装配整体式结构抗连续倒塌受力机制及影响因素分析
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摘要
为了研究压拱和悬链线阶段的受力机理,采用SAP2000软件建立了装配整体式框架(PCF)模型并用试验数据进行验证。在此基础上,建立了分析模型,选取A2模型对这2个阶段的受力机理进行了详细分析,然后将该阶段承载力与经典塑性铰理论承载力相比,定义了压拱和悬链线机制承载力提高系数η和ξ,研究了跨高比、层数、配筋率等参数对结构抗倒塌承载力的影响。结果表明:底部配筋率由0.44%增加到0.88%后,压拱机制承载力最大值F_(u.a)和悬链线机制承载力最大值F_(u.c)分别增加了37%和88.7%,η由1.25减少到1.22,ξ由1.06增加到1.45;顶部配筋率由0.66%增加到1.03%后,F_(u.a)增大了25%,η由1.25减少到1.20,而F_(u.c)变化很小,ξ由1.57减少到1.16;改变跨度导致跨高比由8增加到15时,F_(u.a)和F_(u.c)分别减小了67%和59%,η由1.33减小到1.18,ξ由1.44增加到1.59;改变梁高导致跨高比由8增加到15时,F_(u.a)和F_(u.c)分别减小了87.7%和59.9%,η由1.35减少到1.08,ξ由1.44增加到3.85;层数增加时,η减小,ξ增大;侧向约束的刚度对悬链线效应的影响较大,当柱相对抗弯刚度大或侧向约束的跨数多时,悬链线效应对抗力的提高更为显著。
In order to study the force mechanism of arch compression and catenary stages,the monolithic precast concrete frame(PCF)models were established by SAP2000 and verified by experimental data.On the basis,the analysis models were established,and the A2 model was selected to analyze the mechanism of the two stages in detail.Then,the bearing capacities of two stages were compared with the classical plastic hinge theory,and the capacity increase coefficients of arch compression mechanism and catenary mechanism were defined as η and ξ respectively.The effects of parameters,such as span-to-height ratio,number of storey and reinforcement ratio and on the collapse resistance of the structure were studied.The results show that when the bottom reinforcement ratio increases from 0.44% to 0.88%,the maximum bearing capacities of arch compression mechanism F_(u.a) and catenary mechanism F_(u.c) increase by 37% and 88.7% respectively,and the value of η decreases from 1.25 to 1.22,and the value of η increases from1.06 to 1.45.When the top reinforcement ratio increases from 0.66% to 1.03%,F_(u.a)increases by 25%, η decreases from 1.25 to 1.20,while F_(u.c) changes slightly,and ξ decreases from 1.57 to1.16.When the span-height ratio increases from 8 to 15(changing the span),F_(u.a) and F_(u.c) decrease by 67% and 59% respectively, η decreases from 1.33 to 1.18,and ξ increases from 1.44 to 1.59.When the span-to-height ratio increases from 8 to 15(changing the height of beam),F_(u.a) and F_(u.c) decrease by 87.7% and 59.9% respectively, η decreases from 1.35 to 1.08,and ξ increases from 1.44 to 3.85.When the number of stories increases, η decreases,but ξ increases.The stiffness of lateral restraint has a great influence on the catenary effect.When the column's relative flexural stiffness is large or the number of spans with lateral restraint is large,the effect of catenary is more significant.
In order to study the force mechanism of arch compression and catenary stages,the monolithic precast concrete frame(PCF)models were established by SAP2000 and verified by experimental data.On the basis,the analysis models were established,and the A2 model was selected to analyze the mechanism of the two stages in detail.Then,the bearing capacities of two stages were compared with the classical plastic hinge theory,and the capacity increase coefficients of arch compression mechanism and catenary mechanism were defined as η and ξ respectively.The effects of parameters,such as span-to-height ratio,number of storey and reinforcement ratio and on the collapse resistance of the structure were studied.The results show that when the bottom reinforcement ratio increases from 0.44% to 0.88%,the maximum bearing capacities of arch compression mechanism F_(u.a) and catenary mechanism F_(u.c) increase by 37% and 88.7% respectively,and the value of η decreases from 1.25 to 1.22,and the value of η increases from1.06 to 1.45.When the top reinforcement ratio increases from 0.66% to 1.03%,F_(u.a)increases by 25%, η decreases from 1.25 to 1.20,while F_(u.c) changes slightly,and ξ decreases from 1.57 to1.16.When the span-height ratio increases from 8 to 15(changing the span),F_(u.a) and F_(u.c) decrease by 67% and 59% respectively, η decreases from 1.33 to 1.18,and ξ increases from 1.44 to 1.59.When the span-to-height ratio increases from 8 to 15(changing the height of beam),F_(u.a) and F_(u.c) decrease by 87.7% and 59.9% respectively, η decreases from 1.35 to 1.08,and ξ increases from 1.44 to 3.85.When the number of stories increases, η decreases,but ξ increases.The stiffness of lateral restraint has a great influence on the catenary effect.When the column's relative flexural stiffness is large or the number of spans with lateral restraint is large,the effect of catenary is more significant.
