Output Only Estimation of Inter-story Drift Angle for Buildings Using Small Number of Accelerometers

The Tohoku earthquake of magnitude 9.0 occurred on March 11, 2011. As a result, the need for Structural Health Monitoring (SHM) was highlighted. To assess the health of buildings, modal parameters such as natural frequencies and damping ratios are the basic and important damage indicators. In addition, maximum inter-story drift angle is also recognized as an important indicator. If we have to estimate these indicators very precisely, we need to install accelerometers on all floors. However, it is not realistic due to the cost. In many methods to estimate the response using small number of accelerometers, the excitation (input) is assumed to be available. However, in some cases, some sensors including the input sensor may not be available. Thus, in this paper, we propose the methods for the estimating inter-story drift angle using small number of accelerometers without knowing input information.