基于实测的低矮房屋屋面风压极值计算方法

摘要

The peak pressure estimation methods of field measurement-based wind loads on low-rise buildings were investigated for the design of wind resistance on low-rise buildings. Based on pressure data measured on the roof of the test building during monsoon climate at the wind engineering field measurement base constructed on seashore beside Pudong International Airport of Shanghai by the State Key Laboratory of Disaster Reduction in Civil Engineering of Tongji University,including a full-scale low-rise building with adjustable roof pitches and two anemometer towers respectively with a height of 10 and 40 m,the distribution characteristics of wind pressures were analyzed,and the validity of the peak value estimation method to use the extreme pressure of short time interval samples to estimate that of long time interval samples from field measurement data was discussed. The research result shows that as for the flow separation region,the probability distributions of wind pressure coefficient have non-Gaussian features and a good agreement with the Gamma and lognormal distributions. When the time-history curve of wind pressures on the roof are divided into several sub-sections and the relationships of typeⅠEVD (extreme value distribution )parameters between parent section and sub-sections are used to estimate peak pressures,the estimated peak pressures are more accurate than observed extreme values,and the optimal length of a sub-section can be determined by the auto-correlation analysis of the parent section. For the full-scale data the extreme value distribution has a good conformity with typeⅠEVD when sub-section data are divided by the optimal length,and the peak pressure estimation method based on typeⅠEVD for short time interval samples has reliable results.%探讨了低矮房屋实测风压的极值计算方法，以便为建筑抗风设计提供重要依据。基于同济大学土木工程防灾国家重点实验室在上海浦东国际机场附近海岸边建造的风工程实测基地（包括一栋坡角连续可调的低矮试验房和高分别为10和40 m的测风塔）的现场实测数据，分析了良态气候条件下低矮房屋表面风压的分布特性，并探讨了由短时距样本估计长时距下极值的计算方法对实测风压极值估计的可靠性。研究表明：屋面来流分离区实测风压表现出明显的非高斯性，其概率分布与Gamma分布和对数正态分布符合较好；将屋盖风压时程划分成若干子段时，利用极值Ⅰ型分布参数转换关系计算风压极值，估计极值比观察极值法的结果更准确，且最佳观察时距可由自相关分析确定；以该最佳观察时距划分单个子段风压样本，实测观察极值基本服从极值Ⅰ型分布，估计极值能较准确地给出实测时程极值，表明基于极值I型的短时距极值估计方法合理、有效。