少数の加速度センサを用いた出力のみによる建物の層間変形角推定手法

抄録

 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 two methods for the estimating inter-story drift angle using small number of accelerometers without knowing input information.
 The proposed methods (method 1 and method 2) are based on two assumptions. One is that the response is represented by the superposition of the response of only lower modes. The other is that mode vectors and participation factors are available from the structural design model.
 Based on the assumption, for the method 1, first, we estimate modal frequencies and damping ratios using the subspace method from obtained acceleration data. Second, we decompose observed acceleration data to each mode by solving simultaneous equations using pseudo-inverse matrix. Third, we calculate mode response by focusing on the vibration equation of each mode. On the other hand, for the method 2, we directly calculate the mode response by just solving simultaneous equations. It was verified that these methods could successfully estimate the modal response as well as the inter-story drift angles.