采暖建筑结构屋面雪荷载实测研究
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摘要
为考虑采暖建筑热环境对屋面雪荷载取值的影响,参考国外规范ASCE/SEI 7-10和ISO 4355:2013雪荷载章节中用以量化该影响的热力系数C_t的取值,设计一种装配式可变屋顶热阻及室内采暖温度的建筑实测模型,并完成对屋面自然降雪(低含水率)及人工造雪(高含水率)表观密度与雪荷载值在融雪期(日最高气温大于0℃)与非融雪期(日最高气温不大于0℃)的实测研究。结果表明,融雪期屋面积雪经历从下部融化湿润、湿润区上迁与融雪水外排的过程,其表观密度与环境温度呈正相关关系,而雪荷载值变化呈现出明显的"三段式"形式,即湿润段、质量损失段及再结晶段。相比而言,采暖建筑屋面积雪在非融雪期变化远小于融雪期的,但二者屋面雪荷载值均反映出随屋顶热量损失的增加而减小的规律。最后依据GB 50189—2015和JGJ 134—2010,计算出各组工况下用以量化计算建筑采暖影响的热力系数C_t值,并对室内需维持在0℃左右的建筑建议该系数取值1. 2。
In order to explore the influence of the building thermal environment on the roof snow load,a prefabricated building model for actual measurement was designed based on the requirement of the law of thermal coefficient (C_t) in foreign building load codes (ASCE/SEI 7-10 and ISO 4355: 2013). The proposed model can change the heat resistance of roof and indoor temperature. In detail,the actual measurements of apparent density of snow and snow load under natural snow (with low moisture) and artificial snow (with high moisture) conditions in both the snowmelt period (with daily maximum temperature higher than 0 ℃) and the non-snowmelt period (with daily maximum temperature not higher than 0 ℃) were completed. The results show that the snow-layer on the building roof in the snowmelt period experiences the stages of the melt of lower surface snow,and then upward movement of melt layer with discharge of the snowmelt water. The apparent density and environmental temperature of snow show a positively correlated relationship while the variation of snow load appears a typical three-stage form,including the melting,the mass-loss and the recrystallization. Besides,the variation of snow-layer on the building roof in the non-snowmelt period is less than that in the snowmelt period,but the trend is highly consistent,where the snow load decreases with the increasing of roof heat loss. Finally,according to GB 50189—2015 and JGJ 134—2010,the thermal coefficient values of all measured conditions were calculated,and the C_tvalue of the building with the indoor maximum temperature about 0 ℃ was suggested to be 1. 2.
In order to explore the influence of the building thermal environment on the roof snow load,a prefabricated building model for actual measurement was designed based on the requirement of the law of thermal coefficient (C_t) in foreign building load codes (ASCE/SEI 7-10 and ISO 4355: 2013). The proposed model can change the heat resistance of roof and indoor temperature. In detail,the actual measurements of apparent density of snow and snow load under natural snow (with low moisture) and artificial snow (with high moisture) conditions in both the snowmelt period (with daily maximum temperature higher than 0 ℃) and the non-snowmelt period (with daily maximum temperature not higher than 0 ℃) were completed. The results show that the snow-layer on the building roof in the snowmelt period experiences the stages of the melt of lower surface snow,and then upward movement of melt layer with discharge of the snowmelt water. The apparent density and environmental temperature of snow show a positively correlated relationship while the variation of snow load appears a typical three-stage form,including the melting,the mass-loss and the recrystallization. Besides,the variation of snow-layer on the building roof in the non-snowmelt period is less than that in the snowmelt period,but the trend is highly consistent,where the snow load decreases with the increasing of roof heat loss. Finally,according to GB 50189—2015 and JGJ 134—2010,the thermal coefficient values of all measured conditions were calculated,and the C_tvalue of the building with the indoor maximum temperature about 0 ℃ was suggested to be 1. 2.
引文
[1]章诞武,丛振涛,倪广恒.1956-2010年中国降雪特征变化[J].清华大学学报(自然科学版),2016,56(4):381-386.(ZHANG Danwu,CONG Zhentao,NI Guangheng.Snowfall changes in China during1956-2010[J].Journal of Tsinghua University(Science and Technology),2016,56(4):381-386.(in Chinese))
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[3]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))
[4]梁志远,张航,杨蔚彪.中美规范雪荷载取值方法比较[C]//第12届中国钢协结构稳定与疲劳分会学术交流会暨教学研讨会.北京:中国钢协结构稳定与疲劳分会,2010:899-903.
