基于规范对比的女儿墙屋面雪荷载实测分析
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摘要
在女儿墙屋面雪荷载计算时,日本、美国及欧洲规范中充分考虑了风场对完全暴露屋面雪荷载的侵蚀作用、风力对积雪的搬运作用、上游积雪宽度对下游阻碍物处堆雪量的补充作用和降雪量对堆雪的补充作用。除此之外,也引入了室内采暖、雨雪联合等因素来更真实地实现对屋面雪荷载的估算。相较之下,我国规范仅考虑女儿墙高度的影响。故基于对带女儿墙屋面积雪分布的多年实测结果,参考国外规范中的影响因素,对哈尔滨地区女儿墙屋面积雪分布特征进行了分析。结果显示:风场作用下,积雪会更多地堆积于迎风向女儿墙处;随着上游屋面宽度增加,下游迎风向女儿墙处漂移积雪的峰值深度存在递增趋势,且随着风速增加,搬移堆积作用会增强;上游屋面宽度和地面降雪量对女儿墙处峰值雪深有较大影响,风速对于峰值雪深的影响依赖于地面降雪量,降雪越大,风速的影响越大,反之减小;女儿墙处堆雪长度与女儿墙高度比值多维持在3. 75左右,建议我国规范中堆雪长度与女儿墙高度比值取4. 0。
In the calculation of the snow load on the roof with parapets,standards of Japan,America,and Europe have given full consideration to the erosion effect on the snow load of the fully exposed roof caused by wind field,the movement of snow induced by wind,the supplementation of upstream snow to snow heaped up around downstream obstruction. In addition,factors such as the indoor heating and the combined effect of rain and snow are introduced to realize an accurate estimation of snow load on building roofs. By contrast,the Chinese code only considers the influence of the parapet height. Therefore,based on the measured snow distribution on an actual parapet roof on ages and the influencing factors in foreign codes introduced above,the snow distribution characteristics on the parapet roof were analyzed. The results show that: more snow is blown downstream towards the parapet; the peak snow depth close to the downstream parapet is proportional to the upstream roof width,and with an increasing wind velocity,the drifting effect is enhanced; the upstream roof width and the ground snow load have a great influence on the peak snow depth at the parapet,and the influence of wind velocity depends on the ground snow load; the larger the ground snow load is,the greater influence the wind velocity has; the ratio of the snowdrift length to the parapet height is around 3. 75,and it is suggested to adopt a value of 4. 0 in Chinese code.
In the calculation of the snow load on the roof with parapets,standards of Japan,America,and Europe have given full consideration to the erosion effect on the snow load of the fully exposed roof caused by wind field,the movement of snow induced by wind,the supplementation of upstream snow to snow heaped up around downstream obstruction. In addition,factors such as the indoor heating and the combined effect of rain and snow are introduced to realize an accurate estimation of snow load on building roofs. By contrast,the Chinese code only considers the influence of the parapet height. Therefore,based on the measured snow distribution on an actual parapet roof on ages and the influencing factors in foreign codes introduced above,the snow distribution characteristics on the parapet roof were analyzed. The results show that: more snow is blown downstream towards the parapet; the peak snow depth close to the downstream parapet is proportional to the upstream roof width,and with an increasing wind velocity,the drifting effect is enhanced; the upstream roof width and the ground snow load have a great influence on the peak snow depth at the parapet,and the influence of wind velocity depends on the ground snow load; the larger the ground snow load is,the greater influence the wind velocity has; the ratio of the snowdrift length to the parapet height is around 3. 75,and it is suggested to adopt a value of 4. 0 in Chinese code.
引文
[1]唐悦.江苏因雪灾造成直接经济损失4100多万元,苏南部分地区受灾严重[EB/OL].(2018-01-31)[2019-01-21].http://jsnews.jschina.com.cn/jsyw/201801/t20180131_1387045.shtml.
[2]TOMINAGA Y,OKAZE T,MOCHIDA A.CFDsimulation of drift snow loads for an isolated gable-roof building[C]//8th International Conference on Snow Engineering.Nantes:Centre Scientifique et Technique du Btiment,2016:208-214.
[3]TOMINAGA Y,MOCHIDA A.CFD prediction of flowfield and snowdrift around a building complex in a snowy region[J].Journal of Wind Engineering and Industrial Aerodynamics,1999,81:273-282.
[4]DELPECH P,PALIER P,GANDEMER J.Snowdrifting simulation around antarctic buildings[J].Journal of Wind Engineering and Industrial Aerodynamics,1998,74/75/76:567-576.
[5]FLAGA A,FLAGA.Wind tunnel tests and analysis of snow load distribution on three different large size stadium roofs[C]//8th International Conference on Snow Engineering.Nantes:Centre Scientifique et Technique du Btiment,2016:232-239.
[6]THIIS T K.Large scale studies of development of snowdrifts around buildings[J].Journal of Wind Engineering and Industrial Aerodynamics,2003,91(6):829-839.
