss 10 is extremely small, making it difficult to connect the tensioned mesh to the ring truss 10 after tensioning. If the tensioned mesh is connected to the ring truss 10 first, and then tensioned according to the designed cable force value, the ring truss 10 bears the thrust and deformation constraint from the tensioned mesh, resulting in the form and position accuracy of the tensioned mesh failing to meet the design requirements after tensioning according to the designed cable force value. To solve the above problems, this invention connects the tensioned mesh to the ring truss 10 first, and then tensions it. The tensioning cable force value is not the designed value, but is calculated using the finite element analysis method. The calculation condition is set to the combined roof in a suspended state to ensure that the calculation condition is consistent with the actual on-site condition and to guarantee the accuracy of the calculation. The form and position deviation of the mesh shell 21 in the hovering state is limited to within 10mm to ensure that the form and position accuracy of the mesh shell 21 meets the design requirements.

[0040] The cable force value calculated at this time is the tension value implemented on site.

[0041] Furthermore, structural deformation may occur during the lifting of the composite roof, causing deformation of the cable force value of the cable system 22, thereby affecting the shape and position accuracy of the tensioned mesh. To solve this problem, the present invention sets the lifting points on the support nodes 31, and the number of lifting points is consistent with the number of support nodes 31. This ensures that the stress state of the composite roof during lifting is basically consistent with the design state, avoiding large deformation of the tensioned mesh during lifting. At the same time, since the tensioned mesh is tensioned when the composite roof is in a suspended lifting state, the stress state of the tensioned mesh after tensioning is basically consistent with that during the continued lifting state, further avoiding large deformation of the tensioned mesh during lifting.

[0042] Since asynchronous phenomena are inevitable during the lifting process, which may cause deviations in the shape and position accuracy of the mesh shell 21 after the roof is lifted, the cable system 22 is tensioned a second time after the lifting is completed, and the deflection value of the mesh shell 21 is monitored until it is within 10mm. This can ensure the final shape and position accuracy of the tensioned mesh.

[0043] Furthermore, to prevent the roof from being disturbed during the installation of the support system 30, guy ropes are used to fix the ring truss 10.

[0044] This invention performs stress analysis on the composite roof model and accordingly arranges reinforcement in the basement roof slab 70 to improve its load-bearing capacity. This ensures that the basement roof slab 70 can meet the overall load-bearing capacity requirements of the composite roof and the lifting system 40 under asynchronous lifting conditions. At the same time, by setting up the roadbed box 60, the uniformity of the load borne by the basement roof slab 70 is improved, thereby avoiding local load concentration in the basement and ensuring that the basement roof slab 70 can provide sufficient load-bearing capacity to cope with the problem of uneven lifting load during the installation of the composite roof.

[0045] In addition, by setting up a lifting system 40 through corresponding support nodes 31, the present invention can keep the stress state of the composite roof basically consistent with the design state during the lifting process, and perform phased tensioning of the cable system 22 based on the calculated cable force value A, which can avoid large deformation of the tensioned mesh, while ensuring the final shape and position accuracy of the tensioned mesh, thus solving the problem of large shape and position deviation of the composite roof.

[0046] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for installing a roof combining a large-diameter ring truss and a tensioned grid, characterized in that, Includes the following steps: S1. Using finite element analysis software, a combined roof installation model including a ring truss, a tensioned mesh, a support system, and a lifting system is established on the top slab of the basement. The tensioned mesh includes a mesh shell connected to the ring truss and a cable system that provides elastic support to the mesh shell. The lifting system is arranged circumferentially along the ring truss and corresponds to the support nodes of the ring truss. Based on the fact that the form and position deviation of the grid shell is ≤10mm and the stress ratio at the connection node between the ring truss and the grid shell is ≤0.8 when the roof is in a suspended state under construction conditions, the cable force value A of the cable system is calculated. S2. Reinforcing bars are installed at the corresponding lifting system locations on the basement roof slab to improve the load-bearing capacity of the basement roof slab; S3. Install a frame on the basement roof slab to connect the ring truss and the grid shell; S4. Arrange a lifting system connected to the support nodes on the basement roof slab. Use the lifting system to lift the ring truss and grid shell until they are freed from the jig and suspended. Install the cable system and tension it to the cable force value A. S5. Continue to lift the ring truss to the design position and re-tension the cable system until the deflection of the grid shell is within 10mm; S6. Install the support system.

2. The installation method of the large-diameter ring truss and tensioned grid combined roof according to claim 1, characterized in that: In step S1, finite element analysis software is also used to calculate the support reaction force B at the connection between the lifting system and the basement roof slab during the lifting process of the ring truss and the reticulated shell.

3. The installation method of the large-diameter ring truss and tensioned grid combined roof according to claim 2, characterized in that: The specific reinforcement configuration in step S2 is as follows: the bearing capacity of the basement roof slab at the corresponding lifting system is 1.2-1.3 times that of B.

4. The installation method of the large-diameter ring truss and tensioned grid combined roof according to claim 1, characterized in that: The modeling process also obtains the positions of the lifting system, the formwork, and the reinforcing bars on the basement roof slab, which facilitates the positioning and installation of the lifting system, the formwork, and the reinforcing bars.

5. The installation method of the large-diameter ring truss and tensioned grid combined roof according to claim 1, characterized in that: In step S5, after the ring truss is raised to the design position, the elevation of three support nodes is randomly measured. The position of the ring truss is adjusted using the lifting system so that the elevation difference of the three support nodes is ≤5mm.

6. The installation method of the large-diameter ring truss and tensioned grid combined roof according to claim 1, characterized in that: In step S3, the connection between the ring truss and the grid shell is specifically as follows: the ring truss and the grid shell are connected by corbel pins distributed along the circumference of the ring truss.

7. The installation method of the large-diameter ring truss and tensioned grid combined roof according to claim 1, characterized in that: The lifting system includes a portal frame and a lifting device for lifting the ring truss, which is located at the top center of the portal frame and is connected to the support node.

8. The installation method of the large-diameter ring truss and tensioned grid combined roof according to claim 1, characterized in that: The support system consists of multiple sets of V-shaped columns arranged circumferentially along the ring truss, with each set of V-shaped columns connected to the ring truss at the top to form two support nodes.

9. The installation method of the large-diameter ring truss and tensioned grid combined roof according to claim 1, characterized in that: In step S3, when arranging the jig, a roadbed box is set at the bottom of the jig, and the roadbed box is connected by steel sections.

10. The installation method of the large-diameter ring truss and tensioned grid combined roof according to claim 1, characterized in that: In step S6, when installing the support system, guy ropes are used to fix the ring truss.

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