Design of flexible sensor for wind pressure monitoring of stay cables

Abstract

Strong winds can make a bridge’s cable-stayed cables produce violent vibrations, leading to fatigue of the cable-stayed cables and damaging the cable-stayed bridge’s structure. Accurately and effectively obtaining data on the wind loads applied to the cable-stayed cables is important for assessing the cable-stayed cables’ health. Currently, the more widely used sensing elements include diffuse silicon piezoresistive sensors and strain gauges. However, most of them present such disadvantages as rigidity, difficult to fit the curved surface, high cost and low sensitivity. In this paper, a conductive hydrogel flexible pressure sensor based on TA/CB@PDMS was developed, using carbon black (CB) as the main conductive medium, with good electrical conductivity, high sensitivity (0.95 kPa-1) and excellent tensile properties (210% tensile breakage). Meanwhile, a salt permeation method(Soak the sensor in LiBr solution) was used to effectively inhibit the sensor's water from being evaporated and frozen. Its substrate incorporates tannic acid (TA) to increase the sensor’s adhesion so that it adheres well to the diagonal cable’s surface. In this paper, the wind speed variation around the diagonal cable and the force distribution on the surface with considering the fluid-structure coupling effect are analyzed by ANSYS WORKBECH finite element simulation. Wind tunnel experiments simulate the sensor’s force response when the inclined cable is subjected to different wind speeds, and the detection accuracy reaches 96.17%. The results show the sensor developed in this paper can realize accurate wind pressure detection of the inclined cable. This study provides a new method for wind pressure detection and health inspection of diagonal cables.