Application of reliability-based robustness assessment of steel moment resisting frame structures under post-mainshock cascading events

This paper proposes a reliability-based framework for quantifying structural robustness considering the occurrence of a major earthquake (mainshock) and subsequent cascading hazard events, such as aftershocks that are triggered by the mainshock. These events can significantly increase the probability of failure of buildings, especially for structures that are damaged during the mainshock. The application of the proposed framework is exemplified through three numerical case studies. The case studies correspond to three SAC steel moment frame buildings of three, nine, and 20 stories, which were designed to pre-Northridge codes and standards. Two-dimensional nonlinear finite-element models of the buildings are developed with the Open System for Earthquake Engineering Simulation framework (OpenSees), using a finite length plastic hinge beam model and a bilinear constitutive law with deterioration, and are subjected to multiple mainshock-aftershock seismic sequences. For the three buildings analyzed herein, it is shown that the structural reliability under a single seismic event can be significantly different from that under a sequence of seismic events. The reliability based robustness indicator shows that the structural robustness is influenced by the extent to which a structure can distribute damage

Seismic response assessment of architectural non-structural LWS drywall components through experimental tests

A research project was conducted at University of Naples “Federico II” over the last few years with the aim to give a contribute to overcome the lack of information on seismic behaviour of architectural non-structural lightweight steel (LWS) drywall components, i.e. indoor partition walls, outdoor façades and suspended continuous ceilings. The tested non-structural components were made of LWS frames sheathed with gypsum-based or cement-based boards. The research activity was organized in three levels: ancilliary tests, component tests and assembly tests. Ancilliary tests were carried out for evaluating the local behaviour of partitions, façades and ceilings. Component tests involved out-of-plane quasi-static monotonic and dynamic identification tests and in-plane quasi-static reversed cyclic tests on partitions. Finally, the dynamic behaviour was investigated through shake table tests on different assemblages of partitions, façades and ceilings. The study demonstrated that the tested architectural non-structural LWS drywall components are able to exhibit a very good seismic behaviour with respect to the damage limit states according to the IDR limits given by Eurocode 8 Part 1. The current paper describes the complete experimental activity within the project