Natural Frequency Response Evaluation for RC Beams Affected by Steel Corrosion Using Acceleration Sensors

Abstract

This paper presented a laboratory investigation for analyzing the natural frequency response of reinforced concrete (RC) beams affected by steel corrosion. The electrochemical acceleration technique induced the corroded RC beams until the predetermined value of the steel corrosion ratio was achieved. Then, the natural frequency responses of the corroded beams were tested utilizing piezoelectric acceleration sensors. The damage states of the corroded beams were assessed through the measurement of crack parameters and the equivalent elastic modulus of the beams, which aims to clarify the fundamental characteristics of the dynamic response for the corroded RC beam with the increased steel corrosion ratio. The results revealed that steel corrosion reduces the bending stiffness of the RC beams and, thus, reduces the modal frequency. The variation of natural frequency can identify the corrosion damage even if no surface cracking of the RC beam, and the second-order frequency should be more indicative of the damage scenario. The degradations of stiffness and the natural frequency were estimated in this study by the free vibration equation of a simply supported beam, and a prediction method for the RC beam’s residual service life was established. This study supports the use of variations in natural frequency as one diagnostic indicator to evaluate the health of RC bridge structures.

Damage Assessment of Reinforced Concrete Elements Due to Corrosion Effect Using Dynamic Parameters: A Review

“…Furthermore, the second-order frequency should be more indicative of the damage scenario. Also, the trend of the natural frequency values was consistent with the trend observed in the calculated equivalent elastic modulus values [60].…”

“…The results of the study [60] show that the variation of natural frequency could identify the corrosion damage of the steel bar even without surface cracking of the RC beam. Furthermore, the second-order frequency should be more indicative of the damage scenario.…”

“…Y. Zhang et al [60] presented laboratory research for analyzing the natural frequency response of the two RC beams with dimensions of 2000 mm × 150 mm × 50 mm affected by steel corrosion. After the accelerated steel corrosion test, the natural frequency, cracking area, and equivalent elastic modulus of the test beams were measured [60].…”

“…Changing the natural frequency [10,[50][51][52][53][54][55][56][57][58][59][60] Change in damping coefficient [51][52][53]55,56] Changing modal shapes [52] By applying deviation of basic dynamic parameters…”

A Review of the Vibration Analysis Methods for Frame Structures

“…Finite element method was used to analyze the frames with results showing that natural frequency saw the biggest drop when cracks were located near the nodal connections. The effects of corrosion on the dynamic response of reinforced concrete (RC) beams were investigated by [83]. Experimental results showed that stiffness and natural frequencies decreased.…”