基于极值相关性的超高层建筑风荷载组合研究

Wind load combination method for high-rise buildings based on extreme-value correlation

为研究不同长宽比超高层建筑三维风荷载组合,通过高频测力天平风洞试验得到了5种长宽比的矩形超高层建筑基底剪力、弯矩和扭矩时程。基于试验数据和计算结果,分析了三维风荷载效应的分布及其极值相关性。在此基础上,对比分析了不同长宽比的超高层建筑顺风向与横风向、顺风向与扭转向以及横风向与扭转向之间的风荷载效应极值分布规律和统计参数。最后,采用概率统计方法评估了不同长宽比对结构三维风荷载组合系数的影响,并给出了一组基于极值相关性分析的结构三维风荷载组合系数推荐值。结果表明:对于超高层建筑,虽然不同方向风荷载效应之间相关系数可能很低,但其三维风荷载效应极值相关性不可忽略;以横风向或扭转向为主方向进行组合时,其余方向同步比值存在明显的非高斯分布特性;对于不同长宽比超高层建筑,其极值相关性的差异会导致组合系数存在差别,在确定风荷载组合方法时,应考虑长宽比的影响。

In order to investigate three-dimensional(3-D)wind load combination for high-rise buildings,time histories of base shear forces,bending overturning moments and torques of a series of rectangular high-rise building models with five different side ratios were obtained by high-frequency force balance technique in wind tunnel.Based on the experimental measurement and analysis,distribution of extreme-value correlation of 3-D wind load effects was analyzed.Then,influences of side ratios on extreme-value distribution and on statistical parameters of wind load effects between along-wind and across-wind,along-wind and torsional direction,and across-wind and torsional direction of these high-rise buildings were analyzed.Finally,a statistical method was used to evaluate the influence of side ratios on 3-D wind load combination coefficients.A set of recommended 3-D wind load combination coefficients based on the extreme-value correlation analysis were thereafter proposed.The results show that:for high-rise buildings,although the correlation coefficients between wind loads in different directions may be small,correlation of the extremes cannot be ignored;when an extreme-value of across-wind or torsional direction is taken,wind load effects of the others can have non-Gaussian distribution characteristics;and the correlation of the extremes varies with side ratios of high-rise buildings,and so do the combination coefficients.In determining the wind load combination method,influence of side ratios should be considered.