Reinforced concrete models with bond-interfaces for the nonlinear static and dynamic analysis of reinforced concrete frame structures

This study addresses the problem of modeling bond-slip in the response of reinforced concrete structures under static and dynamic loads. The slips of the reinforcing bars and deterioration of the bond-interfaces above the foundations and in the beam-column connections and plastic hinge regions play a crucial role in describing the behavior of reinforced concrete frames under earthquake excitations. These effects result in the reduction of stiffness and hysteretic energy dissipation, leading to the characteristic pinched hysteretic loop.; The present study considers the nonlinear analysis of reinforced concrete frame structures under static and dynamic loads. Due to the bond-slip effects on the nonlinear behavior of reinforced concrete frame structures, this study is mainly emphasized on the developing new efficient reinforced concrete frame models accounting the partial composite actions between the reinforcing bars and the surrounding concrete.; The problem statement starts from the basic governing differential equations (strong form) for the reinforced concrete frame elements with bond-interfaces. These equations comprise equilibrium, compatibility, and constitutive equations. Three different finite element methods (weak form) are proposed to solve the aforementioned differential equations governing the behavior of reinforced concrete structural systems including partial composite action between concrete and reinforcement. Three different finite element methods are displacement-based, force-based (force hybrid), and Hellinger-Reissner mixed elements.; Several experimental tests under monotonic and cyclic loads are used to distinguish the different characteristics of the different finite element formulations, to verify and compare the accuracy of the proposed analytical models, and to assess the importance of the inclusion of the bond-slip effects into the proposed analytical models. Generally, there are very good agreements between the experimental and analytical results and the bond-slip effects play an important role in realistically predicting response of reinforced concrete structures under static and dynamic loads.; The proposed reinforced concrete frame models with bond-slip were also used to predict the response of reinforced concrete slab or beam strengthened by FRP or steel thin plates. The accuracy of the proposed analytical models was assessed through comparisons between the analytical and experimental results. The proposed analytical models succeeded not only in predicting the stiffness and strengths of the specimens but also in representing the failure modes of the specimens.