钢纤维混凝土动态压缩性能及全曲线模型研究
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摘要
对钢纤维含量分别为0%,1%,2%,4%和6%的C30和C40混凝土进行了常三轴动态压缩试验,C30混凝土试件围压值为0,6,9,12,18和24 MPa,C40混凝土试件围压值为0,8,12,16,24和32 MPa;试验过程中采用位移控制模式下的正弦波分级加载。在此基础上,进行了应力应变全曲线表达式的选择与分析,并对各材料参数与诸因素间的相关性进行了分析。结果表明:(1)通过对Ezeldin等提出的钢纤维混凝土静态荷载作用下的应力-应变全曲线公式进行β参数修正,使该模型可以很好地描述钢纤维混凝土在动态常三轴压缩作用下的应力-应变全曲线关系;(2)混凝土基体强度越高,纤维含量对材料动态抗压强度的改善作用越显著,但受压状态下纤维含量对提高混凝土动态强度总的幅度较小;(3)混凝土动态峰值应力对围压大小较敏感,且随基体强度的提高,其敏感性有所下降。峰值应变与诸因素的相关关系基本上与峰值应力相同;(4)在动态荷载作用下钢纤维混凝土的割线弹性模量、钢纤维含量与割线模量间的相关性均随基体强度的提高而提高;(5)围压与纤维含量对混凝土材料在受压状态下的韧度指数ncmax影响不大。
The regular three-axis dynamic compression tests are conducted for the concrete C30 and C40 with steel fiber content of 0%,1%,2%,4%,6% in this paper.Confining pressure values of 0,6,9,12,18 and 24 MPa are used on the C30 concrete specimens,Confining pressure values 0,8,12,16,24 and 32 MPa are used on the C40 concrete ones;The concrete specimen is loaded by the classified sinusoidal forces under displacement control mode.The expression of the stress-strain curve is chosen and analyzed,the correlation of the material parameters and the factors is analyzed.The results show that the formula parameter of stress-strain curve using for the SFRC under static force presented by Ezeldin is modified,the modified model have provides a good description of the stress-strain curve of the SFRC under the three-axis dynamic compression.The higher fiber content is the more significant role to improve the dynamic compressive strength,but under pressure the fiber content less improves the dynamic strength of concrete.Dynamic peak stress of concrete is sensitive to the confining pressure,and the sensitivity decreases with the increasing of strength.The peak strain correlated to the various factors is basically the same as the peak stress.Under the dynamic load the relationship between the secant elasticity modulus,the steel fiber content and secant modulus of SFRC is improved with the increase of the concrete strength.Confining pressure and fiber content of concrete have not much impact to the index toughness on the state of compression.
The regular three-axis dynamic compression tests are conducted for the concrete C30 and C40 with steel fiber content of 0%,1%,2%,4%,6% in this paper.Confining pressure values of 0,6,9,12,18 and 24 MPa are used on the C30 concrete specimens,Confining pressure values 0,8,12,16,24 and 32 MPa are used on the C40 concrete ones;The concrete specimen is loaded by the classified sinusoidal forces under displacement control mode.The expression of the stress-strain curve is chosen and analyzed,the correlation of the material parameters and the factors is analyzed.The results show that the formula parameter of stress-strain curve using for the SFRC under static force presented by Ezeldin is modified,the modified model have provides a good description of the stress-strain curve of the SFRC under the three-axis dynamic compression.The higher fiber content is the more significant role to improve the dynamic compressive strength,but under pressure the fiber content less improves the dynamic strength of concrete.Dynamic peak stress of concrete is sensitive to the confining pressure,and the sensitivity decreases with the increasing of strength.The peak strain correlated to the various factors is basically the same as the peak stress.Under the dynamic load the relationship between the secant elasticity modulus,the steel fiber content and secant modulus of SFRC is improved with the increase of the concrete strength.Confining pressure and fiber content of concrete have not much impact to the index toughness on the state of compression.
引文
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[2]Bichoff P H,Peng S H.Compressive behavior at highstrain rates[J].Materials and Structures,1991,24(144):425—450.
[3]杜成斌,苏擎柱.混凝土材料动力本构模型研究进展[J].世界地震工程,2002,18(2):94—98.
[4]David W Harris,Caroline E Mohorovic,Timothy PDolen.Dynamic properties of mass concrete obtainedfrom dam cores[J].ACI Material Journal,2000,(97):290—296.
[5]A Brara,F Ccamborde,R Klepaczko,et al.Exper-imental and numerical study of concrete at high strainrates in tension[J].Mechanics of Materials,2001,(33):33—45.
[6]党发宁.岩土破损演化理论()—破损空间[J].岩土力学,2005,26(4):513—519.
[7]党发宁.岩土破损演化()—物理状态指标与分区破损[J].岩土力学,2005,26(5):673—679.
[8]丁卫华,仵彦卿,薄毅彬,等.基于X射线的岩石内部裂纹宽度测量[J].岩石力学与工程学报,2003,22(9):1 421—1 425.
[9]Lu Y,Xu K.Modeling of dynamic behavior ofconcrete materials under blast loading[J].Inter-national Journal of Solids and Structures,2004,41:131—113.
[10]胡时胜,王道荣.冲击载荷下混凝土材料的动态本构关系[J].爆炸与冲击.2002.22(3):242—246.
[11]Burlion N,Gatuingt F,et al.CoMPaction and tensiledamage in concrete:constitutive modeling andapplication to dynamics[J].Computer Methods inApplied Mechanics and Engineering,2000,183(3-4):291—308.
[12]商霖,宁建国.强冲击载荷下混凝土动态本构关系[J].工程力学,2005,22(2):116—119.
[13]王哲,林皋.混凝土的单轴率型本构模型[J].大连理工大学学报,2000.40(5):597—601.
[14]Ezeldin A S,Balaguru P N.Normal and high-strengthfiber reinforced concrete under compression[J].Journal of Materials in Civil Engineering,1992,4(4):415—429.
[15]过镇海,时旭东.钢筋混凝土原理和分析[M].北京:清华大学出版社,2003.
[16]过镇海.混凝土强度和变形[M].北京:清华大学出版社,1997.
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