Research On Some Issues Of Bond Performance Between Steel Bar And Concrete

The topic of this paper is from the National Natural Science Foundation Item (50278039) -Analysis and research on the whole life of concrete structures, which is presided over by Prof. Wei Jun. Bond action is the basic precondition for conjunct work of steel bar and concrete in reinforced concrete structures. Research on bond issue is of great importance in both theory and practice. However, due to multitudinous influencing factors and intricate mechanism, bond action is a sort of complicated interaction. A comprehensive and credible bond theory system hasn't been established. Therefore, bond issue is one of the most active and promising research fields. In this paper, bond issue is analyzed comprehensively based on summary of existing research productions. Further study on some important problems of bond performance is carried out by both theory and experiment means: 1) On theory analysis aspect: (1) Aim at the important problem of how to get exact bond stress from the steel bar strain data derived in steel bar pullout experiment, two means of making out bond stress distributing curve in accordance with different strain gages disposal cases are brought forward. In the case of stain gages asymmetric disposal, a new method of getting bond stresses of test positions is established and proved to be exact and convenient by experiment. (2) A new propositional calculation formula based on data analysis is put forward, which reflects comprehensive factors and has high veracity. So it is convenient for actual application. Subsequently, farther method of getting bond stress-slip relation for mill finish steel bar is put forward. 2) On experiment aspect: Firstly, ultimate bond intensity is compared on two conditions: different steel bar style and different water cement ratio. Afterwards, bond stress-slip curves of different test specimen are compared from four aspects. Conclusions derived from the above work make the law of bond performance more clear. The research productions in this paper promoted the theory and experiment research on bond performance and improved the cognitive level. Reference for future research and instructions for engineering practice are also provided.