Hillman’s master’s thesis at Virginia Tech focused on lightweight floor systems for steel-framed buildings. Hillman worked with Prof. Thomas Murray in a research assistantship funded by the American Institute of Steel Construction.

Work on floor systems led to interest in composites.
Diagrams: John Hillman
Work on floor systems led to interest in composites.
Work on floor systems led to interest in composites.

Hillman’s design used a 7.5-in.-thick steel deck atop a 5/8-in. deck perpendicular to each other and screwed together. The screws became shear connectors. The deck is topped by a layer of concrete.

In his concept, the system could span 30 ft with flooring that was only 9.5 in. deep. Hillman also modeled a system using steel-grid decks and one using fiber-reinforced plastics—his first foray into the composite materials world.

A 30 x 30-ft mockup successfully underwent load and vibration tests. After Hillman graduated, Murray tried to promote further work on the system, but in a cautious industry it failed to gain a foothold.