Parametric Study on Life-Cycle Maintenance and Repair Costs Caused by 'Multi-Hazard' Wind Excitation on a Long-Span Bridge

摘要

This study discusses the implementation of a methodology for the buffeting response of cable-supported bridges (Seo & Caracoglia);the proposed methodology projects uncertainty in the aeroelastic input (i.e., flutter derivatives, FDs) onto the wind-induced bridge response. FDs are the most important part of the loading; the FD coefficients are estimated in wind tunnel and suffer from experimental errors. A simplified second-order polynomial model (designated as "model curve"), originally proposed by Seo & Caracoglia~(1,) Seo & Caracoglia~2 to derive flutter probability due to randomness in FDs, is employed to characterize the second statistical moments of FD errors. These "stochastic" model curves can be employed to estimate the "statistical buffeting" response" (Seo & Caracoglia~1) of the bridge by Monte-Carlo simulation. In the standard buffeting multi-mode approach (e.g., Jones & Scanlan~(3,) Scanlan & Jones~4) the result of the buffeting analysis is the value of the RMS dynamic response of a deck section at a given mean wind speed. In the proposed setting one estimates the probability that a given threshold for the variance of the response is exceeded. The term "multi-hazard" is used to describe buffeting "fragility", rescaled in the case of flutter occurrence. This probability is later used, together with information on the probability of the wind velocity at a given site, to predict the expected value of a "monetary loss function", by projecting FD variability onto the cost associated with interventions needed to ensure bridge safety against buffeting-induced damages or loss of functionality. A 1200-meter suspension bridge is used in this pilot study for the simulations.