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

Yuwei Zhang,Guojin Tan,Yongchun Cheng,Xiang Lyu,Shuting Yang,Yunshuo Bai,Xun Sun

doi:10.3390/s20185335

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.

Highlights

The existing reinforced concrete (RC) structures need regular maintenance during the in-service period, even so, most of the RC structures do not reach their design life
Flexural stiffness is an index that determines the maximum bearing capacity of an RC beam, and this paper aims to study the effect of steel corrosion on the equivalent flexural elastic modulus of the beam
Effect of Steel Corrosion on the Natural Frequency Response of RC Beams can be obtained by reading the value of the dial gauge before and after exerting the constant load

Summary

Introduction

The existing reinforced concrete (RC) structures need regular maintenance during the in-service period, even so, most of the RC structures do not reach their design life. The method for corrosion assessment of steel bars embedded in the RC structure is destructive (such as the steel mass loss measurement after core sampling [6,7]), which is harmful and uneconomical to the RC structures [8,9]. This problem motivated the interest in utilizing nondestructive techniques for structural health monitoring; and the main purpose of structural health monitoring is to detect structural damage and reduce the risk of structural failure which may lead to casualties and property losses. Using piezoelectric acceleration sensors for structural damage identification has become a popular technology for monitoring the health status and the quality acceptance of RC constructions [12]

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