[7]莫华美.典型屋面积雪分布的数值模拟与实测研究[D].哈尔滨:哈尔滨工业大学,2012:23-36.(MOHuamei.Numerical simulation and experimental study of snow distribution on typical roofs[D].Harbin:Harbin Institute of Technology,2012:23-36.(in Chinese))
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[9]范峰,莫华美,洪汉平.中、美、加、欧屋面雪荷载规范对比[J].哈尔滨工业大学学报,2011,43(12):18-22.(FAN Feng,MO Huamei,HONG Hanping.Comparison of snow load requirements in design codes used in China,USA,Canada and EU[J].Journal of Harbin Institute of Technology,2011,43(12):18-22.(in Chinese))
[10]建筑结构荷载规范:GB 50009-2012[S].北京:中国建筑工业出版社,2012.(Load code for the design of building structures:GB 50009-2012[S].Beijing:China Architecture&Building Press,2012.(in Chinese))
[11]AIJ.AIJ recommendations for loads on buildings[S].Tokyo:Architectural Institute of Japan,2004.
[12]ASCE.Minimum design loads for buildings and other structures:ASCE/SEI 7-05[S].Reston,VA:American Society of Civil Engineers,2010.
[13]BSI.Eurocode 1:actions on structures:part 1-3:general actions:snow loads:BS EN 1991-1-3:2003[S].London:BSI,2003.
[14]中国气象局.地面气象观测规范:QX/T 53-2007[S].北京:气象出版社,2007.(China Meteorological Administration.Specifications for surface meteorological observation:QX/T 53-2007[S].Beijing:China Meteorological Press,2007.(in Chinese))
[2]TOMINAGA Y,OKAZE T,MOCHIDA A.CFDsimulation of drift snow loads for an isolated gable-roof building[C]//8th International Conference on Snow Engineering.Nantes:Centre Scientifique et Technique du Btiment,2016:208-214.
[3]TOMINAGA Y,MOCHIDA A.CFD prediction of flowfield and snowdrift around a building complex in a snowy region[J].Journal of Wind Engineering and Industrial Aerodynamics,1999,81:273-282.
[4]DELPECH P,PALIER P,GANDEMER J.Snowdrifting simulation around antarctic buildings[J].Journal of Wind Engineering and Industrial Aerodynamics,1998,74/75/76:567-576.
[5]FLAGA A,FLAGA.Wind tunnel tests and analysis of snow load distribution on three different large size stadium roofs[C]//8th International Conference on Snow Engineering.Nantes:Centre Scientifique et Technique du Btiment,2016:232-239.
[6]THIIS T K.Large scale studies of development of snowdrifts around buildings[J].Journal of Wind Engineering and Industrial Aerodynamics,2003,91(6):829-839.
[7]莫华美.典型屋面积雪分布的数值模拟与实测研究[D].哈尔滨:哈尔滨工业大学,2012:23-36.(MOHuamei.Numerical simulation and experimental study of snow distribution on typical roofs[D].Harbin:Harbin Institute of Technology,2012:23-36.(in Chinese))
[8]张清文,王世玉,张国龙,范峰.地面与屋面积雪的实测研究[C]//第十五届空间结构学术会议.北京:中国建筑科学研究院,2014:395-399.(ZHANGQingwen,WANG Shiyu,ZHANG Guolong,FAN Feng.Field measurement of snow cover on the ground and roof[C]//15th Academic Conference on Space Structure.Beijing:China Academy of Building Research,2014:395-399.(in Chinese))
[9]范峰,莫华美,洪汉平.中、美、加、欧屋面雪荷载规范对比[J].哈尔滨工业大学学报,2011,43(12):18-22.(FAN Feng,MO Huamei,HONG Hanping.Comparison of snow load requirements in design codes used in China,USA,Canada and EU[J].Journal of Harbin Institute of Technology,2011,43(12):18-22.(in Chinese))
[10]建筑结构荷载规范:GB 50009-2012[S].北京:中国建筑工业出版社,2012.(Load code for the design of building structures:GB 50009-2012[S].Beijing:China Architecture&Building Press,2012.(in Chinese))
[11]AIJ.AIJ recommendations for loads on buildings[S].Tokyo:Architectural Institute of Japan,2004.
[12]ASCE.Minimum design loads for buildings and other structures:ASCE/SEI 7-05[S].Reston,VA:American Society of Civil Engineers,2010.
[13]BSI.Eurocode 1:actions on structures:part 1-3:general actions:snow loads:BS EN 1991-1-3:2003[S].London:BSI,2003.
[14]中国气象局.地面气象观测规范:QX/T 53-2007[S].北京:气象出版社,2007.(China Meteorological Administration.Specifications for surface meteorological observation:QX/T 53-2007[S].Beijing:China Meteorological Press,2007.(in Chinese))