Numerical Study on Structural Damage Detection of Pier Based on Modal Parameters

When the lateral vibration of a railway bridge pier is considered, the pier can be simplified as the cantilever beam with lumped mass on the top of the pier. The ground is modeled as springs. This simplified model has the same principles as the cantilever beam model with fixed root when the structural damage of the pier is studied. The first-order mode and the first eigenfrequency of the pier can be obtained easily and precisely by the impact vibration test method, from which three indexes such as the change ratio of the first mode shape, the characteristic parameters and the first curvature mode shape difference can be obtained. Then the three indexes are used as the measure for structural damage detection in a cantilever beam and their change laws before and after the damages are summarized. The analysis results indicate that these indexes are sensitive to the structural damage of the cantilever beam.