Research Of RC Column Under Pressure-Flexure-Shear-Torsion

As one of the most important force components in the architectural structure,the force property of reinforced concrete column is directly related to the safety of the structure.Due to the complexity and diversity of the actual load,columns are rarely subjected to single force.Especially side columns and corner columns which bear the combination of compression,bending,shear and torsion in the earthquake will aggravate the great destruction of the structure and even cause the collapse of the structure in large range once they failed.China's current Code for Design of Concrete Structures uses the method that superimposes individual calculation results to consider the bearing capacity of multiphase composite stress,which can not reasonably reflect the actual force condition of the component.Based on the research results of scholars at home and abroad,this paper has studied the loading conditions of 21 different reinforced concrete columns.The main contents and conclusions are as follows:1.Based on the finite element software ABAQUS,reinforced concrete columns under different loading conditions are established,the study has conducted experiments that the 21 concrete columns bore compression,bending,shear and torsion with cyclic loading,and has analyzed the effects of axial compression ratio,twist ratio and eccentricity on the hysteretic properties,energy dissipation capacity,skeleton curve,ductility,strength degradation,stiffness degradation and bearing capacity of reinforced concrete columns.2.The effect of axial compression ratio on bearing capacity under different conditions is:Unidirectional compression bending shear and torsion>Biaxial compression bending shear and torsion>Biaxial compression bending shear>Unidirectional compression bending shear.Under the action of unidirectional compression bending shear,with the increase of axial compression ratio,the horizontal ultimate bearing capacity increases,the energy consumption capacity decreases,and the ductility of the components deteriorates.3.With the increase of twisting ratio,the total energy consumption capacity of the specimen decreases,the horizontal bearing capacity decreases,and the overall ductility decreases.4.When the axial load acts on the top surface of the column,the total energy dissipation capacity,horizontal bearing capacity,and ductility of the specimen are the best when thedistance is the longest from the lateral force;With the increase of eccentricity,the energy dissipation capacity,horizontal bearing capacity,and ductility coefficient of the specimens are all decreased..5.Three-phase and four-phase composite bearing capacity of the correlation formulas under the condition of composite stress formula are derived from the single-phase and two-phase capacity formulas.Based on the unified formula of composite load,the Bending Shear Torsion correlation curve,the three-phase bearing capacity curve,the two-phase bearing capacity curve and the unidirectional correlation curve are drawn out under the condition of shaft pressure,and revised the unified formula for calculation of bearing capacity.