The role of uncertainty in evaluating condition and vulnerability of constructed systems

Abstract

Condition evaluation of large constructed structures has been widely researched over the last decade. In numerous studies dynamic testing has been used as the primary experimentation tool for measuring the dynamic characteristics and extracting various proposed indicators of structural condition. Despite these efforts, dynamic testing of constructed systems has not yet evolved to a point that it can be standardized as a tool for condition evaluation. Writers believe that two major sources of uncertainty in dynamic test based condition evaluation are the reasons for the gap between concepts and meaningful real-life applications. Most dynamic test methods are built on principles of observability, linearity and stationarity. The first major source of uncertainty is due to constructed systems and their loading environments’ inherent complexity leading to limitations in the application of the above tenets. The second category of uncertainty is related to the experiment, i.e. sensing, data acquisition, processing and analysis for different dynamic test methods. Ambient vibration (i.e. operational modal analysis) and impact testing are two different tools aiming to identify same parameters. Comparative evaluation of different test methods at the presence of different levels of uncertainty will enable us to assess the reliability of dynamic testing tools for condition evaluation. Writers designed a set of experiments on a laboratory physical model to investigate the effects of these two groups of uncertainties on modal parameter identification. Results will be discussed along with mitigation measures of uncertainties in dynamic testing of constructed systems.