Monitoring Strategic Hydraulic Infrastructures by Brillouin Distributed Fiber Optic Sensors

Manuel Bertulessi,Jacopo Morosi,Ilaria Boschini,Maddalena Ferrario,Federica Zambrini,Giovanni Menduni,Marco Brunero,Daniele Fabrizio Bignami,Egon Joseph Paganone

doi:10.3390/w14020188

Manuel Bertulessi, Jacopo Morosi + Show 7 more

Open Access

https://doi.org/10.3390/w14020188

Copy DOI

Journal: Water	Publication Date: Jan 10, 2022
Citations: 4	License type: CC BY 4.0

Affiliation: Politecnico di Milano, Fondazione Politecnico di Milano

Abstract

We present a case study of a Structural Health Monitoring (SHM) hybrid system based on Brillouin Distributed Fiber Optic Sensors (D-FOS), Vibrating Wire (VW) extensometers and temperature probes for an existing historical water penstock bridge positioned in a mountain valley in Valle d’Aosta Region, Northwestern Italy. We assessed Brillouin D-FOS performances for this kind of infrastructure, characterized by a complex structural layout and located in a harsh environment. A comparison with the more traditional strain monitoring technology offered by VW strain gauges was performed. The D-FOS strain cable has been bonded to the concrete members using a polyurethane-base adhesive, ensuring a rigid strain transfer. The raw data from all sensors are interpolated on a unique general timestamp with hourly resolution. Strain data from D-FOS and VW strain gauges are then corrected from temperature effects and compared. Considering the inherent differences between the two monitoring technologies, results show a good overall matching between strain time series collected by D-FOS and VW sensors. Brillouin D-FOS proves to be a good solution in terms of performance and economic investment for SHM systems on complex infrastructures such as hydropower plants, which involve extensive geometry combined with the need for detailed and continuous strain monitoring.

Highlights

Introduction published maps and institutional affilStructural Health Monitoring (SHM) is nowadays a general term used to describe a process of in-service damage identification and health evaluation for an engineering structure through an automated monitoring system [1]
The Distributed Fiber Optic Sensors (D-FOS) loops, connected in series, can be distinguished: the sharper parts correspond with the strain cable, whereas the flatter ones are produced by the temperature cables
The strain cable pattern is produced by the cable installation layout: positions in which ∆Brillouin Frequency Shift (BFS) is not null correspond to the cable portions bonded to concrete members, whereas positions where ∆BFS is almost zero are transition sections between two sensorized members in which the cable is not bonded

Summary

Introduction

Structural Health Monitoring (SHM) is nowadays a general term used to describe a process of in-service damage identification and health evaluation for an engineering structure through an automated monitoring system [1]. Its purpose is to assist and continuously inform operators about the structures’ health under gradual or sudden changes to their state and learn about the related response mechanisms [2]. An SHM system generally includes sensors, data transmission, processing and management systems and health evaluation algorithms [3]. Applying the SHM concept, it is possible to continuously check the serviceability status of a structure or infrastructure, create an early-warning system in case of exceeding specific thresholds, and schedule maintenance cycles more efficiently [4]. SHM offers a strategic tool for monitoring the aging of the structures and infrastructures network, fundamental assets for a nation’s economy.

Objectives

Methods

Results

Conclusion