Bridge Foundation Stiffness Identification

There are great economic incentives motivating the reuse of existing foundations when deteriorated and damaged superstructures are replaced. The increasing reuse of existing bridge foundations warrants investigation into verifying foundation performance and condition of in service bridge foundations. A method is proposed which characterizes the load-response behavior of existing bridge foundations during daily vehicular loading without impeding traffic. It uses a limited number of substructure response measurements from an in service bridge taken during daily traffic heavy truck loadings. The results from this method can be used to verify the vertical, horizontal and rotational load-deformation behavior during daily loadings. Potential applications for the results obtained through this approach are: the detection of structural damage, identification of scour, identification of unknown foundations, and validation the load-deformation behavior predicted by finite element analysis. While loading during the tests would be limited to the magnitude which is caused by daily truck passage, the behavior observed from this loading can be used to update the parameters governing soil behavior which will lead to an improved assessment of the foundation behavior during failure loading or extreme events. A preliminary study is presented as a feasibly study for future use of the proposed method for bridge foundation stiffness identification using substructure measurements.