传统地仗保护圆木柱受火后力学性能的试验研究
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摘要
传统木结构建筑的防火性能是制约其长期安全使用的重要因素。通过6组18根不同表面处理圆木柱受火后力学性能的对比试验研究,分析不同表面处理不同受火时间后圆木柱剩余承载力、初始刚度和炭化速度的变化规律,了解不同表面处理对圆木柱受火后力学性能的影响规律。结果表明,未受火对比试件和受火时间较短的圆木柱均呈轴压破坏特征,受火时间较长圆木柱呈偏压破坏特征。受火后试件剩余承载力较未受火对比试件降低5.3%～80.2%,降低幅度与受火时间成正比、与截面尺寸成反比;传统地仗保护试件剩余承载力损失程度明显小于表面无处理试件和表面涂抹防火涂料试件。受火后圆木柱初始刚度显著降低,降低幅度随受火时间增加而增加,有传统地仗保护试件降低幅度小于表面无处理试件。传统地仗保护试件受火炭化后表面有一层白色覆盖物,其炭化速度小于表面无处理试件。数值模拟结果与试验结果符合较好,可供传统历史木结构受火后的评估鉴定。
The fire performance of traditional timber buildings is one of the important factors restricting their long time safety. To analyze the mechanical behaviors of timbers, including residual ultimate capacity, initial stiffness and charring rate of round timber columns after different surface treatments and exposure times, 6 series and a total of 18 specimens were experimentally studied. Results showed that control specimens without exposure and round columns with short exposure time exhibited axial compressive failure, while round columns with long exposure time suffered an eccentric compressive failure. The residual ultimate load-bearing capacity of exposed specimens decreased between 5.3%～80.2%, compared to that of the control specimens. The decrease of residual ultimate load-bearing capacity was proportional to fire durations, and in inverse proportion to cross-section geometry. The reduction of residual ultimate load-bearing capacity for specimens with traditional craftwork was much lower than untreated specimens and specimens treated with fire-retardant coating. The initial stiffness of round timber columns greatly decreased after fire, and the reduction increased with fire durations.The initial stiffness for specimens with traditional craftwork was much higher than untreated specimens.Specimens with traditional craftwork had a white layer on the char, and its charring rate was smaller than the untreated specimens. The simulation results were in good agreement with the test ones, which can be used for evaluation and appraisal of traditional timber buildings after fire.
The fire performance of traditional timber buildings is one of the important factors restricting their long time safety. To analyze the mechanical behaviors of timbers, including residual ultimate capacity, initial stiffness and charring rate of round timber columns after different surface treatments and exposure times, 6 series and a total of 18 specimens were experimentally studied. Results showed that control specimens without exposure and round columns with short exposure time exhibited axial compressive failure, while round columns with long exposure time suffered an eccentric compressive failure. The residual ultimate load-bearing capacity of exposed specimens decreased between 5.3%～80.2%, compared to that of the control specimens. The decrease of residual ultimate load-bearing capacity was proportional to fire durations, and in inverse proportion to cross-section geometry. The reduction of residual ultimate load-bearing capacity for specimens with traditional craftwork was much lower than untreated specimens and specimens treated with fire-retardant coating. The initial stiffness of round timber columns greatly decreased after fire, and the reduction increased with fire durations.The initial stiffness for specimens with traditional craftwork was much higher than untreated specimens.Specimens with traditional craftwork had a white layer on the char, and its charring rate was smaller than the untreated specimens. The simulation results were in good agreement with the test ones, which can be used for evaluation and appraisal of traditional timber buildings after fire.
