Experimental studies on improving progressive collapse resistance of RC beam–column assemblies using kinked steel plates

Abstract

One of the commonly applied methods to improve the progressive collapse resistance of reinforced concrete (RC) frame structures is to increase the amount of longitudinal rebars in beams. However, this method may lead to the unfavorable failure mode of “strong beam-weak column” for the RC frame structures under earthquakes. To prevent from this failure mode, a novel method is presented in this study using kinked steel plates (KPs) that were locally debonded and longitudinally embedded in the RC beams to improve the progressive collapse resistance of the RC frames. First, quasi-static loading tests were conducted on four 1/3 scale RC beam − column assemblies, including an equal-span specimen without the KPs, an equal-span specimen containing the KPs, an unequal-span specimen without the KPs, and an unequal-span specimen containing the KPs. Test results indicated that the ultimate resistance was improved by 89% and 81%, and the deformation capacities were increased by 39% and 38% for the equal-span and unequal-span beam − column assemblies containing the KPs compared to those without the KPs, respectively. Afterwards, high-fidelity finite element (FE) models were established to analyze the resistance contributions of the RC beam − column assemblies at the catenary action stage. Combining the experimental and FE analysis results, the mechanism was revealed for the RC beam − column assemblies using the KPs, i.e., the KPs could improve the ultimate rotational capacity of the beam-ends and induce the behavior of “two batches of plastic hinges”, resulting in fully mobilizing the catenary action to resist progressive collapse. Finally, an analytical model was developed to predict the ultimate resistance of the RC beam − column assemblies.