To examine the flutter failure probability of long-span bridge due to typhoon winds, a case study of a 1666-m-main-span suspension bridge located in the typhoon-prone region was performed. A number of probabilistic solutions of flutter critical wind speed for two bridges, say a simply supported beam bridge and the Jiangyin Suspension Bridge were achieved by introducing different sources of uncertainty utilizing both 2D step-by-step analysis and 3D multimode techniques. The quantifications of structural uncertainties, as well as aerodynamic uncertainties or the randomness of flutter derivatives, were conducted using both literature survey and experimental methods.
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A series of performance assessments were performed on the present subregion model before it was employed to predict the typhoon wind hazards around the coastal regions of China.Ĭhapter 6 develops a framework to investigate the probabilistic solutions of flutter instability in terms of critical wind speed accounting for multiple resources of uncertainty to facilitate the development of the fragility curve of flutter issue of long-span bridges. Then, the typhoon forward model including the tracking model, intensity model, and wind field parameter model was developed utilizing the GWR method. The storm genesis model was first applied to a circular boundary around the site of interest. To predict the typhoon wind hazard along the coastal region of China, a geographically-weighted-regression (GWR) -based subregion model was proposed in Chapter 5. Then, the probability distributions of gust factor associated with any gust time duration of interest can be readily achieved after introducing the statistical models of skewness and kurtosis of typhoon winds. The real wind data of nine typhoons captured by the structural health monitoring system (SHMS) installed in Xihoumen Bridge were utilized to validate the proposed model. Since the present wind field model can only generate long-time-duration speed, say 10-min mean wind speed, Chapter 4 develops an algorithm to compute the gust factor curve by taking the non-stationary and non-Gaussian characteristics of typhoon winds into account.
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Moreover, this supplementary dataset of R_(max,s) and B_s enables the development of recursive models to facilitate both sub-region typhoon simulations and full track simulations. On this basis, the maximum wind hazard footprints for over-water, roughness only and roughness and topography combined conditions of 184 observed landed or offshore typhoon-scale storms are generated and archived for risk assessment.
The proposed dataset of R_(max,s) and B_s is able to reproduce the JMA wind observations as closely as possible, which allows performing more accurate typhoon wind hazard estimation. the radius to maximum wind speed, R_(max,s) and the Holland pressure profile parameter, B_s in Western Pacific Ocean using the wind data information from best track dataset archived by the Japan Meteorological Agency (JMA) coupled with the present wind field model. Then, Chapter 3 develops a dataset of two wind field parameters, i.e.
Some basic characteristics of the inner structure of typhoon wind field, such as the logarithmic vertical wind profile near the ground and super-gradient winds were reproduced. To reconstruct the mean typhoon wind speed field, a semi-analytical height-resolving typhoon boundary layer wind field model, including a parametric pressure model and an analytical wind model was first developed in Chapter 2 using a scale analysis technique. With more long-span bridges are being constructed along this coastal area, it is of great importance to perform the risk assessments on these flexible or wind-sensitive structures subjected to typhoon winds. The coastal region of China, which is characterized by high population densities and well-developed cities, is always exposed to typhoon threats with 7~8 landfall typhoons every year since Western Pacific Basin is the most active typhoon basin on earth, accounting for almost one-third of global annual storms. Typhoon or hurricane or tropical cyclone, which is a large-scale air rotating system around a low atmospheric pressure center, frequently causing devastating economic loss and human casualties along coastal regions due to violent winds, heavy rainfall, massive storm surges, flash flooding or even landslides in mountainous areas.
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