配置HRB335钢筋的采用柱内搭接的框架顶层端节点抗震性能试验研究
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摘要
本文通过5个按照《混凝土结构设计规范》(GB50010-2002)设计的配置HRB335纵筋的框架顶层端节点循环加载试验,验证了现行规范中框架顶层端节点采用柱内搭接方案时的抗震性能,分析了若林实搭接方案在框架顶层端节点应用中可能存在的问题,通过在节点中上部配置附加水平箍筋,提高了节点斜截面的抗弯能力,对若林实搭接方案进行了改进。本文所针对的具体问题以及主要结论如下:
①框架顶层端节点梁、柱负弯矩钢筋的构造做法:本次试验第1个试件梁、柱负弯矩钢筋搭接方案采取《混凝土结构设计规范》(GB50010-2002)中框架顶层端节点柱内搭接方案,钢筋搭接长度等于1.7laE,柱外侧纵向钢筋伸至柱顶后向节点内水平弯折,弯折段水平投影长度为12倍纵筋直径,钢筋弯弧内直径等于6倍纵筋直径,试验结果显示此构造方案没有出现节点内穿过主弯弧柱侧端点附近及柱负弯矩筋顶点的薄弱面,验证了《混凝土结构设计规范》(GB50010-2002)规定的节点负弯矩钢筋柱内搭接方案的有效性;其余4个试件梁、柱负弯矩钢筋均采用若林实搭接方案,通过在节点中上部配置附加水平箍筋加强斜截面的抗弯能力,有效防止了节点内穿过主弯弧柱侧端点附近及柱负弯矩筋顶点的薄弱面的出现,对若林实搭接方案进行了有效的改进,并对附加箍筋的设置位置及数量进行了分析。
②框架顶层端节点梁下部钢筋锚固:《混凝土结构设计规范》(GB50010-2002)中对顶层端节点梁下部钢筋采用和中间层端节点相同的锚固措施,90°弯折锚固的要求是水平段长度不小于0.4laE,外加15d的竖直尾段。已有试验结果和本次试验结果都显示此锚固措施的效果不是很理想。本次试验第5个试件把梁下部钢筋90°弯折锚固改为末端焊接锚板锚固,试验结果显示锚固效果有所改善。
Five specimens of knee joints in reinforced concrete frames under cyclic reversed loading with HRB335 longitudinal steel designed basing on“Code for Design of Concrete Structures”(GB50010-2002) are tested, which verifies the efficiency of seismic measures in knee joints with the negative moment reinforcement and linear lapped splice joint located at outer side of column top. Meanwhile, relevant issues the application of Wakabajashi lapped method on knee joints are discussed. By disposing the horizontal stirrups in upside of knee joint, the bending resistance of oblique section in knee joint has been improved, and the Wakabajashi lapped method has been developed. The main points and conclusions are summarized as following:
①Construction measures of knee joints in reinforced concrete frames in which the steel bears beam and column negative moment: The first specimen is tested through the method of locating the negative moment reinforcement linear lapped splice joint at outer side of column top according to“Code for Design of Concrete Structures”(GB50010-2002), in which the column flank longitudinal reinforcement horizontally bends to knee joint after its extending to the top of column, the bend length is 12 times of longitudinal steel diameters, the overlapping length in the knee joints is 1.7laE and the inner diameter is equal to 6d. The results of the test illustrate that the weak surface through the ratius of main bar and the apex of the negative moment reinforcement has not appeared. It also proves the efficiency of seismic measures in knee joints which designed basing on“Code for Design of Concrete Structures”(GB50010-2002). Other four specimens adopt Wakabajashi lapped method. And by disposing the horizontal stirrups in upside of knee joint, the bending resistance of oblique section in knee joint has been improved, and the Wakabajashi lapped method has been developed. Moreover, the located position and quantity of the additional horizontal stirrups has been analyzed.
②The anchorage of bottom beam bars of knee joints in reinforced concrete frames: according to“Code for Design of Concrete Structures”(GB50010-2002), the anchorage measures of bottom beam bars in exterior joints is the same with that of knee joints in reinforced concrete frames. Meanwhile, the horizontal length of 90°hooked anchorage should be no less than 0.4laE and the length of end piece should be no less than 15 times of longitudinal steel diameters. The current test shows that the anchorage measure is not effective enough. But the anchorage measure has been improved when the bottom beam bars of the fifth specimen anchored with anchor plate.
