LINEAR TIME-HISTORY ANALYSIS AS EC8-COMPLIANT DESIGN METHOD: WHAT SEISMIC INPUT SELECTION?

Linear Time-History Analysis (LTHA) is employed as EC8-compliant design method for a regular 12-storey archetype Reinforced Concrete (RC) regular Moment Resisting Frame (MRF) including structural features typically not included such as stairs and considering different ground motions selection options. Firstly, a suite of seven pairs of spectrum-compatible ground motions from the European Strong Motion Database is used; secondly, the spectral-matching procedure for three pairs of ground motions suggested by the recent FEMA P-1050/2015 is adopted. The critical aspect is to find a balanced compromise between control of variability in the suite of ground motions, better suiting design purposes, without losing the opportunity to capture, at the design stage, part of the record-to-record variability in far-field and near-field conditions.
Eurocodes are currently in the phase of review for a second-generation release; this study aims to deal with the gap in the code related to the possibility of designing structures through LTHA.
The study employs a new definition of the Eurocode 8 behavior factor (i.e., strength reduction factor) for force-based approaches. Results of this study point to a paradigm shift in design towards a direct performance-based approach at design-stage. Preliminary comparisons suggest that a balance between the close spectral matching of FEMA P-1050/2015 and the current selection procedure of EC8 should be found for LTHA.