Multiple localized force identification and response prediction on a footbridge

A model-based joint input-state estimation algorithm is used to obtain minimum-variance unbiased estimates of the states (modal displacements and velocities) of a structure, as well as the dynamic forces causing these responses. The estimation is performed based on a limited number of acceleration measurements. A distinction is made between two modes of application of the algorithm to problems in structural dynamics. In the first case, the states and input forces are jointly estimated by assuming the positions of the forces known. In the second case, the response in a structure at unmeasured locations is predicted by identifying the states and a set of equivalent forces, that would produce the same measured response, at arbitrarily chosen locations. Both modes of application are validated using data from an in situ experiment on a footbridge. Keywords—force identification, state estimation, response prediction