Estimation of nonlinearities from pseudodynamic and dynamic responses of bridge structures using the Delay Vector Variance method

• First application of a Delay Vector Variance (DVV) based nonlinearity estimation of full scale experiments on large structures.
• First application of DVV based comparison of sensors measuring dynamic responses of full scale large structures.
• Comprehensive study on pseudo-dynamic and dynamic responses.
• Demonstration of comparing dynamic systems using estimated nonlinearity as a measure.
• Establishing the potential of DVV in monitoring and quantitatively comparing events from output-only conditions.

Analysis of the variability in the responses of large structural systems and quantification of their linearity or nonlinearity as a potential non-invasive means of structural system assessment from output-only condition remains a challenging problem. In this study, the Delay Vector Variance (DVV) method is used for full scale testing of both pseudo-dynamic and dynamic responses of two bridges, in order to study the degree of nonlinearity of their measured response signals. The DVV detects the presence of determinism and nonlinearity in a time series and is based upon the examination of local predictability of a signal. The pseudo-dynamic data is obtained from a concrete bridge during repair while the dynamic data is obtained from a steel railway bridge traversed by a train. We show that DVV is promising as a marker in establishing the degree to which a change in the signal nonlinearity reflects the change in the real behaviour of a structure. It is also useful in establishing the sensitivity of instruments or sensors deployed to monitor such changes.