①框架顶层端节点梁、柱负弯矩钢筋的构造做法:本次试验第1个试件梁、柱负弯矩钢筋搭接方案采取《混凝土结构设计规范》(GB50010-2002)中框架顶层端节点柱内搭接方案,钢筋搭接长度等于1.7laE,柱外侧纵向钢筋伸至柱顶后向节点内水平弯折,弯折段水平投影长度为12倍纵筋直径,钢筋弯弧内直径等于6倍纵筋直径,试验结果显示此构造方案没有出现节点内穿过主弯弧柱侧端点附近及柱负弯矩筋顶点的薄弱面,验证了《混凝土结构设计规范》(GB50010-2002)规定的节点负弯矩钢筋柱内搭接方案的有效性;其余4个试件梁、柱负弯矩钢筋均采用若林实搭接方案,通过在节点中上部配置附加水平箍筋加强斜截面的抗弯能力,有效防止了节点内穿过主弯弧柱侧端点附近及柱负弯矩筋顶点的薄弱面的出现,对若林实搭接方案进行了有效的改进,并对附加箍筋的设置位置及数量进行了分析。
②框架顶层端节点梁下部钢筋锚固:《混凝土结构设计规范》(GB50010-2002)中对顶层端节点梁下部钢筋采用和中间层端节点相同的锚固措施,90°弯折锚固的要求是水平段长度不小于0.4laE,外加15d的竖直尾段。已有试验结果和本次试验结果都显示此锚固措施的效果不是很理想。本次试验第5个试件把梁下部钢筋90°弯折锚固改为末端焊接锚板锚固,试验结果显示锚固效果有所改善。
Five specimens of knee joints in reinforced concrete frames under cyclic reversed loading with HRB335 longitudinal steel designed basing on“Code for Design of Concrete Structures”(GB50010-2002) are tested, which verifies the efficiency of seismic measures in knee joints with the negative moment reinforcement and linear lapped splice joint located at outer side of column top. Meanwhile, relevant issues the application of Wakabajashi lapped method on knee joints are discussed. By disposing the horizontal stirrups in upside of knee joint, the bending resistance of oblique section in knee joint has been improved, and the Wakabajashi lapped method has been developed. The main points and conclusions are summarized as following:
①Construction measures of knee joints in reinforced concrete frames in which the steel bears beam and column negative moment: The first specimen is tested through the method of locating the negative moment reinforcement linear lapped splice joint at outer side of column top according to“Code for Design of Concrete Structures”(GB50010-2002), in which the column flank longitudinal reinforcement horizontally bends to knee joint after its extending to the top of column, the bend length is 12 times of longitudinal steel diameters, the overlapping length in the knee joints is 1.7laE and the inner diameter is equal to 6d. The results of the test illustrate that the weak surface through the ratius of main bar and the apex of the negative moment reinforcement has not appeared. It also proves the efficiency of seismic measures in knee joints which designed basing on“Code for Design of Concrete Structures”(GB50010-2002). Other four specimens adopt Wakabajashi lapped method. And by disposing the horizontal stirrups in upside of knee joint, the bending resistance of oblique section in knee joint has been improved, and the Wakabajashi lapped method has been developed. Moreover, the located position and quantity of the additional horizontal stirrups has been analyzed.
②The anchorage of bottom beam bars of knee joints in reinforced concrete frames: according to“Code for Design of Concrete Structures”(GB50010-2002), the anchorage measures of bottom beam bars in exterior joints is the same with that of knee joints in reinforced concrete frames. Meanwhile, the horizontal length of 90°hooked anchorage should be no less than 0.4laE and the length of end piece should be no less than 15 times of longitudinal steel diameters. The current test shows that the anchorage measure is not effective enough. But the anchorage measure has been improved when the bottom beam bars of the fifth specimen anchored with anchor plate.
引文
[1]中华人民共和国国家标准GB 50011—2001.建筑抗震设计规范[S]. 2001.
[2] IBC 2006. International Building Code[S]. International Code Council. Inc. 2006.
[3] ASCE/SEI 7-05. Minimum Design Loads for Buildings and Other Structures[S]. American Society of Civil Engineers. 2005.
[4] NBCC2005. National Building Code of Canada 2005[S]. Institute for Research in Construction. National Research Council of Canada. Ottawa. 2005.
[5] CEN/TC 250(2003). PrEN 1998-1 Eurocode 8: Design of Structures for Earthquake Resistance. Part 1: General Rules, Seismic Actions and Rules for Buildings. Final Draft Dec. 2003.
