Grating structure and method for assembly

Claim 1

A load bearing grate structure comprising: a plurality of longitudinal span bars having lateral locating holes spaced therealong; a plurality of transverse tie bars having a substantially circular cross-sectional shape with oppositely disposed protruding lobes; said lobes having slots cut in them so as to interference fit with said lateral locating holes; and said lateral locating holes on said longitudinal span bars further having holes sized to receive said oppositely disposed protruding lobes, whereby the transverse tie bars are slidably inserted into the holes in the span bars by aligning the lobes with the holes sized to receive them, and then twisting the tie bar approximately 90°, thus allowing the slots cut in the lobes to engage with the span bar; longitudinal lock rods for holding said slots in engagement with said locating holes to prevent rotation of said tie bars with respect to said longitudinal span bars; said transverse tie bars having first and second ends with at least one elongated groove extending from said first end to said second end; and said elongated groove being sized to slidably receive said lock rods.