Reinforced Concrete Structure Of The Nonlinear Finite Element Analysis And Finite Element Method Of Constructing

The content in this paper can be divided into two parts , one being the research work in the nonlinear analysis of finite element of reinforced concrete structures as summarized in the following items 1 to 5 , the other part being the research work of the construction method of finite elements , through item 6. 1. Research of eonstitutive relations of concrete Based on the research of nonlinear elastic theory and elastic梡lastic theory of constitutive relations of concrete and the hysteresis characters of concrete under reciprocating load , the author proposes a scientific description of the degeneration phenomena of the modulus of elasticity of the concrete that occurred along with the development of deformation, in which the differential equation expressing the relation between the degree of degeneration and the deformation is presented. At the same time , the theoretical solution of this differential equation is derived . Then , the author proposes a constitutive relation model of concrete in the state of single directional stress under reciprocating load. Finally , a constitutive relation model of concrete in the state of multi梔irectional stress under reciprocating load is proposed as an extension of that in the case of single directional stress. 2. Construction of nonlinear beam梒olumn element and wall梕lement In this section , the technique to construct beam梒olumn element and wall? element considering nonlinear material behavior by microcosmic method has been focused on. The detailed work will be as follows: 1) A nonlinear beam梒olumn element considering the shearing deformation is achieved by applying the assumption of plane section directly in space body, with which the deep beams, the short columns and even the shearing walls can be simulated. 2) A beam梒olumn element with no shearing deformation considered is presented as a selection in the analysis of ordinary beams and columns 3) The formulations of shearing wall element with a rectangular hole are given , in which the divisional integration is adopted to deal with the rectangular hole. 4) A beam梒olumn element considering the effect of the cohesion and the slippage between concrete and steel bar is derived. 3. Research of failure criteria Firstly , a certain number of failure criteria used in the past are being studied and some inconveniences existing in these failure criteria are pointed out Secondly , based on the theory of stability , the author proposes a new concept HI concerning the failure criteria as a solution to eliminate these inconveniences whereby the definitions of failure criteria of the infinitesimal volume element of material, the cross section of member, the single member and the aggregate of members are given. Finally, the parameters to represent the degree of failure of the objects and the subspace generated by the failure modes are discussed. These new definitions have a compact foundation of mechanics and are convenient in applications. 4.On the method to solve nonlinear equations in FEM The author summarizes some popular methods used to solve nonlinear equations in FEM and certain research works concerning the method of arc條ength control and that of iteration strategy during the course of increment梚teration are done. Some achievements obtained can be listed as follows 1) A new strategy of arc條ength contro...