Buffeting Analysis And Vibration Control Of Large Span Suspension Pipeline Bridge

This paper firstly summarized the characteristics and development of suspension pipeline bridge, then introduced different structure control methods and algorithms, especially emphasis has been put on the fuzzy logic algorithms.This paper use Sino-Burma pipeline Canglan River Crossing project as its engineering background, use finite element method to study the mode and natural frequencies of full bridge model. The results reveal that, this bridge is characterized by low frequencies and close spacing modes, coupling effects exists in many modes. This paper also studied the impact of different elements on natural frequencies. The initial stress and cross section of wind cable mainly influence the lateral bending modes; changing in the stiffness of one single bending direction of pipe will increase the frequency of that mode by about 5%; the torsion stiffness of pipe will has significant impact on bridge's torsion modes even if the cooupling between pipe's and girder's torsion is very week.Then, this paper conducts time-domain analysis of buffeting response of this pipeline bridge. The full bridge wind fields with different mean wind velocity are simulated by WAWS method. During the analysis the self-excited force is taken into consideration as the aerodynamic stiffness and damping. The buffeting response of pipeline bridge has been thoroughly studied by wavelet decomposition and short-time Fourier transform, the results shows that:strong nonlinearity and coupling effects are exists in buffeting response, the participation level of modes change through time, the low frequencies fluctuation contribute a lot to the buffeting response.At last part, this paper firstly introduce the concept of variable-universe fuzzy control, and then design a variable-universe adaptive controller according to the buffeting response and analyze the control effects. The results reveal that:variable-universe fuzzy controller with Weighted Integral Regulation methods excel traditional fuzzy methods in control efficiency, stability, adaptability and feasibility. This paper also studied the influence of initial output universe on control effects. When the given output universe is too large for system, the variable-universe fuzzy controller could contract universe to prevent "overshooting"; however when the give output universe is too small for system, confined by the feasibility, variable-universe fuzzy controller has limited ability in expanding the universe.