Mode matching problem of sectional model flutter tests for a suspension bridge with double main spans

Abstract:

Mode matching problem exists in sectional model flutter tests for a suspension bridge with double main spans. It is necessary to figure out how to match bending modes with torsional modes and seek the mode combination with minimal flutter critical wind speed. According to mode similarity of the Maanshan bridge, three mode combinations were selected. Flutter critical wind speed of every mode combination was tested in wind tunnel tests of sectional bridge model, and then these results of wind tunnel tests were analyzed. The research results show that the mode combination with minimal flutter critical wind speed is the combination matched by first-order antisymmetric vertical bending mode and first-order antisymmetric torsional mode, and it is the key mode combination for flutter of a suspension bridge with double main spans. The flutter critical wind speed for the mode combination of first-order symmetric vertical bending mode and first-order symmetric torsional mode is slightly greater than that for the mode combination of first-order antisymmetric vertical bending mode and first-order symmetric torsional mode. As for empirical formulas of classical coupled flutter, the Van der Put formula and the Selberg formula can estimate the relative value relationship of flutter critical wind speeds for different mode combination, but can’t estimate accurate values.