Input force identification: Application to soil–pile interaction

An identification method for estimating the time varying excitation force acting on a structural system based on its response measurements is presented in this study. The method employs the simple Kalman filter to establish a regression model between the residual innovation and the input excitation forces. In applying the method, first, the ambient vibration measurement of a structural system is collected, then the stochastic subspace identification is applied to estimate the system matrix ‘A’ and the measurement matrix ‘H’. Incorporated with the identified ‘A’ and ‘H’ matrices the dynamic excitation forces are estimated from the measured structural responses by using Kalman filter with a recursive least-square estimator to update the estimation in the sense of real-time computation. Verification of the method on numerical simulation through MIMO system is conducted first. Identification of soil forces during the shaking table test of soil–pile interaction is also demonstrated. Copyright © 2008 John Wiley & Sons, Ltd.