Nonlinearity And Nonstationary Test Of Bridge Dynamic Response Signal Based On Surrogate Signal

Most of the existing analysis methods of bridge dynamic response signals are based on the assumption of linear and stationary signals.It is necessary to test the nonlinearity and nonstationarity of signals before analysis.Surrogate signal technology is the mainstream nonlinear and non-stationary test method at present,but there is little research and application in the field of bridge health monitoring.Based on the Surrogate signal method,combined with the signal nonlinear and nonstationary feature extraction method based on dynamic system theory,recurrence plot and delay vector variance,the nonlinearity and nonstationarity of bridge dynamic response signal are tested.The main research contents are as follows:1.The basic theory of dynamic system is introduced,and the definitions of signal nonlinearity and nonstationarity are then derived.The principle of dynamic mode decomposition is described in detail,and the feasibility of using dynamic mode decomposition to reduce bridge signal noise is explored.The principle and application of nonlinear analysis method delay vector variance are described thoroughly.A complete framework of nonlinear and nonstationary test of bridge dynamic response signal is constructed.2.The advantages and disadvantages of the traditional surrogate signal are compared,and the problems are analyzed and summarized.Aiming at the problems,the improvement is made based on the existing surrogate signal.numerical simulation signals are used to verify the superiority of the improved surrogate signal.3.Based on the acceleration response signals of a cable-stayed bridge and a long-span suspension bridge,the variational modal decomposition and reconstruction technology is used to reduce the noise of the signals.The improved linear surrogate signal and stationary surrogate signal are generated for the denoised signal respectively.The recurrence plot is used for nonlinear and non-stationary analysis,and the delay vector variance is used for nonlinear analysis.The advantages and disadvantages of recurrence plot and delay vector variance are compared.