Performance of Three-Dimensional Reinforced Concrete Beam-Column Substructures under Loss of a Corner Column Scenario

TLDR

Conventional RC structures are vulnerable to progressive collapse when a corner column is lost, yet experimental data are scarce, leaving a knowledge gap for design mitigation. Seven one‑third‑scale RC beam‑column substructures were tested, varying beam transverse reinforcement, seismic versus nonseismic detailing, and span aspect ratios. Tests revealed shear failure at the corner joint with plastic hinges at beam ends, Vierendeel action dominating load redistribution before severe damage and cantilever action thereafter, and highlighted deficiencies in the updated DoD design guidelines.

Abstract

The vulnerability of conventional RC structures to structural failure caused by the loss of corner columns has been emphasized over the past years. However, the lack of experimental tests has led to a gap in the knowledge for the design of RC building structures to mitigate the likelihood of progressive collapse caused by losing a ground corner column. Seven one-third scale RC beam-column substructures were tested to investigate their performance. The variables selected for the test specimens included beam transverse reinforcement ratios, type of design detailing (nonseismic or seismic), and beam span aspect ratios. Shear failure was observed to have occurred in the corner joint, and a plastic hinge was formed at the beam end near the fixed support in the nonseismic detailed specimens. However, plastic hinges were also formed in the beam end near to the corner joint for the seismically detailed specimen. Vierendeel action was identified as the major load redistribution mechanism before severe failure occurred in the corner joint, but a cantilever beam redistribution mechanism dominated after the corner joint suffered severe damage. The test results were compared with the Department of Defense design guidelines to highlight the deficiencies of the recently updated guidelines.