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| HOW TO SPECIFY GRIP STRUT SAFETY GRATING | |||||||||||||||||||
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| HOW TO READ LOAD TABLES |
| GRIP STRUT®
Safety Grating, determine load, clear span and deflection
requirements. Having this information, select from load table the appropriate plank
to meet job requirements. Example: Clear span of 4'-0", concentrated load requirement of 300 lb. at 0.25" max. deflection. Select from the tables following: For eight-diamond 18-3/4" wide, 2-1/2" channel, 12-ga. steel which carries a load of 416 lb. at a 0.18" deflection. This is one size to do the job. Other sizes will carry more load if necessary. For more economical selection, choose the greatest width that will support the load consistent with job requirements and choose deeper channels rather than heavier steel gauges. GRIP STRUT® Safety Grating will generally carry the same concentrated load, tabulated in lb. at mid-span, for a given span, material gauge and channel height regardless of width. (See "How load tables are prepared" described below.) The uniform load tables are tabulated in lb.sq.ft., which accounts for the difference in load capacity shown for various widths. Deflections is in inches. |
HOW LOAD TABLES WERE PREPARED- The values shown in the following tables are based on actual load tests conducted by an independent laboratory. The tables have been prepared in accordance with the provisions of the AISI Specification for the Design of Cold-Formed Steel Structural Members, 1968 edition. To ensure the safety of the tabulated loads, two aspects of GRIP STRUT® Grating strength must be considered. The first consideration is transverse bending in the grating surface, which is referred to as strut flexure. This occurs when the grating is loaded with either a uniform load or a mid-width concentrated load, and the struts (grating surface) deflect relative to the side channels. To determine the allowable strut loads, samples of each grating material and thickness were tested for each plank width. (See Fig. 1, below). The data resulting from these tests was used to prepare strut loading tables, which give allowable loads and deflections considering strut flexure only. These allowable strut loads, along with the results of additional tests performed on 8- and 10-Diamond grating, have been incorporated in the load tables on page 22. The second aspect of GRIP STRUT® Grating strength is channel flexure. This occurs when the channels at mid-span of the plank deflect relative to support points. To verify the performance of the side channels, samples were loaded with concentrated and uniform loads at different spans (See Figs. 2 and 3). To approximate the most severe condition, there were no attachments between the channels and the supports. In cases where spans are shorter, channels deeper and planks wider, strut flexure becomes more critical. |
3-,4- AND 5-DIAMOND ALLOWABLE LOAD AND DEFLECTION TABLES- Since 2-through 5-Diamond planks are relatively narrow (less than 1 ft.wide), it can be assumed that both side channels effectively support the concentrated load and that the grating surface deflection is negligible. Based upon these assumptions, values in the following load tables for 2- through 5-Diamond have been determined. |
ALLOWABLE UNIFORM LOAD (U)- Values indicated in the rows adjacent to "U" are the lowest of the (1) maximum allowable uniform loads considering channel flexure and (2) maximum grating surface flexure. |
| DEFLECTION CORRESPONDING TO "U"- Deflection values are indicated below the uniform loads and are the mid-span side channel deflections for the planks carrying the allowable uniform loads (Fig. 3). |
| ALLOWABLE CONCENTRATED LOAD (C)- Values indicated in the rows labeled "C" are the lowest of the (1) maximum allowable concentrated load considering channel flexure (Fig. 2), with both channels effective, and (2) the maximum allowable strut load (Cs) for a 1-ft. long sample (Fig. 1). |
| DEFLECTION CORRESPONDING TO "C"- Deflection values indicated below "C" values in the tables are the mid-span, side channel deflections produced when the allowable concentrated load is placed at mid-span. If grating surface deflection should be considered when selecting a product to meet a particular specification, then the deflection of the mid-width of the grating, relative to the side channels, can be calculated using both the data in the Strut Loading Tables and the Load Deflection Conversion formula below. Load data based on yield strength of 333,000 psi for steel, 23,000 psi for aluminum, 35,000 psi for Type 304 stainless steel, and 30,000 psi for Type 316L stainless steel. |
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| LOAD/DEFLECTION CONVERSION FORMULAS |
In the elastic range, deflection is proportional to the applied load for both uniform and concentrated loads. This relationship can be used to determine the deflection that any load which is less than the allowable load will produce. |
| EXAMPLE A What deflection will a 300 lb. concentrated load produce on a plank (catalog number 103012) spanning 5'-0"? See item 103012 at a span = 5'-0" C = 480 lb. D = 0.26 D @ 300 lb. = 0.26" x 300 lb. = 0.16" 480 lb. |
EXAMPLE B If a plank (catalog number 103012) is spanning 6'0", what concentrated load will produce a 1/4" deflection? See item 103012 at a span of 6'0" C = 400 lb. D - 0.26" C @ 1/4" = 400lb. x 0.25" = 385 lb. 0.26 |
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U - UNIFORM LOAD (LB./FT.2) |
C - CONCENTRATED LOAD (LB.) |
| Cs - CONCENTRATED STRUT LOAD (LB. / FT.) | D - DEFLECTION (IN.) |
Grip Strut®
Safety Grating
