Influence of beam-to-column connections in seismic vulnerability assessment of steel structures

It is worldwide recognized the importance of assessing the vulnerability of structures in seismic prone zones. Focusing on steel structures, it is well-known that the behavior of beam-to-column connections plays a key role in the seismic response of any moment-resisting frame system. Recently, a research project funded by European Commission investigated the seismic performance of pre-qualified connections through numerical analyses and pseudo-static cyclic testing. From a designer perspective, it is, however, necessary to understand the efficiency of such connections in terms of building performance to take a rational and conscious decision when designing a building. With this in mind, this paper investigates the influence of different beam-to-column connections on the seismic response and vulnerability of medium-rise steel frame structures. The behavior of these structures has been investigated by means of non-linear dynamic analysis for increasing seismic intensity levels using the OpenSeesPy finite element software. The record selection has been carried out through the Average Sabased method. The building performance has been assessed computing both maximum and residual interstory drifts, as well as fragility curves and absolute acceleration floor response spectra. The last mentioned enables to evaluate the likely damages experienced by acceleration sensitive non-structural elements, giving an additional point-of-view for estimating the building content performance. The outcomes of this study provide useful information for practitioners and designers interested in adopting the new set of pre-qualified connections, clarifying their effects on performance of common buildings and their content.