钢筋混凝土梁托柱转换结构节点耐火性能分析
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摘要
为提供钢筋混凝土梁托柱转换结构的防火设计依据,根据结构的受力特点,设计了两种足尺梁托柱节点单元试件,对两种节点单元试件进行了热力耦合作用下的耐火性能试验;采用有限元分析软件进行数值计算,分析了火灾下钢筋混凝土梁托柱节点单元的热力耦合耐火极限,得出各参数变化对梁托柱节点单元耐火极限变化规律.分析结果表明:升温曲线及最高温度对节点单元的耐火极限影响较大;荷载比为0.6的节点单元比荷载比为0.4节点单元耐火极限小;节点单元托梁纵向受拉钢筋的保护层厚度不同,其耐火极限从大到小为保护层厚度50 mm、保护层厚度40 mm、保护层厚度25 mm;转换托梁中受托柱处附加吊筋的设置可有效提高节点单元的耐火极限,并起到避免发生突然破坏的作用;节点单元托梁四面受火的耐火极限小于三面受火的耐火极限;在相同荷载比及相同受火工况作用下,两种钢筋混凝土梁托柱节点单元的耐火极限和破坏特点不同.
To provide the basis for the fire prevention design of reinforced concrete beam supporting column transfer structures, according to the structural characteristics, two kinds of full size beam supporting column transfer structure joints are designed. The reinforced concrete beam supporting column transfer structure joints are exposed to fire,and their fire resistance is tested. Based on the test results,using ABAQUS —a finite element analysis software, considering the influence of raising temperature curve, loading ratio, protective layer thickness,additional steel bars,the number of surfaces in fire of a transfer girder,the fire resistance of beam supporting column transfer structure joints is analyzed and the variation of the fire resistance for these beam supporting column transfer structure joints is summarized. The analysis results show that heating curve and maximum temperature have a significant influence on fire resistance;the fire resistance limit of joint units with load ratio of 0.6 is smaller than that of joint units with load ratio of 0.4;the thickness of the protective layer of the longitudinal tensile reinforcement of the joint unit differs,while the fire resistance limit ranges from large to small for protective layer thickness of 50 mm,40 mm,and 25 mm,respectively;hanging steel bars in the transfer girder can improve the fire resistance and help avoid sudden damage. The more surfaces of the transfer girder are in fire,the shorter is the fire resistance. Under the same loading ratio,two kinds of beam supporting column transfer structure joints have different damage characteristics and fire resistance.
To provide the basis for the fire prevention design of reinforced concrete beam supporting column transfer structures, according to the structural characteristics, two kinds of full size beam supporting column transfer structure joints are designed. The reinforced concrete beam supporting column transfer structure joints are exposed to fire,and their fire resistance is tested. Based on the test results,using ABAQUS —a finite element analysis software, considering the influence of raising temperature curve, loading ratio, protective layer thickness,additional steel bars,the number of surfaces in fire of a transfer girder,the fire resistance of beam supporting column transfer structure joints is analyzed and the variation of the fire resistance for these beam supporting column transfer structure joints is summarized. The analysis results show that heating curve and maximum temperature have a significant influence on fire resistance;the fire resistance limit of joint units with load ratio of 0.6 is smaller than that of joint units with load ratio of 0.4;the thickness of the protective layer of the longitudinal tensile reinforcement of the joint unit differs,while the fire resistance limit ranges from large to small for protective layer thickness of 50 mm,40 mm,and 25 mm,respectively;hanging steel bars in the transfer girder can improve the fire resistance and help avoid sudden damage. The more surfaces of the transfer girder are in fire,the shorter is the fire resistance. Under the same loading ratio,two kinds of beam supporting column transfer structure joints have different damage characteristics and fire resistance.
引文
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[14]European Committee for Standardization.Eurocode 3,design of steel structures,part 1-2:structural fire design:ENV 1993-1-2[S].Brussels:[s.n.],1993.
[2]李国强,韩林海,楼国彪等.钢结构及钢-混凝土组合结构抗火设计[M].北京:中国建筑工业出版社,2006:5-9.
[3]过镇海,时旭东.钢筋混凝土的高温性能及其计算[M].北京:清华大学出版社,2003:1-4.
[4]吴波.火灾后钢筋混凝土结构的力学性能[M].北京:科学出版社,2003:1-14.
[5]董毓利.混凝土结构的火安全设计[M].北京:科学出版社,2001:55-57.
[6]陆洲导.钢筋混凝土梁对火灾反应的研究[D].上海:同济大学,1989.
[7]傅传国,孔维一,宋师雷,等.火灾作用下钢筋混凝土托梁转换结构模型变形有限元分析[J].建筑结构学报,2015,36(S2):175-182.FU Chuanguo,KONG Weiyi,SONG Shilei,et al.Deformation analysis of reinforced concrete structure with bearing column girder transfer floor under fire conditions[J].Journal of Building Structures,2015,36 (S2):175-182.
[8]孔维一,傅传国,褚飞,等.钢筋混凝土叠层空腹桁架转换结构热力耦合反应分析[J].防灾减灾工程学报,2016,36(3):386-393.KONG Weiyi,FU Chuanguo,CHU Fei,et al.Thermal mechanical coupling analysis of reinforced concrete transfer structure with superimposed vierendeel truss[J].Journal of Disaster Prevention and Mitigation Engineering,2016,36(3):386-393.
[9]中国国家标准化管理委员会.建筑构件耐火试验方法:GB/T 9978.8-2008[S].北京:中国标准出版社,2008.
[10]International Organization for Standardization.fireresistance tests elements of building construction:ISO834[S].Geneva:International Standard Organization,1980.
[11]LIE T T,DENHAM E M A.Factors affecting the fire resistance of circular hollow steel columns filled with bar-reinforced concrete[R].Canada:National Research Council of Canada,1993.
[12]LIE T T,LIN T D,ALLEN D E,et al.Fire resistance of reinforced concrete columns[R].Ottawa:National Research Council of Canada,1984.
[13]过镇海,李卫.混凝土耐热力学性能的试验研究总结[R].北京:清华大学土木工程系.1991.
[14]European Committee for Standardization.Eurocode 3,design of steel structures,part 1-2:structural fire design:ENV 1993-1-2[S].Brussels:[s.n.],1993.