GRIP STRUT - General Load Information

How to read load tables

To select size of 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'-O", 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 were 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. Deflection is in inches.

How load tables were prepared

The values shown in the following tables are based on actual load tests conducted by the Research Center of United States Gypsum Company. 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) 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 Product Selection/Design Tables in this catalog.

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.

2-, 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, the values in the following Design 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 on page 31.

Load data based on yield strength of 33,000 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.