Long-term seismic monitoring of base-isolated building with emphasis on serviceability assessment Dionysius M. Siringoringo* ,† and Yozo Fujino Institute of Advanced Sciences, Yokohama National University, 79-1 Tokiwadai, Hodogaya-ku, Yokohama, Kanagawa 240-8501, Japan SUMMARY Seismic monitoring system provides opportunities to observe possible damage or failure and weakening of structural components and to evaluate serviceability performance of a structure during an earthquake. This can be achieved by comparing structure recordings before and after the event or by identifying significant change in characteristics of structural response that may serve as indicators of failure or damage in progress. Excessive vibration on some parts of structure may become a serviceability concern for some buildings, and this also can be detected from continuous monitoring. Several factors such as characteristics of ground mo- tion, soil condition, and geometry of the structure could cause excessive localized structural vibration, and by evaluating the responses, one can take remedial action. For a base-isolated building in particular, reduc- tion of response of upper stories is critical to protect nonstructural elements or sensitive equipments on the building. In this paper, we describe a case study on seismic monitoring of a base-isolated building with the main focus on evaluation of serviceability performance. The study emphasizes on a influence of building asymmetricity on the seismic response. Results of the study are based on a long-term building seismic monitoring program for over 3 years between 2010 and 2012 under various amplitudes of earthquake includ- ing the March 11, 2011 Great East-Japan Earthquake. Copyright © 2014 John Wiley & Sons, Ltd. Received 25 February 2014; Revised 21 August 2014; Accepted 20 November 2014 KEY WORDS: building seismic monitoring; base-isolated building; long-term seismic monitoring; building torsional response 1. INTRODUCTION Structural monitoring system offers opportunities to observe possible damage or failure of structural components during large earthquakes, to identify weakening of structural components in a series of strong earthquakes, and to detect unwanted or peculiar structural response that may not be anticipated in the design. To achieve these objectives, a common approach is to compare structure recordings before and after the event and identify significant change in structural response. The change in response characteristics may serve as indicators of failure or damage in progress. Notable studies on seismic performance evaluation of instrumented buildings are based on this approach, such as evaluation of building during the 1979 Imperial Valley earthquake [1], Alhambra Building during the 1994 Northridge earthquake [2] and 20 instrumented buildings during the 1994 Northridge earthquake [3]. Other studies investigate building performance not only during a specific large earthquake but also for longer observation time, such as the transient and long-term changes of building seismic responses during 3 years [4] and a rare example of continue seismic monitoring of seven-story reinforced concrete building for over 24 years [5]. Various tests on large scale testing *Correspondence to: Dionysius M. Siringoringo, Institute of Advanced Sciences, Yokohama National University, 79-1 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan. † E-mail: dion@ynu.ac.jp Copyright © 2014 John Wiley & Sons, Ltd. EARTHQUAKE ENGINEERING & STRUCTURAL DYNAMICS Earthquake Engng Struct. Dyn. (2014) Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/eqe.2538