[5]罗刚.中美荷载规范雪荷载计算方法的比较[J].安徽建筑,2010,17(6):136-138.
[6]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))
[7]甘晨卉.揭秘中国供暖分界线为什么被视为“时代错误”[EB/OL].(2014-11-18)[2018-07-09].http://www.hinews.cn/news/system/2014/11/18/017123712.shtml.
[8]ASCE.Minimum design loads for buildings and other structures:ASCE/SEI 7-10[S].Reston,VA:ASCE,2011.
[9]BSI.Eurocode1:actions on structures:part 1-3:general actions:snow loads:EN 1991-1-3:2003[S].London:BSI,2003.
[10]IHS.Bases for design of structures:determination of snow loads on roofs:ISO 4355:2013(E)[S].Geneva,Switzerland:IHS,2013.
[11]SACK R L,BURKE G G,PENNINGROTH J.Automated data acquisition for structural snow loads[C]//Proceedings of the 41st Eastern Snow Conference.New Carrolton,MD:ESC,1984:118-127.
[12]Structural Engineers Association of Washington(SEAW).An analysis of building structural failures,due to the holiday snow storms[R].Gig Harbor,WA:SEAW,1998.
[13]BAUMGARTNER A M,SACK P L,SCHELDOR J J.Thermal characteristics of a double roof[C]//First International Conference on Snow Engineering.Santa Barbara,California:CRREL,1988:107-117.
[14]LEPAGE M,SCHUYLER G.A simulation to predict snow sliding and lift-off on buildings[C]//First International Conference on Snow Engineering.Santa Barbara,California:CRREL,1988:128-141.
[15]NIELSEN A.Snow-melting and snow loads on glass roofs[C]//First International Conference on Snow Engineering.Santa Barbara,California:CRREL,1988:167-177.
[16]IRWIN P A,GAMBLE S L,TAYLOR D A.Effects of roof size,heat transfer,and climate on snow loads:studies for the 1995 NBC[J].Canadian Journal of Civil Engineering,1995,22(4):770-784.
[17]O’ROURKE M,WIKOFF J.Snow related roof collapse and implications for building codes[J].Structural Forensics,2013,73(1):18-21.
[18]CLAESSON J,NIELSEN A.Melting of snow on a roof[R].Goteborg,Sweden:Department of Civil and Environmental Engineering,Chalmers University of Technology,2011.
[19]FUKAZAWA D.The snow melting performance of the natural snow melting roof in the wet snow heavy snowfall area-at Tochio Harumachi in case of 2012 winter[J].Research Bulletin of Niigata Institute of Technology,2012,17(1):35-44.
[20]FUJIMOTO A,TERASAKI H,FUKUHARA T.A roof snow load model by a heat,ice,water and air balance method[J].Journal of Japan Society of Civil Engineers,2014,70(4):427-432.
[21]ZHOU Xuanyi,LI Jialiang,GU Ming,et al.A new simulation method on sliding snow load on sloped roofs[J].Natural Hazards,2015,77(1):39-65.
[22]夏热冬冷地区居住建筑节能设计标准:JGJ 134-2010[S].北京:中国建筑工业出版社,2010.(Design standard for energy efficiency of residential buildings in hot summer and cold winter zone:JGJ134-2010[S].Beijing:China Architecture&Building Press,2010.(in Chinese))
[23]公共建筑节能设计标准:GB 50189-2015[S].北京:中国建筑工业出版社,2015.(Design standard for energy efficiency public buildings:GB 50189-2015[S].Beijing:China Architecture&Building Press,2015.(in Chinese))
[24]COLBECK S,AKITAYA E,ARMSTRONG R,et al.The international classification for seasonal snow on the ground[R].Hanover,NH:International Association of Scientific Hydrology,1990.
[25]王世玉.屋面积雪的实测与风洞试验基础研究[D].哈尔滨:哈尔滨工业大学,2013:10.(WANG Shiyu.Basic research on field measurement and wind tunnel test of snow on roofs[D].Harbin:Harbin Institute of Technology,2013:10.(in Chinese))
[2]薛旭霞.南方部分地区低温冷冻和雪灾已造成540余万人受灾[EB/OL].(2018-02-01)[2018-07-09].http://www.jianzai.gov.cn//DRpublish/ywcp/0000000000027786.html.
