Study On Along Wind Revised Wind Spectra Considering Non-stationarity

Typhoon is a common natural phenomenon in southeast coasts of China.Itcauses a large number of casualties and property losses every year because of itsuncontrollability and extremly destructive effect. Davenport spectrum adopted in theload code by our country currently was acquired by statistics research with aassumption of ergodic stationary random process. A typhoon is a strong wind. Theexisting researches have showed that a typhoon possesses obvious non-stationarity.in this dissertation, von Karman spectrum has been revised according to results ofresearches on non-stationarity of typhoon. The revised spectrum would be referencefor a guidance on structural wind resistant design with the purpose of safety andeconomic reasonable.Differences on non-stationarity between monsoons and typhoon ‘Hagupit’ hasbeen contrasted. Rationality of the ergodic assumption about monsoons andsignificance of non-stationarity in typhoon ‘Hagupit’ have been demonstrated by runtest. EMD has been used to extract trend terms. Effectiveness of EMD in extractingtrend terms through run tests with different time distance has been discussed.After different time-frequency domain analysis methods had been comparedand contrasted, HHT was selected to analyse non-stationary samples. HilbertPSDs,which possesses the same physical meaning with Fourier PSDs and reflectsnon-stationarity, have been deduced. A coefficient of revised PSD (n)and aindex of non-stationarity NI (n) have been defined. Expectation of (n)has beenfitted by statistics. Expectation of revised von Karman PSD has been deduced.Contrasts of structural response of structures with different natural periods ofvibration in Davenport,von Karman and revised von Karman PSD have beenconducted with new load code.