Modern suspension bridges have stiffening steel decks and RC towers. The well separated different materials cause damping to be unevenly distributed for the complete bridge, known as “non-classical” damping. The equations of motion for such structures are damping coupled in the modal coordinate system. Most commercial dynamic finite element analysis computer programs can not solve these equations. This paper discusses three methods for solving the equations and their implementation in computer programs. The seismic response analyses of the Tsing Ma bridge and Humen bridge indicate that non-classical damping may have a significant influence on the seismic response of suspension bridges.
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