不等强混凝土空间中节点抗震性能研究及其受剪承载力计算
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摘要
为研究节点核心区采用与梁等强度的低强度混凝土浇筑的夹心节点的抗震性能,通过3组不同柱与梁混凝土强度比的空间夹心节点和传统节点(节点核心区混凝土与柱等强)的对比试件在双向低周往复荷载作用的性能试验研究,对比分析了各组试件的破坏形态、延性、耗能、变形等差异。研究结果表明:中低剪压比夹心节点的整体抗震性能稍弱于传统节点,相差不明显;中低轴压比、剪压比条件下,当柱与梁混凝土强度比小于1.5时,节点区可直接采用与梁相同强度的混凝土浇筑,当柱与梁混凝土强度比大于1.5时,其破坏形式转变为节点核心区剪切破坏,需采取相应的结构措施予以加强;采用平面节点软化拉-压杆模型,建立了承受双向水平荷载的空间节点软化拉-压杆受剪模型与受剪承载力的计算式,并将其计算结果与试验结果进行了校验,两者吻合较好。
In order to study the seismic performance of 3D interior sandwich joints core area made of low strength concrete the same as beams,three groups of specimens with different concrete strength grades,each consisting of three sandwich joints and three corresponding additional joints with higher strength concrete the same as columns were tested under bi-directional reversed cyclic loads. Performance indexes such as the failure mode,ductility,energy dissipation and deformation of the two kinds of joints were analyzed contrastively. Results show that the seismic performance of sandwich joints is insignificantly weaker than traditional joints in the condition of mid-low shear compression ratio. In the condition of mid-low axial compression ratio and shear compression ratio,when the strength ratio of the column and beam is less than 1. 5,the joints core area can be cast with the low strength concrete the same as beams. Otherwise,the failure mode may change from the flexural failure of the beams to the shear failure of the core,and additional strengthening measures are inevitable. At last,based on the plane softened strut-and-tie model,the 3D softened strutand-tie shear model and shear capacity calculation formula under bi-direction horizontal loads are proposed,and the solutions agree well with the experimental results.
In order to study the seismic performance of 3D interior sandwich joints core area made of low strength concrete the same as beams,three groups of specimens with different concrete strength grades,each consisting of three sandwich joints and three corresponding additional joints with higher strength concrete the same as columns were tested under bi-directional reversed cyclic loads. Performance indexes such as the failure mode,ductility,energy dissipation and deformation of the two kinds of joints were analyzed contrastively. Results show that the seismic performance of sandwich joints is insignificantly weaker than traditional joints in the condition of mid-low shear compression ratio. In the condition of mid-low axial compression ratio and shear compression ratio,when the strength ratio of the column and beam is less than 1. 5,the joints core area can be cast with the low strength concrete the same as beams. Otherwise,the failure mode may change from the flexural failure of the beams to the shear failure of the core,and additional strengthening measures are inevitable. At last,based on the plane softened strut-and-tie model,the 3D softened strutand-tie shear model and shear capacity calculation formula under bi-direction horizontal loads are proposed,and the solutions agree well with the experimental results.
引文
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[5]Canadian Standards Association.Design of concrete structures:CSA A23.3-04[S].Mississauga,Canada:CSA,2004.
[6]ZHAO Ming,SU Xiaozu,LU Daoyuan,WANG Dasui.Seismic properties of RC frame sandwich type joint[C]//13th World Conference on Earthquake Engineering.Vancouver BC,Canada:[s.n.],2004:Paper No.335.
[7]李英民,刘建伟.钢筋混凝土框架夹心节点抗震性能试验研究[J].建筑结构学报,2010,31(12):74-82.(LI Yingmin,LIU Jianwei.Pseudo-static test for reinforced concrete sandwich beam-column joints[J].Journal of Building Structures,2010,31(12):74-82(in Chinese))
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[9]唐九如.钢筋混凝土框架节点抗震[M].南京:东南大学出版社,1989:302-303.(TANG Jiuru.Seismic resistance of jonts in reinfoced concrete frame[M].Nanjing:Southeast University Press,1989:302-303.(in Chinese))
[10]LIU Aizhen.Seismic assessment and retrofit of pre-1970s reinforced concrete frame structures[D].Christchurch:University of Canterbury,2001:106-111.
[11]LI Bing,TRAN Cao Thanh,PAN Tso-Chien.Experimental and numerical investigations on the Seismic behavior of lightly reinforced concrete beamColumn Joints[J].Journal of Structural Engineering,ASCE,2009,35(9):1007-1018.
[12]PARK Sangjoon,MOSALAM Khalid M.Experimental investigation of nonductile RC corner beam-column joints with floor slabs[J].Journal of Structural Engineering,ASCE,2013,139(1):1-14.
[13]HWANG S J,LEE H J.Analytical model for predicting shear strengths of interior reinforced concrete beamcolumn joints for seismic resistance[J].ACI Structural Journal,2000,97(1):35-44.
