4 Appendix A – Load Table Notes

1. Standards & Method

   All molded and pultruded grating load tests were performed in accordance with the ANSI FRP Composites Grating Manual for Pultruded and Molded Grating and Stair Treads . Testing and calculations follow the procedures and definitions established in that standard.

2. Load Testing Approach
   1. Test Specimen Dimensions – Test specimens consist of grating panels cut to a width of 12 in (305 mm) and a length sufficient to achieve the required clear span. Loads are applied across the full specimen width unless otherwise noted.
   2. Span Condition – Unless otherwise specified, test values are based on a simple-span condition with the grating supported on two parallel supports at the specified clear span.
   3. Deflection Measurement – Deflection values reported in the tables represent mid-span vertical deflection, identified as Δ, in inches under the applied load.
   4. Uniform Load – Uniform loads represent a load distributed evenly across the entire exposed surface area of the grating panel. During testing or calculation, the equivalent load is applied uniformly across the specimen width and clear span.
   5. Line Load – Line loads represent a concentrated load applied along a line parallel to the supports and centered across the specimen width. This condition can simulate loads such as equipment rails, narrow structural members, or concentrated traffic distributed along a line.

   

   

3. Ultimate Load Determination
   1. Ultimate load represents the maximum load capacity of the grating section before structural failure, as defined by the ANSI FRP Composites Grating Manual for Pultruded and Molded Grating and Stair Treads .
   2. Ultimate capacity is determined using the procedure defined in the ANSI FRP Composites Grating Manual and is based on the limiting flexural strength of the grating section.
   3. Ultimate load corresponds to the load that produces a maximum bending stress equal to the material’s ultimate flexural strength, or the load at which structural failure occurs during physical testing.
   4. For purposes of these tables, failure is defined as the load at which the grating experiences structural rupture, including cracking or breaking of load-bearing members, or reaches the calculated flexural strength limit of the section. Excessive deflection alone does not constitute failure unless accompanied by permanent structural damage or fracture.
   5. For uniform loads, ultimate load is expressed in lb/ft². For line loads, ultimate load is expressed in lb/ft of panel width. For point loads, where used, ultimate load is expressed in pounds (lb).
4. Safety Factor & Maximum Recommended Load
   1. Maximum Recommended Load is derived by applying a safety factor of 5:1 to the Ultimate Load.
   2. Maximum Recommended Load equals Ultimate Load divided by 5.
   3. This safety factor accounts for uncertainties associated with installation conditions, dynamic loading, long-term creep behavior of FRP materials, and normal service variability.
   Maximum Recommended Load = Ultimate Load ÷ 5
5. Units & Load Types
   Uniform Load Reported in lb/ft², with deflection reported in inches.

   Concentrated Line Load Reported in lb/ft of panel width, with deflection reported in inches.

   Concentrated Point Load Where applicable, reported in pounds (lb), with deflection reported in inches.
6. Covered Plate, When Applicable
   1. When a solid cover plate is bonded to the grating, the composite section stiffness increases.
   2. To approximate this effect, the deflection values shown in the tables may be multiplied by 0.5 for covered gratings with depths between 1 in and 2 in. This represents an estimated deflection reduction of approximately 50%.
   3. The addition of a cover plate does not change the Maximum Recommended Load or Ultimate Load values shown in the tables.
   4. Covered plates are not recommended for grating depths of 0.75 in or 0.5 in due to reduced structural efficiency.
   Approximate Covered-Grating Deflection = Open-Grating Deflection × 0.5
   Covered-grating limitation: The 0.5 multiplier is an approximate stiffness adjustment for covered grating between 1 in and 2 in deep. It does not replace project-specific analysis or testing where deflection, concentrated loading, bonding performance, or service conditions are critical.