Identification of Structures Through Records Obtained During Strong Earthquake Ground Motion

The problem of estimating a space dependent coefficient in a forced linear hyperbolic differential equation from the knowledge of the solution at one or more isolated points is dealt with. The continuous model of a structural system by a shear beam is used to study the utility of earthquake records in determining structural models. Starting with an initial “guess,” a systematic method of iteratively improving the estimate of the structural stiffness using the information contained in the measured response to a known ground excitation is developed. A highly efficient and automatic numerical algorithm for this purpose, based on an optimal control formulation of the problem of history matching is developed. Numerical examples are presented showing the dependence of the estimate on the initial guess. The nonunicity of the estimate is demonstrated, pointing to the fact that though history matching at one or more points in a structure may be a necessary condition for arriving at an adequate model, it may not be a sufficient one.