Bond stress and slip modeling in nonlinear finite element analysis of reinforced concrete structures

The stress transfer behavior between reinforcing steel and surrounding concrete through bond and slip plays an important role in the response of reinforced concrete structures, especially in their hysteretic response. This thesis studies the bond-slip relationship under both monotonic loading and cyclic loading. Two types of bond elements, contact elements and linkage elements, are developed and bond stiffness matrices are derived. Four bond-slip models are presented based on the findings of previous experimental studies. The degradation of bond resistance is included in the bond-slip models. The two bond elements and four bond-slip models are added into the nonlinear finite element program TRIX99. The finite element models are then used to study the behavior of reinforced concrete walls subjected to cyclic lateral load. The accuracy of the models are assessed by comparison of the finite element numerical response with experimental data from four reinforced concrete shear walls tested under cyclic loading.;The NLFEA program with the nonlinear material models for concrete, reinforcing bar and bond-slip is capable of reproducing the important features of the measured hysteretic response of reinforced concrete walls with a variety of cyclic loading histories and configurations of walls. The program is able to successfully predict the load-deflection values of the reinforced concrete structures under cyclic loading. The proposed finite element method provides an efficient method for evaluating the monotonic and cyclic response of the reinforced concrete structures.