Wind-induced Fatigue Analysis Of Transfusion Tower Structures

The transfusion tower structure is an important part of lifeline engineering. The windload is the controlling load. Recently, many the collapse cases occur because of the windload. It not only has great influence on people’s work and life, but also leads to severesecondary disaster. Therefore, it is of practical engineering significance to perform afatigue analysis of transfusion tower structure. Based on a500-kV power transmissionproject in Longkaikou whose characteristic height is45m, this thesis introduces awind-induced fatigue analysis based on Damage Cumulating Theory and ProbabilisticFracture Mechanics.First of all, based on the Damage Cumulating Theory, the thesis firstly introduces themethod of wind-induce fatigue time-domain analysis of transfusion tower. The fatigue lifeis also estimated. The main content includes the method to establish finite element modelof transfusion tower structure and the wind-induced vibration of tower subjected torandom wind loads. It is assumed that the existence of average wind speed comforms toWeibull distribution, so that the influence of wind speed distribution on the cumulativefatigue damage of structure can be considered.Then a fatigue analysis based on crack propagation model is adopted hereinafter. Thestress intensity factor is an important fundamental concept in fracture mechanics, and itreflects the intensity of stress field at crack tip. The third session of this thesis introducesthe process of establishing the FEA model and the calculation of stress intensity factor. Toverify the result of numerical simulation, the result is compared with that calculated byNewman&Raju empirical formula. Based on this, an approximate method is given hereto calculate the stress intensity factors of mixed mode cracks.In Chapter Four, the thesis investigates the structure fatigue problems based on Fracture Mechanics Theory while considering the stochastic properties of material crack propagation speed. Based on the crack propagation theory and Paris formula, an estimationformula of constant amplitude fatigue life of structures is deduced here. Finally, astochastic crack propagation model is obtained by introducing a stable logarithm normalstochastic process.