W-shaped structural beam assembly for use in a foam filled structural plank

A structural plank assembly, comprising:

• a plurality of structural beams connected together to define a structural plank building foundation, wherein the structural beams define an enclosure therebetween and an outer perimeter therearound;
• a bottom wall on the enclosure;
• a top wall on the enclosure;
• and
• a structural foam filling the enclosure, the structural foam being in direct contact with the structural beams and with the top wall and the bottom wall of the enclosure, and
• wherein at least one of the structural beams comprises:
• a top planar member;
• a bottom planar member;
• two or more vertical end members, each vertical end member being connected to the top planar member and to the bottom planar member;
• a series of repeating angled planar members, each angled planar member being connected to the top planar member and to the bottom planar member.