Finite Element Analysis Of Bond Slip Relationship Of Reinforced Concrete Under Low Cyclic Loading

This thesis concerns about simulating bond-slip relationships in reinforced concrete using finite element method. It is assumed that it can be treated as a plane stress problem. Different material models are used to simulate concrete and longitudinal steel. And link element is inserted between the two models to simulate bond between concrete and longitudinal steel.The main contents of the thesis are as following:①Based on the previous research on this point, equivalent uniaxial strain model for concrete was chosen, tension stiffening effect was taken into account in the concrete strain-stress relationship.②Nodes were added between longitudinal steel and concrete element. Seckin's model was used in which the Baushinger effect is considered to represent the train-stress relationship of the longitudinal steel.③Bond-slip model were established by the author to describe the relationship between concrete and longitudinal steel. Eligehausen's model was adopted under monotonic loading .Bond-slip model under reversed cyclic loading was based on Teng zhiming's model. Bsed on Eligehausen's testing results, some parameters of Teng zhiming's model were refined.④On the basis of previous research in our group, concrete, steel and bond limk elements were integrated into FEAPpv (Finite Element Analysis Program Personal Version) to form user-defined element module and their strain-stress models were integrated to form material module. Displacement controlled loading algorithm which provided by FEAPpv was used in the program.⑤Testing results of anchoraged steel under monotonic and cyclic loading conducted by Viwathanatepa, Eligehausen et al were used to verify the above- mentioned bond-slip models. The effect of anchorage length on steel behavior, bar diameter and concrete strength on bond-slip relationships are evaluated.⑥Two different models,one is the integrated model without considering bond-slip and the other is the discrete model, were used to simulate load-deflection response of simply-supported RC beams.Effect of bond-slip on both under-reinforced and over-reinforced concrete beams was recognized.⑦Comparison of the computed results with tested ones was carried out in both loacl and overall responses to verify the finite element modelling of bond-slip in this thesis.The link element to simulate bond-slip, together with hysteretic rules under reversed cyclic loading ,are available to carry out realistic nonlinear finite element analysis.