Analysis On Wind Characteristic Of Strong Wind/Typhoon And Wind Effect Numerical Simulation Of Long-Span Cable-Supported Bridge

Wind characteristic measurement and structural wind effect analysis are significant topics in bridge wind engineering research.The development of the Structural Health Monitoring System(SHMS)and the Computational Fluid Dynamics(CFD)provides efficient tools for refined wind effects research on the long-span bridges.In this work,the Sutong cable stayed bridge(SCB)is selected as the engineering background to conduct the wind characteristic analysis of the strong wind/typhoon and the wind effects numerical simulation of long-span bridges.The main contents of this dissertation mainly include:(1)Analysis on the measured wind characteristics of the strong winds and typhoons.The SCB is selected as the engineering background.Based on the SHMS,the measured wind data of Typhoon “Rumbia” and strong winds in winter are utilized to conduct the comparison research on the stationary and non-stationary wind characteristics,including mean wind speed and direction,turbulence intensity,gust wind factor,turbulence integral length et al.Results show that the large-scale vortex is eliminated by the non-stationary wind model,the obtained turbulence component represents the medium and small scales of the turbulence.(2)The probabilistic turbulent wind spectrum model on bridge site.Based on the wind characteristic analysis results on the Sutong Bridge site,the probabilistic turbulent wind spectrum model in different wind directions is established using the general turbulent wind spectrum.Then the availability and reliability of the model are validated.Meanwhile,the established model is compared with Solari-Piccardo model.Results show that the established probabilistic turbulent wind spectrum can reasonably describe the uncertainty of the turbulence at the bridge site.It is necessary to model the probabilistic turbulent spectrum at the specific region based on the long-term monitoring wind data.(3)The time-domain buffeting analysis of the long-span bridge considering the uncertainty of the turbulence.Based on the established probabilistic turbulence spectrum and the quasi-steady hypothesis,the time-domain buffeting analysis of the SCB considering the uncertainty of the turbulence is conducted using the general finite element method software ANSYS.Results are also compared with that obtained using the design spectrum.Results show that there exists difference between the RMS of the bridge buffeting response obtained by the design spectrum and that obtained by the probabilistic turbulent wind spectrum.(4)The fast simulation method of the non-stationary turbulent wind field of the long-span bridge based on the Non-negative Matrix Factorization(NMF).Using the classical spectral representation method(SRM)as the simulation frame,the NMF technique is utilized to decouple the cross power spectral density matrix.Then,FFT technique is utilized to enhance the simulation efficiency of the turbulent wind field.Results show that the method realize the fast simulation of the non-stationary turbulent wind field of the bridge.What’s more,it can provide convenience to analyze structural random vibration under the non-stationary excitations.(5)The flow-structural-interaction(FSI)numerical simulation of buffeting analysis of the section model.The narrowband synthetic random flow generation(NSRFG)method is embedded in the Fluent with the user defined function(UDF)to generate the inflow turbulence for large eddy simulation(LES)of atmospheric boundary layer flow.Meanwhile,the FSI program of the wind effect analysis on the section model is achieved using the UDF.Then,the FSI numerical simulation of buffeting analysis on the standard girder section model of the SCB is achieved.Finally,the buffeting mechanism analysis on the section model is also conducted using the simulation results.Results show that the proposed simulation flowchart can achieve the simulation of the LES turbulent atmospheric boundary layer and the buffeting responses of the bridge sectional model.In addition,the characteristic turbulence has little effects on the buffeting responses of the bridge deck.