The Study Of Dynamic Properties On Concrete And Its Component Materials

The critical factor in structural earthquake-resistance design, the research on dynamic properties of concrete is recognized to be 'bottleneck' for dynamic analysis of structures. In 1917, Abram found there was rate sensitivity in the compressive strength of concrete. Research in about 90 years concluded that there were a lot of factors influencing concrete dynamic properties. The increase of concrete strength and Young's modulus under dynamic loads depends on the loading speed, initial stress state, the size of specimen, the property and mixture ratio of concrete component materials. With the development of calculation theory and computer performance, the study of dynamic property of concrete and its component materials comes into a new state.This paper is a sub-subject of Academician Development Funds of HoHai university-'The study on dynamic property and its dynamic damage mechanics ofconcrete'(Academician Funds 02-01). This thesis summarized the research history and achievements on the dynamic property of concrete and its component materials: cement mortar, aggregate and the interface between them. The hot point and hard point in the research of this subject were pointed out. From the macro aspect, the paper introduced the method of the quality control of concrete component materials and mixture of full-graded concrete. I was strongly recommended to record the basic performance of component materials and working performance of concrete mixture in specimen pour. From the meso aspect, this paper used Fortran language and Ansys finite element software to establish a 3-D meso concrete model. The calculation model method and meso finite element method, which can calculate the equavelent Young's modulus of concrete are introduced. The concrete Young's modulus can be forcast, when the basic property and mixture rato are known. Based on the Hirsh model, this paper presented a calculation model of concretedynamic equavelent Young's modulus-Hirsh-D. This model can calculate the Young'smodulus of concrete under diffirent strain-rate, considering motar cement and aggregate have different strain-rate effect.Through the work mentioned above, the following conclutions can be reached: firstly, the tendency in the research of concrete dynamic property is to consider concrete as a three phase complex material, and associate the macro research and meso research together. Secondly, this paper makes a suggestion to select concrete component material suitable tothe research, record the fundamental characteristics of each material, and control the working performance of the mixture, so as to ensure the pouring quality, and increase the comparability of diffirent experimental results. Thirdly, this paper used the Mente Carlo method, Fortran language and Ansys software to create an meso concrete model. The model can simulate the concrete as a three phase complex material, which is composed of motar cement, aggregate and the interface. Finally, the Young's modulus is an important index to describe the deformation of concrete. With these parameters,- such as: Young's modulus, mixture ratio of aggregate and aggregate volume content of component materials to calculate the equivalent modulus of concrete is a reasonable method.