Current platform semi-trailers are constructed using a beam and cross member structural system. Two main beams typically span the longitudinal length of the platform (usually forty eight feet) and cross members typically span the transverse width of the platform (usually eight feet or eight feet and six inches). The cross members typically have a spacing of six to twenty-four inches. The main beams and the cross members cooperate to create a grid or support structure for supporting the floor deck of the platform. The floor deck is typically secured to the cross members.
Two categories of platforms are currently produced. Composite platforms have steel main beams and steel or aluminum cross members. Aluminum platforms have aluminum main beams and aluminum cross members.
The floor deck usually includes wood boards, extruded aluminum decking, or a combination of the two. The majority of currently produced platforms utilize extruded aluminum decking with two to four wood boards (typically referred to as “nailers”). The extruded aluminum decking is nearly as long as the platform. Currently, there are two categories of extruded aluminum decking: T-style decking; and multi-hollow decking. T-style decking has two subcategories that may be called nail type and screw type.
As shown in FIGS. 1 and 2, Nail type, T-style decking 10 is fastened to the cross members 12 with powder actuated nails 14. The nails 14 penetrate an upper surface of the extruded aluminum decking 10, pass through a void, and penetrate an upper flange 16 of the cross member 12. The faying surface is separated in this type of connection.
As shown in FIGS. 3 and 4, screw type, T-style decking 10 is fastened to the cross members 12 with screws 18. The screws 18 penetrate the upper surface of the extruded aluminum decking 10 and penetrate the upper flange 16 of the cross member 12. The faying surface is not separated in this type of connection.
As shown in FIGS. 5, and 6, multi-hollow decking is typically used only with aluminum cross members 12. A bottom face of the extruded aluminum decking 10 is welded to the upper flange 16 of the cross member 12 with a fillet weld 19. The fillet weld 19 can be nearly the full width of the extruded aluminum decking 10. The faying surface is not separated in this type of connection.
The primary function of the connection between the floor deck and the cross members is to prevent vertical separation of the floor deck from the platform trailer. Side rails are welded or bolted to ends of the cross members to prevent the floor deck from sliding laterally and separating from the platform trailer. Front and rear ends of the floor deck are enclosed by trailer framing in order to prevent longitudinal separation of the floor deck from the platform trailer.
Many factors contribute to longitudinal movement of the floor deck relative to the cross members. Temperature changes cause the long extruded aluminum decking to expand or contract and change length. Deflection of the main beams force the extruded aluminum decking to bend and move relative to the cross members. This longitudinal movement causes shear forces to occur at the connections of the floor deck. Severe prying forces can be developed when the faying surfaces are separated from the cross members. Due to the long length of the floor deck, these shear forces due to longitudinal movement of the floor deck are much greater than shear forces due to lateral movement of the floor deck. These shear forces due to longitudinal movement can eventually cause the connections to fail. Accordingly, there is a need in the art for an improved system and method for fastening floor deck of a cargo carrier.