Ductility of bolted T‐stubs under multiple loading scenarios

Abstract The robustness of multi‐story steel frame buildings and, in general, of any construction structure, is an important issue, with a particular impact on the safety of people and the built environment. However, as has been seen from many previous catastrophic events, there is still a need for an improvement in design provisions that will allow structural engineers to ensure adequate structural robustness. In the particular case of steel frames, the structural joints at the ends of the beams play a key role when the frames are subjected to extreme events, as these joints may be subject to load conditions not foreseen by the design process under classical “load conditions”. The consequences can be aggravated in case of cascading or multiple events, e.g., seismic aftershocks, explosion or localized fire after an earthquake. If their capacity is exceeded, the building will be exposed to unacceptable damage and risk levels. On this aim, a quantitative definition of the residual characteristics of beam‐to‐column joints is of significant importance. The study presents the results obtained on a set of T‐stub elements subjected to monotonic, cyclic and combined protocol (cyclic plus monotonic). The influence of several parameters, including the loading protocol, the plastic deformation demands in cyclic loading, and the geometry of T‐stub elements is also investigated. Numerical models calibrated based on experimental data are used in a parametric study.