Patent ID: 7849643

Claim:
Two interconnected structural elements forming two run portions and two rise portions, each structural element having a single run portion and a single rise portion, and each structural element comprising: a first L-shaped section roll formed or bent from a metal plate and including first and second sides, a second L-shaped section roll formed or bent from a metal plate and consisting of a horizontal portion and a vertical portion, the second L-shaped section disposed adjacent the first L-shaped section so as to form a sandwich structure including a core of a compact thermosetting polyurethane elastomer material disposed between the first side and the horizontal portion so as to transfer shear forces therebetween, and the vertical portion closing one side of the cavity in which the core is formed, wherein the single run portion is formed by the sandwich structure, and wherein the single rise portion is formed by the second side of the first L-shaped section, and a lip extending from an end of said second side, wherein the lip of a first of the structural elements is in contact with the first side of a second of the structural elements.