INNOVATIVE COLD-FORMED STEEL I-JOIST
R. A. LaBoube
Department of Civil Engineering, University of Missouri-Rolla, Rolla, MO 65409, USA
The use of cold-formed steel framing members as a method of both commercial and residential construction has increased markedly in recent years. Cold-formed steel members are used as the main framing members in low-rise and mid-rise commercial structures as well as for single and multiple family construction in the United States.
The predominant member of choice for the floor joist has been the C-section (Figure 1). The Csection possesses steel’s many attributes to include high strength-to-weight-ratio; rapid construction times; high levels of dimensional stability; and favorable "green construction”. Although the C-section’s attributes are admirable, it does not lend itself to long spans and they are not utilities friendly. The standard web punching, typically 1.5 in by 4 in, does not readily accommodate mechanical, plumbing, and HVAC systems.
To provide a cold-formed steel member that addresses the short-comings of the standard Csec- tion, research and development has been in progress to develop an I-shaped profile.