Finite element model updating: Multiple alternatives

This paper focuses on the model updating of complex structural systems. Traditional model updating techniques optimize an objective function to calculate one single optimal model that behaves similarly to the real structure and represents the physical characteristics of the structure. One can argue that due to numerical and identification errors, and the limited number of sensors in structures, a local minimum rather than the global minimum could be a better representation of the physical properties of the structure. The methodology proposed in this paper identifies physically different local minima, giving the analyst the power to decide what model would better describe the system base on his/her experience and engineering judgment. Two examples are used in the paper to explore the capabilities of the technique. First, a simple numerical example is used to demonstrate the existence and correct identification of local minima in a model updating objective function. The second problem identifies model updating alternatives for a finite element model of the Bill Emerson Memorial Bridge. Acceleration records from the bridge’s permanent instrumentation are used to update the model.