引文
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[2]梁思成.清工部《工程做法则例》图解[M].北京:清华大学出版社,2006
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[8]李向民,李帅希,许清风,等.四面受火木柱耐火极限的试验研究[J].建筑结构,2010,40(3):115-117(Li Xiangmin,Li Shuaixi,Xu Qingfeng,et al.Experimental research on fire endurance of timber columns exposed to four-side fire[J].Building Structure,2010,40(3):115-117(in Chinese))
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[13]冯鹏,强翰霖,叶列平.材料、构件、结构的“屈服点”定义与讨论[J].工程力学,2017,34(3):36-46(Feng Peng,Qiang Hanlin,Ye Lieping.Discussion and definition on yield points of materials,members and structures[J].Engineering Mechanics,2017,34(3):36-46(in Chinese))
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[15]Babrauskas V.Charring rate of wood as a tool for fire investigations[J].Fire Safety Journal,2005,40(6):528-554
[16]EN 1995-1-2:Eurocode 5:Design of timber structuresPart 1-2:General-Structural fire design[S].Brussels:European Committee for Standardization,2004
[17]GB 50005-2017木结构设计标准[S].北京:中国建筑工业出版社,2017(GB 50005-2017 Standard for design of timber structures[S].Beijing:China Architecture and Building Press,2017(in Chinese))
[18]李林峰.梁柱式木结构框架抗火数值模拟研究[D].南京:东南大学,2014(Li Linfeng.Numerical analysis of the fire resistance of post-beam timber frame[D].Nanjing:Southeast University,2014(in Chinese))
[19]《木结构设计手册》编辑委员会.木结构设计手册[M].第三版.北京:中国建筑工业出版社,2005
[2]梁思成.清工部《工程做法则例》图解[M].北京:清华大学出版社,2006
[3]许清风,徐强,李向民.木结构火灾性能研究进展[J].四川建筑科学研究,2011,37(4):87-92(Xu Qingfeng,Xu Qiang,Li Xiangmin.Research progress of fire performance of timber structure[J].Sichuan Building Science,2011,37(4):87-92(in Chinese))
[4]许清风,李向民,张晋,等.木柱四面受火后力学性能的试验研究[J].土木工程学报,2012,45(3):79-85,173(Xu Qingfeng,Li Xiangmin,Zhang Jin,et al.Experimental study on the mechanical behavior of timber columns after exposure to fire on four sides[J].China Civil Engineering Journal,2012,45(3):79-85,173(in Chinese))
[5]许清风,李向民,张晋,等.木梁三面受火后力学性能的试验研究[J].土木工程学报,2011,44(7):64-70(Xu Qingfeng,Li Xiangmin,Zhang Jin,et al.Experimental study of the mechanical behavior of timber beams exposed to three-side fire[J].China Civil Engineering Journal,2011,44(7):64-70(in Chinese))
[6]许清风,李向民,穆保岗,等.石灰膏抹面木梁受火后受力性能静力试验研究[J].建筑结构学报,2011,32(7):73-79(Xu Qingfeng,Li Xiangmin,Mu Baogang,et al.Static experimental research on mechanical behavior of timber beams with lime putty finishing after fire[J].Journal of Building Structures,2011,32(7):73-79(in Chinese))
[7]倪照鹏,彭磊,邱培芳,等.木结构建筑构件耐火性能试验研究[J].土木工程学报,2012,45(12):108-114(Ni Zhaopeng,Peng Lei,Qiu Peifang,et al.Experimental study on fire resistance performance of timber assemblies[J].China Civil Engineering Journal,2012,45(12):108-114(in Chinese))
[8]李向民,李帅希,许清风,等.四面受火木柱耐火极限的试验研究[J].建筑结构,2010,40(3):115-117(Li Xiangmin,Li Shuaixi,Xu Qingfeng,et al.Experimental research on fire endurance of timber columns exposed to four-side fire[J].Building Structure,2010,40(3):115-117(in Chinese))
[9]翁文国,范维澄.中国古建筑防火研究[J].消防科学与技术,2001(5):20-22
[10]陈晓军,杨立中,邓志华,等.木材在火灾环境中热解行为的数值模拟[J].燃烧科学与技术,2002,8(4):333-337(Chen Xiaojun,Yang Lizhong,Deng Zhihua,et al.A mathematical model for pyrolysis of wood in fire environment[J].Journal of Combustion Science and Technology,2002,8(4):333-337(in Chinese))
[11]文化部文物保护科研所.中国古建筑修缮技术[M].北京:中国建筑工业出版社,1983
[12]王正昌,许清风,韩重庆,等.一麻五灰传统保护处理圆木柱的耐火极限试验研究[J].建筑结构,2017,47(17):14-19(Wang Zhengchang,Xu Qingfeng,Han Chongqing,et al.Experimental study on fire endurance of round timber column with traditional craftwork with one hemp fiber and five plastering application[J].Building Structure,2017,47(17):14-19(in Chinese))
[13]冯鹏,强翰霖,叶列平.材料、构件、结构的“屈服点”定义与讨论[J].工程力学,2017,34(3):36-46(Feng Peng,Qiang Hanlin,Ye Lieping.Discussion and definition on yield points of materials,members and structures[J].Engineering Mechanics,2017,34(3):36-46(in Chinese))
[14]Buchanan A.Fire resistance of solid timber structures[R].Christchurch New Zealand:University of Canterbury,2005
[15]Babrauskas V.Charring rate of wood as a tool for fire investigations[J].Fire Safety Journal,2005,40(6):528-554
[16]EN 1995-1-2:Eurocode 5:Design of timber structuresPart 1-2:General-Structural fire design[S].Brussels:European Committee for Standardization,2004
[17]GB 50005-2017木结构设计标准[S].北京:中国建筑工业出版社,2017(GB 50005-2017 Standard for design of timber structures[S].Beijing:China Architecture and Building Press,2017(in Chinese))
[18]李林峰.梁柱式木结构框架抗火数值模拟研究[D].南京:东南大学,2014(Li Linfeng.Numerical analysis of the fire resistance of post-beam timber frame[D].Nanjing:Southeast University,2014(in Chinese))
[19]《木结构设计手册》编辑委员会.木结构设计手册[M].第三版.北京:中国建筑工业出版社,2005