Comparative assessment of nonlinear static and dynamic methods for analysing building response under sequential earthquake and tsunami

Abstract

This paper presents a comprehensive comparison of different dynamic andstatic approaches for assessing building performance under sequential earthquakes and tsunami. A 10‐storey reinforced concrete seismically designedJapanese vertical evacuation structure is adopted as a case study for the investigation. The case study building is first assessed under sequential earthquakeand tsunami nonlinear response history analyses: the first time this is donein the literature. The resulting engineering demand parameters are then compared with those obtained when the analysis procedure is systematicallysimplified by substituting different static approaches for the nonlinear responsehistory analyses in both the earthquake and tsunami loading phases. Differentunloading approaches are also tested for the cases when an earthquakepushover is adopted. The results show that an earthquake nonlinear responsehistory analysis, followed by a transient free vibration and a tsunami variabledepth pushover, provides the best alternative to full dynamic analyses in termsof accuracy and computational efficiency. This structural analysis combinationis recommended and has the advantage that it does not require the tsunamiinundation time history to be known in advance. The proposed double pushover approach is instead deemed only suitable for the collapse assessment ofregular low to mid‐rise buildings and for the development of collapse fragilityfunctions. An important observation made is that sustained earthquakedamage seems not to affect the tsunami resistance of the case study buildingwhen the fully dynamic analysis is carried out for the sequential loading. Thisobservation will be the subject of future work.