基于不同加载制度的轻骨料混凝土动态冲击性能
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摘要
以SHPB冲击试验及落锤试验为依据,建立EPS混凝土有限元数值模型,运用连续损伤理论分析不同冲击加载制度对轻骨料混凝土动态缓冲性能的影响。对该类材料的动态响应进行时程分析,揭示峰值速度发生时间及加载周期对整体和局部材料动态冲击响应的影响。分析结果表明:在冲击势能相同的前提下,整体材料的动态耗能特性随着冲击峰值时间的推迟呈现先上升而后下降的趋势,随着加载时程的延长(冲击峰值速度降低)其对冲击势能的转化能力逐渐提高;而单位体积材料的动态耗能特性则随着峰值时间的延迟和加载周期的延长均呈现先上升而后下降的趋势。在材料的冲击损伤演化方面,冲击峰值时间的变化对材料的损伤度影响较小,且材料在峰值时间出现于中期阶段的冲击荷载下的损伤程度相对严重;同时,延长加载周期并降低冲击峰值对于材料冲击损伤的影响显著,并建立了基于加载周期预测材料损伤度的数学模型。
Based on theory of continuum damage,the influences of dynamic buffering properties for lightweighting aggregates concrete subjected to varied impact loading regimes were analyzed by means of FEM numerical models in the foundation of SHPB shocking test and drop hammer experiment. It revealed the effect of occurrence time-point of peak velocity and loading span on dynamic responses of this materials via time-history method. The results show that its energy-absorption properties could be improved firstly and then degraded with the delay of peak velocity time-point; meanwhile,that are improved gradually as the increase of loading span in the assumption that shocking potential energy are constant in all cases.And dynamic buffering properties of unit volume are strengthened firstly and then worsen with the delay of peak time and the expansion of loading span. In terms of dynamic damage evolution,the shocking damage degree of materials is affected infinitesimally by the change of peak-velocity time point,and that will be worse relatively if the peak time occurs in medium phase. And there is an obvious influence on impact damage of materials subjected to shock loading by extending load period or decreasing its peak speed,and the mathematic models among dynamical damage of materials and loading span was proposed,predetermining availably the damage degree according to its loading span.
Based on theory of continuum damage,the influences of dynamic buffering properties for lightweighting aggregates concrete subjected to varied impact loading regimes were analyzed by means of FEM numerical models in the foundation of SHPB shocking test and drop hammer experiment. It revealed the effect of occurrence time-point of peak velocity and loading span on dynamic responses of this materials via time-history method. The results show that its energy-absorption properties could be improved firstly and then degraded with the delay of peak velocity time-point; meanwhile,that are improved gradually as the increase of loading span in the assumption that shocking potential energy are constant in all cases.And dynamic buffering properties of unit volume are strengthened firstly and then worsen with the delay of peak time and the expansion of loading span. In terms of dynamic damage evolution,the shocking damage degree of materials is affected infinitesimally by the change of peak-velocity time point,and that will be worse relatively if the peak time occurs in medium phase. And there is an obvious influence on impact damage of materials subjected to shock loading by extending load period or decreasing its peak speed,and the mathematic models among dynamical damage of materials and loading span was proposed,predetermining availably the damage degree according to its loading span.
引文
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[3]Ail A S,Juan V T,Thomas R N,et.al.Effects of expanded polystyrene(EPS)particles on fire resistance,thermal conductivity and compressive strength of foamed concrete[J].Construction and Building Materials,2016,112:716-724.
[4]Shivokhin M,Garca M M,Partal P,et al.Rheological behavior of polymer-modified bituminous mastics-a comparative analysis between physical and chemical modification[J].Construction and Building Materials,2012,27:234-240.
[5]Ranjbar M M,Mousavi S Y.Strength and durability assessment of self-compacted lightweight concrete containing expanded polystyrene[J].Materials and Structure,2015,48(4):1001-1011.
[6]Ferrándiz-Mas V,García-Alcocel E.Durability of expanded polystyrene mortars[J].Construction and Building Materials,2013,46:175-182.
[7]Tonyan T D,Gibson L J.Strengthening of cement foams[J].Journal of Materials Science,1992,27:6379-6386.
[8]Bouvard D,Chaix J M,Dendievel R,et al.Characterization and simulation of microstructure and properties of EPS lightweight concrete[J].Cement and Concrete Research,2007,37:1666-1673.
[9]袁勇,郑磊.橡胶混凝土动力性能试验研究[J].同济大学学报(自然科学版),2008,36(9):1186-1190.
[10]Hernandez-Olivaresa F,Barluenga G,Bollatib M,et al.Static and dynamic behavior of recycled tire rubber-filled concrete[J].Cement and Concrete Research,2002,32(10):1578.
[11]袁兵,刘峰,丘晓龙,等.橡胶混凝土不同应变率下抗压性能试验研究[J].建筑材料学报,2010,13(1):12-16.
[12]巫绪涛,胡俊,谢思发.EPS混凝土的动态劈裂强度与能量耗散[J].爆炸与冲击,2013,33(4):369-374.
[13]胡泽斌,许金余,彭高丰,等.冲击荷载下聚苯乙烯混凝土的吸能特性[J].硅酸盐学报,2010,38(7):1173-1178.
[14]白二雷,徐金余,高志刚.冲击荷载作用下EPS混凝土动态性能研究[J].振动与冲击,2012,31(13):53-57.
[15]Liu Y,Ma D,Jiang Z,et al.Dynamic response of expanded polystyrene concrete during low speed[J].Construction and Building Materials,2016,122:72-80.
[16]Dong X,Wang S,Gong C,et al.Effects of aggregate gradation and polymer modifiers on properties of cement-EPS/vitrified microsphere mortar[J].Construction and Building Materials,2014,73:255-260.
[17]Chen B,Liu J.Mechanical properties of polymer-modified concretes containing expanded polystyrene beads[J].Construction and Building Materials,2007,21(1):7-11.
[18]Bhattacharya B,Ellingwood B.Continuum damage mechanics-based model of stochastic damage growth[J].Journal of Engineering Mechanics,1998,124(9):1000-1009.
[19]Lemaitre J.A continuous damage mechanics model for ductile fracture[J].Journal of Engineering Materials and Technology,1985,107(1):83-89.
[20]James F H,Young R P.Micromechanical modeling of cracking and failure in brittle rocks[J].Journal of Geophysical Research,2000,105(B7):16683-16697.
[21]Gangnant A,Saliba J,Borderie C,et al.Modeling of the quasibrittle of concrete at meso-scale:effect of classes of aggregates on global and local behavior[J].Cement and Concrete Research,2016,89:35-44.
[22]Ju J W.Energy-based coupleed elastoplastic damage models at finite strain[J].Journal of Engineering Mechanics,1989,115(11):2507-2525.