English：

The bolt⁃ball grid has problems such as easy corrosion and aging. As the service timeincreases, the lack of maintenance will greatly affect the bearing capacity of the structure. The load factoris updated in the latest building structure load code putting forward higher requirements for the bearingcapacity of grid structures. Therefore, most grid structures need to be recalculated and checked, andthose that do not meet the code requirements should be strengthened. This paper describes thestrengthening of the bolt⁃ball grid in the art classroom raf of a middle school in Beijing by using theexternal steel structure joint method combined with the cable support synergy mechanism. The point clouddata of the grid before strengthening was collected and processed using a 3D scanning device. The designand construction technology of the joints were elaborated in detail. The finite element software was used toanalyze the stress of the structure and joints after strengthening. The results show that the strengtheningand renovation greatly improves the bearing capacity and deformation of the grid, making it ultimatelymeet the relevant code requirements.