钢筋混凝土联肢墙小跨高比复合斜筋连梁抗震性能试验研究
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摘要
钢筋混凝土联肢剪力墙或联肢筒壁中的连梁是抗震关键部件。小跨高比连梁因剪弯比高,不采取特殊措施难以满足高剪力条件下的高延性要求。现行设计规范使用的交叉暗撑连梁虽抗震抗剪能力及延性好,但钢筋绑扎困难;现行规范降低抗剪能力上限、强化配箍要求的普通配箍连梁则抗剪能力过低、延性依然不足。为此,有必要寻求一种不需内力或刚度折减的高抗剪能力、高延性、便于施工的小跨高比连梁设计方案。为适应小跨高比连梁的受力特征,提出一种由交叉斜筋和上、下L形斜筋复合配筋的新设计方案,并完成19个具有不同跨高比、不同剪压比和不同斜筋———L形筋用量比的足尺连梁低周交变加载试验。试验结果表明,采用新方案配筋的连梁具有良好的抗震性能;剪跨比为0.8~2.5的该类连梁在剪压比高达0.3及以上时仍具有不低于4.0~5.0的位移延性,且施工难度明显降低。这种新的连梁配筋方案可推荐用于高抗震等级的建筑结构。
Coupled beams in reinforced concrete structural walls or tubes are key anti-seismic members.In general,coupling beams of small aspect ratios cannot meet the requirement of high ductility in the context of high shear forces due to the large ratio of shear to flexural moment,unless specific reinforcement arrangements are implemented.Although coupled beams reinforced with two intersecting groups of diagonally placed bars can provide satisfactory seismic shear capacity and excellent ductility,it is always very difficult to place the reinforcements in construction.The current codified reinforcement scheme of coupled beams,with enhanced ordinary closed-stirrups and with reduced upper limit of shear capacity,results in significant reduction of shear capacity and insufficient ductility.Therefore,there is an impetus to find a reinforcement arrangement scheme that can provide high seismic shear capacities and excellent ductility for coupled beams and make construction convenient,under the condition that no reduction of internal forces or stiffness is needed in design.In this paper,a new reinforcement arrangement scheme,namely combined cross slanting reinforcements and upper and lower L-shaped inclined reinforcements,is presented on the basis of internal-force characteristics of such small-aspect-ratio coupled beams.Nineteen full-scale specimens with different shear-compression ratios and different ratios of diagonal to L-shaped inclined reinforcements were tested under reversed cyclical loading.The results show that with this new reinforcement scheme,the coupled beams exhibit excellent seismic behaviors.For this type of coupled beams with shear-span ratios ranging from 0.8 to 2.5,the displacement ductility coefficients are higher than 4.0 even when the shear-compression ratios are as high as or higher than 0.3,and at the same time,the difficulty in placement of reinforcements is remarkably alleviated.Such a new scheme of reinforcement arrangement is feasible for coupled beams of high seismic grades in reinforced concrete buildings.
Coupled beams in reinforced concrete structural walls or tubes are key anti-seismic members.In general,coupling beams of small aspect ratios cannot meet the requirement of high ductility in the context of high shear forces due to the large ratio of shear to flexural moment,unless specific reinforcement arrangements are implemented.Although coupled beams reinforced with two intersecting groups of diagonally placed bars can provide satisfactory seismic shear capacity and excellent ductility,it is always very difficult to place the reinforcements in construction.The current codified reinforcement scheme of coupled beams,with enhanced ordinary closed-stirrups and with reduced upper limit of shear capacity,results in significant reduction of shear capacity and insufficient ductility.Therefore,there is an impetus to find a reinforcement arrangement scheme that can provide high seismic shear capacities and excellent ductility for coupled beams and make construction convenient,under the condition that no reduction of internal forces or stiffness is needed in design.In this paper,a new reinforcement arrangement scheme,namely combined cross slanting reinforcements and upper and lower L-shaped inclined reinforcements,is presented on the basis of internal-force characteristics of such small-aspect-ratio coupled beams.Nineteen full-scale specimens with different shear-compression ratios and different ratios of diagonal to L-shaped inclined reinforcements were tested under reversed cyclical loading.The results show that with this new reinforcement scheme,the coupled beams exhibit excellent seismic behaviors.For this type of coupled beams with shear-span ratios ranging from 0.8 to 2.5,the displacement ductility coefficients are higher than 4.0 even when the shear-compression ratios are as high as or higher than 0.3,and at the same time,the difficulty in placement of reinforcements is remarkably alleviated.Such a new scheme of reinforcement arrangement is feasible for coupled beams of high seismic grades in reinforced concrete buildings.
