Investigating Damage in Reinforced Concrete Members by Using Vibrating Wire Strain Gauge

Abstract

Recently the use of vibrating wire strain gauges has increased to find out the damage in a reinforced concrete structure. The assembly and functioning of this acoustic strain gauge are presented. This gauge provides numerous benefits including its sensitivity to measure strain (up to 1micron) and its property of being easily attached on any concrete surface. The gauge apparatus can be made in a lab due to its low cost which gives it an edge over the conventional systems. The gauge was calibrated after considering the variations in temperature. The purpose of the experimentation was to set up a low-cost vibrating wire strain gauge, calibrate it and use it for static strain damage assessment of a reinforced concrete beam. The strain readings from the vibrating wire strain gauge were cross-checked using a Demec gauge. Discrete Fourier transforms moving window was utilised to analyse the vibration signals specifically the change in natural frequency with respect to time. The gauge setup provided a cheap and accurate way for measuring long-term static strain in reinforced concrete structures. The results are presented and reviewed.