Special features of space frame structure in seismic design

1.Structural characteristics and seismic performance:

   As a kind of space rod system structural system, space frame structure has three-way force strength and can bear loads in different directions. The stiffness of the space frame structure is large, the material strength is high, and the seismic resistance is strong. This makes the space frame structure has a natural advantage in seismic design, which can effectively disperse and withstand seismic forces.

2.Vertical and horizontal seismic calculation:

   In the area with seismic intensity of 8 degrees, vertical seismic calculation should be carried out for peripherally supported small and medium-span space frame structure, and vertical and horizontal seismic calculation should be carried out for other space frame structures; in the area with seismic intensity of 9 degrees, vertical and horizontal seismic calculation should be carried out for all kinds of space frame structures. This shows that the seismic design requirements of the space frame structure  in different areas are different, and it is necessary to carry out the corresponding calculations according to the specific seismic defense intensity.

3.Vibration mode decomposition reaction spectrum method:

   When using the mode decomposition response spectrum method to analyze the seismic effect of space space frame structure , it is appropriate to take at least the first 10~15 vibration modes for the space frame structure  to perform the effect combination; for the complex or important large-span space space frame structure , more vibration modes need to be taken to perform the effect combination. This is especially important in seismic design, because it involves the dynamic response of the structure under seismic action.

4.Determination of damping ratio:

   When analyzing the seismic effect of the structure, for the peripheral landing space space frame structure , the damping ratio value can be taken as 0.02; for the space space frame structure  with concrete structural support system, the damping ratio value can be taken as 0.03. The selection of damping ratio has a significant impact on the results of the seismic analysis, and therefore it needs to be determined according to the specific characteristics of the structure.

5.Seismic performance of bearing nodes:

   The bearing nodes of the space frame structure are very critical in the seismic design, and the strength and stiffness of the bearing nodes must be considered and the seismic performance of the overall structure must be given full play. In addition, as the main damage form of the space frame structure in the actual earthquake, the bearing damage has a great influence on the dynamic response of the space frame structure, so the influence of the bearing damage should be considered in the seismic performance analysis of the space frame structure.

6.Seismic vulnerability analysis:

   The seismic performance of the space frame structure is analyzed and discussed using seismic vulnerability, and the analysis results show that the selection of structural performance indexes should be combined with the actual seismic damage when evaluating the performance of the space frame structure . This provides a method for the seismic performance assessment of space frame structures, which helps to predict and assess the seismic capacity of structures at the design stage.

In summary, the special features of space frame structures in seismic design are their unique structural characteristics, detailed seismic calculation requirements, the application of the vibration mode decomposition reaction spectrum method, the determination of the damping ratio value, the seismic performance considerations of the bearing nodes, and the application of seismic vulnerability analysis. Together, these factors ensure the safety performance of the space frame structure under seismic action.