考虑实测台风风压非平稳非高斯特征的低层建筑设计风荷载

Low-rise buildings in typhoon-prone areas are vulnerable to typhoon-induced wind loading. This project therefore aims at the design wind loading of a low-rise building which accounts for typhoon winds and the attendant wind pressures given by field measurement. Both non-stationary and non-Gaussian characteristics of typhoon-induced wind pressures as displayed by measurements are considered. First, appropriate methods are proposed to extract non-stationary and non-Gaussian characteristics from one sample time-history of measured typhoon-induced wind pressure. Secondly, the non-stationary and non-Gaussian correlation are investigated between multi time-histories from varied spatial locations and time ranges. Non-stationary and non-Gaussian characteristics of one wind pressures and between multi wind pressures then lead to the probabilistic model of the whole measured wind pressure field. Thirdly, the probabilistic model of wind pressure field identified from measurements during one typhoon are utilized to result in the attendant wind loading on both envelops and structures of the low-rise building, on the basis of extreme typhoon-induced force responses. Finally, a prediction model is proposed for estimating the design wind loading of the low-rise building in terms of the probabilistic model of typhoon wind field and field measurements during a limited amount of typhoons. This project yields a type of design wind loading of the low-rise building in consideration of the effects of typhoon winds and the attendant non-stationary non-Gaussian wind pressures.

低层建筑在台风荷载下易于破坏。本项目基于台风作用下低层建筑足尺模型风压现场实测结果，研究台风非平稳特征与风压非高斯特征对低层建筑风荷载的联合作用，为低层建筑确定设计风荷载。首先研究从单条实测台风风压时程中合理提取非高斯和非平稳特征以建立其概率模型；其次研究多条与多点实测风压时程非平稳非高斯特征间的相关关系；再次研究从概率意义下的极值角度考虑非平稳非高斯特征确定某次实测台风下低层建筑的风荷载；最后提出预测模型,该模型可根据少量台风风压实测来预测考虑台风风场不确定因素影响的设计风荷载。本项目可望得到一种考虑台风风压非平稳非高斯特征的低层建筑设计风荷载。

本项目在非平稳风的特征分析、结构物上的非平稳非高斯风荷载模拟、非平稳风作用下结构的响应分析与设计荷载确定等三个方面开展研究。首先提出了一种基于时变相关函数的演变谱估计方法，可以给出非平稳风速演变谱的无偏估计；在估计演变谱的基础上，结合非平稳热带风暴的物理特征，提出了物理兼容的非平稳演变谱解析模型。其次，用随机摄动法对非高斯风压场进行模拟，并编制了一套模拟程序；另一方面研究了非平稳随机过程（包含非平稳风与地震动）的模拟误差，提出了模拟误差的解析公式并用于指导模拟；还研究了非平稳非高斯风压场条件模拟的直接迭代方法。最后，提出了一个精细化的非平稳风响应分析方法，包含对谱模型的修正、相干函数传递矩阵、时变气动导纳函数、非线性气动力以及水平向风速剖面。在此基础上，提出了非平稳风荷载链的概念，并通过多种时频分析方法对非平稳风荷载链进行了描述，结合阵风荷载因子，可用于为结构确定考虑各种非平稳作用的设计荷载。