On the Contribution of Experimental Data to the Reduction of the Uncertainty of Fragility Curves

Ambient vibrations in buildings is of increasing interest for applications in mechanical engineering, civil engineering and earthquake engineering. For example, elastic fundamental frequency and damping ratio are two key-parameters for simplified seismic design and vulnerability assessment methods. Empirical relationships exist in codes to estimate this frequency and damping but experimental data could be used to improve them, accounting for national features of building design and, above all, the corresponding uncertainties. With advances in data acquisition systems (the number of measurement points, continuous recording, low-noise instruments) and advances in signal processing algorithms, further and better studies can be conducted on civil engineering structures for evaluating their modal parameters and their physical properties, with a high level of confidence. Moreover, permanent instrumentations also provide earthquake data helping in the improvement of the building response in case of a severe event. The aim of this paper is to show how the experimental data, providing from temporary or permanent instrumentation, can be used for adjusting behaviour models for each class of structure for vulnerability assessment, for monitoring the wandering effect of the elastic parameters on the fragility curves and their uncertainties.