Fusion of GNSS and Speedometer Based on VMD and Its Application in Bridge Deformation Monitoring Realtime dynamic displacement and spectral response on the midspan of Jiangyin Bridge were calculated using Global Navigation Satellite System (GNSS) and a speedometer for the purpose of understanding the dynamic behavior and the temporal evolution of the bridge structure. Considering that the GNSS measurement noise is large and the velocityacceleration sensors cannot measure the lowfrequency displacement, the Variational Mode Decomposition (VMD) algorithm was used to extract the lowfrequency displacement of GNSS. Then, the lowfrequency displacement extracted from the GNSS time series and the highfrequency vibration calculated by speedometer were combined in this paper in order to obtain the high precision threedimensional dynamic displacement of the bridge in real time. Simulation experiment and measured data show that the VMD algorithm could effectively resist the modal aliasing caused by noise and discontinuous signals compared with the commonly used Empirical Mode Decomposition (EMD) algorithm, which is guaranteed to get highprecision fusion data. Finally, the fused displacement results can identify highfrequency vibrations and lowfrequency displacements of a mm level, which can be used to calculate the spectral characteristics of the bridge and provide reference to evaluate the dynamic and static loads, and the health status of the bridge in the full frequency domain and the full time domain.

Bridge Damage Identification Using Vehicle Bump Based on Additional Virtual Masses Structural damage identification plays an important role in providing effective evidence for the health monitoring of bridges in service. Due to the limitations of measurement points and lack of valid structural response data, the accurate identification of structural damage, especially for largescale structures, remains difficult. Based on additional virtual mass, this paper presents a damage identification method for bridges using a vehicle bump as the excitation. First, general equations of virtual modifications, including virtual mass, stiffness, and damping, are derived. A theoretical method for damage identification, which is based on additional virtual mass, is formulated. The vehicle bump is analyzed, and the bumpinduced excitation is estimated via a detailed analysis in four periods: separation, freefall, contact, and coupled vibrations. The precise estimation of bumpinduced excitation is then applied to a bridge. This allows the additional virtual mass method to be used, which requires knowledge of the excitations and acceleration responses in order to construct the frequency responses of a virtual structure with an additional virtual mass. Via this method, a virtual mass with substantially more weight than a typical vehicle is added to the bridge, which provides a sufficient amount of modal information for accurate damage identification while avoiding the bridge overloading problem. A numerical example of a twospan continuous beam is used to verify the proposed method, where the damage can be identified even with 15% Gaussian random noise pollution using a 1degree of freedom (DOF) car model and 4DOF model.