[3]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))
[4]梁志远,张航,杨蔚彪.中美规范雪荷载取值方法比较[C]//第12届中国钢协结构稳定与疲劳分会学术交流会暨教学研讨会.北京:中国钢协结构稳定与疲劳分会,2010:899-903.
[5]罗刚.中美荷载规范雪荷载计算方法的比较[J].安徽建筑,2010,17(6):136-138.
[6]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))
[7]甘晨卉.揭秘中国供暖分界线为什么被视为“时代错误”[EB/OL].(2014-11-18)[2018-07-09].http://www.hinews.cn/news/system/2014/11/18/017123712.shtml.
[8]ASCE.Minimum design loads for buildings and other structures:ASCE/SEI 7-10[S].Reston,VA:ASCE,2011.
[9]BSI.Eurocode1:actions on structures:part 1-3:general actions:snow loads:EN 1991-1-3:2003[S].London:BSI,2003.
[10]IHS.Bases for design of structures:determination of snow loads on roofs:ISO 4355:2013(E)[S].Geneva,Switzerland:IHS,2013.
[11]SACK R L,BURKE G G,PENNINGROTH J.Automated data acquisition for structural snow loads[C]//Proceedings of the 41st Eastern Snow Conference.New Carrolton,MD:ESC,1984:118-127.
[12]Structural Engineers Association of Washington(SEAW).An analysis of building structural failures,due to the holiday snow storms[R].Gig Harbor,WA:SEAW,1998.
[13]BAUMGARTNER A M,SACK P L,SCHELDOR J J.Thermal characteristics of a double roof[C]//First International Conference on Snow Engineering.Santa Barbara,California:CRREL,1988:107-117.
[14]LEPAGE M,SCHUYLER G.A simulation to predict snow sliding and lift-off on buildings[C]//First International Conference on Snow Engineering.Santa Barbara,California:CRREL,1988:128-141.
[15]NIELSEN A.Snow-melting and snow loads on glass roofs[C]//First International Conference on Snow Engineering.Santa Barbara,California:CRREL,1988:167-177.
[16]IRWIN P A,GAMBLE S L,TAYLOR D A.Effects of roof size,heat transfer,and climate on snow loads:studies for the 1995 NBC[J].Canadian Journal of Civil Engineering,1995,22(4):770-784.
[17]O’ROURKE M,WIKOFF J.Snow related roof collapse and implications for building codes[J].Structural Forensics,2013,73(1):18-21.
[18]CLAESSON J,NIELSEN A.Melting of snow on a roof[R].Goteborg,Sweden:Department of Civil and Environmental Engineering,Chalmers University of Technology,2011.
[19]FUKAZAWA D.The snow melting performance of the natural snow melting roof in the wet snow heavy snowfall area-at Tochio Harumachi in case of 2012 winter[J].Research Bulletin of Niigata Institute of Technology,2012,17(1):35-44.
[20]FUJIMOTO A,TERASAKI H,FUKUHARA T.A roof snow load model by a heat,ice,water and air balance method[J].Journal of Japan Society of Civil Engineers,2014,70(4):427-432.
[21]ZHOU Xuanyi,LI Jialiang,GU Ming,et al.A new simulation method on sliding snow load on sloped roofs[J].Natural Hazards,2015,77(1):39-65.
[22]夏热冬冷地区居住建筑节能设计标准:JGJ 134-2010[S].北京:中国建筑工业出版社,2010.(Design standard for energy efficiency of residential buildings in hot summer and cold winter zone:JGJ134-2010[S].Beijing:China Architecture&Building Press,2010.(in Chinese))
[23]公共建筑节能设计标准:GB 50189-2015[S].北京:中国建筑工业出版社,2015.(Design standard for energy efficiency public buildings:GB 50189-2015[S].Beijing:China Architecture&Building Press,2015.(in Chinese))
[24]COLBECK S,AKITAYA E,ARMSTRONG R,et al.The international classification for seasonal snow on the ground[R].Hanover,NH:International Association of Scientific Hydrology,1990.
[25]王世玉.屋面积雪的实测与风洞试验基础研究[D].哈尔滨:哈尔滨工业大学,2013:10.(WANG Shiyu.Basic research on field measurement and wind tunnel test of snow on roofs[D].Harbin:Harbin Institute of Technology,2013:10.(in Chinese))