Lessons from the Behavior of a Monitored 11-Story Building during the 2011 Tohoku Earthquake for Robustness against Design Uncertainties

Specifically detailed pin-supported walls with steel dampers have been used to seismically strengthen an 11-story steel reinforced concrete building. By looking at the observed damage and monitored motions of the building during the M9.0 Tohoku earthquake in 2011, it is demonstrated that nonstructural reinforced concrete partition walls have had a major effect on its seismic behavior during the earthquake, the neglect of which constitutes a major design uncertainty. A finite element model used to assist the retrofit design is calibrated, taking advantage of the accelerograms obtained during the earthquake. The results of nonlinear time-history analysis investigations with the modified model identify both the positive and negative effects of the nonstructural walls at various ground motion intensities, and suggest that the pin-supported wall-frame system exhibits higher robustness against both record-to-record and modeling uncertainties than its bare-frame counterpart does.