引文
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[15]PHAM A T,TAN K H,YU J.Numerical Investigations on Static and Dynamic Responses of Reinforced concrete Sub-assemblages Under Progressive Collapse[J].Engineering Structures,2017,149:2-20.
[16]JGJ 1-2014,装配式混凝土结构技术规程[S].JGJ 1-2014,Technical Specification for Precast Concrete Structures[S].
[17]DoD 2010,Design of Buildings to Resist Progressive Collapse[S].
[2]王英,顾祥林,林峰.考虑压拱效应的钢筋混凝土双跨梁竖向承载力分析[J].建筑结构学报,2013,34(4):32-42.WANG Ying,GU Xiang-lin,LIN Feng.Vertical Bearing Capacity of RC Two-bay Beams Considering Compressive Arch Action[J].Journal of Building Structures,2013,34(4):32-42.
[3]周育泷,李易,陆新征,等.钢筋混凝土框架抗连续倒塌的压拱机制分析模型[J].工程力学,2016,33(4):34-42.ZHOU Yu-long,LI Yi,LU Xin-zheng,et al.An Analytical Model of Compressive Arch Action of Reinforced Concrete Frames to Resist Progressive Collapse[J].Engineering Mechanics,2016,33(4):34-42.
[4]VALIPOUR H R,FOSTER S J.Finite Element Modelling of Reinforced Concrete Framed Structures Including Catenary Action[J].Computers&Structures,2010,88(9/10):529-538.
[5]李易,陆新征,叶列平.基于能量方法的RC框架结构连续倒塌抗力需求分析Ⅱ:悬链线机制[J].建筑结构学报,2011,32(11):9-16.LI Yi,LU Xin-zheng,YE Lie-ping.Progressive Collapse Resistance Demand of RC Frame Structures Based on Energy MethodⅡ:Catenary Mechanism[J].Journal of Building Structures,2011,32(11):9-16.
[6]SU Y P,TIAN Y,SONG X S.Progressive Collapse Resistance of Axially-restrained Frame Beams[J].ACI Structural Journal,2009,106(5):600-607.
[7]YU J,TAN K H.Structural Behavior of RC Beamcolumn Subassemblages Under a Middle Column Removal Scenario[J].Journal of Structural Engineering,2013,139(2):233-250.
[8]潘元,刘伯权,邢国华,等.基于破坏准则的钢筋混凝土结构抗倒塌研究进展[J].建筑科学与工程学报,2010,27(2):51-60.PAN Yuan,LIU Bo-quan,XING Guo-hua,et al.Research Progress of Seismic Collapse Resistance of Rein-forced Concrete Structures Based on Damage Criteria[J].Journal of Architecture and Civil Engineering,2010,27(2):51-60.
[9]姚宇飞,师燕超,李忠献.爆炸荷载下钢筋混凝土框架结构连续倒塌分析方法比较[J].建筑科学与工程学报,2015,32(1):64-72.YAO Yu-fei,SHI Yan-chao,LI Zhong-xian.Comparison of Progressive Collapse Analysis Methods for RCFrame Structures Under Blast Loads[J].Journal of Architecture and Civil Engineering,2015,32(1):64-72.
[10]MENDIS P.Plastic Hinge Lengths of Normal and High-strength Concrete in Flexure[J].Advances in Structural Engineering,2002,4(4):189-195.
[11]DHAKAL R P,FENWICK R C.Detailing of Plastic Hinges in Seismic Design of Concrete Structures[J].ACI Structural Journal,2008,105(6):740-749.
[12]QIAN K,LI B,MA J X.Load-carrying Mechanism to Resist Progressive Collapse of RC Buildings[J].Journal of Structural Engineering,2015,141(2):04014107.
[13]YU J,TAN K H.Experimental and Numerical Investigation on Progressive Collapse Resistance of Reinforced Concrete Beam Column Sub-assemblages[J].Engineering Structures,2013,55:90-106.
[14]易伟建,何庆锋,肖岩.钢筋混凝土框架结构抗倒塌性能的试验研究[J].建筑结构学报,2007,28(5):104-109,117.YI Wei-jian,HE Qing-feng,XIAO Yan.Collapse Performance of RC Frame Structure[J].Journal of Building Structures,2007,28(5):104-109,117.
[15]PHAM A T,TAN K H,YU J.Numerical Investigations on Static and Dynamic Responses of Reinforced concrete Sub-assemblages Under Progressive Collapse[J].Engineering Structures,2017,149:2-20.
[16]JGJ 1-2014,装配式混凝土结构技术规程[S].JGJ 1-2014,Technical Specification for Precast Concrete Structures[S].
[17]DoD 2010,Design of Buildings to Resist Progressive Collapse[S].