  Large-scale seismic vulnerability assessment methods use simplified formulas
and curves, often without providing uncertainties. They are seldom compared to
experimental data. Therefore, we recorded ambient vibrations and estimated
modal parameters (resonance frequencies, modal shapes and damping) of 60
buildings in Grenoble (France) of various types (masonry and reinforced
concrete). The knowledge of resonance frequencies in the linear domain is
essential in the seismic design. Hence, we compared resonance frequency
formulas given in the design code with this experimental data. The variability
is underestimated and only two parameters (type and height of the building)
seem to be statistically significant. Moreover, we compared the linear part of
capacity curves used in European Risk-UE method to the measured frequencies.
The variability is still very large and these curve are often not relevant for
the French buildings. As a result, ambient vibration recordings may become an
interesting tool in order to calibrate the linear part of capacity curves.
