Dynamic characteristics of Megami cable-stayed bridge - A comparison of experimental and analytical results

The Megami Bridge, with a main span of 480 in, is the 6th longest cable-stayed bridge in Japan. A comparison of experimental and analytical modal analysis is performed to determine the dynamic characteristic of this bridge. The ambient vibration test is carried out using very few accelerometers. Parameter identification is carried out using the stochastic subspace-based identification (SSI) method in the time-domain as proposed by Katayama. The SSI method used in this paper can be used for estimating the modal properties of a long span cable-stayed bridge by comparing with the maximum entropy method (MEM). Furthermore, the effectiveness of the tuned mass dampers (TMDs) used in the bridge is evaluated through a human excitation test. Logarithmic damping is about 0.030 when the TMD is activated, a little higher than the design value 0.026, so proving that the TMDs are effective. Finally, the analytical eigenvalues obtained from finite element analysis agree well with the experimental values, thus verifying the analytical model.