EC8 design through linear time history analysis versus response spectrum analysis - is it an enhancement for PBEE?

Eurocode 8-conforming design of a 12-storey Reinforced Concrete building is carried out through Response Spectrum Analysis (RSA) and Linear Time History Analysis (LTHA). RSA is the reference design method; it accounts for higher modes effects through an approximate combination of modal results, and the input is characterized by a smoothed response spectrum. On the other hand, assessment of structures in the Performance Based Earthquake Engineering framework is primarily carried through Nonlinear Time-History Analysis, selecting sets of accelerograms. LTHA as design methodology allows direct comparison of linear and nonlinear response between design and assessment phases with the same set of accelerograms. This approach decouples the linear-nonlinear modelling problem from the spectrum-accelerogram input selection problem. This preliminary study investigates whether the Eurocode 8-design process is affected by the change in the linear analysis methodology; i.e., LTHA in lieu of RSA, and how the force-based design should be implemented when using LTHA. Two 12-storey RC archetype buildings are designed for different ductility classes. Spectrum-compatible accelerograms provide conservative results and similar design outcome for RSA and LTHA. Moreover, the high variability of LTHA results can be an issue since Eurocode 8-record selection does not provide restraints on the standard deviation of the input. LTHA has also a great potential as methodology for the assessment of approximate fragility curves for intermediate level of damage (excluding collapse), serviceability limit states and for bespoke analyses for near source conditions. The target is to come up with a robust methodological procedure both force-based and displacement-based to promote this method as option in future versions of Eurocode 8.