The Steel Diaphragm Innovation Initiative (SDII) is a multi-year industry-academic partnership to advance the seismic performance of steel floor and roof diaphragms utilized in steel buildings through better understanding of diaphragm-structure interaction, new design approaches, and new three-dimensional modeling tools that provided enhanced capabilities to designers utilizing steel diaphragms in their building systems.
SDII was created through collaboration between the American Iron and Steel Institute and the American Institute of Steel Construction with contributions from the Steel Deck Institute, the Metal Building Manufacturers Association, and the Steel Joist Institute in partnership with the Cold-Formed Steel Research Consortium; including, researchers from Johns Hopkins University, Virginia Tech, Northeastern University, and Walter P Moore. SDII specifically seeks additional internal industry partners and external (federal research, state research, foundations) partners to advance its objective.
Steel deck diaphragms have a number of strengths: low weight, use of recycled material, competitive cost, and a large number of connection points between the diaphragm and other structural elements creating potential redundancies. In addition, steel diaphragm systems may be realized across a wide range of stiffness (from bare deck to composite floor systems) giving the designer a great deal of flexibility. However, weaknesses exist as well: there is limited data on performance, and available data focuses on strength of isolated systems, not the ductility nor the whole building performance. Steel diaphragm design lacks a design paradigm consistent with seismic performance-based design. Further, insufficient knowledge and expertise exists to refute or improve upon design proposals advanced by other industries that have the potential to negatively impact steel diaphragms.
The opportunity to consider steel diaphragms as a system, an integral part of the building, and not just as a distribution element is significant. As we re-engineer steel diaphragms for seismic performance the potential to fully consider new demands such as energy, acoustic, fire, all provide a means to advance performance in novel ways. In addition, advancing our understanding and modeling of diaphragms is the most important piece in the puzzle towards modeling, designing, and optimizing buildings as fully three-dimensional – significant opportunities open up for the first to harness this approach. Without innovation in steel diaphragms threats exist: multi-year research investment in other materials, particularly in seismic performance, has created a knowledge gap that is now being realized in design specifications that are unfavorable to steel diaphragms. Since the floor system can drive the material choice in the building system, lack of innovation in steel diaphragms may impede adoption of other steel solutions. Without innovation, steel diaphragms will be threatened by advances made by competing diaphragm solutions. SDII proposes to utilize the strength of steel solutions and capitalize on the opportunity to overcome the weakness and threats the industry currently faces.