Comparative analysis on field-measured and numerically simulated buffeting responses of long-span bridge in mountainous terrain

ObjectiveThis study compared the differences between field-measured and numerically simulated wind-induced vibrations of long-span bridges, and analyzed the reasons for the deviations. Influences of wind spectra, spatial correlation of turbulence, aerodynamic admittance, aero-elastic effect, structural damping, and signature turbulence on buffeting response were discussed qualitatively.MethodBased on long-term monitoring of structural vibrations and wind data of a long-span bridge in mountainous terrain, the key parameters were analyzed, including mean wind speeds, wind directions, angles of attack, turbulence intensities, turbulence integral scales, and wind spectra. According to parameters specified in wind-resistant design specification for highway bridges, a finite-element model was established, and frequency-domain simulations of buffeting responses were conducted for comparative analysis.ResultObvious distinctions are found between specified wind parameters and field-measured values, which substantially affect wind-induced stochastic vibrations. Due to the stochastic traffic flows, monitored structural vibrating data exhibit high discreteness, showing no obvious correlation to the wind speeds in general. However, the bottom-edge samples are largely proportional to the square of wind speeds, being in agreement with theoretical expectations.ConclusionThe measured wind angles of attack and turbulence intensities within the observed range in mountainous terrain considerably exceed the specified values. Significant discrepancies also exist between measured and specified wind spectra within the wind-sensitive structural frequency range. Simulated buffeting responses using specified wind parameters are significantly lower than the measured values; the deviation can be more than 1 times. This deviation is a concentrated reflection of uncertainties in wind spectrum differences, field wind speed correlation, aero-admittance and its wind field dependence, structural damping, characteristic turbulent, etc. In absence of field measurements, the obvious defects and challenges remain in numerical simulations of buffeting response of mountainous bridges.