On-line computation of dynamic displacements from measured strains through mode superposition

초록

A simple algorithm is proposed for computing dynamic displacements from measured strain data. The algorithm can be applied to any beam-type structure including a plate-girder bridge and a long span suspension or cable-stayed bridge. Modal superposition using generalized coordinates are applied to relate the curvature and displacement based on the beam theory. Theoretical mode shapes of some low modes of a simply supported beam are used for the modal superposition instead of using mode shapes extracted from measured response. The proposed algorithm can be directly applied to the field measurement without any additional post signal processing. Through numerical studies, errors in the mode shapes related to the discrepancy in the boundary condition have been examined. The proposed algorithm has been applied to laboratory and also field data successfully.