[6] UBC 1997: Uniform Building Code[S]. International Council of Building Officials (ICBO). Whittier, California. 1997.
[7] Fib (CEB-FIP). Seismic Design of Reinforced Concrete Structures for Controlled Inelastic Response(Design concepts)[R]. 2003.
[8] Fib (CEB-FIP).白绍良译.控制非弹性反应的钢筋混凝土结构抗震设计(设计原理)[R].重庆大学土木工程学院. 2003.
[9]吴雪萍.考虑R–μ规律及其它综合影响的二级抗震措施改进方案研究[D].重庆大学. 2007.5
[10]白绍良,周起敬等.钢筋混凝土现浇框架顶层边节点的静力及抗震性能试验研究[R] .重庆建筑工程学院. 1991.
[11]刘兰花.多自由度体系R–μ规律初步分析及超静定次数对结构超强的影响[D].重庆大学. 2007.5
[12]韦锋.钢筋混凝土框架和框架-剪力墙结构非弹性地震反应性态的识别[D].重庆大学. 2005
[13]李刚强.抗震设计的R–μ基本准则及钢筋混凝土典型框架结构超强特征分析[D].重庆大学. 2006
[14]韦锋,李英民,傅剑平,白绍良.对我国钢筋混凝土框架抗震性态控制效果的识别[J].土木工程学报, 2008, 41(4):8-16.
[15]林书佚.基于非线性动力分析的框-筒结构抗震规定及节点抗剪设计方法的验证[D].重庆大学. 2005.5
[16] Architectural Institute of Japan(1990). Design Guidelines for Earthquake Resistant Reinforced Concrete Buildings Based on Ultimate Strength Concept, November 1990.
[17]傅剑平.钢筋混凝土框架节点抗震性能与设计方法研究[D].重庆大学. 2002.
[18]中华人民共和国国家标准GB 50010—2002.混凝土结构设计规范[S]. 2002.
[19]冯长征.配置HRB500钢筋的框架顶层端节点抗震性能研究[D].重庆大学.2007.5
[20] Cote,P.A., Wallace,J.W., 1994. A study of reinforced concrete knee joints subjected to cyclic lateral loading. Report No.CU/CEE 94/04, Department of Civil Engineering, Clarkson University, Potsdam, New York, 143pp.
[21] Mazzoni,S., Moehle,J.P., Thewalt,C.R., 1991. Cyclic response if RC beam-column knee joints-Test and retrofit.Report No.UCB/EERC-91/14, EERC and Dept.of Civil Engineering, Berkeley, California, 18pp.
[22] Mcconnell,S.W., Wallace,J.W., 1994. A study of the cyclic behavior of reinforced concrete knee joints. Report No.CU/CEE 94/11, Structural Engineering Mechanics and Materials, Clarkson Univesity, New York.
[23] Megget,L.M.. The Seismic Design and Performance of Reinforced Concrete Beam-Column Knee Joints in Buildings[J]. Earthquake Spectra, 2003, 19(4):863-895.
[24] Ingham,J.M., Priestley,M.J.N., Seible,F., 1994. Seismic performance of bridge knee joints. Report No.SSRP 94/12, Structural System Research, University of California, San Diego, La Jolla, California.
[25] Wallace, J. W.; McConnell, S. W.; Gupta, P.; and Cote, P. A.. "Use of Headed Reinforcement in Beam-Column Joints Subjected to Earthquake Loads" , ACI Structural Journal, V. 95, No. 5, Sept.-Oct. 1998, pp. 590-606.
[26] NZS3101. Concrete Structures Standards[S]. New Zealand. Wellington. 1995.
[27] ACI-ASCE Committee 352, Recommendations for Design of Beam-Column Connections in Monolithic Reinforced Concrete Structures. 2002.
[28]粘结锚固专题组.钢筋混凝土粘结锚固的研究及设计建议[J].建筑结构学报, 1986, 7(4).
[29]邵卓民,沈文都,徐有邻.钢筋混凝土的锚固可靠度及锚固设计[J].建筑结构, 1987, 17(4):36-49.
[30]周兴杰.框架边柱节点90°弯折月牙纹锚固钢筋粘结锚固性能地试验研究[D].重庆建筑工程学院. 1988.
[2] IBC 2006. International Building Code[S]. International Code Council. Inc. 2006.
[3] ASCE/SEI 7-05. Minimum Design Loads for Buildings and Other Structures[S]. American Society of Civil Engineers. 2005.
[4] NBCC2005. National Building Code of Canada 2005[S]. Institute for Research in Construction. National Research Council of Canada. Ottawa. 2005.
