低矮建筑屋面局部极值风压特性的风洞试验研究

发布时间：2018-04-22 09:07

本文选题：低矮房屋 + 极值风压　；参考：《湖南科技大学》2017年硕士论文

【摘要】：我国沿海地区分布着量大而广的低矮建筑,每年受台风影响造成巨大的损失。风灾统计表明,低矮房屋的损毁主要表现为迎风屋面角部、边缘和屋脊等易损部位先损毁并进而引发建筑的整体倒塌,而风压极值往往是研究屋面局部风压提高建筑抗风能力的关键。为此,本文采用风洞试验方法,对双坡低矮建筑屋面风压概率分布特性、非高斯特性等极值特性以及极值估计方法展开研究,为我国低矮建筑抗风设计提供理论支撑。首先,本文采用缩尺比为1:20、体型比为1.5:1:1的风洞试验刚性模型,以风向角、坡角和地貌为变量,针对双坡低矮房屋表面风压分布规律进行了分析,验证了风洞试验数据的准确性。探讨了不同坡角、风向角及地貌下屋面风压概率密度以及峰度与偏度分布特征并对概率密度分布进行了拟合分析。试验结果表明,坡角的改变对屋面风压高斯与非高斯区分布影响明显,风向角与地貌的改变主要是对屋面来流分离区域偏度与峰度影响较大,但地貌的改变并未改变屋面偏度与峰度的变化规律。相比Gaussian分布与Gamma分布,GEV分布和Lognormal分布都能较好拟合不同工况下的屋面风压概率密度分布。其次,基于风洞试验数据对比分析了Quan法、Wang法和峰值因子法对屋面风压极值的估计精度,同时探讨坡角、风向角及地貌对几种常用极值方法对应的风压峰值因子取值的影响。试验结果表明,Wang法较适用于低矮建筑屋面风压极值估计。改进峰值因子法计算得到的峰值因子取值较为合理。最后,以风向角和屋面坡角为变量,探讨了B类地貌下屋面局部分区阵风系数以及风压极值的变化规律,同时与我国现行规范阵风系数取值进行了对比分析。结果表明,风向角对45°坡角低矮房屋迎风屋檐、屋脊、角部区域阵风系数影响较明显。我国规范阵风系数和风压极值的建议取值小于风洞试验值,可能低估屋面局部设计风荷载,不利于结构抗风。
[Abstract]:There are large and wide low buildings in coastal areas of China. Wind disaster statistics show that the damage of low-rise houses is mainly manifested in the corner of the upwind roof, the edge and the roof ridge and other vulnerable parts first damaged and then caused the overall collapse of the building. The extreme value of wind pressure is the key to study the local wind pressure of roof to improve building wind resistance. Therefore, in this paper, the wind tunnel test method is used to study the probability distribution characteristics of wind pressure, non- characteristics and extreme value estimation method of the roof of double-slope low-rise buildings, which provides theoretical support for the wind-resistant design of low-rise buildings in China. Firstly, a rigid wind tunnel test model with a scale ratio of 1: 20 and a figure ratio of 1.5: 1: 1 is adopted in this paper. The wind direction angle, slope angle and geomorphology are taken as variables, and the distribution of wind pressure on the surface of double-slope low-rise buildings is analyzed, and the accuracy of wind tunnel test data is verified. The probability density, kurtosis and skewness distribution of roof wind pressure under different slope angles, wind direction angles and geomorphology are discussed, and the distribution of probability density is analyzed by fitting. The results show that the change of slope angle has obvious influence on the distribution of roof wind pressure in Gao Si and non- area, and the change of wind direction angle and geomorphology mainly affects the deviation and kurtosis of roof flow separation area. But the change of geomorphology does not change the law of roof deviation and kurtosis. Compared with Gaussian distribution, Gamma distribution and Lognormal distribution, the probability density distribution of roof wind pressure under different working conditions can be fitted well. Secondly, based on the wind tunnel test data, the estimation accuracy of wind pressure extreme value of roof by Quan method and peak factor method is analyzed. At the same time, the influence of slope angle, wind direction angle and geomorphology on the value of wind pressure peak factor corresponding to several commonly used extreme value methods is discussed. The test results show that Wang's method is more suitable for estimating wind pressure extremum of low building roof. The value of peak factor calculated by improved peak factor method is reasonable. Finally, taking wind direction angle and roof slope angle as variables, the variation law of wind coefficient and wind pressure extreme value of local partitioning of roof under type B geomorphology are discussed, and the results are compared with the values of gusty wind coefficient in current codes of our country. The results show that the wind direction angle has an obvious effect on the gust coefficient in the eaves, ridges and corners of low buildings at 45 掳slope angle. The suggested values of gust coefficient and wind pressure extremum in the code of our country are smaller than those in wind tunnel test, which may underestimate the local design wind load of roof, which is unfavorable to the wind resistance of structures.
【学位授予单位】：湖南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU312.1

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