Research On The Accumulative Damage Constitutive Of HSC Under Large Strain

The main destruction of constructions suffering from earthquake is brought by the accumulated damage of structures under low cycle fatigue. In the past 20 years, many researchers of home and broad have gradually studied the hysteretic character of RC specimen in this dynamic response process and the constitutive model and the accumulative damage rule of steel and concrete under cyclic loading with different strain levels. It was found that the low cycle fatigue character has close internal relations with the high cycle fatigue character. In the research of high cycle fatigue of concrete, the test means of cyclic loading between the set constant of force or stress has been extensively used. But this kind of test means can't be used in studying the behavior of concrete low cycle fatigue under large strain. The test means of cyclic loading between the set constant of strain seem to be more reasonable for low cycle fatigue with large strain.In this paper, the test means of cyclic loading between the set constant of strain is used. Based on the experiments of common concrete with this means by Mu, in this paper, serial experiments with HSC (high-strength concrete) are finished by us. Many things have been obtained, such as the stress-strain curve of every fatigue test specimen in various damage state under cyclic loading with different constant and various strain amplitude, the stress-strain curve of every specimen under initial axial monotonic compression, and the stress-strain curve of destructive specimens under axial monotonic loading after certain cycles. Moreover, several quantities, such as the behavior regression rule of concrete fatigue stress, secant stiffness, maximum strain and hysteretic energy of single cycle and the character points in the cyclic loading history, have also been studied.Besides the factor of ground motion, the accuracy of the simulation is depended on the rationality of analytic model and material model. The fiber model (beam-column element) used in this paper has been proved to be accurate enough for the beam-column analysis of bending members, so the accuracy of the material model plays an important role.Based on the results of experiments, in order to reflect the influence of loading history on the intensity, stiffness and hysteretic energy of concrete under cyclic loading, this paper has modified the former concrete unloading-reloading constitutive model and puts up a kind of constitutive model which is valid under random loading history on the...