Comparison of system identification methods using operational data of a bridge test

One of the aims of the BRITE-EURAM project SIMCES is the comparison, adaptation and application of system identification methods to civil engineering structures. Special attention is paid to techniques making use of operational data. In this paper the peak-picking method, the polyreference LSCE and the stochastic subspace identification method are studied and compared. The basic principles of all three methods are briefly reviewed and the practical aspects of their application to bridge vibration data is discussed. The paper shows how the modal parameters can be extracted for increasing model orders and plotted in so-called stabilisation diagrams. These diagrams aid the engineer to find the correct model order and to distinguish the spurious modes from the true system modes, which is often a difficult task for the simple peak-picking method.