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An Experimental and Computational Study of Steel Moment Connections under a Column Removal Scenario



Fahim H. Sadek, Joseph Main, Hai S. Lew, Stephen D. Robert, Vincent Chiarito, Sherif El-Tawil


This report presents an experimental and computational study of two steel beam-column assemblies, each comprising three columns and two beams. The two beam-column assemblies represent portions of the structural framing system of two ten-story steel frame buildings, which were designed as part of the National Institute of Standards and Technology research program aimed at prevention of disproportionate structural collapse. One building was designed for Seismic Design Category C (SDC C) and the other for Seismic Design Category D (SDC D). The beam-column assemblies were taken from the exterior moment-resisting frames of these buildings. One test specimen, which was part of the SDC C building, had welded unreinforced flange-bolted web (WUF-B) connections, and the other, which was part of the SDC D building, had reduced beam section (RBS) connections. The specimens were subjected to monotonically increasing vertical displacement of the unsupported center stub column to observe their behavior under a simulated column removal scenario, including the development of catenary action in the beams. The test was terminated when a collapse mechanism of each assembly was developed and the vertical load-carrying capacity was depleted. The primary test specimen response characteristics were measured. These included vertical and horizontal displacements at specific locations, rotations at beam ends, strains at various locations, and the applied load. In addition, a high speed video camera was used to record the specimen response, including the failure mode of the beam-to-column connections at the center column.
Technical Note (NIST TN) - 1669 rev2
Report Number
1669 rev2


buildings, catenary action, computational model, computer simulation, design standards, disproportionate collapse, finite element analysis, moment resisting connections, progressive collapse, steel structures, structural robustness, testing


Sadek, F. , Main, J. , Lew, H. , Robert, S. , Chiarito, V. and El-Tawil, S. (2011), An Experimental and Computational Study of Steel Moment Connections under a Column Removal Scenario, Technical Note (NIST TN), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed April 13, 2024)
Created February 28, 2011, Updated October 12, 2021