38. bridge scour monitoring using buried, passive, piezoelectric sensors

Department: Structural Engineering
Research Institute Affiliation: Center for Extreme Events Research
Faculty Advisor(s): Kenneth J. Loh

Primary Student
Name: Morgan Leigh Funderburk
Email: mfunderb@ucsd.edu
Phone: 214-236-0814
Grad Year: 2021

Abstract
When bridge piers are built over flowing water, they disturb the smooth fluid flow that is typically seen in a stable riverbed. The resulting disturbances, amplified near the offending pier, cause localized erosion of directly surrounding sediments. This erosion, known as local scour, occurs when a downward flow is induced on the upstream face of the bridge pier and is further exacerbated by vortices formed after an initial hole develops. In the United States, local scour damage is arguably the most pressing issue regarding the safety and longevity of the bridge infrastructure. The goal of this project is the development of a buried or driven piezoelectric rod for the detection of local scour effects. The system uses sensors made of plastic rods outfitted with a piezoelectric sensor spanning the length of the rod. Due to the piezoelectric effect, ambient excitation allows for passive data collation. The sensor is then driven or buried into sediment vertically to produce a cantilever when exposed. As sediment is eroded from around the sensor, the exposed length increases causing a drop in natural frequency. Frequency analysis is performed on the cantilever to determine exposed length. The deployment of multiple rods in tandem produces a data set from which a topographical map of sediment depth can be produced. Recent developments in piezoelectric sensor technology are presented. These developments include lengthening and validation of sensors made from commercially available polyvinylidene fluoride (PVDF) sheets and material testing of screen-printed lead zirconate titanate (PZT) ceramic. Furthermore, experimental results show mapping of multiple sensors deployed around a mock bridge pier to validate a driven-rod system with real-time data monitoring.

Industry Application Area(s)
Civil/Structural Engineering | Materials

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