Extraction of bridge modal parameters using a moving instrumented vehicle by SSI technique

![CDATA[Research on indirect bridge structural identification from the dynamic response of a moving instrumented vehicle has been very attractive in recent years. Unlike conventional bridge structural health monitoring methods that many sensors are installed directly on a bridge to obtain structural dynamic responses, the indirect bridge monitoring utilises an instrumented vehicle to capture the bridge dynamic information during its moving over the bridge. The bridge response often exhibits an inherent randomness due to the road surface roughness as well as the traffic excitation. It is suggested stochastic analysis should be performed. In this paper, the stochastic subspace identification (SSI) method is used for the structural dynamic parameter identification from the vehicle dynamic response only. To reduce the blurring effect of road surface roughness on the indirect structural model identification, two connected identical vehicles are adopted. The white noise support excitation is added to briefly simulate the traffic excitation to the bridge. Cases studies show that the improved SSI using the subtraction residual of the two connected vehicles' responses is very effective. The bridge frequencies can be successfully identified from dynamic responses of the instrumented vehicles.]]