It is most unlikely that all three types of loading will be imposed on a floor simultaneously. If racks are being utilized, there is unlikely to be any uniform loading on the floor; hence the floor is designed either for uniform and wheel loading or for rack and wheel loading.
In the uniform and wheel loading case, the wheel loading occurs only along the aisle and results in compensating bending moments when combined with the uniform loading. Consequently the design of floors for this loading combination is based on the more critical case of either the wheel loading or the uniform loading.
The combination of rack and wheel loading may result in cumulative bending moments. The rack loads have to be treated in a manner similar to additional wheel loads and this cumulative effect has to be accounted for in the design. Therefore the design is for a combination of rack and wheel loading. In practice, however, the racks are often placed back to back and the two leg loads in close proximity will normally control the design.