[5] CEN/TC 250(2003). PrEN 1998-1 Eurocode 8: Design of Structures for Earthquake Resistance. Part 1: General Rules, Seismic Actions and Rules for Buildings. Final Draft Dec. 2003.
[6] UBC 1997: Uniform Building Code[S]. International Council of Building Officials (ICBO). Whittier, California. 1997.
[7] Fib (CEB-FIP). Seismic Design of Reinforced Concrete Structures for Controlled Inelastic Response(Design concepts)[R]. 2003.
[8] Fib (CEB-FIP).白绍良译.控制非弹性反应的钢筋混凝土结构抗震设计(设计原理)[R].重庆大学土木工程学院. 2003.
[9]吴雪萍.考虑R–μ规律及其它综合影响的二级抗震措施改进方案研究[D].重庆大学. 2007.5
[10]白绍良,周起敬等.钢筋混凝土现浇框架顶层边节点的静力及抗震性能试验研究[R] .重庆建筑工程学院. 1991.
[11]刘兰花.多自由度体系R–μ规律初步分析及超静定次数对结构超强的影响[D].重庆大学. 2007.5
[12]韦锋.钢筋混凝土框架和框架-剪力墙结构非弹性地震反应性态的识别[D].重庆大学. 2005
[13]李刚强.抗震设计的R–μ基本准则及钢筋混凝土典型框架结构超强特征分析[D].重庆大学. 2006
[14]韦锋,李英民,傅剑平,白绍良.对我国钢筋混凝土框架抗震性态控制效果的识别[J].土木工程学报, 2008, 41(4):8-16.
[15]林书佚.基于非线性动力分析的框-筒结构抗震规定及节点抗剪设计方法的验证[D].重庆大学. 2005.5
[16] Architectural Institute of Japan(1990). Design Guidelines for Earthquake Resistant Reinforced Concrete Buildings Based on Ultimate Strength Concept, November 1990.
[17]傅剑平.钢筋混凝土框架节点抗震性能与设计方法研究[D].重庆大学. 2002.
[18]中华人民共和国国家标准GB 50010—2002.混凝土结构设计规范[S]. 2002.
[19]冯长征.配置HRB500钢筋的框架顶层端节点抗震性能研究[D].重庆大学.2007.5
[20] Cote,P.A., Wallace,J.W., 1994. A study of reinforced concrete knee joints subjected to cyclic lateral loading. Report No.CU/CEE 94/04, Department of Civil Engineering, Clarkson University, Potsdam, New York, 143pp.
[21] Mazzoni,S., Moehle,J.P., Thewalt,C.R., 1991. Cyclic response if RC beam-column knee joints-Test and retrofit.Report No.UCB/EERC-91/14, EERC and Dept.of Civil Engineering, Berkeley, California, 18pp.
[22] Mcconnell,S.W., Wallace,J.W., 1994. A study of the cyclic behavior of reinforced concrete knee joints. Report No.CU/CEE 94/11, Structural Engineering Mechanics and Materials, Clarkson Univesity, New York.
[23] Megget,L.M.. The Seismic Design and Performance of Reinforced Concrete Beam-Column Knee Joints in Buildings[J]. Earthquake Spectra, 2003, 19(4):863-895.
[24] Ingham,J.M., Priestley,M.J.N., Seible,F., 1994. Seismic performance of bridge knee joints. Report No.SSRP 94/12, Structural System Research, University of California, San Diego, La Jolla, California.
[25] Wallace, J. W.; McConnell, S. W.; Gupta, P.; and Cote, P. A.. "Use of Headed Reinforcement in Beam-Column Joints Subjected to Earthquake Loads" , ACI Structural Journal, V. 95, No. 5, Sept.-Oct. 1998, pp. 590-606.
[26] NZS3101. Concrete Structures Standards[S]. New Zealand. Wellington. 1995.
[27] ACI-ASCE Committee 352, Recommendations for Design of Beam-Column Connections in Monolithic Reinforced Concrete Structures. 2002.
[28]粘结锚固专题组.钢筋混凝土粘结锚固的研究及设计建议[J].建筑结构学报, 1986, 7(4).
[29]邵卓民,沈文都,徐有邻.钢筋混凝土的锚固可靠度及锚固设计[J].建筑结构, 1987, 17(4):36-49.
[30]周兴杰.框架边柱节点90°弯折月牙纹锚固钢筋粘结锚固性能地试验研究[D].重庆建筑工程学院. 1988.