细观结构不均匀性对混凝土动弯拉强度的影响
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摘要
本文在随机骨料模型的基础上,提出了既能反映混凝土骨料分布随机性又能反映混凝土细观各相材料力学特性随机性的随机骨料随机参数模型。利用该模型并考虑材料的细观力学的应变率效应,对湿筛混凝土和全级配混凝土梁进行了三分点冲击弯拉断裂数值模拟,分析了混凝土材料参数的离散性、混凝土级配以及初始静预载水平对其动弯拉强度的影响。研究表明:(1)随混凝土材料的弹性模量和抗拉强度的离散性增大,静弯拉强度和动弯拉强度降低,但动弯拉强度增强系数得到提高;(2)一定条件下全级配的混凝土梁的动弯拉强度增强系数高于湿筛混凝土梁的动弯拉强度增强系数;(3)为了更准确地确定动弯拉强度增强系数,应该考虑混凝土级配和初始预静载水平所产生的应变率效应对其的影响。
Based on the random aggregate model a radom aggregated and random parametric model describing the random characteristics of meso-structure and mechanical properties of concrete material is proposed.The model is applied to numerically calculate the dynamic bending strength of concrete trisection beams subjected to impact load with the strain-rate effects of the meso-structure taken into account.The effects of concrete grading,divergence of elemental mechanical behaviors and static preload levels on dynamic bending strength are investigated.It is found that:1.the static bending strength and dynamic bending strength decrease but the dynamic enhancement coefficients increase when the elastic modulus of concrete and the divergence of tensile strength increases;2.the enhancement coefficients of dynamic bending strength of full grading concrete beams are greater than those of wet-screened concrete,under the given condition;3.concrete grading and static preload effects should be considered in valuating the dynamic bending strength of concrete.
Based on the random aggregate model a radom aggregated and random parametric model describing the random characteristics of meso-structure and mechanical properties of concrete material is proposed.The model is applied to numerically calculate the dynamic bending strength of concrete trisection beams subjected to impact load with the strain-rate effects of the meso-structure taken into account.The effects of concrete grading,divergence of elemental mechanical behaviors and static preload levels on dynamic bending strength are investigated.It is found that:1.the static bending strength and dynamic bending strength decrease but the dynamic enhancement coefficients increase when the elastic modulus of concrete and the divergence of tensile strength increases;2.the enhancement coefficients of dynamic bending strength of full grading concrete beams are greater than those of wet-screened concrete,under the given condition;3.concrete grading and static preload effects should be considered in valuating the dynamic bending strength of concrete.
引文
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[2]YonJH,HawkinsNM,KobayashiAS.Strain ratesensitivityofconcretemechanicalproperties[J].ACIMaterialJournal,1992,89(2):146-153.
[3]李兆霞.工程材料的应变率效应及其损伤本构模拟计算[J].河海大学学报,1994,22(计算力学专辑):75-82.
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[7]DanZheng,QingbinLi.Anexplanationforrateeffectofconcretestrengthbasedonfracturetoughnessincludingfreewater viscosity[J].EngineeringFractureMechanics,2004,71(1617):2319-2327.
[8]马怀发,陈厚群,黎保琨.应变率效应对混凝土动载弯拉强度的影响[J].水利学报,2005,36(1):69-76.
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[10]中国水利水电科学研究院.高拱坝地震应力控制标准和抗震结构工程措施研究-高拱坝全级配混凝土动态试验研究[R].北京:中国水利水电科学研究院,2000.
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[12]马怀发,陈厚群,黎保琨.混凝土细观力学研究进展及评述[J].中国水利水电科学研究院学报,2004,2(2):124-130.
[13]WalravenJC.AggregateInterlock:AtheoreticalandexperimentalAnalysis[M].DelftUniversityPress,1980.67-72.
[14]马怀发,陈厚群,黎保琨.混凝土试件细观结构的数值模拟[J].水利学报,2004,(10):27-35.
[15]中山大学数学力学系.概率论及数理统计[M].北京:人民教育出版社,1980.343-364.
[16]DL T5150-2001.水工混凝土试验规程[S].
[17]SeyitAK.Factorsaffectingtherelationshipbetweenrateofloadingandmeasuredcompressivestrengthofconcrete[J].MagazineofConcreteResearch,1980,32(11):79-88.
[2]YonJH,HawkinsNM,KobayashiAS.Strain ratesensitivityofconcretemechanicalproperties[J].ACIMaterialJournal,1992,89(2):146-153.
[3]李兆霞.工程材料的应变率效应及其损伤本构模拟计算[J].河海大学学报,1994,22(计算力学专辑):75-82.
[4]李兆霞,钱济成,佘颖禾.动态损伤力学进展[J].河海大学学报,1994,22(计算力学专辑):112-118.
[5]肖诗云,林皋,王哲,等.应变率对混凝土抗拉特性影响[J].大连理大学学报,2001,(6):721-725.
[6]肖诗云,林皋,逯静洲,等.应变率对混凝土抗压特性的影响[J].哈尔滨建筑大学学报,2002,(10):35-39.
[7]DanZheng,QingbinLi.Anexplanationforrateeffectofconcretestrengthbasedonfracturetoughnessincludingfreewater viscosity[J].EngineeringFractureMechanics,2004,71(1617):2319-2327.
[8]马怀发,陈厚群,黎保琨.应变率效应对混凝土动载弯拉强度的影响[J].水利学报,2005,36(1):69-76.
[9]侯顺载,李金玉,曹建国,等.高拱坝全级配混凝土动态试验研究[J].水力发电,2002,(1):51-53.
[10]中国水利水电科学研究院.高拱坝地震应力控制标准和抗震结构工程措施研究-高拱坝全级配混凝土动态试验研究[R].北京:中国水利水电科学研究院,2000.
[11]中国水利水电科学研究院.全级配大坝混凝土动态性能研究报告[R].北京:中国水利水电科学研究院,2004.
[12]马怀发,陈厚群,黎保琨.混凝土细观力学研究进展及评述[J].中国水利水电科学研究院学报,2004,2(2):124-130.
[13]WalravenJC.AggregateInterlock:AtheoreticalandexperimentalAnalysis[M].DelftUniversityPress,1980.67-72.
[14]马怀发,陈厚群,黎保琨.混凝土试件细观结构的数值模拟[J].水利学报,2004,(10):27-35.
[15]中山大学数学力学系.概率论及数理统计[M].北京:人民教育出版社,1980.343-364.
[16]DL T5150-2001.水工混凝土试验规程[S].
[17]SeyitAK.Factorsaffectingtherelationshipbetweenrateofloadingandmeasuredcompressivestrengthofconcrete[J].MagazineofConcreteResearch,1980,32(11):79-88.
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