Dynamic pretest on ground of steel girder section units of Tsing Ma bridge

The presented paper discusses dynamic test of a group of steel girder section units of Tsing Ma bridge. The test is one of pretests for the research on the Wind and Structural Health Monitoring System (WAHMS) of Tsing Ma bridge under the Highway Department of Hong Kong. In consideration of very short time period before open to traffic and after its completion, and importance of local vibration modes of the steel girder of Tsing Ma bridge to detect its damage, four girder section units are selected and tested on the ground. The test includes ambient test and impulse response tests on each unit. The test identifies up to 18 vibration modes including wrapping and distortion of cross section of closed profiles of the girder and local modes of each section unit, that are mostly coupled modes of the units with their support pile foundations. Nonlinearity in the vibration responses of the combined systems of a unit and a pile foundation is identified.