The composition of the spherical grid node can use bolt balls and welding balls, which are common finished products in the processing of grid accessories. Regardless of the different names of these two accessories, in fact, their composition is basically the same. They have important tasks for the overall structure of the grid. The following editor of Jiangsu Huahai Steel Structure will briefly introduce the construction technology of this spherical grid.

1. Before assembling the spherical grid, the positioning axis, elevation, levelness and anchoring position of the grid structure support should be measured. Use theodolite, level and steel ruler for actual measurement.

2. The type, specification, placement and orientation of the supporting pad must meet the design requirements. Because the internal force of the members and the deformation of the nodes are calculated based on the support nodes under certain constraints, the type, specification, placement and orientation of the supporting blocks will have a direct impact on the constraints of the grid nodes .

3. For example, the position and orientation of the support points include peripheral support, point support, combination of peripheral support and point support, three-sided support with one opening, two-sided support with two openings, etc. If the position and orientation of the support points are changed, the distribution of the support points will inevitably be changed, and eventually the boundary conditions of the grid structure will be changed.

4. The form of the grid support shall not be changed or substituted at will. For example, changing the spherical, plate-type rubber bearings, etc. will change the boundary constraints. The change of boundary constraints will inevitably lead to changes in the form of the structural system, which may change the unchanging system into a variable system and cause structural instability.

5. The transition board of the grid support shall not be changed or substituted at will. The anchor bolt must be anchored, and the plate welding of the plate welding must meet the design requirements, otherwise it may change the free constraint into elastic constraint or change from fixed constraint to forced constraint, causing the tie rod to become a compression rod, and the rod exceeds the allowable Stress, loss of stability, forming a morbid grid.


The grid structure is a hinged space link structure, therefore, any node has three degrees of freedom; at the same time, in order to ensure the geometry of the grid structure is unchanged, there must be more than six supporting and restraining chain rods outside. Because the grid structure is a spatial structure, it is more complicated to analyze the sufficient conditions for its geometric invariance.