Blind Analysis Of The Benchmark Tests On RC Beam-Column Joints Under Cyclic Loading

It is well known that Non-linear cyclic behavior of reinforced concrete (RC) beam-column joint sub-assemblage is complex and known to be sensitive to many factors interacting each other. In traditional analysis of the RC frames, beam-column joints were always assumed rigid or semi-rigid. However, this is not the case and it brings non-neglectable analytical errors. So a model is needed in which the material non-linearity is modeled appropriately with all-around ability with less arbitrary parameters as much as possible.The behavior of reinforcing steel may affect the response of RC beam-column joints as much as to RC structural elements subject to cyclic loading. Thus, it is necessary to develop an analytical model that predicts the fundamental hysteretic characteristics of the reinforcing bars. Through an overview of the literature, two sophisticated models for defining cyclic behavior of reinforcing steel are selected and introduced detailedly in the current dissertation work. Modification of the numerical stability is later introduced for case of the small reversals in the strain history. The modified model is then implemented into the finite element (FE) software for seismic design and a case study is subsequently followed to check the accuracy and efficiency of them. Considering the actual characteristic of reinforcement in the benchmark tests, one of the two models is used in the blind analysis.As part of the material content, a uniaxial nonlinear constant confinement concrete model, which is modified for the numerical stability, is also introduced and implemented into the FE software.Based on the materials models, a new simplified beam-column joint model is subsequently presented, which is capable of modeling three main failure mechanisms by using rotation and shear springs.Blind analysis of the benchmark tests for beam-column joint under cyclic loading which was carried out in 2006 in Tokyo University, are finally carried out employing the adopted and modified reinforcing steel, concrete and beam-column joint models. Additional comparison is also made between the analytical and experimental results with a brief conclusion attached. Comparison shows that the new joint model is not only robust but also easy the control and the need for future development is also introduced in this work.