Performance of a Passively-controlled Steel Building Before and After the 2011 Great East Japan Earthquake

Abstract

An eight-story Administration Building in Sendai City, Japan with oil dampers survived the 2011 Great East Japan Earthquake, but leaving the oil dampers on the first floor completely damaged. A novel retrofit plan using rubber bearings instead of oil dampers is proposed and tested, which are able to accommodate larger inter-story drifts. This building has experienced damage, rehabilitation and verification periods with different damping scenarios. For each scenario, the modal analysis is conducted to identify the dynamic characteristics and evaluate the performance of the structural frame and dampers. To identify the dynamic properties of the building, two kinds of modal identification techniques are implemented: Peak-Picking method (PP) combined with the half-power bandwidth method, the autoregressive with exogenous excitation (ARX) models method. The fundamental frequencies and damping ratios in two translational directions are extracted. Based on the identified results and long-term observation of seismic responses during various levels of earthquakes between 2003 and 2013