The key to the warehouse technology is the shelf system, so its design basis is mainly reflected in the shelf. The force analysis and calculation of the cantilever shelf are the focus of this technology.
The design basis mainly starts from the following aspects:
1. Forced and constant load: Constant load refers to the self-weight of the shelf itself, which connects the C-shaped steel to the weight of the frame, purlin, frame, roof panel, and wall panel.
2. Forced live load: Live load refers to the weight of the goods and pallets placed on the shelves, and also involves the snow (rain) load on the roof.
3. Vertical impact load: refers to the impact load generated by the stacker when storing goods.
4. Wind load: It is the focus of the force calculation of the integral three-dimensional warehouse.
Generally speaking, the investors of the monolithic warehouse are based on the rational and effective use of space, so the height of the monolithic warehouse is relatively high, generally the aspect ratio: L (height) = 1.5-2W (width), so, The safety of the warehouse under wind load is an important indicator.
The calculation of the influence of wind load on the rack column will generally be completed by the steel structure force calculation software, and at the same time, the system force simulation and theoretical calculation must be used for review.
5. Seismic cracking degree: According to GBJ11-89 "Code for Seismic Design of Buildings", the seismic cracking degree fortification level is generally taken as 7.
The structure of warehouse rack fittings should be designed according to the most unfavorable combination of load effects listed above.
When designing the structure of the integrated three-dimensional warehouse rack, pay special attention to the following two most unfavorable load combinations: the force under the empty state of the whole warehouse when the wind load is applied, and the force under the full load of the whole warehouse when the horizontal earthquake is applied. .
In addition, full consideration should be given to the distribution status of the warehouse goods, that is, when one side of the warehouse is full and the other side is empty, the force analysis of the warehouse foundation.
Although there is a theory of warehouse goods distribution and storage; although the warehouse instructions have stipulated that the distribution of goods in the warehouse is as even as possible, we must consider the worst possible when designing and calculating.
The choice of rack type is also a key issue for integrated automatic warehouses.
According to its structure, the shelves are divided into integral welded shelves and assembled shelves.
According to the standard, the maximum vertical deviation of the column of the assembled shelf should not be greater than 1/120 of the full height, and the vertical deviation of the column of the integrated shelf of the warehouse should not be greater than 1/1000 of the full height, and the vertical absolute deviation should not be greater than 10mm. It can be seen that the processing and installation accuracy of the integral shelf is higher than that of the combined shelf.
The shelf type selection of the integrated automatic warehouse mainly depends on the calculation of various loads and the external dimensions of the warehouse.
Because custom-made medium-sized loft shelves have greater uncertainty in installation and construction, integral welded shelves are often used in the design of integrated warehouses.
The column material selection of the integral welded rack also includes square tubes, rectangular tubes, channel steel and other materials. According to the characteristics and indicators of the profile itself, it is better to choose square tubes. For higher warehouses, it is also common to choose materials with variable cross-sections and different wall thicknesses for the columns.
