Application and Installation of Bolted Ball Grids in the Design of Large-Span Roof Structures

 Large-span roofs are a common structural form in modern buildings and are widely used in large-scale public buildings such as stadiums, exhibition centres and airport terminals. In these projects, the structural design should not only meet the functional requirements, but also take into account the economy, aesthetics and construction feasibility. As an efficient space grid structure, bolted ball space frame is widely used in large-span roofing projects due to its advantages of light dead weight, strong bearing capacity and convenient construction.

I. Structural design characteristics of bolted ball grid frame

Bolted ball mesh rack is a kind of three-dimensional space  structure composed of ball nodes and rods, and its core feature is to connect the rods and ball nodes through bolts to form an overall force system. Compared with traditional steel joist, bolted ball grid has the following structural design advantages:

Light deadweight: the rods of bolted ball space structure usually adopt steel pipe or round steel, with smaller cross-section size, so the overall structural deadweight is lighter, which reduces the bearing pressure of foundation and substructure.
Strong load-bearing capacity: through reasonable node design and rod arrangement, the bolted ball space structure can effectively disperse the load, and has high load-bearing capacity and anti-seismic performance.

Convenient construction: the rods and nodes of bolted ball frame are prefabricated components, which only need to be assembled and connected at the construction site, reducing the welding workload and shortening the construction period.

Strong adaptability: Bolted ball space structure is suitable for roof design of various spans and shapes, and can meet different functional requirements of buildings.

In the design of large-span roofs, the bolted ball space structure is usually used in conjunction with purlins, roof panels and other components to form a complete roofing system. Load distribution, node stiffness, rod stability and other factors need to be considered comprehensively to ensure the safety and economy of the structure.

II.Installation method of bolted ball space structure

The installation of bolted ball space structure is the key link of the whole project, and its construction quality directly affects the safety and service life of the structure. The following are the main installation methods of bolted ball net frame:

Prefabrication and transport
The rods and nodes of bolted ball net frame are prefabricated components, which need to be processed and assembled in the factory. After assembly, the components are transported to the construction site by special means of transport.

Foundation preparation
Before installation, the foundation should be checked and accepted to ensure that the plane degree and elevation of the foundation meet the design requirements. At the same time, temporary support frames should be set up to provide a stable working platform for the installation of the net frame.

Assembly and lifting
The installation of bolted ball net frame usually adopts the method of assembling in pieces or lifting as a whole.

Block assembly method: the net frame is divided into several blocks, which are assembled on the ground, then lifted to the designed position by hoisting equipment, and then connected as a whole.

Overall lifting method: After assembling the whole net frame on the ground, the whole net frame will be lifted to the designed height by hydraulic lifting equipment.

Node connection and adjustment
After the net frame is lifted to the design position, the nodes need to be bolted together and the length of the rods and the position of the nodes need to be adjusted to ensure the overall geometric accuracy of the net frame.

The plane position, elevation and node spacing of the net frame are detected by measuring instruments to ensure that they meet the design requirements.
For the parts that are out of the error range, they need to be corrected by adjusting the length of the bars or applying pre-stress.

Inspection and acceptance
After the installation is completed, the net frame needs to be tested comprehensively, including node connection quality, rod straightness, overall geometric accuracy. After passing the test, the roof panel can be installed.

III. the future development trend of bolted ball space structure

With the continuous progress of construction technology, the application of bolted ball space structure in large-span roofing has a broader prospect. In the future, its development trend is mainly reflected in the following aspects:

Intelligent design

Through BIM technology, finite element analysis and other means, the intelligent design and optimisation of bolted ball space structure can be achieved to improve the economy and safety of the structure.

Modular construction

Adopt modular prefabrication and assembly technology to further improve the construction efficiency and quality of bolted ball grid frame.

Green Environment

In the selection of materials and construction process, focus on green environmental protection, adopt recyclable materials and energy-saving construction technology to reduce the impact on the environment.
 
As an efficient spatial grid structure, bolted ball mesh racking shows unique advantages in large-span roofing projects. Its flexible structural design, convenient construction and strong bearing capacity can meet the dual demands of modern buildings for function and aesthetics. With the continuous progress of technology, the application range of bolted ball space structure will be further expanded, injecting new vitality for the development of the construction industry.