Extreme Wind Speed Estimation In Mixed Wind Climates And Study On Analysis Models Of Wind-induced Responses Of A Tall Building

Recent trends towards developing increasingly taller and irregularly-shaped buildings have led to slender complex structures that are highly sensitive and susceptible to wind-induced deflection and vibration.Wind loads impacting on engineering structures are largely dependent on the strength of wind speeds,which could be represented by the extreme wind speed quantiles(design wind speeds)associated with various mean recurrence intervals for a particular site.Therefore,it is of great significance and economic value in wind engineering practice to carry out the research on extreme wind speed estimation in mixed wind climates and study on analysis models of wind-induced responses of a tall building.The dissertation took an irregularly-shaped tall building with three-dimensional coupled nonlinear mode shapes as the research object.Combining with field measurement,wind tunnel test,numerical simulation and theoretical analysis,the following studies were carried out:1.Extreme wind speed estimation considering long-term change factors:The detection for the existence of any temporal trend in the original wind speed series for the Hangzhou area was implemented.An exposure correction procedure was adopted attempting to correct the original extreme wind speed series to the standard exposure category referenced in the Chinese load code(i.e.,the 10-min mean wind speed at 10m height for open rural exposure).The non-stationarity of the extreme wind speed series considering a changing climate was then evaluated.A non-stationary statistical modeling method that incorporates time as a covariate was used to model the distribution parameters of the extreme wind speeds in the presence of a temporal trend.The generalized maximum likelihood approach was adopted to estimate the distribution parameters.Based on the adjusted daily/annual maximum wind speed data,the non-stationary extreme wind speed quantiles were estimated and compared to the corresponding stationary ones with various MRIs.2.Extreme wind speed estimation considering correlation of wind speed and wind direction:Based on the daily maximum wind speed series in Hangzhou area,the Kernel Density-Generalized Pareto model was introduced to describe the marginal distributions of the multi-directional extreme wind speed such that the accuracy of the Up-crossings method was improved for estimating the design wind speed.The joint probability distribution model of the multi-directional extreme wind speeds were established based on the selected Copula functions.The design wind speeds associated with various return periods were then estimated for different wind directions by considering the multi-directional correlations,and compared with those results without considering the correlation.3.Typhoon extreme wind speed estimation based on Monte-Carlo simulation:An empirical regression model for simulating tropical cyclone tracks from the genesis to lysis was developed based on the historical CMA-STI best-track dataset for western North Pacific basin.Tracks were systematically simulated using the developed empirical regression model.The model parameters were corrected for some partial areas in the western North Pacific.A random sample of tropical cyclone tracks of 100000 years that accorded with the characteristics of historical samples was generated.The Yan Meng model and the improved Thompson and Cardone model were used to simulate the wind field respectively and the typhoon extreme wind speeds of various return periods in 10 key cities along the southeastern coast of China were determined under extreme value analysis.Combining with the wind speed observations of monsoons in Hangzhou area,the extreme wind speeds of various return periods under the mixed climate were estimated.4.HFFB-based three-dimensional wind-induced response analysis of a tall building:The main procedures and assumptions for the assessments of generalized wind forces related to available six HFFB-based analysis methods/models were reviewed,in order to estimate the three-dimensional wind-induced dynamic responses of a tall building.For a complex tall building with irregular structural form and coupled non-linear mode shapes,the synchronous multi-pressure sensing system test was conducted in the wind tunnel to provide the benchmark results of the wind loads and a virtual set of HFFB base reactions were obtained through integration of the measured pressure field.Based on the set of equivalent HFFB measurements,the effectiveness of each HFFB-based model for estimating the generalized wind forces was taken into evaluation.5.Uncertainty quantification in wind-induced dynamic analyses of a tall building:Based on the Bayesian model averaging and the adjustment factor approach,a framework of HFFB-based model-selection uncertainty quantification has been developed for predicting dynamic responses of a complex tall building with minimum uncertainties.A practical complex tall building was used to demonstrate the effectiveness of the proposed framework in the case study due to its irregular structural form and coupled non-linear mode shapes.Based on the results of the case study,a relatively superior model among the six HFFB-based candidate models could be selected,and exhibited its robust and reliability for the estimation of generalized wind forces and wind-induced responses of the complex tall building with nonlinear mode shapes.