Research On The Effects Of Core Concrete Lateral Deformation On Longitudinal Bar Buckling In Columns

Under strong earthquake, the ends of column in the reinforced concrete frame structure designed according to the current specification in our country will hinge more or less. In some conditions, the buckling of longitudinal reinforcement in column appears. And this leads to a rapid reduction of capacity of column, eventually leads to structural damage, even collapse. Therefore, to evaluate the seismic performance and the performance of standing up to collapse of reinforced concrete structure, it is full of great significance to establish accurate constitutive model considering buckling of longitudinal reinforcement.The previous studies including the theoretical analysis and experimental research just expound the buckling mechanism of single steel bar accurately. But, because of the interaction between core concrete, longitudinal reinforcement and stirrups in the reinforced concrete column, the longitudinal reinforcement buckling mechanism appears very complex. This paper mainly studies the interaction between core concrete and longitudinal reinforcement. Under axial pressure, core concrete would impacting laterally longitudinal reinforcement because of expanding, also longitudinal reinforcement due to the bending stiffness restrains core concrete.In this paper, studying the correlation between the core concrete lateral deformation and the longitudinal reinforcement lateral deflection is based on the Freytag and Brown’s test data of University of Washington. According to the effect law of core concrete lateral deformation impacting longitudinal reinforcement buckling,combining the simplified reinforcement buckling model considering the influence of core concrete lateral deformation by Chenjinke and optimizing the longitudinal reinforcement buckling model through reasonable simplification.After the optimizing is completed, the effectiveness of the modified model considering the core concrete expanding laterally is validated through comparison with available experimental data of four groups of reinforcing bar tests and two groups of reinforced concrete column tests. And the result indicates that the modified model is able to simulate all the tests more accurately than modified G-A model by Chenjinke.