Corrosion monitoring of flexural reinforced concrete members under service loads using distributed long-gauge carbon fiber sensors

Abstract

Currently, corrosion of steel reinforcements is a major topic for several researchers because of the early deterioration and shortening of the service life of structures, particularly those prone to salt attacks. This study proposes a new technique for monitoring corrosion of steel reinforcements in flexural reinforced concrete structures using distributed embedded long-gauge packaged carbon fiber line sensors with self-compensation under service loads. Three different approaches including continuous-strain ratio, distributed-strain ratio, and section fiber model were proposed to evaluate corrosion levels using strain measurements. Different groups of distributed packaged carbon fiber line sensors were installed on the concrete surface and steel reinforcements of the reinforced concrete beam to verify the proposed approaches experimentally using the accelerated corrosion technique. The sensors installed on the concrete surface affected by cracks can only localize the corrosion locations but are unable to determine the actual values of corrosion levels. The degree of corrosion calculated using each approach was compared with the weight loss of an experimental corrosion model. The results showed that the continuous-strain ratio approach will be suitable to localize and evaluate the corrosion degrees if corrosion occurs before the formation of cracks, while the distributed-strain ratio is more effective in the presence of cracks. In highly damaged conditions, the section fiber model will be the most accurate method to evaluate and localize corrosion in steel reinforcements.

Application of a Novel Long-Gauge Fiber Bragg Grating Sensor for Corrosion Detection via a Two-level Strategy

“…(1) The traditional point strain sensors are unsuitable for large-scale civil engineering because they cannot successfully detect unforeseen corrosion with a short gauge length (around 1–2 cm), unless the sensors are installed in the corrosion domain [ 16 ]. Also, as a point sensor, corrosion rust can affect the fixation point [ 17 ]. (2) As a kind of structural damage, it has been found that the level of steel corrosion at the early stages of corrosion can be indicated by using a measure of the stiffness [ 18 ].…”

Advances of Area-Wise Distributed Monitoring Using Long Gauge Sensing Techniques

“…This method uses distributed embedded long-gauge packaged carbon fiber line (PCFL) sensors to realize self-compensation under working load. Two different methods of continuous-strain ratio (CSR) and distributed-strain ratio (DSR) are used to evaluate the corrosion levels [ 67 ].…”

“… ( a ) A comparison of average crack width between long gauge FBG [ 37 ]; ( b ) Corrosion levels along the length of the beam based on CSR [ 67 ]. …”

Bolt-looseness detection by a new percussion-based method using multifractal analysis and gradient boosting decision tree

“…8 Therefore, to prevent accidents caused by bolt loosening in a timely manner, some conventional methods were developed in industries, including the human vision, strain gauges, and the vibration-based methods. 9 Then, with the rapid development of smart materials, particularly the piezoelectric materials, 10–12 several attractive structural health monitoring (SHM) approaches 13–15 have been proposed, for example, the electromechanical impedance (EMI) methods 16,17 and the acousto-ultrasonic methods. 18–20 Compared to the EMI method that is very sensitive to surroundings, 21,22 the active sensing method, 23,24 which is based on linear acousto-ultrasonic features, and nonlinear acousto-ultrasonic approaches (including the sub-harmonic method, 25 higher-order harmonic method, 26,27 and the vibro-acoustic modulation method) 28 have better performance in detecting bolt looseness.…”