Study On Macroscopic Constitutive Relations Of Reinforced Concrete Under Axis-compression Test

Unified nominal stress and macroscopic strain constructive relations of reinforced concrete were discussed during the whole loading process, according to the subject "Study on the Theory of Behavioral Evolution and Safety Monitoring Method of Bridge Structure" which is beard by professor Zhixiang Zhou and pertains to national 973 plan project. Main work and conclusions are as follows:(1)A new idea is proposed in allusion to the complexity of modeling the whole-process analysis of reinforced concrete bridge and the large calculation quantity. This idea can both include the interaction between the steel bar and concret and cover the unified constitutive relationship of cracks occurring and development situation. The relationship between nominal stress and macroscopic strain of the reinforced concrete is built.(2) Base on the basic knowledge of elastoplastic theory of reinforced concrete under axis-compression,12 groups experimental studies on reinforced concrete short column with different reinforcement ratio and different concrete strength are conducted. Under the condition of axial compression,the mechanical behavior, form of crack propagation, failure pattern and macroscopic stress-strain curve during the whole process are obtained.(3) By analyzing the observed macroscopic stress-strain curve and using the Matlab numerical analysis software to simulate, the stress-strain curve equation of the whole process of reinforced concrete under axis-compression is obtained.(4) Use the traditional method (separate model) and the constitutive relation proposed in this paper to build the finite element model of an actual bridge pier.The contrastive analysis shows that the equation matches with the theoretical value well.