Abstract：Investigation of vibration control for benchmark problem on large span cable-stayed bridge has been one of the most important research topics in the current International Symposium on Structural Control. The second stage Benchmark problem on Bill Emerson Memorial cable-stayed bridge in US was studied in this paper. In the frame of Hamiltonian theory for nonlinear stochastic dynamics and control， the benchmark model under seismic excitations was investigated using MATLAB simulation analysis， which is based on the stochastic averaging method and the stochastic dynamic programming principle. By comparison of the analysis results for optimal forces as well as performance evaluation indices between using the nonlinear stochastic optimal （NSO） control strategy and the linear quadratic Gaussian （LQG） control strategy， it came out t that the former control strategy can mitigate the seismic response of the cable-stayed bridge more effectively than that of the latter， thereby enhancing structural dynamic stability and earthquake resistance. In conclusion， the NSO control strategy demonstrates better control effect and presents instructive references and practical significance for vibration control of bridge engineering application.
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