Whether the ground bearing capacity to meet the requirements, you need to consult the civil information and computational analysis to determine, this work involves process planning, mechanical structure and civil engineering expertise, more complex. In this paper, through the study and analysis of logistics warehousing equipment load types, building structural load specifications and concrete structure design specifications, combined with long-term experience, summed up the logistics warehouse ground bearing capacity calculation method, and applied to actual engineering cases.
There are various types of logistics and warehousing equipment, and the type of load formed by different equipment on the ground and the bearing requirements on the ground are different, and there are various forms of ground damage due to overloading. Whether the ground bearing capacity to meet the requirements, the need to consult the civil engineering information and calculation analysis to determine, the work involves process planning, mechanical structure and civil engineering and other professional knowledge. It is difficult to make scientific and reasonable calculation, analysis in place, and appropriate safety margin. Generally, it is easy to calculate the average load of equipment, but it is often helpless to calculate the ground punching and shearing load.
In this paper, through studying and analyzing the load types of logistics warehouse equipment, building structural load codes and concrete structure design codes, and combining with long-term experience, this paper sums up the ground bearing capacity calculation method for logistics warehouses and applies it to actual engineering cases.
The warehouse of logistics automation upgrade is divided into two cases: The use of old warehouses and new warehouses. For the existing warehouse buildings, in the process planning stage of the project, you need to determine whether the ground bearing capacity to meet the requirements of the new logistics equipment. For the new warehouse building, only the civil construction can put forward the load-bearing requirements. In this paper, according to the collection of civil information, determine the storage load, ground bearing capacity check and evaluation of the conclusion of the process.
The overview of the warehouse ground
Require the original stacking engines, mechanical parts and other ground storage to be transformed into automated stacker crane three-dimensional warehouse.
The floor of the warehouse is poured with c20 plain concrete (as shown in figure 1), the spacing of ground expansion joint is 6m ground extension, the thickness of concrete poured is 150mm~160mm, the lower part of plain concrete has 100mm gravel pad, the design average load of ground is 7t/m2. The above civil construction parameters are introduced orally during technical exchange between the two sides, because the warehouse construction era is early, the customer can’t provide detailed civil construction information, so the site is not a good place to build. The ground sampling cores confirm basic agreement with the verbally provided civil construction parameters.
Composition and load distribution of the modified storage equipment
The technically modified automated stacker crane three-dimensional warehouse is 115m long, 42m wide, double pallet spaces, 7.1m high shelves, 5 layers.
The three-dimensional warehouse load consists of three parts: Shelves, pallet unit storage and stacker crane. These three parts of the load on the warehouse floor are collectively known as variable loads.
The rated load of each pallet unit is 1.5t, and the average self-weight of each pallet space structure is 40kg, the load of each foot of the middle column is 5 unit pallet load plus 5 pallet space self-weight, and the total load of a single foot is 7.7t.
When the stacker crane is working, the size and position of the pressure load on the ground are constantly changing due to walking start and stop, no-load full-load, lifting start and stop, etc. The walking and lifting start and stop of the stacker crane is the same as that of the palletizer crane. The stacker crane adopts s-curve control technology for walking and lifting start-stop, and the maximum acceleration is 0.5m/s2.
Conclusion and handling of abnormal situation
As a result of the design check and analysis, the conclusions and key points of exception handling are summarized below.
- The average ground bearing of the automatic storage project meets the requirements; when the foot plate is reduced to 150×100 (mm), the punching bearing and compressive bearing are in line with the requirements, which achieves the effect of safety and economy.
From the index calculation results show that the concrete compressive capacity of the general affluence of large, conventional design verification may not take into account this index of verification.
- If the average bearing capacity does not meet the requirements, the load needs to be reduced or the ground or floor needs to be reinforced according to the reinforced concrete structure design code (gb50367-2013). For example, to increase the thickness of concrete on the original ground to improve the average ground bearing capacity; when the warehouse is located on the second floor, carbon fiber bonding on the bottom surface of the floor slab to improve the average bearing capacity of the floor and other reinforcement measures to improve the average bearing capacity.
- If the punching load does not meet the load requirements, it can be increased by increasing the foot plate area of the shelf column or increase the overall steel structure bearing grid on the ground (floor); for new warehouse buildings, you can take measures to solve the problem by increasing the thickness of concrete or concrete ground reinforcement.
- Automated three-dimensional warehouse on the ground uneven settlement requirements <uniform settlement requirements. If the lower part of the foundation is the original soil, there is no backfill such as pits or ditches, do not consider the problem of uneven settlement exceeds the standard. If there is local backfill, uneven settlement will need to attract enough attention, after the warehouse is put into use to increase regular settlement observation, and take countermeasures in due time. Generally after 6-8 months, the foundation tends to stabilize, the need to re-level the shelf column feet. If the uneven ground settlement occurs seriously exceeds the standard, you need to hire professionals to deal with. This indicator depends on the foundation and the production of ground foundation, which is not within the scope of this paper.
- The project has been delivered and the ground bearing calculations have been verified.
If you’re interested in ground design, check out our blog-Floor Design