基於眾包技術利用智慧型手機量測建築受震時反應並進行基礎自然頻率識別之研究

為了在震後盡快得到各地區的災損情形，本研究希望利用建物內智慧型手機結合眾包技術獲得個別建物的基礎自然頻率，進而輔助救災。本研究利用手機配備之加速度計量測加速度資料，並利用Wi-Fi直連技術把手機進行時間同步，之後上傳到伺服器並將訊號方向對齊後，使用系統識別之方法獲得結構基礎自然頻率。所使用的系統識別方法中有唯輸出分析方法，和輸入－輸出分析方法，並模擬智慧型手機感測器之品質及所獲得之訊號進行分析，探討在不同情形下適合之系統識別方法。

關鍵字

智慧型手機；建築震後損傷診斷；基礎自然頻率；群眾外包

並列摘要

To estimate the potential damage of buildings in various regions as soon as possible after an earthquake, this research employs the crowdsourcing technology to lever the smartphones in the buildings to estimate the fundamental natural frequency of the individual building to assist in disaster relief. This study uses the accelerometer embedded in the smartphones to measure acceleration response of the buildings during earthquake excitations, and uses Wi-Fi Direct technology to synchronize the acceleration data. After uploading it to the server and aligning the acceleration direction, the system identification method is used to obtain the fundamental natural frequency of the buildings. Two system identification methods are the output-only ones and the input-output ones. The output-only system identification methods including the Frequency Domain Decomposition (FDD) and Stochastic Subspace Identification (SSI) methods and the input-output ones including the Combined stochastic and deterministic Subspace Identification (CSI) and Frequency Response Function (FRF) methods are employed in this study. In case the ground motion is not available, only the output-only system identification methods can be used in system identification methods. However, according to the results of numerical simulations, even under ideal situation, i.e., time is synchronized, orientation aligned, and without noise, the estimated fundamental natural frequency using the output-only system identification methods is not reliable because they are affected by the characteristic of earthquake excitations. Therefore, an algorithm to identify the ground motion signals from the measured time history of different smartphones is proposed. Based on the assumption that the ground motion signals are available, the input-output system identification methods can be used. The results of numerical simulation indicate that whether time synchronization has a great influence on the CSI approach and whether orientation alignment has a great influence on the FRF approach. Shaking table tests of a four-story steel building were conducted to verify the proposed methods. The results show that the maximum frequency error and root-mean-square-error using CSI with time synchronization and without orientation alignment are 0.9% and 0.5% respectively, while the ones using FRF with time asynchronization and orientation alignment are 3.5% and 1.1% respectively. This trend is similar to the numerical simulation. Therefore, it is suggested to use CSI when time synchronization is valid, and use FRF instead when time synchronization is not available.

並列關鍵字

smartphone ； damage detection of buildings ； fundamental natural frequency ； crowd sourcing

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