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Long-Slotted Plate Connections for Enhancing the Robustness of Steel Gravity Systems against Column Loss: Preliminary Results



Jonathan M. Weigand, Travis E. Thonstad, Andrew Seamone


Steel gravity frames are commonly used in United States building construction practice, but they are potentially vulnerable to disproportionate collapse under column loss, as has been shown by recent experimental and analytical studies. To overcome these vulnerabilities, a new type of connection has been developed. These “enhanced” gravity connections, which could be implemented in new or existing structures, incorporate long-slotted steel plates that are welded to the column and bolted to the top and bottom flanges of the beam. This paper presents results from an experimental program designed to evaluate the influence of the key geometric factors on the coupled flexural-axial performance of these enhanced connections. Long-slotted plates were axially tested in a single-lapped bolted configuration under monotonic tensile loads, to characterize the behavior and failure modes of the components. Eight replicate specimens, with nominally identical geometries, were tested to evaluate the variability of the response. The aggregate results showed that the connection bolts maintained pretension while slipping within the slot, and did not lose appreciable pretension until bearing occurred, and (ii) the failure mode depended on the ratio of the ratio of the bolt single-shear strength to the tensile rupture strength of the slotted plate. Results from eight replicate tests with nominally identical geometry showed that the results were highly repeatable; the coefficient of variation in the peak tensile load, and displacement at the peak tensile load was 0.025 and 0.032, respectively.
Proceedings Title
Proceedings of the 2019 Structures Congress
Conference Dates
April 24-27, 2019
Conference Location
Orlando, FL


Weigand, J. , Thonstad, T. and Seamone, A. (2019), Long-Slotted Plate Connections for Enhancing the Robustness of Steel Gravity Systems against Column Loss: Preliminary Results, Proceedings of the 2019 Structures Congress, Orlando, FL, [online], (Accessed April 17, 2024)
Created April 27, 2019, Updated May 28, 2019