Identification and uncertainty quantification of structural flexibility for reliability analysis

Abstract

In recent years, research on the effect of uncertainty on the results of structural system identification in order to effectively enhance structural safety has been rarely conducted. This paper studies identification and uncertainty quantification of structural flexibility from ambient vibration measurements to develop an efficient reliability analysis. The structural deflection with a confidence interval can be predicted under static loads via the uncertainty quantification on structural flexibility, and can then be used for the reliability analysis of the deflection serviceability limit state. First, the evaluation method for the uncertainty bounds of the modal parameters by a first-order perturbation analysis is reviewed. Then, the perturbation analysis method is extended to structural flexibility identification with considering the uncertainty in the identified modal parameters and the uncertainty in the reduced mass matrix. In addition, the structural deflection and its confidence interval under static load can be simultaneously derived with the identified structural flexibility. Eventually, by combining fuzzy criteria with the confidence intervals of the deflection prediction under the ultimate design load, the reliability index of the deflection serviceability limit state can be formulated. Both numerical and experimental examples were conducted to verify the efficiency of the proposed method. This study provides a scheme to directly link the structural identification with the structural safety evaluation.