System Identification of One Historical Bridge Using Dynamic Test Data

Obtaining accurately estimation of modal parameters from dynamic test data is an essential part for analyzing civil engineering structures. A set of dynamic field tests were conducted at a historic bridge. These tests provided an opportunity to identify the modal properties of the bridge in current condition. The system identification of the bridge was performed by using two different methods: (1) peak picking method and (2) eigensystem realization algorithm. By analyzing the output-only data, the natural frequencies in the vertical, lateral and torsional directions were identified. After comparing the data between measurements and the finite element model, the identified parameters using these system identification methods are found to be considerable for each type of tests. And through eigensystem realization algorithm, much more comprehensive results were obtained than peak picking method.