Dynamic Reliability Research Of Buffeting For Long-span Bridges With Random Structural Parameters

As far as determinate structural models are concerned, two mature approaches, which analysed in frequency-domain and in time-domain, have been formed for the buffeting response analysis in long-span bridges. However, constructed bridge structures can not be under comprehensive observation. Futhermore, the structural parameters of constructing bridge can not be under complete control. For these reasons, bridge structure parameters present randomness, which should not be negligible for buffeting analysis on bridges. It is more reasonable to employ stochastic structural models to reflect the problem of buffeting. The proposed model is very important and significant to dynamic reliability analysis on bridge buffeting behaviour.Specific work of this dissertation consists of four parts. The first part introduces analysis methods of buffeting for long-span bridges and research brief about dynamic reliability of buffeting. The second part elaborates a buffeting analysis approach in time-domain and corresponding program, which are based on correctional and unified description of aerodynamic loading. Meanwhile, stationarity and ergodicity of buffeting responses are verified by means of the buffeting analysis program. The third part places much emphasis on a method for buffeting reliability analysis of long-span bridges. The method includes two sections: (1) Dynamic reliability analysis of buffeting in terms of determinate bridge structure. (2) In view of stochastic structural parameters, a computing method is raised for dynamic reliability of buffeting in long-span bridges. In the last part of the dissertation, dynamic reliability of buffeting in the Phoenix Bridge and the Yamen Bridge is calculated.Main creative work of this dissertation proposes a computing method associtated with dynamic reliability analysis in view of stochastic structural parameters.The major conclusions obtained in the dissertation are as follows. (1) Buffeting response processes of the Phoenix Bridge and the Yamen Bridge are stationary and ergodic by close verification. (2) Under the effects of basic wind speed, dynamic reliabilities of tower lateral and middle girder displacement for the two bridges is greatly big both in the case of determinate structural parameters. When the parameters are stochastic, it is big enough to meets requirements for dynamic reliability of the middle girder and tower lateral displacement in the Phoenix Bridge. Dynamic reliability of the tower lateral displacement in the Yamen Bridge is very small and must be taken some measures of control. Whereas, it is big enough to meets requirements for dynamic reliability of the middle girder displacement. (3) Randomness of material and geometric parameters exert a greater affect on dynamic reliability of lateral displacement on the top of tower than that on static coefficients of girder. (4) For vertical displacement response in the middle of girder, sensitive stochastic variables are elastic modulus and lifting coefficients of girder. Furthermore, torsional moment of inertia and lifting moment coefficients exhibit rising effects on the dynamic reliability of vertical displacement with the increasing of span.