This article presents a damage detection method for prestressed reinforced concrete (PRC) elements based on free vibration tests and nonlinear damping identification. Integrated static and dynamic experiments were carried out on three precast PRC beam specimens. The static loading induced different levels of damage to the beams. At each damage level, impulsive loading was applied to the beams a...

To experimentally identify the dynamic characteristics of a structure, also referred to as system identification, two methods are available: Forced Vibration Testing (FVT) and Ambient Vibration Testing (AVT). The basic ideas of these methods are shortly presented. The main part of the paper deals with practical problems which are to be overcome when performing such a system identification test....

A versatile vibration energy harvesting platform based on a triboelectricity is proposed and analyzed. External mechanical vibration repeats an oscillating motion of a polymer-coated metal oscillator floating inside a surrounding tube. Continuous sidewall friction at the contact interface of the oscillator induces current between the inner oscillator electrode and the outer tube electrode to co...

I recall someone once saying to me that “perception is reality.” But say this to scientists or engineers who need to take experimental data at midnight because their lab equipment is sensitive to even the minutest vibration and they may tell you otherwise. The reality is that imperceptible vibrations can and do impact sensitive experiments, and identifying the sources and selecting the proper e...

Reliability when applied to engineering devices or systems is defined as ‘the probability that the system will operate to an agreed level of performance for a specified period, subject to specified environmental conditions’. Thus the reliability of a small computer might be given as 80% over a 200hr period, with an ambient temperature off 25degree C and no vibration. It is important that the en...

Advances in mechatronics have renewed interest in the harvesting and storage of ambient vibration energy. This work documents recent efforts to model a novel electromagnetic transducer design that is intended for use in energy harvesting. The thesis details methods of experimental characterization as well as model validation. Also presented are methods of state space and parametric modelling ef...

The vibration data obtained from ambient, drop-weight, and shaker excitation tests of the Z24 Bridge in Switzerland are analyzed to extract modal parameters such as natural frequencies, damping ratios, and mode shapes. System identification techniques including Frequency Domain Decomposition and Eigensystem Realization Algorithm are employed for the extraction of modal parameters and the statio...

The objective of this chapter is to examine and obtain a better understanding of practical issues that are a result of monitoring the health of structures in an uncontrolled field environment. The effects of external boundary and environmental condition changes and other structural variations on the impedance-based health monitoring technique are investigated. Examples of the factors that consi...

In Operational Modal Analysis, the modal parameters (natural frequencies, damping ratios and mode shapes), obtained from Stochastic Subspace Identification of structures, are subject to statistical uncertainty from ambient vibration measurements. It is hence neccessary to evaluate the confidence intervals of these obtained results. This paper will propose an algorithm that can efficiently estim...