An Indirect Method for Monitoring Dynamic Deflection of Beam-Like Structures Based on Strain Responses

Wan Hong,Xuan Fang,Kui Lv,Zheng Qin

doi:10.3390/app8050811

Abstract

An indirect method for monitoring dynamic deflection of beam-like structures using strain responses measured by long-gauge fiber Bragg grating (FBG) sensors is proposed in this paper. Firstly, a theoretical derivation shows that structural deflection is in direct and linear relationship to long-gauge strain. Meanwhile, the method is suitable for structures with different boundary conditions and irrelevant to external loads. Secondly, the influence of boundary conditions, load type and sensor gauge length on the method is investigated by numerical simulation. Finally, an experiment of a simply supported beam subjected to dynamic loads was designed to verify the method. Experimental results show that both deflection time-history of arbitrary points of structures and deflection distribution along structures at a certain time can be obtained with high-precision. Therefore, the method presented can be a new alternative for the deflection evaluation and maintenance of engineering structures.

Highlights

IntroductionThe ability to extract key parameters of existing structures using smart sensors attracted growing attention in past decades due to these parameters accurately reflecting structural in-service conditions
The ability to extract key parameters of existing structures using smart sensors attracted growing attention in past decades due to these parameters accurately reflecting structural in-service conditions.Such information is vital for decision-making in terms of maintenance and retrofitting
The objective of this paper is to develop an improved moment-area method for the deflection estimation of engineering structures

Summary

Introduction

The ability to extract key parameters of existing structures using smart sensors attracted growing attention in past decades due to these parameters accurately reflecting structural in-service conditions. Such information is vital for decision-making in terms of maintenance and retrofitting. Among these performance parameters, deflection is a commonly used index. Basalt fiber-packaged FBG sensors are utilized in the experiment. The plastic separation tube outside the bare FBG makes sure the average strain between two anchoring points can be measured, and the length of the separation tube indicates the sensing length. Detailed sensing properties about this kind of sensor can be found in [26]

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Conclusion