考虑风速风向分布的干煤棚结构风振疲劳分析

Wind-induced vibration and fatigue analysis of long span lattice structures considering distribution of wind speed and direction

针对大跨开敞式干煤棚结构在风荷载作用下易发生风致疲劳破坏的问题,基于干煤棚结构的多点同步测压风洞试验结果,结合Miner疲劳线性累积损伤理论,分别采用雨流法、等效应力法、等效窄带法和等效宽带法等时域与频域内多种方法,计算得到干煤棚网架的风致疲劳损伤结果.通过建立风速风向联合概率密度函数,考虑煤棚所在地实际风速风向联合分布特性对风致疲劳损伤分析的影响,利用高强螺栓应力经验公式,估算网架结构球节点的疲劳损伤.结果表明,等效宽带法是频域法中较精确的疲劳损伤计算方法.与其他风向角相比,干煤棚网架结构在40°~60°斜风向作用下更容易引发疲劳损伤.在考虑风速风向联合分布的条件下,螺栓球节点的年均累积疲劳损伤比杆件本身更显著.

Wind-induced vibration related fatigue analysis of a long-span lattice structure was performed both in the time and frequency domains based on the multiple point pressure measurement wind tunnel test data according to the Miner’s linear cumulative damage theory in order to analyze the wind-induced fatigue damage of long span lattice structures under wind load. Four methods were applied for estimating wind-induced damage on the structure, i.e., the time domain rain-flow method, the equivalent stress method, the equivalent narrow band method and the equivalent wide band method. The influences of the joint distribution of wind speed and direction on the fatigue damage of the structure were carefully assessed by constructing the joint probabilistic distribution function. The wind-induced fatigue damage of spherical joints in the steel lattice structure was evaluated with the empirical formula of highstrength bolt stresses. Results show that the equivalent wide band method is a more accurate method for fatigue damage calculation in frequency domain. The fatigue damage of the lattice structure is more likely to occur under the wind directions of 40°~60° compared with other wind direction angles. The cumulative fatigue damage of spherical joints is more significant than that of the structural members themselves considering the joint distribution of wind speed and direction.