Experimental Studies On The Effect Of Buckling Of Reinforcing Steel On Seismic Behavior Of Columns

Several times after the earthquake disaster, we found that the emergence of thecolumn plastic hinge in the structure of the damaged buildings, and in this location, thebuckling of longitudinal reinforcement is widespread occurrence. As an importantvertical force transmission component, the seismic performance (plastic deformationcapacity and energy dissipation capacity, etc.) of column not only affect the entirebuilding’s seismic performance, but also related to the seismic fortification could bereached. In present, the majority of countries’ norms (such as China,the United States,European Union,New Zealand, etc),generally through the column plastic hinge in thecolumn encryption by limiting the diameter of the stirrup and spacing to ensure there issufficient plastic deformation capacity and energy dissipation capacity.In order to check the conditions to meet the specification, the seismicperformance of reinforced concrete columns as well as the buckling of longitudinalreinforcement. Four reinforcement concrete columns tested under the reversed cycliclateral loads; all the longitudinal bars and stirrups in the specimens made up of HRB500bars. The author discussed the axial load ratio, stirrup spacing, L/d and other factorsthat influence whether or not the longitudinal reinforcement buckles, and furthercomparison the seismic performance of columns which the longitudinal reinforcementbuckling or not. The experimental results show that: the buckling of longitudinalreinforcement was disadvantage to the seismic performance of columns. In the samestirrups constraints and L/d conditions, the axial compression ratio increases, thebuckling of longitudinal reinforcement occurred sooner, the seismic performances ofcolumns were worse. In the same stirrups constraints and axial compression ratioconditions, limiting the value of L/d can avoid the phenomenon of longitudinalreinforcement buckling, and the columns show better ductility capacity and energydissipation capacity.In addition, based on experiment study, this article attempts to through the finiteelement analysis program (OpenSees), use of confined concrete constitutive model andconstitutive modeling of reinforced buckling to simulated the seismic behavior of thecolumns. It found that the simulation results agree well with the experimental results.The numerical simulation analysis program can be used in design and research.