Load and force analysis of grid structure

更新时间:2021-03-04 09:51:43点击:875 Grid Knowledge

Grid structure load and force analysis, grid structure load mainly includes permanent load, variable load, temperature effect and seismic effect, as follows:




Grid structure load

1. Permanent load

The permanent load acting on the grid structure includes the self-weight of the grid structure, floor or roof structure, insulation layer, suspended ceiling, equipment pipes and other materials.

2. Variable load
The variable loads acting on the grid structure include roof or floor live load, snow load, ash load, wind load, and suspended crane load. The snow load and roof live load do not have to be considered at the same time, and the larger value of the two .
For the surrounding support, the wind load of the grid frame with the support node in the upper chord is borne by the surrounding walls, and the wind load may not be considered in the calculation; for other support conditions, the horizontal wind load should be considered according to the actual engineering situation. Due to the good stiffness of the grid frame and the relatively small natural vibration period, the influence of the wind vibration coefficient may not be considered when calculating the wind load.

3. Temperature effect
Temperature effect refers to the additional temperature stress generated by the grid members due to temperature changes, which must be considered in calculations and structural measures.

4. Seismic action
my country is an area prone to earthquakes and the effect of earthquakes cannot be ignored. According to my country’s "Technical Regulations for Spatial Grid Structures", when the surrounding support grid is built in areas with a design intensity of 8 degrees or above, vertical seismic action should be considered; when built in areas with a design intensity of 9 degrees, the Horizontal seismic action should be considered
Force analysis of grid structure

The reticulated shell structure is divided according to the number of layers. There are mainly single-layer reticulated shells, double-layer reticulated shells and three-layer reticulated shells; according to Gaussian curvature, they are divided into reticulated shells with zero Gauss curvature, reticulated shells with positive Gaussian curvature and reticulated shells with negative Gaussian curvature. ; According to the surface shape, it is divided into cylindrical reticulated shell, spherical reticulated shell, double-sided parabolic reticulated shell and complex curved surface reticulated shell.

The force aspect of the grid structure: when the rod is under tension, the force transmission route is the tension-steel pipe-cone or sealing plate-bolt-steel ball; at this time, the sleeve is not stressed. When the rod is compressed, its force transmission path is the pressure plate-steel plate-cone or sealing plate-sleeve-steel ball. At this time, the bolt is not stressed, and the pressure is transmitted by the contact surface between the parts. The grid sealing plate and the cone head mainly play the role of connecting steel pipes and bolts, and bear the tension and pressure from the rods. When the pipe diameter of the rod is greater than or equal to 76mm, it is advisable to use the taper connection; when the pipe diameter of the rod is less than 76mm, the sealing plate can be used for connection.

According to the analysis of some grid structures using the mode decomposition reaction popularization method, it is shown that in areas with a fortification intensity of 6 degrees or 7 degrees, under the action of vertical earthquakes, the seismic internal forces and displacements of the grid are not significant. Therefore, it is not necessary to carry out vertical earthquakes. To the seismic check. In areas where the seismic fortification intensity is 8 or 9 degrees, the grid structure should be subjected to vertical seismic check and horizontal check.

Recommended Reading