新旧荷载规范关于风振系数表达形式的比较研究

采用随机振动理论建立新、旧两种荷载规范中风振系数表达式之间的内在联系,指出新规范计算风振系数的参数与旧规范中的脉动增大系数、脉动影响系数、位置函数的关系;建立新规范的背景分量因子Bz的具体表达式,可适用于各质点质量、受风面积、阻力系数及振型值任意变化的情况;指出新规范计算风振系数时将用10 m高处的紊流度代替旧规范的脉动系数。数值算例表明,新规范的风振系数比旧规范的有所提高,这种提高主要来自于新规范中峰值因子与紊流度取值的提高;新规范与旧规范相比,由等效静力风荷载引起的结构基底剪力,除了D类地貌的有所减小外,其它3种地貌的基底剪力都有所增大。

Comparative study on wind-induced vibration coefficient between new and old China codes

The intrinsic link of wind-induced vibration coefficients (WVC) between the new and old codes was established by random vibration theory. It is proved that some of the parameters in the new code which are used to calculate the new WVC are related to some of the coefficients in the old code, such as the fluctuating amplifying coefficient, the fluctuating influence coefficient and the location coefficient. Formula of the background component factor in the new code was built, which can apply to each particle mass, the area under wind load, drag coefficient, and modal shape values arbitrarily changing conditions. It is shown that the fluctuating wind pressure coefficient in the old code is replaced by turbulence intensity at 10 m height when the WVC is evaluated in the new code. Numerical example shows that the WVC increases in the new code mainly from the increasing of peak factor and turbulence intensity values. Compared with the old code, structural base shear forces in the new code which are caused by static equivalent wind loads(SEWL) decrease in the exposure category D, but increase in other three exposure categories.