Avoiding Disproportionate Collapse
Full Session with Abstracts
339808-5 - Experimental Characterization of Long-Slotted Plate Components for Enhancing the Robustenss of Steel Gravity Connections Against Disproportionate Collapse
Friday, April 20
3:30 PM - 5:00 PM
Recent computational and experimental research has demonstrated the potential effectiveness of a new type of enhanced connection for mitigation of disproportionate collapse in steel gravity frames subjected to column loss (Weigand (2014), Weigand and Main (2016), Cortes and Liu (2017)). These enhanced gravity connections incorporate long-slotted steel plates that are welded to the column and bolted to the top and bottom flanges of the beam. The coupled flexural-axial performance of these enhanced connections, and the resulting capacity of the structural system under column loss, depend sensitively on a number of factors, such as the bolt diameter, plate thickness, slot geometry, and bolt pre-tension. This paper presents results from a systematic experimental investigation of the influence of these factors on the behavior of the proposed long-slotted plate components. The long-slotted plates were tested in a single-lapped bolted configuration under several different loading protocols, including monotonic and reversed cyclic loading, to fully-characterize the behavior and failure modes of the components. Results from these component tests are used to (i) characterize the influence of the investigated factors on the strength and deformation limits of the long-slotted plate components and (ii) validate a previously developed component-based model that accounts for bolt pre-tension and slot length. After the validation, the component-based model is used to optimize the connection performance to mitigate disproportionate collapse in steel gravity frames subjected to column loss.
The topic of this presentation is of current national interest. The target audience for this presentation includes (i) researchers interested in steel design, connection behavior, structural robustness, and disproportionate collapse, and (ii) design professionals interested in the analysis and design of buildings against disproportionate collapse. This presentation will provide the audience with an improved understanding of the key issues influencing the performance of steel gravity connections subjected to column removal and demonstrate an economically viable strategy for enhancing the robustness of steel gravity frames. This research also supports the development of the new ASCE/SEI Disproportionate Collapse Mitigation Standard and the Alternative Load Path Analysis Guidelines being developed by the ASCE/SEI Disproportionate Collapse Technical Committee.
-Weigand, J. M. (2014). “The integrity of steel gravity framing system connections subjected to column removal loading.” Ph.D. dissertation, University of Washington, Seattle.
-Weigand, J. M. and Main, J. A. (2016) “Enhanced Connections for Improved Robustness of Steel Gravity Frames." Proceedings of the Eighth International Workshop on Connections in Steel Structures (Connections VIII), Boston, Massachusetts, May, 2016.
-Cortes, G. and Liu, J. (2017). “Behavior of conventional and enhanced gravity connections subjected to column loss.” Journal of Constructional Steel Research, 133, pp. 475-484.