Research
Projects
Finite Element Model Updating Using Frequency Response Function
Figure 1: Shaker and accelerometer setup from July 2010 VAB Load Test 
One method of dynamic based finite element model updating uses frequency response
functions obtained from a dynamic load test and compares them with frequency response
functions obtained from a finite element model. The measured frequency response
functions for the Vernon Avenue Bridge were obtained using an array of 9 accelerometers
to measure response and a shaker to excite the bridge. Frequency response functions are
ratios of input/output data in frequency domain, typically acceleration data, which in
turn provide full characterization of the linear system that is the bridge. The
frequency response functions obtained from the finite element model are created using
either full system mass, damping, and stiffness matrices or may be accurately approximated
using mode shapes obtained from the finite element model. The goal of this research is
to perform model calibration on a full scale bridge by updating a model to closely match
onsite conditions. Researchers hope to do this by creating an automated process to update
the finite element model as parameter estimation is being performed.
Figure 2: Transfer function
