360R-06 Design of Slabs-on-Ground
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- Điều hướng trang này:
- Table 4.1—Representative axle loads and wheel spacings for various lift truck capacities
- DESIGN OF SLABS-ON-GROUND 360R-19
| 4.3—Concentrated loads
Warehousing improvements in efficiency and storage densities have trended toward increased rack post loads. These changes include narrower aisles, higher pallet or material stacking, and the use of automated stacking equipment. Pallet Fig. 4.1—Controlling design considerations for various types of slab-on-ground loading (Packard 1976). (Note: 1 in. 2 = 645.2 mm 2 ; 1 ft 2 = 0.09290 m 2 .) Table 4.1—Representative axle loads and wheel spacings for various lift truck capacities Truck rated capacity, lb Total axle load static reaction, lb Center-to-center of opposite wheel tire, in. 2000 5600 to 7200 24 to 32 3000 7800 to 9400 26 to 34 4000 9800 to 11,600 30 to 36 5000 11,600 to 13,800 30 to 36 6000 13,600 to 15,500 30 to 36 7000 15,300 to 18,100 34 to 37 8000 16,700 to 20,400 34 to 38 10,000 20,200 to 23,800 37 to 45 12,000 23,800 to 27,500 38 to 40 15,000 30,000 to 35,300 34 to 43 20,000 39,700 to 43,700 36 to 53 Note: The concentrated reaction per tire is calculated by dividing the total axle load reaction by the number of tires on that axle. Figures givens are for standard trucks. The application of attachments and extended high lifts may increase these values. In such cases, the manufacturer should be consulted. Weights given are for trucks handling the rated loads at 24 in. from load center to face of fork with mast vertical. 1 lb = 0.004448 kN; 1 in. = 25.4 mm. DESIGN OF SLABS-ON-GROUND 360R-19 storage racks may be higher than 80 ft (24 m) and may produce concentrated post loads of 40,000 lb (180 kN) or more. For the higher rack loads, racks that cover a large plan area (which will affect the deeper soil layers), and racks with long-term loading, the effect of the long-term soil settlement should also be considered in the design of the slab. Cracking can also be caused by early installation of rack systems that may restrain the slab and prevent joint activation. The racks may restrain the slab with the rack system bracing or by the increase in base friction from additional storage loads. The concentrated load variables that affect design of the slab-on-ground are: • Maximum or representative post load; • Duration of load; • Spacings between posts and aisle width; • Location of the concentrated load relative to slab joint location and the amount of shear transfer across the slab joint; and • Area of contact between post or post plate and slab. Material-handling systems are major parts of the building layout and should be well defined early in the project. Rack data can be obtained from the manufacturer. It is not uncommon to specify a larger base plate than is normally supplied to reduce the flexural stress caused by the concentrated load. The base plate should be sized to distribute the load over the plate area. tải về 2.35 Mb. Chia sẻ với bạn bè của bạn:
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