The installation of embedded ultrasonic transducers inside a bridge to monitor temperature and load influence using coda wave interferometry technique

Abstract

This article presents a unique method of installing a special type of embedded ultrasonic transducers inside a 36-m-long section of an old bridge in Germany. A small-scale load test was carried out by a 16 ton truck to study the temperature and load influence on the bridge, as well as the performance of the embedded transducers. Ultrasonic coda wave interferometry technique, which has high sensitivity in detecting subtle changes in a heterogeneous medium, was used for the data evaluation and interpretation. The separation of two main influence factors (load effect and temperature variation) is studied, and future applications of wave velocity variation rate [Formula: see text] for structural health condition estimation are discussed. As a preliminary research stage, the installation method and the performance of the ultrasonic transducer are recognized. Load- and temperature-induced weak wave velocity variations are successfully detected with a high resolution of 10−4%. The feasibility of the whole system for long-term structural health monitoring is considered, and further research is planned.

Feasibility of Using Shear Wave Ultrasonic Probes as Pump-Wave Sources in Concrete Microcrack Detection and Monitoring by Nonlinear Ultrasonic Coda Wave Interferometry

“…The development of these parametric experimental studies in conjunction with an appropriate simulation of nonlinear elastic behavior induced by the pump-source may help to design strategies for the selection and placement of pump-wave sources to improve the performance of the NCWI technique. These strategies may be tested in structural concrete under more realistic conditions by using embedded ultrasound transducers [ 17 , 18 , 19 , 20 ]. We believe that all of these studies may help to improve the performance of the NCWI technique and also to study the dynamical processes behind the microcrack growth and further large crack formation.…”

“…While extensive research on the optimisation of the CWI technique has been performed (for example, thermal bias control technique [ 8 , 9 , 10 ], small damage localisation [ 11 ], selection of frequency range [ 12 ], use of continuous wave excitation [ 16 ], use of embedded ultrasonic sensors to apply the CWI technique to concrete structures under operational conditions [ 17 , 18 , 19 , 20 ], and simulation studies by numerical approaches as the discrete element method [ 21 ]), only limited studies on the optimization of nonlinear modulation processes have been performed to date [ 22 , 23 , 24 ]. These studies have been focused mainly on the influence of the pump-wave emitter position, temperature variation and combining the NCWI technique with the well-know time-reversal method.…”

“…These improvements may be relevant for the inspection of microcracking evolution in concrete structures under operational conditions and for the assessment of their structural integrity, where the structure size and a specific loading condition can limit the performance of the NCWI technique. Here, a strategic selection (between longitudinal, shear-wave or dual-mode ultrasonic probes) and placement of pump-wave sources may be used during the embedding process of ultrasonic sensors within the concrete as the CWI studies described before [ 18 , 19 , 20 ].…”

A novel method for steel bar all-stage pitting corrosion monitoring using the feature-level fusion of ultrasonic direct waves and coda waves

“…Recently, many pioneering studies have been conducted using code waves in condition monitoring of composite structures, 30 steel structures, 31 and concrete structures. [32][33][34] In terms of steel bars, ultrasonic waves will be reflected back and forth after pulse excitation is applied at one end of the reinforcement, which allows the generation of coda-like waveforms inside the rebar. Longdistance propagation and multiple interactions with perturbations result in weak changes can be perceived by coda waves.…”

“…Recently, many pioneering studies have been conducted using code waves in condition monitoring of composite structures, 30 steel structures, 31 and concrete structures. 32-34…”