結合振形之微振索力估算法中量測點位配置對精度的影響

Effect of sensor deploymentonen on the accuracy of ambient vibration method incorporating mode shape functions for cable tension estimation

10.6849/SE.202009_35(3).0005

陳建州(Chien-Chou Chen)；吳文華(Wen-Hwa Wu)；陳欣怡(Shin-Yi Chen)；賴國龍(Gwolong Lai)

微振法 ； 索力估算 ； 振形 ； 有效振動長度 ； 多點同步量測 ； 量測點位配置 ； ambient vibration method ； cable tension estimation ； mode shape ； effective vibration length ； multiple synchronous measurements ； sensor deployment

結構工程

35卷3期（2020 / 09 / 01）

99 - 117

繁體中文

為克服複雜錨定條件造成微振索力估算法的較大誤差問題，本研究團隊近年來提出一項創新的方法，藉由導入振形函數正弦分量的擬合來決定各振態有效振動長度以排除索力計算公式中複雜邊界條件的影響，而其關鍵則在如何經由多點同步量測精準重現振形函數之正弦分量。本文首先根據理論推導出的頻率方程式與振形函數闡述此一索力量測方法的基本原理；接著再進一步利用有限元素模型，於考慮實測作業限制條件下建立包括數目與間距等量測點位配置準則；最後則進行實驗室單根鋼絞線索力量測，充分驗證所擬定量測點位配置準則的適用性以及對應的索力估算精度。

The complicated boundary conditions resulted from the anchorage systems at both ends usually deteriorate the accuracy of the ambient method for cable tension estimation. Motivated by tackling such a problem, a novel method incorporating the mode shape functions was recently proposed by this research group. More specifically, the fitting for the sinusoidal components of mode shape functions was adopted to determine the effective vibration length for each mode such that the interference from the complicated boundary conditions can be eliminated. The success of this method is most critically decided by the accurate reproduction of the sinusoidal components of mode shape functions based on multiple synchronous measurements. The current paper first explains the basic concepts of this cable tension estimation method with the theoretically derived mode shape functions and frequency equations. The finite element models are further employed to evaluate the accuracy of this method and establish the guidelines for the preferred sensor deployment in measurement points and spacing with the consideration of practical measurement limitations. Finally, the applicability of the developed guidelines and the corresponding accuracy in tension estimation are verified by demonstrative laboratory experiments with a prestressed strand.

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