The platen consists of a closed steel box structure constructed in three separate pieces with an overall dimension of 7.6 m x 12.2 m x 2.2 m. The platen is supported on six hydrostatic bearings, three along each longitudinal side, located 0.9 m from the edge of the table on center. Through holes are provided on a grid of 0.61 m on center to accommodate 44 mm Dywidag tie-rods with tie-down capacity of 890 kN per bar for affixing specimens to the platen. Detailed platen specifications are provided in the following table.
|Platen Footprint||7.6 m × 12.2 m × 2.4 m|
|Platen Weight||1.128 MN|
|Specimen Payload||20 MN|
|Specimen CG||10 m|
|Maximum Overturning Moment||50 MN-m|
|Unloaded Mode 1||74 Hz|
|Loaded Mode 1||44 Hz|
|Top Plate Thickness||50 mm|
|Bottom Plate Thickness||20 mm|
|Side Plate Thickness||12 mm|
|Ribs||10 mm & 20 mm|
To satisfy stiffness requirements, the fundamental mode of vibration of the platen was specified to be greater than 65 Hz. The platen is stiffened transversally with 10 mm and 20 mm plates. To satisfy strength requirements throughout the entire operation of the LHPOST facility, the platen was designed to remain elastic with localized yielding only permitted upon impact of a collapsing body and extensive yielding allowed only upon unanticipated loss of control of the LHPOST. The platen was designed for a factor of safety of 3.0 against wall stability.