Reference based stochastic subspace identification in civil engineering

A specific strategy is required when performing vibration tests on civil engineering structures. The use of artificial excitation sources such as shakers or drop weights is often unpractical and expensive. Ambient excitation on the contrary is freely available (traffic, wind), but it causes other challenges. The ambient input remains unknown and the system identification algorithms have to deal with output-only measurements. Also typical for vibration testing of large structures is that not all degrees of freedom can be measured at once but that they are divided in several setups with overlapping reference sensors. These reference sensors are needed to obtain global mode shapes. In this paper a novel approach of stochastic subspace identification is presented that incorporates the idea of the reference sensors already in the identification step. The algorithm is validated with an extensive Monte-Carlo simulation study and two real-life examples.