Determination of the Real Cracking Moment of Two Reinforced Concrete Beams through the Use of Embedded Fiber Optic Sensors

Abstract

This article investigates the possibility of applying weldable optic fiber sensors to the corrugated rebar in reinforced concrete structures to detect cracks and measure the deformation of the steel. Arrays have initially been designed comprised of two weldable optic fiber sensors, and one temperature sensor to compensate its effect in measuring deformations. A series of tests were performed on the structures to evaluate functioning of the sensors, and the results obtained from the deformation measures shown by the sensors have been stored using specific software. Two reinforced concrete beams simply resting on the support have been designed to perform the tests, and they have been monitored in the zones with maximum flexion moment. Different loading steps have been applied to the beams at the center of the span, using a loading cylinder, and the measurement of the load applied has been determined using a loading cell. The analysis of the deformation measurements of the corrugated rebar obtained by the optic fiber sensors has allowed us to determine the moment at which the concrete has cracked due to the effect of the loads applied and the deformation it has suffered by the effect of the different loading steps applied to the beams. This means that this method of measuring deformations in the corrugated rebar by weldable optic fiber sensors provides very precise results. Future lines of research will concentrate on determining an expression that indicates the real cracking moment of the concrete.

Application of Rotation Rate Sensors in Modal and Vibration Analyses of Reinforced Concrete Beams

“…For this purpose, full scale, 6-m long, ultra-high performance concrete (UHPC) beams were measured in intact and partly damaged states in laboratory conditions. The monitoring of vibrations of concrete and UHPC beams brings particular challenges to the field of SHM (see, e.g., [ 34 , 35 , 36 , 37 , 38 , 39 ]). For these reasons, the application of rotation rate sensors in the modal extraction and vibration analyses of these beams can bring particular advantages.…”

Three-Dimensional Frequency Selective Surface Displacement Sensor Using Complementary Dielectrics

“…FSS and meta-materials have been proposed for applications in strain [12], remote [13], chemical liquid [14], thin film [15], CO2 [16], bridge columns structural health monitoring [17] Biochemical [18] and corrosion [19] sensing. Displacement can be detected using a variety of sensors, the most common being based on resistive, capacitive, inductive, ultrasonic [20] and optical principles [21]. In the microwave spectrum, displacement sensors employing transmission line structures have been developed [22] - [24].…”

Surface Cracking and Fractal Characteristics of Cement Paste after Exposure to High Temperatures

“…Analysis of the development of surface cracks yields valuable insight; therefore, the accurate detection of cracks is important. At present, concrete crack detection methods can be divided into fiber grating network detection [14,15], ultrasonic detection [16,17], acoustic emission detection [18,19] and image detection [20][21][22][23][24]. Fiber grating network detection, ultrasonic detection, and acoustic emission detection are all forms of contact measurement, which requires one to install several sensors in advance in order to determine the parameters of cracks.…”