引文
[1]陈文科.基于非线性动力分析的八度区一级框-剪和框-筒结构抗震规定研究[D].重庆:重庆大学,2007(ChenWenke.Study on seismic provisions for RC seismic designcategory I frame-wall and frame-tube structures based onnonlinear-dynamic analysis[D].Chongqing:ChongqingUniversity,2007(in Chinese))
[2]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:重庆大学,2007(Wei Feng.Verifications of inelastic seismic response performance ofreinforced concrete frame and frame-wall structures[D].Chongqing:Chongqing University,2005(in Chinese))
[3]GB 50011—2001建筑抗震设计规范[S].北京:中国建筑工业出版社,2001(GB 50011—2001 Code for seismicdesign of buildings[S].Beijing:China Architecture&Building Press,2001(in Chinese))
[4]JGJ 3—2002高层建筑混凝土结构技术规程[S].北京:中国建筑工业出版社,2002(JGJ 3—2002 Technicalspecification for concrete structures of tall building[S].Beijing:China Architecture&Building Press,2002(inChinese))
[5]Paulay T.Coupling beams of reinforced concrete shearwalls[J].Journal of the Structural Division,1971,97(3):843-862
[6]ACI 318—08 Building code requirements for structuralconcrete and ACI318R-08 commentary[S].US:AmericanConcrete Institute,2007
[7]EN 1998—1:2004 Design of structures for earthquakeresistance—Part 1:general rules,seismic actions andrules for buildings[S]
[8]NZS 3101 Concrete structures standard—Part I:the designof concrete structures[S]
[9]王建.配置特定钢筋的剪力墙小跨高比洞口连梁抗震性能的试验研究[D].重庆:重庆大学,2009(Wang Jian.Experimental study on seismic behavior of small span-to-depth ratio coupling beams with special detailing[D].Chongqing:Chongqing University,2009(in Chinese))
[10]王智勤.配有500MPa级钢筋对角斜筋小跨高比连梁抗震性能对比试验研究[D].重庆:重庆大学,2009(WangZhiqin.Contrast study on small span-to-depth ratio couplingbeams of diagonal reinforcement with 500MPa steel bar[D].Chongqing:Chongqing University,2009(inChinese))
[11]皮天祥.钢筋混凝土剪力墙小跨高比连梁抗震性能试验和设计方法研究[D].重庆:重庆大学,2008(PiTianxiang.Experimental study on seismic behavior anddesign method study of small span-to-depth ratio couplingbeams of seismic RC Shear walls[D].Chongqing:Chongqing University,2008(in Chinese))
[12]龚炳年,方鄂华.反复荷载下联肢剪力墙结构连系梁的性能[J].建筑结构学报,1988(1):34-41(GongBingnian,Fang Ehua.Behavior of reinforced concretecoupling beams between shear walls under cyclic loading[J].Journal of Building Structures,1988(1):34-41(inChinese))
[13]李英民,刘立平.汶川地震建筑震害与思考[M].重庆:重庆大学出版社,2008
[14]Tassios T P,Moretti M,Bezas A.On the behavior andductility of reinforced concrete coupling beams of shearwalls[J].ACI Structural Journal,1996,93(6):711-720
[15]Komiya Y,Nakatsuka T,Onal T,et al.Experimentalstudy on structural characteristics of diagonally reinforcedshort span beam[J].Journal of Structural and ConstructionEngineering,2007(615):173-180(in Japanese)
[2]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:重庆大学,2007(Wei Feng.Verifications of inelastic seismic response performance ofreinforced concrete frame and frame-wall structures[D].Chongqing:Chongqing University,2005(in Chinese))
[3]GB 50011—2001建筑抗震设计规范[S].北京:中国建筑工业出版社,2001(GB 50011—2001 Code for seismicdesign of buildings[S].Beijing:China Architecture&Building Press,2001(in Chinese))
[4]JGJ 3—2002高层建筑混凝土结构技术规程[S].北京:中国建筑工业出版社,2002(JGJ 3—2002 Technicalspecification for concrete structures of tall building[S].Beijing:China Architecture&Building Press,2002(inChinese))
[5]Paulay T.Coupling beams of reinforced concrete shearwalls[J].Journal of the Structural Division,1971,97(3):843-862
[6]ACI 318—08 Building code requirements for structuralconcrete and ACI318R-08 commentary[S].US:AmericanConcrete Institute,2007
[7]EN 1998—1:2004 Design of structures for earthquakeresistance—Part 1:general rules,seismic actions andrules for buildings[S]
[8]NZS 3101 Concrete structures standard—Part I:the designof concrete structures[S]
[9]王建.配置特定钢筋的剪力墙小跨高比洞口连梁抗震性能的试验研究[D].重庆:重庆大学,2009(Wang Jian.Experimental study on seismic behavior of small span-to-depth ratio coupling beams with special detailing[D].Chongqing:Chongqing University,2009(in Chinese))
[10]王智勤.配有500MPa级钢筋对角斜筋小跨高比连梁抗震性能对比试验研究[D].重庆:重庆大学,2009(WangZhiqin.Contrast study on small span-to-depth ratio couplingbeams of diagonal reinforcement with 500MPa steel bar[D].Chongqing:Chongqing University,2009(inChinese))
[11]皮天祥.钢筋混凝土剪力墙小跨高比连梁抗震性能试验和设计方法研究[D].重庆:重庆大学,2008(PiTianxiang.Experimental study on seismic behavior anddesign method study of small span-to-depth ratio couplingbeams of seismic RC Shear walls[D].Chongqing:Chongqing University,2008(in Chinese))
[12]龚炳年,方鄂华.反复荷载下联肢剪力墙结构连系梁的性能[J].建筑结构学报,1988(1):34-41(GongBingnian,Fang Ehua.Behavior of reinforced concretecoupling beams between shear walls under cyclic loading[J].Journal of Building Structures,1988(1):34-41(inChinese))
[13]李英民,刘立平.汶川地震建筑震害与思考[M].重庆:重庆大学出版社,2008
[14]Tassios T P,Moretti M,Bezas A.On the behavior andductility of reinforced concrete coupling beams of shearwalls[J].ACI Structural Journal,1996,93(6):711-720
[15]Komiya Y,Nakatsuka T,Onal T,et al.Experimentalstudy on structural characteristics of diagonally reinforcedshort span beam[J].Journal of Structural and ConstructionEngineering,2007(615):173-180(in Japanese)
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