Crack sensor with embedded optical fibre : Sustainable Bridges. Background document 5.3

Abstract

This document reports the development of a distributed optical fibre crack sensor. This sensor can be employed for detection of cracks and measurement of crack widths in concrete structures. The basic principle of operation for the crack sensor is based on intensity variation of the optical power within the optical fibre due to the initiation and opening of cracks. The present report summarizes the improvements introduced in the sensor to make it appropriate for crack monitoring in bridges, performed by researchers of the University of Minho, in Portugal. The primary objectives of the work were: 1) To select the proper polymeric material for making the plate; 2) To optimize the manufacture process; 3) To assure the bonding between the plate sensor and concrete members; 4) To determine the corresponding calibration curves of intensity losses versus the crack aperture; 5) The application of the plate sensor to the monitoring of single crack RC beams and masonry slabs and the monitoring of multiple cracks on RC beams; 6) The field implementation of the plate sensor. The field implementation of the plate sensor in the destructive test carried out in the ÖvikBridge, in the north of Sweden, is also included. The main purpose of this test was to demonstratethe capability of the sensor plate to detect cracks and measure the crack opening in concrete railway bridges. This report provides the description of the bridge and gives an overview of the procedures for wiring and installing the sensor plate.EC FP6, Sixth Framework ProgramSustainable Bridges – Assessment for Future Traffic Demands and Longer LivesTIP3-CT-2003-001653</p