The overall goal of this research 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 to quantify this role. In design of steel buildings, the gravity framing is not usually considered as contributing to the resistance of seismic lateral load. In reality, however, the gravity framing can contribute substantial lateral load resistance and significantly improve seismic performance. At present, a full understanding of this role is still lacking. Moreover, the data and models needed to quantify the effect of the gravity framing system on seismic performance are also largely lacking. This study will develop a database of previous experiments on typical simple beam-to-column shear connections used in gravity framing, generate new experimental data from a series of large-scale experiments on simple shear connections under combined gravity and cyclic lateral load, develop connection models at various levels of complexity and detail, and develop preliminary system level models for gravity framing. This research will also provide information needed to conduct a follow-on research project examining system level behavior of combined gravity and lateral systems in steel buildings.
This research has the potential for significant practical impact on seismic design and evaluation procedures for new and existing steel buildings in the United States, with a broader goal of improved safety and economy. The largest impact is likely to be on the evaluation of seismic safety of existing steel buildings, where inclusion of the gravity system in the evaluation may, in a number of cases, preclude the need for costly seismic retrofit measures. This research will also provide greater insights into how the gravity system affects seismic performance of new steel buildings, and will provide information on best practices for the design and detailing of the gravity system in new buildings. This research also has potential impact on the seismic design of new steel buildings in lower seismic zones in the United States, where the contribution of the gravity framing to lateral seismic resistance may be substantial. Data from this project will be archived and made available to the public through the NEES data repository. This award is part of the National Earthquake Hazards Reduction Program (NEHRP).
