Sponsor: National Science Foundation
PI: Michael Engelhardt
Co-PI's: Todd Helwig, Eric Williamson, Patricia Clayton
In typical U.S. design practice for steel buildings, lateral seismic loads are resisted by a small number of lateral force resisting frames (moment frames, braced frames, etc.). The remainder of the structural system is designed to resist gravity loads, and normally consists of columns, beams, and girders with a composite floor system, wherein girders and beams are connected to columns using simple shear connections. The gravity framing, although not specifically designed for lateral load resistance, can in fact contribute significant lateral stiffness, strength, and deformation capacity to a steel building. Results of previous research have shown that the role of gravity framing is most important when the lateral frames experience non-ductile failures as may occur in older buildings. Previous work has also demonstrated that the gravity framing can often make the difference between collapse and survival of such buildings in a large earthquake. Even for new buildings, the gravity framing plays an important role as a back-up system that can prevent collapse under very large earthquake ground motions. While a considerable amount of previous work has been done to examine the role of gravity framing in the seismic performance of steel buildings, much information is still lacking.
As such, the overall goal of this project is to develop a better understanding of the role of gravity framing in the seismic performance of steel buildings, along with the data, models and tools are needed to quantify this role. This research will develop experimental data and computational models that will provide a greater understanding of the response of gravity framing in steel buildings subjected to earthquakes, and will provide the tools needed to quantify this response. This study will develop a database of previous experiments on simple shear connections, will generate new experimental data from a series of large-scale experiments on simple shear connections under combined gravity and cyclic lateral load, will develop connection models at various levels of complexity and detail, and will develop preliminary system level models for gravity framing. This research will also provide information needed to conduct a follow-on project examining system level behavior of combined gravity and lateral systems.