[14]邢国华,刘伯权,吴涛.基于软化拉-压杆模型的钢筋混凝土框架节点受剪分析[J].建筑结构学报,2011,32(5):125-134.(XING Guohua,LIU Boquan,WU Tao.Shear strength of reinforced concrete frame joints using softened strut and tie model[J].Journal of Building Structures,2011,32(5):125-134.(in Chinese))
[15]邢国华,刘伯权,牛荻涛.钢筋混凝土框架中节点受剪承载力计算的修正软化拉压杆模型[J].工程力学,2013,30(8):60-66.(XING Guohua,LIU Boquan,NIU Ditao.Shear strength of reinforced concrete frame joints using modified softened strut-andtie model[J].Engineering Mechanics,2013,30(8):60-66.(in Chinese))
[16]魏巍巍,贡金鑫.按我国规范的压杆-拉杆设计方法[J].建筑结构学报,2008,29(增刊1):287-193.(WEI Weiwei,GONG Jinxin.Strut-and-tie design method based on Chinese code[J].Journal of Building Structures,2008,29(Suppl.1):287-193.(in Chinese))
[2]LEE J H,YOON Y S.Prediction of effective compressive strength of corner columns composing weaker slab-column joint[J].Magazine of Concrete Research,2012,64(12):1113-1121.
[3]SUBRAMANIAN N.Transmission of HSC column loads through NSC slabs[J].Indian Concrete Journal,2006,80(1):44-49.
[4]American Concrete Institute.Building code requirements for structural concreteand commentary:ACI 318-08[S].Farmington Hills:ACI,2008.
[5]Canadian Standards Association.Design of concrete structures:CSA A23.3-04[S].Mississauga,Canada:CSA,2004.
[6]ZHAO Ming,SU Xiaozu,LU Daoyuan,WANG Dasui.Seismic properties of RC frame sandwich type joint[C]//13th World Conference on Earthquake Engineering.Vancouver BC,Canada:[s.n.],2004:Paper No.335.
[7]李英民,刘建伟.钢筋混凝土框架夹心节点抗震性能试验研究[J].建筑结构学报,2010,31(12):74-82.(LI Yingmin,LIU Jianwei.Pseudo-static test for reinforced concrete sandwich beam-column joints[J].Journal of Building Structures,2010,31(12):74-82(in Chinese))
[8]混凝土结构设计规范:GB 50010—2010[S].北京:中国建筑工业出版社.2010.(Code for design of concrete structures:GB 50010—2010[S].Beijing:China Architecture&Building Press,2010.(in Chinese))
[9]唐九如.钢筋混凝土框架节点抗震[M].南京:东南大学出版社,1989:302-303.(TANG Jiuru.Seismic resistance of jonts in reinfoced concrete frame[M].Nanjing:Southeast University Press,1989:302-303.(in Chinese))
[10]LIU Aizhen.Seismic assessment and retrofit of pre-1970s reinforced concrete frame structures[D].Christchurch:University of Canterbury,2001:106-111.
[11]LI Bing,TRAN Cao Thanh,PAN Tso-Chien.Experimental and numerical investigations on the Seismic behavior of lightly reinforced concrete beamColumn Joints[J].Journal of Structural Engineering,ASCE,2009,35(9):1007-1018.
[12]PARK Sangjoon,MOSALAM Khalid M.Experimental investigation of nonductile RC corner beam-column joints with floor slabs[J].Journal of Structural Engineering,ASCE,2013,139(1):1-14.
[13]HWANG S J,LEE H J.Analytical model for predicting shear strengths of interior reinforced concrete beamcolumn joints for seismic resistance[J].ACI Structural Journal,2000,97(1):35-44.
[14]邢国华,刘伯权,吴涛.基于软化拉-压杆模型的钢筋混凝土框架节点受剪分析[J].建筑结构学报,2011,32(5):125-134.(XING Guohua,LIU Boquan,WU Tao.Shear strength of reinforced concrete frame joints using softened strut and tie model[J].Journal of Building Structures,2011,32(5):125-134.(in Chinese))
[15]邢国华,刘伯权,牛荻涛.钢筋混凝土框架中节点受剪承载力计算的修正软化拉压杆模型[J].工程力学,2013,30(8):60-66.(XING Guohua,LIU Boquan,NIU Ditao.Shear strength of reinforced concrete frame joints using modified softened strut-andtie model[J].Engineering Mechanics,2013,30(8):60-66.(in Chinese))
[16]魏巍巍,贡金鑫.按我国规范的压杆-拉杆设计方法[J].建筑结构学报,2008,29(增刊1):287-193.(WEI Weiwei,GONG Jinxin.Strut-and-tie design method based on Chinese code[J].Journal of Building Structures,2008,29(Suppl.1):287-193.(in Chinese))