Average acceleration discrete algorithm for force identification in state space

A discrete force identification method based on average acceleration discrete algorithm is proposed in this paper. The method is formulated in state space and the external excitation acting on a structure is estimated with regularization method. A three-dimensional three-storey frame structure subject to an impact force and random excitations is studied respectively with numerical simulations. Uncertainties such as measurement noise, model error and unexpected environmental disturbances are included in the investigation of the accuracy and robustness of the proposed method. Experimental results from a seven-storey planar frame structure in laboratory are also used for the validation. The above results are also compared with those from two existing force identification methods, which are based on the Zeroth-Order-Hold (ZOH) discrete algorithm and the First-Order-Hold (FOH) discrete algorithm. Model of a fourteen-storey concrete shear wall building is studied experimentally with shaking table tests to further validate the proposed method. The shear wall structure has a two-storey steel frame on top with base isolation. The interface force in the isolation at the bottom of the steel frame during the seismic excitation is estimated with the proposed force identification method. Results from both numerical simulations and laboratory tests indicate that the proposed method can be used to identify external excitations and interface forces effectively based on the structural acceleration responses from only a few accelerometers with accurate results. The proposed method is capable to identify the dynamic load fairly accurately with measurement noise, model error and environmental disturbances. (C) 2013 Elsevier Ltd. All rights reserved.